Science.gov

Sample records for ii faint infrared

  1. Faint Infrared-Excess Field Galaxies: FROGs

    NASA Astrophysics Data System (ADS)

    Moustakas, L. A.; Davis, M.; Zepf, S. E.; Bunker, A. J.

    Deep near-infrared and optical imaging surveys in the field reveal a curious population of galaxies that are infrared-bright (I-K>4), yet with relatively blue optical colors (V-I<2). Their surface density, several per square arcminute at K>20, is high enough that if placed at z>1 as our models suggest, their space densities are about one-tenth of phi-*. The colors of these ``faint red outlier galaxies'' (fROGs) may derive from exceedingly old underlying stellar populations, a dust-embedded starburst or AGN, or a combination thereof. Determining the nature of these fROGs, and their relation with the I-K>6 ``extremely red objects,'' has implications for our understanding of the processes that give rise to infrared-excess galaxies in general. We report on an ongoing study of several targets with HST & Keck imaging and Keck/LRIS multislit spectroscopy.

  2. Galaxy evolution and large-scale structure in the far-infrared. II - The IRAS faint source survey

    NASA Astrophysics Data System (ADS)

    Lonsdale, Carol J.; Hacking, Perry B.; Conrow, T. P.; Rowan-Robinson, M.

    1990-07-01

    The new IRAS Faint Source Survey data base is used to confirm the conclusion of Hacking et al. (1987) that the 60 micron source counts fainter than about 0.5 Jy lie in excess of predictions based on nonevolving model populations. The existence of an anisotropy between the northern and southern Galactic caps discovered by Rowan-Robinson et al. (1986) and Needham and Rowan-Robinson (1988) is confirmed, and it is found to extend below their sensitivity limit to about 0.3 Jy in 60 micron flux density. The count anisotropy at f(60) greater than 0.3 can be interpreted reasonably as due to the Local Supercluster; however, no one structure accounting for the fainter anisotropy can be easily identified in either optical or far-IR two-dimensional sky distributions. The far-IR galaxy sky distributions are considerably smoother than distributions from the published optical galaxy catalogs. It is likely that structure of the large size discussed here have been discriminated against in earlier studies due to insufficient volume sampling.

  3. Galaxy evolution and large-scale structure in the far-infrared. II. The IRAS faint source survey

    SciTech Connect

    Lonsdale, C.J.; Hacking, P.B.; Conrow, T.P.; Rowan-Robinson, M. Queen Mary College, London )

    1990-07-01

    The new IRAS Faint Source Survey data base is used to confirm the conclusion of Hacking et al. (1987) that the 60 micron source counts fainter than about 0.5 Jy lie in excess of predictions based on nonevolving model populations. The existence of an anisotropy between the northern and southern Galactic caps discovered by Rowan-Robinson et al. (1986) and Needham and Rowan-Robinson (1988) is confirmed, and it is found to extend below their sensitivity limit to about 0.3 Jy in 60 micron flux density. The count anisotropy at f(60) greater than 0.3 can be interpreted reasonably as due to the Local Supercluster; however, no one structure accounting for the fainter anisotropy can be easily identified in either optical or far-IR two-dimensional sky distributions. The far-IR galaxy sky distributions are considerably smoother than distributions from the published optical galaxy catalogs. It is likely that structure of the large size discussed here have been discriminated against in earlier studies due to insufficient volume sampling. 105 refs.

  4. Galaxy evolution and large-scale structure in the far-infrared. II - The IRAS faint source survey

    NASA Technical Reports Server (NTRS)

    Lonsdale, Carol J.; Hacking, Perry B.; Conrow, T. P.; Rowan-Robinson, M.

    1990-01-01

    The new IRAS Faint Source Survey data base is used to confirm the conclusion of Hacking et al. (1987) that the 60 micron source counts fainter than about 0.5 Jy lie in excess of predictions based on nonevolving model populations. The existence of an anisotropy between the northern and southern Galactic caps discovered by Rowan-Robinson et al. (1986) and Needham and Rowan-Robinson (1988) is confirmed, and it is found to extend below their sensitivity limit to about 0.3 Jy in 60 micron flux density. The count anisotropy at f(60) greater than 0.3 can be interpreted reasonably as due to the Local Supercluster; however, no one structure accounting for the fainter anisotropy can be easily identified in either optical or far-IR two-dimensional sky distributions. The far-IR galaxy sky distributions are considerably smoother than distributions from the published optical galaxy catalogs. It is likely that structure of the large size discussed here have been discriminated against in earlier studies due to insufficient volume sampling.

  5. Fainting

    MedlinePlus

    ... tunnel vision) or noises are fading into the background. Causes Fainting may occur while or after you: ... a seizure or heart rhythm disturbance), and to figure out the cause of the fainting episode. If ...

  6. X-ray Counterparts of Infrared Faint Radio Sources

    NASA Astrophysics Data System (ADS)

    Schartel, Norbert

    2011-10-01

    Infrared Faint Radio Sources (IFRS) are radio sources with extremely faint or even absent infrared emission in deep Spitzer Surveys. Models of their spectral energy distributions, the ratios of radio to infrared flux densities and their steep radio spectra strongly suggest that IFRS are AGN at high redshifts (2infrared fluxes, will constrain the class-specific SED.

  7. Fainting

    MedlinePlus

    ... brain does not get enough oxygen. You lose consciousness, or "pass out," for a brief time (usually ... syncope, exertional syncope, fainting, hyperventilation, hypovolemic syncope, lose consciousness, loss of consciousness, micturition syncope, orthostatic syncope, pass ...

  8. Fainting

    MedlinePlus

    ... En Español Making a Change – Your Personal Plan Hot Topics Am I in a Healthy Relationship? Who ... reasons why teens faint: Physical triggers. Getting too hot or being in a crowded, poorly ventilated setting ...

  9. Are the infrared-faint radio sources pulsars?

    NASA Astrophysics Data System (ADS)

    Cameron, A. D.; Keith, M.; Hobbs, G.; Norris, R. P.; Mao, M. Y.; Middelberg, E.

    2011-07-01

    Infrared-faint radio sources (IFRS) are objects which are strong at radio wavelengths but undetected in sensitive Spitzer observations at infrared wavelengths. Their nature is uncertain and most have not yet been associated with any known astrophysical object. One possibility is that they are radio pulsars. To test this hypothesis we undertook observations of 16 of these sources with the Parkes Radio Telescope. Our results limit the radio emission to a pulsed flux density of less than 0.21 mJy (assuming a 50 per cent duty cycle). This is well below the flux density of the IFRS. We therefore conclude that these IFRS are not radio pulsars.

  10. Spectrophotometric Redshifts in the Faint Infrared Grism Survey

    NASA Astrophysics Data System (ADS)

    Pharo, John; Malhotra, Sangeeta; Rhoads, James E.

    2016-06-01

    We have combined HST grism spectroscopy and deep broadband imaging to measure spectro-photometric redshifts (SPZs) of faint galaxies. Using a technique pioneered by Ryan et al. 2007, one can combine spectra and photometry to yield an SPZ that is more accurate than pure photometric redshifts, and can probe more deeply than ground-based spectroscopic redshifts. By taking mid-resolution spectra from the HST Faint Infrared Grism Survey (FIGS), SPZs can be found for measurements potentially down to 27th magnitude (the typical brightness of a dwarf galaxy at redshift ˜1.5). A galaxy’s redshift is vital for understanding its place in the growth and evolution of the universe. The measurement of high-accuracy SPZs for FIGS sources will improve the faint-end and high-redshift portions of the luminosity function, and make possible a robust analysis of the FIGS fields for signs of Large Scale Structure (LSS). The improved redshift and distance measurements allowed for the identification of a structure at z=0.83 in one of the FIGS fields.

  11. NIFTE: The Near Infrared Faint-Object Telescope Experiment

    NASA Technical Reports Server (NTRS)

    Bock, James J.; Lange, Andrew E.; Matsumoto, T.; Eisenhardt, Peter B.; Hacking, Perry B.; Schember, Helene R.

    1994-01-01

    The high sensitivity of large format InSb arrays can be used to obtain deep images of the sky at 3-5 micrometers. In this spectral range cool or highly redshifted objects (e.g. brown dwarfs and protogalaxies) which are not visible at shorter wavelengths may be observed. Sensitivity at these wavelengths in ground-based observations is severly limited by the thermal flux from the telescope and from the earth's atmosphere. The Near Infrared Faint-Object Telescope Experiment (NIFTE), a 50 cm cooled rocket-borne telescope combined with large format, high performance InSb arrays, can reach a limiting flux less than 1 micro-Jy(1-sigma) over a large field-of-view in a single flight. In comparison, the Infrared Space Observatory (ISO) will require days of observation to reach a sensitivity more than one order of magnitude worse over a similar area of the sky. The deep 3-5 micrometer images obtained by the rocket-borne telescope will assist in determining the nature of faint red objects detected by ground-based telescopes at 2 micrometers, and by ISO at wavelengths longer than 5 micrometers.

  12. Morphology and astrometry of Infrared-Faint Radio Sources

    NASA Astrophysics Data System (ADS)

    Middelberg, Enno; Norris, Ray; Randall, Kate; Mao, Minnie; Hales, Christopher

    2008-10-01

    Infrared-Faint Radio Sources, or IFRS, are an unexpected class of object discovered in the Australia Telescope Large Area Survey, ATLAS. They are compact 1.4GHz radio sources with no visible counterparts in co-located (relatively shallow) Spitzer infrared and optical images. We have detected two of these objects with VLBI, indicating the presence of an AGN. These observations and our ATLAS data indicate that IFRS are extended on scales of arcseconds, and we wish to image their morphologies to obtain clues about their nature. These observations will also help us to select optical counterparts from very deep, and hence crowded, optical images which we have proposed. With these data in hand, we will be able to compare IFRS to known object types and to apply for spectroscopy to obtain their redshifts.

  13. Do the enigmatic ``Infrared-Faint Radio Sources'' include pulsars?

    NASA Astrophysics Data System (ADS)

    Hobbs, George; Middelberg, Enno; Norris, Ray; Keith, Michael; Mao, Minnie; Champion, David

    2009-04-01

    The Australia Telescope Large Area Survey (ATLAS) team have surveyed seven square degrees of sky at 1.4GHz. During processing some unexpected infrared-faint radio sources (IFRS sources) were discovered. The nature of these sources is not understood, but it is possible that some of these sources may be pulsars within our own galaxy. We propose to observe the IFRS sources with steep spectral indices using standard search techniques to determine whether or not they are pulsars. A pulsar detection would 1) remove a subset of the IFRS sources from the ATLAS sample so they would not need to be observed with large optical/IR telescopes to find their hosts and 2) be intrinsically interesting as the pulsar would be a millisecond pulsar and/or have an extreme spatial velocity.

  14. VLBI observations of Infrared-Faint Radio Sources

    NASA Astrophysics Data System (ADS)

    Middelberg, Enno; Phillips, Chris; Norris, Ray; Tingay, Steven

    2006-10-01

    We propose to observe a small sample of radio sources from the ATLAS project (ATLAS = Australia Telescope Large Area Survey) with the LBA, to determine their compactness and map their structures. The sample consists of three radio sources with no counterpart in the co-located SWIRE survey (3.6 um to 160 um), carried out with the Spitzer Space Telescope. This rare class of sources, dubbed Infrared-Faint Radio Sources, or IFRS, is inconsistent with current galaxy evolution models. VLBI observations are an essential way to obtain further clues on what these objects are and why they are hidden from infrared observations: we will map their structure to test whether they resemble core-jet or double-lobed morphologies, and we will measure the flux densities on long baselines, to determine their compactness. Previous snapshot-style LBA observations of two other IFRS yielded no detections, hence we propose to use disk-based recording with 512 Mbps where possible, for highest sensitivity. With the observations proposed here, we will increase the number of VLBI-observed IFRS from two to five, soon allowing us to draw general conclusions about this intriguing new class of objects.

  15. The radio properties of infrared-faint radio sources

    NASA Astrophysics Data System (ADS)

    Middelberg, E.; Norris, R. P.; Hales, C. A.; Seymour, N.; Johnston-Hollitt, M.; Huynh, M. T.; Lenc, E.; Mao, M. Y.

    2011-02-01

    Context. Infrared-faint radio sources (IFRS) are objects that have flux densities of several mJy at 1.4 GHz, but that are invisible at 3.6 μm when using sensitive Spitzer observations with μJy sensitivities. Their nature is unclear and difficult to investigate since they are only visible in the radio. Aims: High-resolution radio images and comprehensive spectral coverage can yield constraints on the emission mechanisms of IFRS and can give hints to similarities with known objects. Methods: We imaged a sample of 17 IFRS at 4.8 GHz and 8.6 GHz with the Australia Telescope Compact Array to determine the structures on arcsecond scales. We added radio data from other observing projects and from the literature to obtain broad-band radio spectra. Results: We find that the sources in our sample are either resolved out at the higher frequencies or are compact at resolutions of a few arcsec, which implies that they are smaller than a typical galaxy. The spectra of IFRS are remarkably steep, with a median spectral index of -1.4 and a prominent lack of spectral indices larger than -0.7. We also find that, given the IR non-detections, the ratio of 1.4 GHz flux density to 3.6 μm flux density is very high, and this puts them into the same regime as high-redshift radio galaxies. Conclusions: The evidence that IFRS are predominantly high-redshift sources driven by active galactic nuclei (AGN) is strong, even though not all IFRS may be caused by the same phenomenon. Compared to the rare and painstakingly collected high-redshift radio galaxies, IFRS appear to be much more abundant, but less luminous, AGN-driven galaxies at similar cosmological distances.

  16. Evidence for Infrared-faint Radio Sources as z > 1 Radio-loud Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Huynh, Minh T.; Norris, Ray P.; Siana, Brian; Middelberg, Enno

    2010-02-01

    Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey which have no observable mid-infrared counterpart in the Spitzer Wide-area Infrared Extragalactic (SWIRE) survey. The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6-70 μm) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the spectral energy distribution of these objects shows that they are consistent with high-redshift (z >~ 1) active galactic nuclei.

  17. Infrared-faint radio sources are at high redshifts. Spectroscopic redshift determination of infrared-faint radio sources using the Very Large Telescope

    NASA Astrophysics Data System (ADS)

    Herzog, A.; Middelberg, E.; Norris, R. P.; Sharp, R.; Spitler, L. R.; Parker, Q. A.

    2014-07-01

    Context. Infrared-faint radio sources (IFRS) are characterised by relatively high radio flux densities and associated faint or even absent infrared and optical counterparts. The resulting extremely high radio-to-infrared flux density ratios up to several thousands were previously known only for high-redshift radio galaxies (HzRGs), suggesting a link between the two classes of object. However, the optical and infrared faintness of IFRS makes their study difficult. Prior to this work, no redshift was known for any IFRS in the Australia Telescope Large Area Survey (ATLAS) fields which would help to put IFRS in the context of other classes of object, especially of HzRGs. Aims: This work aims at measuring the first redshifts of IFRS in the ATLAS fields. Furthermore, we test the hypothesis that IFRS are similar to HzRGs, that they are higher-redshift or dust-obscured versions of these massive galaxies. Methods: A sample of IFRS was spectroscopically observed using the Focal Reducer and Low Dispersion Spectrograph 2 (FORS2) at the Very Large Telescope (VLT). The data were calibrated based on the Image Reduction and Analysis Facility (IRAF) and redshifts extracted from the final spectra, where possible. This information was then used to calculate rest-frame luminosities, and to perform the first spectral energy distribution modelling of IFRS based on redshifts. Results: We found redshifts of 1.84, 2.13, and 2.76, for three IFRS, confirming the suggested high-redshift character of this class of object. These redshifts and the resulting luminosities show IFRS to be similar to HzRGs, supporting our hypothesis. We found further evidence that fainter IFRS are at even higher redshifts. Conclusions: Considering the similarities between IFRS and HzRGs substantiated in this work, the detection of IFRS, which have a significantly higher sky density than HzRGs, increases the number of active galactic nuclei in the early universe and adds to the problems of explaining the formation of

  18. Infrared Faint Radio Sources in the Extended Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Huynh, Minh T.

    2009-01-01

    Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey (ATLAS) which have no observable counterpart in the Spitzer Wide-area Infrared Extragalactic Survey (SWIRE). The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6 to 70 micron) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the SED of these objects shows that they are consistent with high redshift AGN (z > 2).

  19. EVIDENCE FOR INFRARED-FAINT RADIO SOURCES AS z > 1 RADIO-LOUD ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Huynh, Minh T.; Norris, Ray P.; Siana, Brian; Middelberg, Enno

    2010-02-10

    Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey which have no observable mid-infrared counterpart in the Spitzer Wide-area Infrared Extragalactic (SWIRE) survey. The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6-70 {mu}m) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the spectral energy distribution of these objects shows that they are consistent with high-redshift (z {approx}> 1) active galactic nuclei.

  20. The Search for Faint Infrared Calibration Standards - Extending Landolt's Standards to V=19

    NASA Astrophysics Data System (ADS)

    Kidger, M.; González-Pérez, J. N.; Martín-Luis, F.; Cohen, M.

    ISO has shown the need to obtain a reliable calibration network of good pedigree to permit data from a wide range of instruments, covering an enormous wavelength range, to be calibrated on a consistent scale. We describe the first results of a programme to extend the Landolt calibration standards to at least V=19. At the same time we calibrate into the near-infrared JHK bands and measure fields separated from the celestial equator. This programme is one of several coordinated efforts to find faint type AV and KIII stars suitable for the mid-IR calibration of the Spanish 10-m Gran Telescopio Canarias (GTC). We have obtained a total of 34 712 measurements of 373 stars in 26 quasar fields between Declination -30o and +70o, calculating magnitudes with high precision in the visible and near-infrared (UBVRIJHK). We describe the results obtained and the characteristics of the sample of stars. The typical error on the magnitude in a single band is <1%, including all error sources. Very few candidate type AV or KIII stars are found, either in our sample, or amongst the fainter Landolt stars. We conclude that both samples are increasingly dominated by local dwarfs at increasingly faint magnitudes. We discuss the implications for taking mid-infrared calibration to the increasingly faint limits required by post-ISO instrumentation. The next steps in this project will be: -- To increase significantly the number of fields covered to ˜40. -- To take additional observations of all poorly covered fields and to add JHK data where none is available. -- To use our existing database to extend Landolt photometry of Selected Areas to include many stars not previously measured. -- To assign a spectral type to all candidate KIII and AV stars in our sample.

  1. The radio spectral energy distribution of infrared-faint radio sources

    NASA Astrophysics Data System (ADS)

    Herzog, A.; Norris, R. P.; Middelberg, E.; Seymour, N.; Spitler, L. R.; Emonts, B. H. C.; Franzen, T. M. O.; Hunstead, R.; Intema, H. T.; Marvil, J.; Parker, Q. A.; Sirothia, S. K.; Hurley-Walker, N.; Bell, M.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Callingham, J. R.; Deshpande, A. A.; Dwarakanath, K. S.; For, B.-Q.; Greenhill, L. J.; Hancock, P.; Hazelton, B. J.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A. D.; Kaplan, D. L.; Lenc, E.; Lonsdale, C. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Morgan, J.; Oberoi, D.; Offringa, A.; Ord, S. M.; Prabu, T.; Procopio, P.; Udaya Shankar, N.; Srivani, K. S.; Staveley-Smith, L.; Subrahmanyan, R.; Tingay, S. J.; Wayth, R. B.; Webster, R. L.; Williams, A.; Williams, C. L.; Wu, C.; Zheng, Q.; Bannister, K. W.; Chippendale, A. P.; Harvey-Smith, L.; Heywood, I.; Indermuehle, B.; Popping, A.; Sault, R. J.; Whiting, M. T.

    2016-10-01

    Context. Infrared-faint radio sources (IFRS) are a class of radio-loud (RL) active galactic nuclei (AGN) at high redshifts (z ≥ 1.7) that are characterised by their relative infrared faintness, resulting in enormous radio-to-infrared flux density ratios of up to several thousand. Aims: Because of their optical and infrared faintness, it is very challenging to study IFRS at these wavelengths. However, IFRS are relatively bright in the radio regime with 1.4 GHz flux densities of a few to a few tens of mJy. Therefore, the radio regime is the most promising wavelength regime in which to constrain their nature. We aim to test the hypothesis that IFRS are young AGN, particularly GHz peaked-spectrum (GPS) and compact steep-spectrum (CSS) sources that have a low frequency turnover. Methods: We use the rich radio data set available for the Australia Telescope Large Area Survey fields, covering the frequency range between 150 MHz and 34 GHz with up to 19 wavebands from different telescopes, and build radio spectral energy distributions (SEDs) for 34 IFRS. We then study the radio properties of this class of object with respect to turnover, spectral index, and behaviour towards higher frequencies. We also present the highest-frequency radio observations of an IFRS, observed with the Plateau de Bure Interferometer at 105 GHz, and model the multi-wavelength and radio-far-infrared SED of this source. Results: We find IFRS usually follow single power laws down to observed frequencies of around 150 MHz. Mostly, the radio SEDs are steep (α < -0.8; %), but we also find ultra-steep SEDs (α < -1.3; %). In particular, IFRS show statistically significantly steeper radio SEDs than the broader RL AGN population. Our analysis reveals that the fractions of GPS and CSS sources in the population of IFRS are consistent with the fractions in the broader RL AGN population. We find that at least % of IFRS contain young AGN, although the fraction might be significantly higher as suggested by

  2. 2D Emission Line Galaxies in the Faint Infrared Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Pirzkal, Nor; Ryan, Russell E.; Rothberg, Barry; Meurer, Gerhardt R.; Malhotra, Sangeeta; Rhoads, James E.; Koekemoer, Anton M.; Finkelstein, Steven; Grogin, Norman A.

    2015-08-01

    The Faint Infrared Galaxy Survey (FIGS) provides us with a unique opportunity to identify emission line galaxies. Emission lines such as [OII], [OIII], Hα and Lya lines can be identified in the FIGS slitless spectroscopic observations down to faint line fluxes of a few times 10-17 erg/s/cm2. Crucially, the use of multiple observations, taken at different position angles on the sky allows us to accurately determine the location of these star forming regions within individual galaxies using the Emission Line 2D (EM2D) method. Our ability to detect high equivalent width lines independently of any host galaxies allows us to search for naked emission line objects. Combining this method with the wavelength coverage of the G102 grism, we are able to identify emission line objects using [OII] and [OIII], and Hα over 0.2 < z < 2 and using Lyman alpha from 6 < z < 8. Here, we present the first results on star forming galaxies selected using this method and demonstrate the wealth of data to be expected from the FIGS project.

  3. Infrared-faint radio sources remain undetected at far-infrared wavelengths. Deep photometric observations using the Herschel Space Observatory

    NASA Astrophysics Data System (ADS)

    Herzog, A.; Norris, R. P.; Middelberg, E.; Spitler, L. R.; Leipski, C.; Parker, Q. A.

    2015-08-01

    Context. Showing 1.4 GHz flux densities in the range of a few to a few tens of mJy, infrared-faint radio sources (IFRS) are a type of galaxy characterised by faint or absent near-infrared counterparts and consequently extreme radio-to-infrared flux density ratios up to several thousand. Recent studies showed that IFRS are radio-loud active galactic nuclei (AGNs) at redshifts ≳2, potentially linked to high-redshift radio galaxies (HzRGs). Aims: This work explores the far-infrared emission of IFRS, providing crucial information on the star forming and AGN activity of IFRS. Furthermore, the data enable examining the putative relationship between IFRS and HzRGs and testing whether IFRS are more distant or fainter siblings of these massive galaxies. Methods: A sample of six IFRS was observed with the Herschel Space Observatory between 100 μm and 500 μm. Using these results, we constrained the nature of IFRS by modelling their broad-band spectral energy distribution (SED). Furthermore, we set an upper limit on their infrared SED and decomposed their emission into contributions from an AGN and from star forming activity. Results: All six observed IFRS were undetected in all five Herschel far-infrared channels (stacking limits: σ = 0.74 mJy at 100 μm, σ = 3.45 mJy at 500 μm). Based on our SED modelling, we ruled out the following objects to explain the photometric characteristics of IFRS: (a) known radio-loud quasars and compact steep-spectrum sources at any redshift; (b) starburst galaxies with and without an AGN and Seyfert galaxies at any redshift, even if the templates were modified; and (c) known HzRGs at z ≲ 10.5. We find that the IFRS analysed in this work can only be explained by objects that fulfil the selection criteria of HzRGs. More precisely, IFRS could be (a) known HzRGs at very high redshifts (z ≳ 10.5); (b) low-luminosity siblings of HzRGs with additional dust obscuration at lower redshifts; (c) scaled or unscaled versions of Cygnus A at any

  4. Infrared-faint radio sources in the SERVS deep fields. Pinpointing AGNs at high redshift

    NASA Astrophysics Data System (ADS)

    Maini, A.; Prandoni, I.; Norris, R. P.; Spitler, L. R.; Mignano, A.; Lacy, M.; Morganti, R.

    2016-12-01

    Context. Infrared-faint radio sources (IFRS) represent an unexpected class of objects which are relatively bright at radio wavelength, but unusually faint at infrared (IR) and optical wavelengths. A recent and extensive campaign on the radio-brightest IFRSs (S1.4 GHz≳ 10 mJy) has provided evidence that most of them (if not all) contain an active galactic nuclei (AGN). Still uncertain is the nature of the radio-faintest IFRSs (S1.4 GHz≲ 1 mJy). Aims: The scope of this paper is to assess the nature of the radio-faintest IFRSs, testing their classification and improving the knowledge of their IR properties by making use of the most sensitive IR survey available so far: the Spitzer Extragalactic Representative Volume Survey (SERVS). We also explore how the criteria of IFRSs can be fine-tuned to pinpoint radio-loud AGNs at very high redshift (z > 4). Methods: We analysed a number of IFRS samples identified in SERVS fields, including a new sample (21 sources) extracted from the Lockman Hole. 3.6 and 4.5 μm IR counterparts of the 64 sources located in the SERVS fields were searched for and, when detected, their IR properties were studied. Results: We compared the radio/IR properties of the IR-detected IFRSs with those expected for a number of known classes of objects. We found that IR-detected IFRSs are mostly consistent with a mixture of high-redshift (z ≳ 3) radio-loud AGNs. The faintest ones (S1.4 GHz 100 μJy), however, could be also associated with nearer (z 2) dust-enshrouded star-burst galaxies. We also argue that, while IFRSs with radio-to-IR ratios >500 can very efficiently pinpoint radio-loud AGNs at redshift 2 < z < 4, lower radio-to-IR ratios ( 100-200) are expected for higher redshift radio-loud AGNs.

  5. The first VLBI image of an infrared-faint radio source

    NASA Astrophysics Data System (ADS)

    Middelberg, E.; Norris, R. P.; Tingay, S.; Mao, M. Y.; Phillips, C. J.; Hotan, A. W.

    2008-11-01

    Context: We investigate the joint evolution of active galactic nuclei and star formation in the Universe. Aims: In the 1.4 GHz survey with the Australia Telescope Compact Array of the Chandra Deep Field South and the European Large Area ISO Survey - S1 we have identified a class of objects which are strong in the radio but have no detectable infrared and optical counterparts. This class has been called Infrared-Faint Radio Sources, or IFRS. 53 sources out of 2002 have been classified as IFRS. It is not known what these objects are. Methods: To address the many possible explanations as to what the nature of these objects is we have observed four sources with the Australian Long Baseline Array. Results: We have detected and imaged one of the four sources observed. Assuming that the source is at a high redshift, we find its properties in agreement with properties of Compact Steep Spectrum sources. However, due to the lack of optical and infrared data the constraints are not particularly strong.

  6. A search for AGN activity in Infrared-Faint Radio Sources (IFRS)

    NASA Astrophysics Data System (ADS)

    Lenc, Emil; Middelberg, Enno; Norris, Ray; Mao, Minnie

    2010-04-01

    We propose to observe a large sample of radio sources from the ATLAS (Australia Telescope Large Area Survey) source catalogue with the LBA, to determine their compactness. The sample consists of 36 sources with no counterpart in the co-located SWIRE survey (3.6 um to 160 um), carried out with the Spitzer Space Telescope. This rare class of sources, dubber Infrared-Faint Radio Sources (IFRS), is inconsistent with current galaxy evolution models. VLBI observations are an essential way to obtain further clues on what these objects are and why they are hidden from infrared observations. We will measure the flux densities on long baselines to determine their compactness. Only five IFRS have been previously targeted with VLBI observations (resulting in two detections). We propose using single baseline (Parkes-ATCA) eVLBI observations with the LBA at 1 Gbps to maximise sensitivity. With the observations proposed here we will increase the number of VLBI-observed IFRS from 5 to 36, allowing us to draw statistical conclusions about this intriguing new class of objects.

  7. A search for AGN activity in Infrared-Faint Radio Sources (IFRS)

    NASA Astrophysics Data System (ADS)

    Lenc, Emil; Middelberg, Enno; Norris, Ray; Mao, Minnie

    2009-04-01

    We propose to observe a large sample of radio sources from the ATLAS (Australia Telescope Large Area Survey) source catalogue with the LBA, to determine their compactness. The sample consists of 36 sources with no counterpart in the co-located SWIRE survey (3.6 um to 160 um), carried out with the Spitzer Space Telescope. This rare class of sources, dubber Infrared-Faint Radio Sources (IFRS), is inconsistent with current galaxy evolution models. VLBI observations are an essential way to obtain further clues on what these objects are and why they are hidden from infrared observations. We will measure the flux densities on long baselines to determine their compactness. Only five IFRS have been previously targeted with VLBI observations (resulting in two detections). We propose using single baseline (Parkes-ATCA) eVLBI observations with the LBA at 1 Gbps to maximise sensitivity. With the observations proposed here we will increase the number of VLBI-observed IFRS from 5 to 36, allowing us to draw statistical conclusions about this intriguing new class of objects.

  8. A Study of Planetary Nebulae using the Faint Object Infrared Camera for the SOFIA Telescope

    NASA Technical Reports Server (NTRS)

    Davis, Jessica

    2012-01-01

    A planetary nebula is formed following an intermediate-mass (1-8 solar M) star's evolution off of the main sequence; it undergoes a phase of mass loss whereby the stellar envelope is ejected and the core is converted into a white dwarf. Planetary nebulae often display complex morphologies such as waists or torii, rings, collimated jet-like outflows, and bipolar symmetry, but exactly how these features form is unclear. To study how the distribution of dust in the interstellar medium affects their morphology, we utilize the Faint Object InfraRed CAmera for the SOFIA Telescope (FORCAST) to obtain well-resolved images of four planetary nebulae--NGC 7027, NGC 6543, M2-9, and the Frosty Leo Nebula--at wavelengths where they radiate most of their energy. We retrieve mid infrared images at wavelengths ranging from 6.3 to 37.1 micron for each of our targets. IDL (Interactive Data Language) is used to perform basic analysis. We select M2-9 to investigate further; analyzing cross sections of the southern lobe reveals a slight limb brightening effect. Modeling the dust distribution within the lobes reveals that the thickness of the lobe walls is higher than anticipated, or rather than surrounding a vacuum surrounds a low density region of tenuous dust. Further analysis of this and other planetary nebulae is needed before drawing more specific conclusions.

  9. OPTICAL–INFRARED PROPERTIES OF FAINT 1.3 mm SOURCES DETECTED WITH ALMA

    SciTech Connect

    Hatsukade, Bunyo; Yabe, Kiyoto; Ohta, Kouji; Seko, Akifumi; Makiya, Ryu; Akiyama, Masayuki

    2015-09-10

    We report optical-infrared (IR) properties of faint 1.3 mm sources (S{sub 1.3mm} = 0.2–1.0 mJy) detected with the Atacama Large Millimeter/submillimeter Array (ALMA) in the Subaru/XMM-Newton Deep Survey field. We searched for optical/IR counterparts of eight ALMA-detected sources (≥4.0σ, the sum of the probability of spurious source contamination is ∼1) in a K-band source catalog. Four ALMA sources have K-band counterpart candidates within a 0.″4 radius. Comparison between ALMA-detected and undetected K-band sources in the same observing fields shows that ALMA-detected sources tend to be brighter, more massive, and more actively forming stars. While many of the ALMA-identified submillimeter-bright galaxies (SMGs) in previous studies lie above the sequence of star-forming galaxies in the stellar mass–star formation rate plane, our ALMA sources are located in the sequence, suggesting that the ALMA-detected faint sources are more like “normal” star-forming galaxies rather than “classical” SMGs. We found a region where multiple ALMA sources and K-band sources reside in a narrow photometric redshift range (z ∼ 1.3–1.6) within a radius of 5″ (42 kpc if we assume z = 1.45). This is possibly a pre-merging system and we may be witnessing the early phase of formation of a massive elliptical galaxy.

  10. A chemical confirmation of the faint Boötes II dwarf spheroidal galaxy

    SciTech Connect

    Koch, Andreas; Rich, R. Michael

    2014-10-10

    We present a chemical abundance study of the brightest confirmed member star of the ultra-faint dwarf galaxy Boötes II from Keck/HIRES high-resolution spectroscopy at moderate signal-to-noise ratios. At [Fe/H] = –2.93 ± 0.03(stat.) ± 0.17(sys.), this star chemically resembles metal-poor halo field stars and the signatures of other faint dwarf spheroidal galaxies at the same metallicities in that it shows enhanced [α/Fe] ratios, Solar Fe-peak element abundances, and low upper limits on the neutron-capture element Ba. Moreover, this star shows no chemical peculiarities in any of the eight elements we were able to measure. This implies that the chemical outliers found in other systems remain outliers pertaining to the unusual enrichment histories of the respective environments, while Boo II appears to have experienced an enrichment history typical of its very low mass. We also re-calibrated previous measurements of the galaxy's metallicity from the calcium triplet (CaT) and find a much lower value than reported before. The resulting broad metallicity spread, in excess of one dex, the very metal-poor mean, and the chemical abundance patterns of the present star imply that Boötes II is a low-mass, old, metal-poor dwarf galaxy and not an overdensity associated with the Sagittarius Stream as has been previously suggested based on its sky position and kinematics. The low, mean CaT metallicity of –2.7 dex falls right on the luminosity-metallicity relation delineated over four orders of magnitude from the more luminous to the faintest galaxies. Thus Boötes II's chemical enrichment appears representative of the galaxy's original mass, while tidal stripping and other mass loss mechanisms were probably not significant as for other low-mass satellites.

  11. Stellar kinematics and metallicities in the ultra-faint dwarf galaxy Reticulum II

    SciTech Connect

    Simon, J. D.

    2015-07-23

    With this study, we present Magellan/M2FS, Very Large Telescope/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on the spectra of 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity of $62.8\\pm 0.5\\;\\mathrm{km}\\;{\\rm{s}}^{-1}$ and a velocity dispersion of $3.3\\pm 0.7\\;\\mathrm{km}\\;{\\rm{s}}^{-1}$. The mass-to-light ratio of Ret II within its half-light radius is $470\\pm 210\\ {M}_{\\odot }/{L}_{\\odot }$, demonstrating that it is a strongly dark matter-dominated system. Despite its spatial proximity to the Magellanic Clouds, the radial velocity of Ret II differs from that of the LMC and SMC by 199 and 83 $\\mathrm{km}\\ {{\\rm{s}}}^{-1}$, respectively, suggesting that it is not gravitationally bound to the Magellanic system. The likely member stars of Ret II span 1.3 dex in metallicity, with a dispersion of 0.28 ± 0.09 dex, and we identify several extremely metal-poor stars with ${\\rm{[Fe/H]}}\\lt -3$. In combination with its luminosity, size, and ellipticity, these results confirm that Ret II is an ultra-faint dwarf galaxy. With a mean metallicity of ${\\rm{[Fe/H]}}=-2.65\\pm 0.07$, Ret II matches Segue 1 as the most metal-poor galaxy known. Although Ret II is the third-closest dwarf galaxy to the Milky Way, the line-of-sight integral of the dark matter density squared is ${\\mathrm{log}}_{10}(J)=18.8\\pm 0.6\\;\\;\\mathrm{GeV}{\\;}^{2}\\;{\\mathrm{cm}}^{-5}\\;$ within 0fdg2, indicating that the predicted gamma-ray flux from dark matter annihilation in Ret II is lower than that of several other dwarf galaxies.

  12. Stellar Kinematics and Metallicities in the Ultra-faint Dwarf Galaxy Reticulum II

    NASA Astrophysics Data System (ADS)

    Simon, J. D.; Drlica-Wagner, A.; Li, T. S.; Nord, B.; Geha, M.; Bechtol, K.; Balbinot, E.; Buckley-Geer, E.; Lin, H.; Marshall, J.; Santiago, B.; Strigari, L.; Wang, M.; Wechsler, R. H.; Yanny, B.; Abbott, T.; Bauer, A. H.; Bernstein, G. M.; Bertin, E.; Brooks, D.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Dodelson, S.; Cunha, C. E.; Estrada, J.; Evrard, A. E.; Fausti Neto, A.; Fernandez, E.; Finley, D. A.; Flaugher, B.; Frieman, J.; Gaztanaga, E.; Gerdes, D.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Maia, M. A. G.; March, M.; Martini, P.; Miller, C. J.; Miquel, R.; Ogando, R.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Schubnell, M.; Sevilla, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Tucker, D.; Vikram, V.; Walker, A. R.; Wester, W.; DES Collaboration

    2015-07-01

    We present Magellan/M2FS, Very Large Telescope/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on the spectra of 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity of 62.8+/- 0.5 {km} {{{s}}}-1 and a velocity dispersion of 3.3+/- 0.7 {km} {{{s}}}-1. The mass-to-light ratio of Ret II within its half-light radius is 470+/- 210 {M}⊙ /{L}⊙ , demonstrating that it is a strongly dark matter-dominated system. Despite its spatial proximity to the Magellanic Clouds, the radial velocity of Ret II differs from that of the LMC and SMC by 199 and 83 {km} {{{s}}}-1, respectively, suggesting that it is not gravitationally bound to the Magellanic system. The likely member stars of Ret II span 1.3 dex in metallicity, with a dispersion of 0.28 ± 0.09 dex, and we identify several extremely metal-poor stars with {{[Fe/H]}}\\lt -3. In combination with its luminosity, size, and ellipticity, these results confirm that Ret II is an ultra-faint dwarf galaxy. With a mean metallicity of {{[Fe/H]}}=-2.65+/- 0.07, Ret II matches Segue 1 as the most metal-poor galaxy known. Although Ret II is the third-closest dwarf galaxy to the Milky Way, the line-of-sight integral of the dark matter density squared is {{log}}10(J)=18.8+/- 0.6 {GeV}{ }2 {{cm}}-5 within 0.°2, indicating that the predicted gamma-ray flux from dark matter annihilation in Ret II is lower than that of several other dwarf galaxies. Based on data obtained from the ESO Science Archive Facility under request number 157689.

  13. Chemical Diversity in the Ultra-faint Dwarf Galaxy Tucana II

    NASA Astrophysics Data System (ADS)

    Ji, Alexander P.; Frebel, Anna; Ezzeddine, Rana; Casey, Andrew R.

    2016-11-01

    We present the first detailed chemical abundance study of the ultra-faint dwarf galaxy Tucana II, based on high-resolution Magellan/MIKE spectra of four red giant stars. The metallicities of these stars range from [Fe/H] = -3.2 to -2.6, and all stars are low in neutron-capture abundances ([Sr/Fe] and [Ba/Fe] < -1). However, a number of anomalous chemical signatures are present. One star is relatively metal-rich ([Fe/H] = -2.6) and shows [Na, α, Sc/Fe] < 0, suggesting an extended star formation history with contributions from AGB stars and SNe Ia. Two stars with [Fe/H] < -3 are mildly carbon-enhanced ([C/Fe] ˜ 0.7) and may be consistent with enrichment by faint supernovae, if such supernovae can produce neutron-capture elements. A fourth star with [Fe/H] = -3 is carbon-normal, and exhibits distinct light element abundance ratios from the carbon-enhanced stars. This carbon-normal star implies that at least two distinct nucleosynthesis sources, both possibly associated with Population III stars, contributed to the early chemical enrichment of this galaxy. Despite its very low luminosity, Tucana II shows a diversity of chemical signatures that preclude it from being a simple “one-shot” first galaxy yet still provide a window into star and galaxy formation in the early universe. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  14. The Dark Matter Content of the Triangulum II Ultra-Faint Dwarf Galaxy

    NASA Astrophysics Data System (ADS)

    Kirby, Evan N.; Cohen, Judith G.; Simon, Joshua D.

    2017-01-01

    Triangulum II is an ultra-faint galaxy with a luminosity of 450 L⊙ discovered through Pan-STARRS imaging in 2015. Since then, two independent studies—including one of our own—based on Keck/DEIMOS spectroscopy found that the galaxy has a stellar velocity dispersion of about 5 km/s, indicating a very high concentration of dark matter. Here, we present additional DEIMOS observations over six epochs. We show that a combination of radial velocity variability (likely due to binarity) and inaccuracies in the previous measurements led to a spurious detection of a velocity dispersion in excess of what would be expected from the stellar population alone. Instead, we place an upper limits of 3.4 km/s (90% C.L.) and 4.3 km/s (95% C.L.) on the velocity dispersion. While these limits are compatible with very high mass-to-light ratios (1700 at 90% C.L. or 2600 at 95% C.L.), Triangulum II no longer seems extreme compared to dwarf galaxies of similar luminosity. Because the stars still span a large range of metallicity (-2.8 < [Fe/H] < -1.5), the galactic nature of Triangulum II is not in dispute.

  15. Stellar kinematics and metallicities in the ultra-faint dwarf galaxy Reticulum II

    DOE PAGES

    Simon, J. D.

    2015-07-23

    With this study, we present Magellan/M2FS, Very Large Telescope/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on the spectra of 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity ofmore » $$62.8\\pm 0.5\\;\\mathrm{km}\\;{\\rm{s}}^{-1}$$ and a velocity dispersion of $$3.3\\pm 0.7\\;\\mathrm{km}\\;{\\rm{s}}^{-1}$$. The mass-to-light ratio of Ret II within its half-light radius is $$470\\pm 210\\ {M}_{\\odot }/{L}_{\\odot }$$, demonstrating that it is a strongly dark matter-dominated system. Despite its spatial proximity to the Magellanic Clouds, the radial velocity of Ret II differs from that of the LMC and SMC by 199 and 83 $$\\mathrm{km}\\ {{\\rm{s}}}^{-1}$$, respectively, suggesting that it is not gravitationally bound to the Magellanic system. The likely member stars of Ret II span 1.3 dex in metallicity, with a dispersion of 0.28 ± 0.09 dex, and we identify several extremely metal-poor stars with $${\\rm{[Fe/H]}}\\lt -3$$. In combination with its luminosity, size, and ellipticity, these results confirm that Ret II is an ultra-faint dwarf galaxy. With a mean metallicity of $${\\rm{[Fe/H]}}=-2.65\\pm 0.07$$, Ret II matches Segue 1 as the most metal-poor galaxy known. Although Ret II is the third-closest dwarf galaxy to the Milky Way, the line-of-sight integral of the dark matter density squared is $${\\mathrm{log}}_{10}(J)=18.8\\pm 0.6\\;\\;\\mathrm{GeV}{\\;}^{2}\\;{\\mathrm{cm}}^{-5}\\;$$ within 0fdg2, indicating that the predicted gamma-ray flux from dark matter annihilation in Ret II is lower than that of several other dwarf galaxies.« less

  16. Deep 610-MHz Giant Metrewave Radio Telescope observations of the Spitzer extragalactic First Look Survey field - III. The radio properties of infrared-faint radio sources

    NASA Astrophysics Data System (ADS)

    Garn, Timothy; Alexander, Paul

    2008-12-01

    Infrared-faint radio sources (IFRSs) are a class of source which are bright at radio frequencies, but do not appear in deep infrared images. We report the detection of 14 IFRSs within the Spitzer extragalactic First Look Survey field, eight of which are detected near to the limiting magnitude of a deep R-band image of the region, at R ~ 24.5. Sensitive Spitzer Space Telescope images are stacked in order to place upper limits on their mid-infrared flux densities, and using recent 610-MHz and 1.4-GHz observations we find that they have spectral indices which vary between α = 0.05 and 1.38, where we define α such that Sν = S0ν-α, and should not be thought of as a single source population. We place constraints on the luminosity and linear size of these sources, and through comparison with well-studied local objects in the Revised Revised Third Cambridge catalogue demonstrate that they can be modelled as being compact (<20 kpc) Fanaroff-Riley type II (FRII) radio galaxies located at high redshift (z ~ 4).

  17. Faint Submillimeter Galaxies Identified through Their Optical/Near-infrared Colors. I. Spatial Clustering and Halo Masses

    NASA Astrophysics Data System (ADS)

    Chen, Chian-Chou; Smail, Ian; Swinbank, A. M.; Simpson, James M.; Almaini, Omar; Conselice, Christopher J.; Hartley, Will G.; Mortlock, Alice; Simpson, Chris; Wilkinson, Aaron

    2016-11-01

    The properties of submillimeter galaxies (SMGs) that are fainter than the confusion limit of blank-field single-dish surveys ({S}850 ≲ 2 mJy) are poorly constrained. Using a newly developed color selection technique, Optical-Infrared Triple Color (OIRTC), that has been shown to successfully select such faint SMGs, we identify a sample of 2938 OIRTC-selected galaxies, dubbed Triple Color Galaxies (TCGs), in the UKIDSS-UDS field. We show that these galaxies have a median 850 μm flux of {S}850=0.96+/- 0.04 mJy (equivalent to a star formation rate SFR ˜ 60{--}100 {M}⊙ yr-1 based on spectral energy distribution fitting), representing the first large sample of faint SMGs that bridges the gap between bright SMGs and normal star-forming galaxies in S 850 and L IR. We assess the basic properties of TCGs and their relationship with other galaxy populations at z˜ 2. We measure the two-point autocorrelation function for this population and derive a typical halo mass of log10({M}{halo}) = {12.9}-0.3+0.2, {12.7}-0.2+0.1, and {12.9}-0.3+0.2 {h}-1 {M}⊙ at z=1{--}2, 2-3, and 3-5, respectively. Together with the bright SMGs ({S}850≳ 2 mJy) and a comparison sample of less far-infrared luminous star-forming galaxies, we find a lack of dependence between spatial clustering and S 850 (or SFR), suggesting that the difference between these populations may lie in their local galactic environment. Lastly, on the scale of ˜ 8{--}17 {kpc} at 1\\lt z\\lt 5 we find a tentative enhancement of the clustering of TCGs over the comparison star-forming galaxies, suggesting that some faint SMGs are physically associated pairs, perhaps reflecting a merging origin in their triggering.

  18. A new network of faint calibration stars from the near infrared spectrometer (NIRS) on the IRTS

    NASA Technical Reports Server (NTRS)

    Freund, Minoru M.; Matsuura, Mikako; Murakami, Hiroshi; Cohen, Martin; Noda, Manabu; Matsuura, Shuji; Matsumoto, Toshio

    1997-01-01

    The point source extraction and calibration of the near infrared spectrometer (NIRS) onboard the Infrared Telescope in Space (IRTS) is described. About 7 percent of the sky was observed during a one month mission in the range of 1.4 micrometers to 4 micrometers. The accuracy of the spectral shape and absolute values of calibration stars provided by the NIRS/IRTS were validated.

  19. Infrared-faint radio sources: a cosmological view. AGN number counts, the cosmic X-ray background and SMBH formation

    NASA Astrophysics Data System (ADS)

    Zinn, P.-C.; Middelberg, E.; Ibar, E.

    2011-07-01

    Context. Infrared-faint radio sources (IFRS) are extragalactic emitters clearly detected at radio wavelengths but barely detected or undetected at optical and infrared wavelengths, with 5σ sensitivities as low as 1 μJy. Aims: Spectral energy distribution (hereafter SED) modelling and analyses of their radio properties indicate that IFRS are consistent with a population of (potentially extremely obscured) high-redshift AGN at 3 ≤ z ≤ 6. We demonstrate some astrophysical implications of this population and compare them to predictions from models of galaxy evolution and structure formation. Methods: We compiled a list of IFRS from four deep extragalactic surveys and extrapolated the IFRS number density to a survey-independent value of (30.8 ± 15.0) deg-2. We computed the IFRS contribution to the total number of AGN in the Universe to account for the cosmic X-ray background. By estimating the black hole mass contained in IFRS, we present conclusions for the SMBH mass density in the early universe and compare it to relevant simulations of structure formation after the Big Bang. Results: The number density of AGN derived from the IFRS density was found to be ~310 deg-2, which is equivalent to a SMBH mass density of the order of 103 M⊙ Mpc-3 in the redshift range 3 ≤ z ≤ 6. This produces an X-ray flux of 9 × 10-16 W m-2 deg-2 in the 0.5-2.0 keV band and 3 × 10-15 W m-2 deg-2 in the 2.0-10 keV band, in agreement with the missing unresolved components of the Cosmic X-ray Background. To address SMBH formation after the Big Bang we invoke a scenario involving both halo gas accretion and major mergers.

  20. FAINT CO LINE WINGS IN FOUR STAR-FORMING (ULTRA)LUMINOUS INFRARED GALAXIES

    SciTech Connect

    Leroy, Adam K.; Walter, Fabian; Decarli, Roberto; Zschaechner, Laura; Bolatto, Alberto; Weiss, Axel

    2015-09-20

    We report the results of a search for large velocity width, low-intensity line wings—a commonly used signature of molecular outflows—in four low redshift (ultra)luminous infrared galaxies that appear to be dominated by star formation. The targets were drawn from a sample of fourteen targets presented in Chung et al., who showed the stacked CO spectrum of the sample to exhibit 1000 km s{sup −1}-wide line wings. We obtained sensitive, wide bandwidth imaging of our targets using the IRAM Plateau de Bure Interferometer. We detect each target at very high significance but do not find the claimed line wings in these four targets. Instead, we constrain the flux in the line wings to be only a few percent. Casting our results as mass outflow rates following Cicone et al. we show them to be consistent with a picture in which very high mass loading factors preferentially occur in systems with high active galactic nucleus contributions to their bolometric luminosity. We identify one of our targets, IRAS 05083 (VII Zw 31), as a candidate molecular outflow.

  1. TURNING THE TIDES ON THE ULTRA-FAINT DWARF SPHEROIDAL GALAXIES: COMA BERENICES AND URSA MAJOR II

    SciTech Connect

    Munoz, Ricardo R.; Geha, Maria; Willman, Beth E-mail: marla.geha@yale.ed

    2010-07-15

    We present deep CFHT/MegaCam photometry of the ultra-faint Milky Way satellite galaxies: Coma Berenices (ComBer) and Ursa Major II (UMa II). These data extend to r {approx} 25, corresponding to 3 mag below the main-sequence turn-offs in these galaxies. We robustly calculate a total luminosity of M{sub V} = -3.8 {+-} 0.6 for ComBer and M{sub V} = -3.9 {+-} 0.5 for UMa II, in agreement with previous results and confirming that these galaxies are among the faintest of the known dwarf satellites of the Milky Way. ComBer shows a fairly regular morphology with no signs of active tidal stripping down to a surface brightness limit of 32.4 mag arcsec{sup -2}. Using a maximum likelihood analysis, we calculate the half-light radius of ComBer to be r{sub half} = 74 {+-} 4 pc (5.8 {+-} 0.'3) and its ellipticity {epsilon} = 0.36 {+-} 0.04. In contrast, UMa II shows signs of ongoing disruption. We map its morphology down to {mu}{sub V} = 32.6 mag arcsec{sup -2} and found that UMa II is larger than previously determined, extending at least {approx}600 pc (1.{sup 0}1 on the sky) and it is also quite elongated with an overall ellipticity of {epsilon} = 0.50 {+-} 0.2. However, our estimate for the half-light radius, 123 {+-} 3 pc (14.1 {+-} 0.'3) is similar to previous results. We discuss the implications of these findings in the context of potential indirect dark matter detections and galaxy formation. We conclude that while ComBer appears to be a stable dwarf galaxy, UMa II shows signs of ongoing tidal interaction.

  2. Fainting (Syncope)

    MedlinePlus

    ... Adults Making Your Wishes Known Home & Community Home › Aging & Health A to Z › Fainting (Syncope) Font size A A A Print Share Glossary Basic Facts & Information Causes & Symptoms Diagnosis & Tests Care & Treatment Lifestyle & Management Other Resources Caregiving How ...

  3. Active galactic nuclei cores in infrared-faint radio sources. Very long baseline interferometry observations using the Very Long Baseline Array

    NASA Astrophysics Data System (ADS)

    Herzog, A.; Middelberg, E.; Norris, R. P.; Spitler, L. R.; Deller, A. T.; Collier, J. D.; Parker, Q. A.

    2015-06-01

    Context. Infrared-faint radio sources (IFRS) form a new class of galaxies characterised by radio flux densities between tenths and tens of mJy and faint or absent infrared counterparts. It has been suggested that these objects are radio-loud active galactic nuclei (AGNs) at significant redshifts (z ≳ 2). Aims: Whereas the high redshifts of IFRS have been recently confirmed based on spectroscopic data, the evidence for the presence of AGNs in IFRS is mainly indirect. So far, only two AGNs have been unquestionably confirmed in IFRS based on very long baseline interferometry (VLBI) observations. In this work, we test the hypothesis that IFRS contain AGNs in a large sample of sources using VLBI. Methods: We observed 57 IFRS with the Very Long Baseline Array (VLBA) down to a detection sensitivity in the sub-mJy regime and detected compact cores in 35 sources. Results: Our VLBA detections increase the number of VLBI-detected IFRS from 2 to 37 and provide strong evidence that most - if not all - IFRS contain AGNs. We find that IFRS have a marginally higher VLBI detection fraction than randomly selected sources with mJy flux densities at arcsec-scales. Moreover, our data provide a positive correlation between compactness - defined as the ratio of milliarcsec- to arcsec-scale flux density - and redshift for IFRS, but suggest a decreasing mean compactness with increasing arcsec-scale radio flux density. Based on these findings, we suggest that IFRS tend to contain young AGNs whose jets have not formed yet or have not expanded, equivalent to very compact objects. We found two IFRS that are resolved into two components. The two components are spatially separated by a few hundred milliarcseconds in both cases. They might be components of one AGN, a binary black hole, or the result of gravitational lensing.

  4. First Simultaneous Detection of Lyman-alpha Emission and Lyman Break from a Galaxy at Redshift 7.51 from Faint Infrared Grism Survey (FIGS)

    NASA Astrophysics Data System (ADS)

    Tilvi, Vithal; Pirzkal, Norbert; Malhotra, Sangeeta; Finkelstein, Steven L.; Rhoads, James E.; Windhorst, Rogier A.; Grogin, Norman A.; Koekemoer, Anton M.; Zakamska, Nadia L.; Ryan, Russell E.; Christensen, Lise; Hathi, Nimish P.; Pharo, John; Joshi, Bhavin; Yang, Huan; Gronwall, Caryl; Cimatti, Andrea; Walsh, J.; O'Connell, Robert W.; Straughn, Amber; Östlin, Göran; Rothberg, Barry; Livermore, Rachael C.; Hibon, Pascale; Gardner, Jonathan P.; FIGS Team

    2017-01-01

    Galaxies at high-redshifts provide a powerful tool to probe cosmic dawn, and therefore it is crucial to reliably identify these galaxies. Here, we present an unambiguous and first simultaneous detection of a Lyman-alpha line and a Lyman break from a galaxy (FIGS_GN1_1292) at z=7.51, observed in the Faint Infrared Grism Survey (FIGS: PI Mlahotra). FIGS is currently the most sensitive G102 grism survey, with 160-orbit depth equally distributed in four different fields in GOODS-N and GOODS-S. FIGS_GN1_1292 is detected independently in multiple position angles, and has a Lyman-alpha line flux of 1.06e-17 erg/s/cm^2, nearly a factor of four higher than in the archival MOSFIRE spectroscopic observations. This higher flux in the grism data is consistent with other recent observations implying that ground-based near-infrared spectroscopy may underestimate the total emission line fluxes, and if confirmed, can have strong implications for reionization studies that are based on ground-based Lyman-alpha measurements. The successful detection of continuum in such a high-redshift galaxy demonstrates the sensitivity of the FIGS survey, and the capability of grism spectroscopy to study the epoch of reionization using upcoming missions like the Wide Field Infrared Survey Telescope (WFIRST).

  5. Near-infrared spectroscopy of faint discrete X-ray point sources constituting the Galactic ridge X-ray emission

    NASA Astrophysics Data System (ADS)

    Morihana, Kumiko; Tsujimoto, Masahiro; Dubath, Pierre; Yoshida, Tessei; Suzuki, Kensuke; Ebisawa, Ken

    2016-08-01

    The Galactic Ridge X-ray Emission (GRXE) is an apparently extended X-ray emission along the Galactic plane. The X-ray spectrum is characterized by a hard continuum with a strong Fe K emission feature in the 6-7 keV band. A substantial fraction (˜80%) of the GRXE in the Fe band was resolved into point sources by deep Chandra imaging observations; thus GRXE is mostly composed of dim Galactic X-ray point sources, at least in this energy band. To investigate the populations of these dim X-ray point sources, we carried out near-infrared (NIR) follow-up spectroscopic observations in two deep Chandra fields located in the Galactic plane at (l, b) = (0.1°, -1.4°) and (28.5°, 0.0°) using NTT/SofI and Subaru/MOIRCS. We obtained well-exposed NIR spectra from 65 objects and found that there are three main classes of Galactic sources based on the X-ray color and NIR spectral features: those having (A) hard X-ray spectra and NIR emission features such as H I (Brγ), He I, and He II (2 objects), (B) soft X-ray spectra and NIR absorption features such as H I, Na I, Ca I, and CO (46 objects), and (C) hard X-ray spectra and NIR absorption features such as H I, Na I, Ca I, and CO (17 objects). From these features, we argue that class A sources are cataclysmic variables (CVs), and class B sources are late-type stars with enhanced coronal activity, which is in agreement with current knowledge. Class C sources possibly belong to a new group of objects, which has been poorly studied so far. We argue that the candidate sources for class C are the binary systems hosting white dwarfs and late-type companions with very low accretion rates. It is likely that this newly recognized class of sources contribute to a non-negligible fraction of the GRXE, especially in the Fe K band.

  6. STELLAR POPULATIONS AND STRUCTURAL PROPERTIES OF ULTRA FAINT DWARF GALAXIES, CANES VENATICI I, BOOeTES I, CANES VENATICI II, AND LEO IV

    SciTech Connect

    Okamoto, Sakurako; Arimoto, Nobuo; Yamada, Yoshihiko; Onodera, Masato

    2012-01-10

    We take deep images of four ultra faint dwarf (UFD) galaxies, Canes Venatici I (CVn I), Booetes I (Booe I), Canes Venatici II (CVn II), and Leo IV, using the Suprime-Cam on the Subaru Telescope. Color-magnitude diagrams (CMDs) extend below main-sequence turnoffs (MSTOs) and yield measurements of the ages of stellar populations. The stellar populations of three faint galaxies, the Booe I, CVn II, and Leo IV dwarf spheroidal galaxies (dSphs), are estimated to be as old as the Galactic globular cluster M92. We confirm that Booe I dSph has no intrinsic color spread in the MSTO and no spatial difference in the CMD morphology, which indicates that Booe I dSph is composed of an old single stellar population. One of the brightest UFDs, CVn I dSph, shows a relatively younger age ({approx}12.6 Gyr) with respect to Booe I, CVn II, and Leo IV dSphs, and the distribution of red horizontal branch (HB) stars is more concentrated toward the center than that of blue HB stars, suggesting that the galaxy contains complex stellar populations. Booe I and CVn I dSphs show the elongated and distorted shapes. CVn II dSph has the smallest tidal radius of a Milky Way satellite and has a distorted shape, while Leo IV dSph shows a less concentrated spherical shape. The simple stellar population of faint UFDs indicates that the gases in their progenitors were removed more effectively than those of brighter dSphs at the occurrence of their initial star formation. This is reasonable if the progenitors of UFDs belong to less massive halos than those of brighter dSphs.

  7. HUBBLE SPACE TELESCOPE Near-infrared and Optical Imaging of Faint Radio Sources in the Distant Cluster CL 0939+4713

    NASA Astrophysics Data System (ADS)

    Smail, Ian; Morrison, G.; Gray, M. E.; Owen, F. N.; Ivison, R. J.; Kneib, J.-P.; Ellis, R. S.

    1999-11-01

    We present deep Hubble Space Telescope Near-Infrared Camera and Multiobject Spectrograph (NICMOS) and Wide Field and Planetary Camera 2 (WFPC2) optical imaging of a small region in the core of the distant rich cluster Cl 0939+4713 (z=0.41). We compare the optical and near-infrared morphologies of cluster members and find apparent small-scale optical structures within the galaxies that are absent in the near-infrared. We conclude that strong dust obscuration is a common feature in the late-type galaxies in distant clusters. We then concentrate on a sample of 10 faint radio galaxies lying within our NICMOS field and selected from a very deep 1.4 GHz VLA map of the cluster with a 1 σ flux limit of 9 μJy. Using published data we focus on the spectral properties of the eight radio-selected cluster members and show that these comprise a large fraction of the poststarburst population in the cluster. The simplest interpretation of the radio emission from these galaxies is that they are currently forming massive stars, contradicting their classification as poststarburst systems based on the optical spectra. We suggest that this star formation is hidden from view in the optical by the same obscuring dust that is apparent in our comparison on the optical and near-infrared morphologies of these galaxies. We caution that even in the rest-frame optical the effects of dust cannot be ignored when comparing samples of distant galaxies to low-redshift systems, particularly if dust is as prevalent in distant galaxies as appears to be the case in our study.

  8. First Results from the Faint Infrared Grism Survey (FIGS): First Simultaneous Detection of Lyα Emission and Lyman Break from a Galaxy at z = 7.51

    NASA Astrophysics Data System (ADS)

    Tilvi, V.; Pirzkal, N.; Malhotra, S.; Finkelstein, S. L.; Rhoads, J. E.; Windhorst, R.; Grogin, N. A.; Koekemoer, A.; Zakamska, N. L.; Ryan, R.; Christensen, L.; Hathi, N.; Pharo, J.; Joshi, B.; Yang, H.; Gronwall, C.; Cimatti, A.; Walsh, J.; O'Connell, R.; Straughn, A.; Ostlin, G.; Rothberg, B.; Livermore, R. C.; Hibon, P.; Gardner, Jonathan P.

    2016-08-01

    Galaxies at high redshifts are a valuable tool for studying cosmic dawn, therefore it is crucial to reliably identify these galaxies. Here, we present an unambiguous and first simultaneous detection of both the Lyα emission and the Lyman break from a z=7.512 +/- 0.004 galaxy, observed in the Faint Infrared Grism Survey (FIGS). These spectra, taken with the G102 grism on the Hubble Space Telescope (HST), show a significant emission line detection (6σ ) in two observational position angles (PAs), with Lyα line flux of 1.06+/- 0.19× {10}-17 {erg} {{{s}}}-1 {{cm}}-2. The line flux is nearly a factor of four higher than that in the archival MOSFIRE spectroscopic observations. This is consistent with other recent observations, implying that ground-based near-infrared spectroscopy underestimates the total emission line fluxes, and if confirmed, can have strong implications for reionization studies that are based on ground-based Lyα measurements. A 4σ detection of the NV line in one PA also suggests a weak active galactic nucleus (AGN), and if confirmed, would make this source the highest-redshift AGN yet found. These observations from HST thus clearly demonstrate the sensitivity of the FIGS survey, and the capability of grism spectroscopy for studying the epoch of reionization.

  9. HerMES: Current Cosmic Infrared Background Estimates Can Be Explained by Known Galaxies and Their Faint Companions at z < 4

    NASA Astrophysics Data System (ADS)

    Viero, M. P.; Moncelsi, L.; Quadri, R. F.; Béthermin, M.; Bock, J.; Burgarella, D.; Chapman, S. C.; Clements, D. L.; Conley, A.; Conversi, L.; Duivenvoorden, S.; Dunlop, J. S.; Farrah, D.; Franceschini, A.; Halpern, M.; Ivison, R. J.; Lagache, G.; Magdis, G.; Marchetti, L.; Álvarez-Márquez, J.; Marsden, G.; Oliver, S. J.; Page, M. J.; Pérez-Fournon, I.; Schulz, B.; Scott, Douglas; Valtchanov, I.; Vieira, J. D.; Wang, L.; Wardlow, J.; Zemcov, M.

    2015-08-01

    We report contributions to cosmic infrared background (CIB) intensities originating from known galaxies and their faint companions at submillimeter wavelengths. Using the publicly available UltraVISTA catalog and maps at 250, 350, and 500 μm from the Herschel Multi-tiered Extragalactic Survey, we perform a novel measurement that exploits the fact that uncataloged sources may bias stacked flux densities—particularly if the resolution of the image is poor—and intentionally smooth the images before stacking and summing intensities. By smoothing the maps we are capturing the contribution of faint (undetected in {K}S˜ 23.4) sources that are physically associated, or correlated, with the detected sources. We find that the cumulative CIB increases with increased smoothing, reaching 9.82 ± 0.78, 5.77 ± 0.43 and 2.32+/- 0.19 {{nWm}}-2 {{sr}}-1 at 250, 350, and 500 μm at 300 {arcsec} FWHM. This corresponds to a fraction of the fiducial CIB of 0.94 ± 0.23, 1.07 ± 0.31, and 0.97 ± 0.26 at 250, 350, and 500 μm, where the uncertainties are dominated by those of the absolute CIB. We then propose, with a simple model combining parametric descriptions for stacked flux densities and stellar mass functions, that emission from galaxies with log(M/{M}⊙ )\\gt 8.5 can account for most of the measured total intensities and argue against contributions from extended, diffuse emission. Finally, we discuss prospects for future survey instruments to improve the estimates of the absolute CIB levels, and observe any potentially remaining emission at z\\gt 4.

  10. Detection of faint broad emission lines in type 2 AGN - I. Near-infrared observations and spectral fitting

    NASA Astrophysics Data System (ADS)

    Onori, F.; La Franca, F.; Ricci, F.; Brusa, M.; Sani, E.; Maiolino, R.; Bianchi, S.; Bongiorno, A.; Fiore, F.; Marconi, A.; Vignali, C.

    2017-01-01

    We present medium resolution near-infrared spectroscopic observations of 41 obscured and intermediate class active galactic nuclei (AGN; type 2, 1.9 and 1.8; AGN2) with redshift z ≲ 0.1, selected from the Swift/Burst Alert Telescope 70-month catalogue. The observations have been carried out in the framework of a systematic study of the AGN2 near-infrared spectral properties and have been executed using Infrared Spectrometer And Array Camera/VLT, X-shooter/VLT and LUCI/LBT, reaching an average S/N ratio of ˜30 per resolution element. For those objects observed with X-shooter, we also obtained simultaneous optical and UV spectroscopy. We have identified a component from the broad line region in 13 out of 41 AGN2, with full width at half-maximum (FWHM) > 800 km s-1. We have verified that the detection of the broad line region components does not significantly depend on selection effects due to the quality of the spectra, the X-ray or near-infrared fluxes, the orientation angle of the host galaxy or the hydrogen column density measured in the X-ray band. The average broad line region components found in AGN2 has a significantly (a factor 2) smaller FWHM if compared with a control sample of type 1 AGN.

  11. OPTICAL-FAINT, FAR-INFRARED-BRIGHT HERSCHEL SOURCES IN THE CANDELS FIELDS: ULTRA-LUMINOUS INFRARED GALAXIES AT z > 1 AND THE EFFECT OF SOURCE BLENDING

    SciTech Connect

    Yan, Haojing; Stefanon, Mauro; Ma, Zhiyuan; Willner, S. P.; Ashby, Matthew L. N.; Somerville, Rachel; Davé, Romeel; Pérez-González, Pablo G.; Cava, Antonio; Wiklind, Tommy; Kocevski, Dale; Rafelski, Marc; Kartaltepe, Jeyhan; Cooray, Asantha; Koekemoer, Anton M.; Grogin, Norman A.

    2014-07-01

    The Herschel very wide field surveys have charted hundreds of square degrees in multiple far-IR (FIR) bands. While the Sloan Digital Sky Survey (SDSS) is currently the best resource for optical counterpart identifications over such wide areas, it does not detect a large number of Herschel FIR sources and leaves their nature undetermined. As a test case, we studied seven ''SDSS-invisible'', very bright 250 μm sources (S {sub 250} > 55 mJy) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey fields where we have a rich multi-wavelength data set. We took a new approach to decompose the FIR sources, using the near-IR or the optical images directly for position priors. This is an improvement over the previous decomposition efforts where the priors are from mid-IR data that still suffer from the problem of source blending. We found that in most cases the single Herschel sources are made of multiple components that are not necessarily at the same redshifts. Our decomposition succeeded in identifying and extracting their major contributors. We show that these are all ultra-luminous infrared galaxies at z ∼ 1-2 whose high L {sub IR} is mainly due to dust-obscured star formation. Most of them would not be selected as submillimeter galaxies. They all have complicated morphologies indicative of mergers or violent instability, and their stellar populations are heterogeneous in terms of stellar masses, ages, and formation histories. Their current ultra-luminous infrared galaxy phases are of various degrees of importance in their stellar mass assembly. Our practice provides a promising starting point for developing an automatic routine to reliably study bright Herschel sources.

  12. A search for near-infrared counterparts of two faint neutron star X-ray transients: XMMU J174716.1-281048 and SAX J1806.5-2215

    NASA Astrophysics Data System (ADS)

    Kaur, Ramanpreet; Wijnands, Rudy; Kamble, Atish; Cackett, Edward M.; Kutulla, Ralf; Kaplan, David; Degenaar, Nathalie

    2017-01-01

    We present our near-infrared (NIR) imaging observations of two neutron star low-mass X-ray binaries XMMU J174716.1-281048 and SAX J1806.5-2215 obtained using the PANIC instrument on the 6.5-metre Magellan telescope and the WIYN High-Resolution Infrared Camera instrument on the 3.5-metre WIYN telescope, respectively. Both sources are members of the class of faint to very faint X-ray binaries and undergo very long X-ray outburst, hence classified as `quasi-persistent X-ray binaries'. While XMMU J174716.1-281048 was active for almost 12 yr between 2003 and 2015, SAX J1806.5-2215 has been active for more than 5 yr now since 2011. From our observations, we identify two NIR stars consistent with the Chandra X-ray error circle of XMMU J174716.1-281048. The comparison of our observations with the United Kingdom Infrared Telescope (UKIRT) Galactic plane observations taken during the same outburst, colour-colour diagram analysis and spectral energy distribution suggest that both stars are probably a part of the field population and are likely high-mass stars. Hence possibly neither of the two stars is a true NIR counterpart. For the faint X-ray binary SAX J1806.5-2215 during its current outburst, we detected an NIR star in our K-band WIYN observations consistent with its Chandra error circle. The identified NIR star was not detected during the UKIRT observations taken during its quiescent state. The comparison of two observations suggests that there was an increase in flux by at least one magnitude of the detected star during our observations, and hence suggests the detection of the likely counterpart of SAX J1806.5-2215.

  13. Infrared Space Observatory Measurements of a [C II] 158 micron Line Deficit in Ultraluminous Infrared Galaxies

    DTIC Science & Technology

    1998-07-23

    INFRARED SPACE OBSERVATORY1 MEASUREMENTS OF A [C ii] 158 MICRON LINE DEFICIT IN ULTRALUMINOUS INFRARED GALAXIES M. L. Luhman ,2,3 S. Satyapal,4,5 J. Fischer...PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 L12 LUHMAN ET AL. Vol. 504 TABLE 1 Observing Log Source a2000 d2000 AOT...e.g., Wolfire et al. 1990; Carral et al. 1994; Fischer et al. 1996), L14 LUHMAN ET AL. Vol. 504 which suggests that if [C ii] line saturation alone

  14. Type-II superlattice materials for mid-infrared detection

    NASA Astrophysics Data System (ADS)

    Brown, Gail J.; Haugan, Heather; Szmulowicz, Frank; Mahalingam, Krishnamur; Grazulis, L.; Houston, Shanee

    2005-03-01

    Type-II superlattices composed of alternating thin layers of InAs and GaSb, have been shown to be a highly flexible infrared materials system in which the energy band gap can be adjusted anywhere between 360 meV and 40 meV. These superlattices (SLs) are the III-V equivalent to the well established HgxCd1-xTe alloys used for infrared detection in the short, mid and long wavelength bands of the infrared spectrum. There are many possible designs for these superlattices that will produce the same narrow band gap by adjusting individual layer thicknesses and interface composition. Systematic growth and characterization studies were performed to determine optimum superlattice designs suitable for infrared detection in the 3 to 5 μm wavelength band. For these studies the individual layer thicknesses were less than 35Å. The effects of adding different thickness InSb-like interfaces were also studied. Through precision molecular beam epitaxy, design changes as small as 3Å to the SL layers could be studied. Significant changes were observed in the infrared photoresponse spectra of the various SL samples. The infrared properties of the various designs of these type-II superlattices were modeled using an 8-band Envelope Function Approximation. The infrared photoresponse spectra, combined with quantum mechanical modeling of predicted absorption spectra, were a key factor in the design optimization of the InAs/GaSb superlattices with band gaps in the range of 200 to 360 meV.

  15. Fainting: First Aid

    MedlinePlus

    ... brain is momentarily inadequate, causing you to lose consciousness. This loss of consciousness is usually brief. Fainting can have no medical ... be a serious disorder. Therefore, treat loss of consciousness as a medical emergency until the signs and ...

  16. Dizziness and Fainting Spells

    MedlinePlus

    ... or Animals Genitals and Urinary Tract Glands & Growth Head Neck & Nervous System Heart Infections Learning Disabilities Obesity Orthopedic ... Vaccine Preventable Diseases Healthy Children > Health Issues > Conditions > Head Neck & Nervous System > Dizziness and Fainting Spells Health Issues ...

  17. Imaging stellar faint companions

    NASA Astrophysics Data System (ADS)

    Cagigal, Manuel P.; Canales, Vidal F.

    . The conclusion is that the use of the Dark Speckle technique in a compensated nulling interferometer could be a promising way to detect faint objects, although the application of the technique in the infrared range requires the development of appropriate detectors.

  18. Type-II superlattice infrared detector technology at Fraunhofer IAF

    NASA Astrophysics Data System (ADS)

    Rehm, Robert; Daumer, Volker; Hugger, Tsvetelina; Kohn, Norbert; Luppold, Wolfgang; Müller, Raphael; Niemasz, Jasmin; Schmidt, Johannes; Rutz, Frank; Stadelmann, Tim; Wauro, Matthias; Wörl, Andreas

    2016-05-01

    For more than two decades, Antimony-based type-II superlattice photodetectors for the infrared spectral range between 3-15 μm are under development at the Fraunhofer Institute for Applied Solid State Physics (IAF). Today, Fraunhofer IAF is Germany's only national foundry for InAs/GaSb type-II superlattice detectors and we cover a wide range of aspects from basic materials research to small series production in this field. We develop single-element photodetectors for sensing systems as well as two-dimensional detector arrays for high-performance imaging and threat warning systems in the mid-wavelength and long-wavelength region of the thermal infrared. We continuously enhance our production capabilities by extending our in-line process control facilities. As a recent example, we present a semiautomatic wafer probe station that has developed into an important tool for electrooptical characterization. A large amount of the basic materials research focuses on the reduction of the dark current by the development of bandgap engineered device designs on the basis of heterojunction concepts. Recently, we have successfully demonstrated Europe's first LWIR InAs/GaSb type-II superlattice imager with 640x512 pixels with 15 μm pitch. The demonstrator camera already delivers a good image quality and achieves a thermal resolution better than 30 mK.

  19. Optical properties of infrared FELs from the FELI Facility II

    SciTech Connect

    Saeki, K.; Okuma, S.; Oshita, E.

    1995-12-31

    The FELI Facility II has succeeded in infrared FEL oscillation at 1.91 {mu} m using a 68-MeV, 40-A electron beam from the FELI S-band linac in February 27, 1995. The FELI Facility II is composed of a 3-m vertical type undulator ({lambda}u=3.8cm, N=78, Km a x=1.4, gap length {ge}20mm) and a 6.72-m optical cavity. It can cover the wavelength range of 1-5{mu}m. The FELs can be delivered from the optical cavity to the diagnostics room through a 40-m evacuated optical pipeline. Wavelength and cavity length dependences of optical properties such as peak power, average power, spectrum width, FEL macropulse, FEL transverse profile are reported.

  20. Proposal for strained type II superlattice infrared detectors

    NASA Astrophysics Data System (ADS)

    Smith, D. L.; Mailhiot, C.

    1987-09-01

    It is shown that strained type II superlattices made of InAs-Ga(1-x)In(x)Sb(x) about 0.4 have favorable optical properties for infrared detection. By adjusting the layer thicknesses and the alloy composition, a wide range of wavelengths can be reached. Optical absorption calculations for a case where the cutoff wavelength is about 10 microns show that, near threshold, the absorption is as good as for the HgCdTe alloy with the same band gap. The electron effective mass is nearly isotropic and equal to 0.04 m. This effective mass should give favorable electrical properties, such as small diode tunneling currents and good mobilities, and diffusion lengths.

  1. Near-Infrared Faint Galaxies in the Subaru Deep Field: Comparing the Theory with Observations for Galaxy Counts, Colors, and Size Distributions to K ~ 24.5

    NASA Astrophysics Data System (ADS)

    Totani, Tomonori; Yoshii, Yuzuru; Maihara, Toshinori; Iwamuro, Fumihide; Motohara, Kentaro

    2001-10-01

    Galaxy counts in the K band, (J-K) colors, and apparent size distributions of faint galaxies in the Subaru Deep Field (SDF) down to K~24.5 were studied in detail. Special attention has been paid to take into account various selection effects, including the cosmological dimming of surface brightness, to avoid any systematic bias that may be the origin of controversy in previously published results. We also tried to be very careful about systematic model uncertainties; we present a comprehensive survey of these systematic uncertainties and dependence on various parameters, and we have shown that the dominant factors to determine galaxy counts in this band are cosmology and number evolution. We found that the pure luminosity evolution (PLE) model is very consistent with all the SDF data down to K~22.5, without any evidence for number or size evolution in a low-density, Λ-dominated flat universe, which is now favored by various cosmological observations. On the other hand, a number evolution of galaxies with η~2, when invoked as the luminosity conserving mergers as φ*~(1+z)η and L*~(1+z)-η for all types of galaxies, is necessary to explain the data in the Einstein-de Sitter universe. If the popular Λ-dominated universe is taken for granted, our result then gives a strong constraint on the number evolution of giant elliptical or early-type galaxies to z~1-2 that must be met by any models in the hierarchically clustering universe, since such galaxies are the dominant population in this magnitude range (K<~22.5). A number evolution with η~1 is already difficult to reconcile with the data in this universe. On the other hand, number evolution of late-type galaxies and/or dwarf galaxies, which has been suggested by previous studies of optical galaxies, is allowed from the data. In the fainter magnitude range of K>~22.5, we found a slight excess of observed counts over the prediction of the PLE model when elliptical galaxies are treated as a single population. We

  2. Faint Submillimeter Galaxies Behind Lensing Clusters

    NASA Astrophysics Data System (ADS)

    Hsu, Li-Yen; Lauchlan Cowie, Lennox; Barger, Amy J.; Desai, Vandana; Murphy, Eric J.

    2017-01-01

    Faint submillimeter galaxies are the major contributors to the submillimeter extragalactic background light and hence the dominant star-forming population in the dusty universe. Determining how much these galaxies overlap the optically selected samples is critical to fully account for the cosmic star formation history. Observations of massive cluster fields are the best way to explore this faint submillimeter population, thanks to gravitational lensing effects. We have been undertaking a lensing cluster survey with the SCUBA-2 camera on the James Clerk Maxwell Telescope to map nine galaxy clusters, including the northern five clusters in the HST Frontier Fields program. We have also been using the Submillimeter Array and the Very Large Array to determine the accurate positions of our detected sources. Our observations have discovered high-redshift dusty galaxies with far-infrared luminosities similar to that of the Milky Way or luminous infrared galaxies. Some of these galaxies are still undetected in deep optical and near-infrared images. These results suggest that a substantial amount of star formation in even the faint submillimeter population may be hidden from rest-frame optical surveys.

  3. Fourier Transform Infrared Spectroscopy: Part II. Advantages of FT-IR.

    ERIC Educational Resources Information Center

    Perkins, W. D.

    1987-01-01

    This is Part II in a series on Fourier transform infrared spectroscopy (FT-IR). Described are various advantages of FT-IR spectroscopy including energy advantages, wavenumber accuracy, constant resolution, polarization effects, and stepping at grating changes. (RH)

  4. Diffuse far-infrared [C II] line emission from high Galactic latitude

    NASA Astrophysics Data System (ADS)

    Makiuti, S.; Shibai, H.; Nakagawa, T.; Okuda, H.; Okumura, K.; Matsuhara, H.; Hiromoto, N.; Doi, Y.

    2002-02-01

    The Far-Infrared Line Mapper (FILM) onboard the Infrared Telescope in Space (IRTS) made a survey for the far-infrared [C Ii] 158 mu m line emission with high sensitivity and moderate spatial resolution. We have found that diffuse [C Ii] line emission extends to high Galactic latitude regions. The [C Ii] line intensity at | b | ~ 60deg ranges from 2*E-7 to 1.5*E-6 erg cm-2 s-1 sr-1. Comparisons of the distribution of the [C Ii] line emission with those of the H I column density and far-infrared radiation show some correlations, but the [C Ii] line emission differs from the far-IR and HI emission at high Galactic latitudes. These differences suggest that the [C Ii] line primarily comes from ionized gas in the high-latitude regions. The intensities of the [C Ii] line emission on the southern side (b < 0deg) of the Galactic plane are systematically larger than those on the northern side (b > 0deg). We infer from this difference that there is a displacement of the Sun with respect to the center of interstellar medium from which the [C Ii] line comes. When an exponential distribution is assumed for the [C Ii] emitting gas, it is expected that the Sun is located at the distance of about 17% of the scale height above the center of the gas. This is consistent with the previously reported displacement of the Sun from the Galactic plane.

  5. Spitzer UltRa Faint SUrvey Program (SURFS UP). II. IRAC-detected Lyman-Break Galaxies at 6 ≲ z ≲ 10 behind Strong-lensing Clusters

    NASA Astrophysics Data System (ADS)

    Huang, Kuang-Han; Bradač, Maruša; Lemaux, Brian C.; Ryan, R. E., Jr.; Hoag, Austin; Castellano, Marco; Amorín, Ricardo; Fontana, Adriano; Brammer, Gabriel B.; Cain, Benjamin; Lubin, L. M.; Merlin, Emiliano; Schmidt, Kasper B.; Schrabback, Tim; Treu, Tommaso; Gonzalez, Anthony H.; von der Linden, Anja; Knight, Robert I.

    2016-01-01

    We study the stellar population properties of the IRAC-detected 6 ≲ z ≲ 10 galaxy candidates from the Spitzer UltRa Faint SUrvey Program. Using the Lyman Break selection technique, we find a total of 17 galaxy candidates at 6 ≲ z ≲ 10 from Hubble Space Telescope images (including the full-depth images from the Hubble Frontier Fields program for MACS 1149 and MACS 0717) that have detections at signal-to-noise ratios ≥ 3 in at least one of the IRAC 3.6 and 4.5 μm channels. According to the best mass models available for the surveyed galaxy clusters, these IRAC-detected galaxy candidates are magnified by factors of ˜1.2-5.5. Due to the magnification of the foreground galaxy clusters, the rest-frame UV absolute magnitudes M1600 are between -21.2 and -18.9 mag, while their intrinsic stellar masses are between 2 × 108M⊙ and 2.9 × 109M⊙. We identify two Lyα emitters in our sample from the Keck DEIMOS spectra, one at zLyα = 6.76 (in RXJ 1347) and one at zLyα = 6.32 (in MACS 0454). We find that 4 out of 17 z ≳ 6 galaxy candidates are favored by z ≲ 1 solutions when IRAC fluxes are included in photometric redshift fitting. We also show that IRAC [3.6]-[4.5] color, when combined with photometric redshift, can be used to identify galaxies which likely have strong nebular emission lines or obscured active galactic nucleus contributions within certain redshift windows.

  6. SPITZER ULTRA FAINT SURVEY PROGRAM (SURFS UP). II. IRAC-DETECTED LYMAN-BREAK GALAXIES AT 6 ≲ z ≲ 10 BEHIND STRONG-LENSING CLUSTERS

    SciTech Connect

    Huang, Kuang-Han; Bradač, Maruša; Hoag, Austin; Cain, Benjamin; Lubin, L. M.; Knight, Robert I.; Lemaux, Brian C.; Ryan, R. E. Jr.; Brammer, Gabriel B.; Castellano, Marco; Amorin, Ricardo; Fontana, Adriano; Merlin, Emiliano; Schmidt, Kasper B.; Schrabback, Tim; Treu, Tommaso; Gonzalez, Anthony H.; Linden, Anja von der E-mail: astrokuang@gmail.com

    2016-01-20

    We study the stellar population properties of the IRAC-detected 6 ≲ z ≲ 10 galaxy candidates from the Spitzer UltRa Faint SUrvey Program. Using the Lyman Break selection technique, we find a total of 17 galaxy candidates at 6 ≲ z ≲ 10 from Hubble Space Telescope images (including the full-depth images from the Hubble Frontier Fields program for MACS 1149 and MACS 0717) that have detections at signal-to-noise ratios  ≥ 3 in at least one of the IRAC 3.6 and 4.5 μm channels. According to the best mass models available for the surveyed galaxy clusters, these IRAC-detected galaxy candidates are magnified by factors of ∼1.2–5.5. Due to the magnification of the foreground galaxy clusters, the rest-frame UV absolute magnitudes M{sub 1600} are between −21.2 and −18.9 mag, while their intrinsic stellar masses are between 2 × 10{sup 8}M{sub ⊙} and 2.9 × 10{sup 9}M{sub ⊙}. We identify two Lyα emitters in our sample from the Keck DEIMOS spectra, one at z{sub Lyα} = 6.76 (in RXJ 1347) and one at z{sub Lyα} = 6.32 (in MACS 0454). We find that 4 out of 17 z ≳ 6 galaxy candidates are favored by z ≲ 1 solutions when IRAC fluxes are included in photometric redshift fitting. We also show that IRAC [3.6]–[4.5] color, when combined with photometric redshift, can be used to identify galaxies which likely have strong nebular emission lines or obscured active galactic nucleus contributions within certain redshift windows.

  7. Deep infrared galaxies

    NASA Technical Reports Server (NTRS)

    Ashby, Matthew; Houck, J. R.; Hacking, Perry B.

    1992-01-01

    High signal-to-noise ratio optical spectra of 17 infrared-bright emission-line galaxies near the north ecliptic pole are presented. Reddening-corrected line ratios forbidden O III 5007/H-beta, N II 6583/H-alpha, S II (6716 + 6731)/H-alpha, and O I 6300/H-alpha are used to discriminate between candidate energy generation mechanisms in each galaxy. These criteria have frequently been applied to optically selected samples of galaxies in the past, but this is the first time they have been applied to a set of faint flux-limited infrared-selected objects. The analysis indicates the sample contains seven starburst galaxies and three (AGN). However, seven galaxies in the present sample elude the classification scheme based on these line ratios. It is concluded that a two-component (starburst plus AGN) model for energy generation is inadequate for infrared galaxies.

  8. 77 FR 36579 - II-VI, Inc., Infrared Optics-Saxonburg Division, Saxonburg, PA; Leased Workers From Adecco, Carol...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-19

    ... Employment and Training Administration II-VI, Inc., Infrared Optics-Saxonburg Division, Saxonburg, PA; Leased...., Infrared Optics-Saxonburg Division, Saxonburg, PA; Notice of Revised Determination on Reconsideration The... period. The determination was applicable to workers and former workers of II-VI, Inc., Infrared...

  9. Galactic Cepheids with Spitzer. II. Search for Extended Infrared Emission

    NASA Astrophysics Data System (ADS)

    Barmby, P.; Marengo, M.; Evans, N. R.; Bono, G.; Huelsman, D.; Su, K. Y. L.; Welch, D. L.; Fazio, G. G.

    2011-02-01

    A deep and detailed examination of 29 classical Cepheids with the Spitzer Space Telescope has revealed three stars with strong nearby extended emission detected in multiple bands which appears to be physically associated with the stars. RS Pup was already known to possess extended infrared emission, while the extended emission around the other two stars (S Mus and δ Cep) is newly discovered in our observations. Four other stars (GH Lup, ell Car, T Mon, and X Cyg) show tentative evidence for extended infrared emission. An unusual elongated extended object next to SZ Tau appears to be a background or foreground object in a chance alignment with the Cepheid. The inferred mass-loss rate upper limits for S Mus and δ Cep are in the range from 10-9 to 10-8 M sun yr-1, with the upper limit for RS Pup as high as 10-6 M sun yr-1. Mass loss during post-main-sequence evolution has been proposed as a resolution to the discrepancy between pulsational and dynamical masses of Cepheid variable stars: dust in the lost material would make itself known by the presence of an infrared bright nebula or unresolved infrared excess. The observed frequency of infrared circumstellar emission (<24%) and the mass-loss rate we estimate for our sources show that dusty mass loss can only account for part of the Cepheid mass-loss discrepancy. Nevertheless, our direct evidence that mass loss is active during the Cepheid phase is an important confirmation that these processes need to be included in evolutionary and pulsation models of these stars and should be taken into account in the calibration of the Cepheid distance scale.

  10. AKARI INFRARED CAMERA SURVEY OF THE LARGE MAGELLANIC CLOUD. II. THE NEAR-INFRARED SPECTROSCOPIC CATALOG

    SciTech Connect

    Shimonishi, Takashi; Onaka, Takashi; Kato, Daisuke; Sakon, Itsuki; Ita, Yoshifusa; Kawamura, Akiko; Kaneda, Hidehiro

    2013-02-01

    We performed a near-infrared spectroscopic survey toward an area of {approx}10 deg{sup 2} of the Large Magellanic Cloud (LMC) with the infrared satellite AKARI. Observations were carried out as part of the AKARI Large-area Survey of the Large Magellanic Cloud (LSLMC). The slitless multi-object spectroscopic capability of the AKARI/IRC enabled us to obtain low-resolution (R {approx} 20) spectra in 2-5 {mu}m for a large number of point sources in the LMC. As a result of the survey, we extracted about 2000 infrared spectra of point sources. The data are organized as a near-infrared spectroscopic catalog. The catalog includes various infrared objects such as young stellar objects (YSOs), asymptotic giant branch (AGB) stars, supergiants, and so on. It is shown that 97% of the catalog sources have corresponding photometric data in the wavelength range from 1.2 to 11 {mu}m, and 67% of the sources also have photometric data up to 24 {mu}m. The catalog allows us to investigate near-infrared spectral features of sources by comparison with their infrared spectral energy distributions. In addition, it is estimated that about 10% of the catalog sources are observed at more than two different epochs. This enables us to study a spectroscopic variability of sources by using the present catalog. Initial results of source classifications for the LSLMC samples are presented. We classified 659 LSLMC spectra based on their near-infrared spectral features by visual inspection. As a result, it is shown that the present catalog includes 7 YSOs, 160 C-rich AGBs, 8 C-rich AGB candidates, 85 O-rich AGBs, 122 blue and yellow supergiants, 150 red super giants, and 128 unclassified sources. Distributions of the classified sources on the color-color and color-magnitude diagrams are discussed in the text. Continuous wavelength coverage and high spectroscopic sensitivity in 2-5 {mu}m can only be achieved by space observations. This is an unprecedented large-scale spectroscopic survey toward the

  11. CANOES II; Dynamics of Atmospheric Infrared Thermochemical Excitation. Volume 2

    DTIC Science & Technology

    1989-03-01

    4 8 which carried at least 6.5 eV internal energy, in their studies on the excitation of mercuric halides by N2 (A). The energy of the companion...as auroral precursors of infrared radiation ., 20. DISTRIBUTION /AVAILABILITY OF ABSTRACT 21 ABSTRACT SECURITY CLASSIFICATION MUNCLASSIFIED/tINLIMITED...investigate chemiluminescent reactions of atmospherically important radiators which could significantly contribute to emissions in several important

  12. A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers. II. Program Design, Absorption-line Measurements, and Absorber Statistics

    NASA Astrophysics Data System (ADS)

    Burchett, Joseph N.; Tripp, Todd M.; Prochaska, J. Xavier; Werk, Jessica K.; Tumlinson, Jason; O'Meara, John M.; Bordoloi, Rongmon; Katz, Neal; Willmer, C. N. A.

    2015-12-01

    To investigate the evolution of metal-enriched gas over recent cosmic epochs as well as to characterize the diffuse, ionized, metal-enriched circumgalactic medium, we have conducted a blind survey for C iv absorption systems in 89 QSO sightlines observed with the Hubble Space Telescope Cosmic Origins Spectrograph. We have identified 42 absorbers at z < 0.16, comprising the largest uniform blind sample size to date in this redshift range. Our measurements indicate an increasing C iv absorber number density per comoving path length (d{N}/{dX}= 7.5 ± 1.1) and modestly increasing mass density relative to the critical density of the universe (ΩC iv = 10.0 ± 1.5 × 10-8) from z ˜ 1.5 to the present epoch, consistent with predictions from cosmological hydrodynamical simulations. Furthermore, the data support a functional form for the column density distribution function that deviates from a single power law, also consistent with independent theoretical predictions. As the data also probe heavy element ions in addition to C iv at the same redshifts, we identify, measure, and search for correlations between column densities of these species where components appear to be aligned in velocity. Among these ion-ion correlations, we find evidence for tight correlations between C ii and Si ii, C ii and Si iii, and C iv and Si iv, suggesting that these pairs of species arise in similar ionization conditions. However, the evidence for correlations decreases as the difference in ionization potential increases. Finally, when controlling for observational bias, we find only marginal evidence for a correlation (86.8% likelihood) between the Doppler line width b(C iv) and column density N(C iv).

  13. Detecting stellar-wind bubbles through infrared arcs in H ii regions

    NASA Astrophysics Data System (ADS)

    Mackey, Jonathan; Haworth, Thomas J.; Gvaramadze, Vasilii V.; Mohamed, Shazrene; Langer, Norbert; Harries, Tim J.

    2016-02-01

    Mid-infrared arcs of dust emission are often seen near ionizing stars within H ii regions. A possible explanations for these arcs is that they could show the outer edges of asymmetric stellar wind bubbles. We use two-dimensional, radiation-hydrodynamics simulations of wind bubbles within H ii regions around individual stars to predict the infrared emission properties of the dust within the H ii region. We assume that dust and gas are dynamically well-coupled and that dust properties (composition, size distribution) are the same in the H ii region as outside it, and that the wind bubble contains no dust. We post-process the simulations to make synthetic intensity maps at infrared wavebands using the torus code. We find that the outer edge of a wind bubble emits brightly at 24 μm through starlight absorbed by dust grains and re-radiated thermally in the infrared. This produces a bright arc of emission for slowly moving stars that have asymmetric wind bubbles, even for cases where there is no bow shock or any corresponding feature in tracers of gas emission. The 24 μm intensity decreases exponentially from the arc with increasing distance from the star because the dust temperature decreases with distance. The size distribution and composition of the dust grains has quantitative but not qualitative effects on our results. Despite the simplifications of our model, we find good qualitative agreement with observations of the H ii region RCW 120, and can provide physical explanations for any quantitative differences. Our model produces an infrared arc with the same shape and size as the arc around CD -38°11636 in RCW 120, and with comparable brightness. This suggests that infrared arcs around O stars in H ii regions may be revealing the extent of stellar wind bubbles, although we have not excluded other explanations.

  14. Type-II indium arsenide/gallium antimonide superlattices for infrared detectors

    NASA Astrophysics Data System (ADS)

    Mohseni, Hooman

    In this work, the unique properties of type-II InAs/GaSb heterojunctions were utilized for the realization of novel infrared photodetectors with higher operating temperature, detectivity and uniformity than the commonly available infrared detectors. This effort was concentrated on two major devices: uncooled infrared detectors in the long wavelength infrared (LWIR) range, and cooled devices in the very long wavelength infrared (VLWIR) range. Uncooled infrared (IR) detectors are required for low-cost, lightweight sensor systems that have many industrial and medical applications. Commercially available uncooled IR sensors use ferroelectric or microbolometer detectors. These sensors are inherently slow and cannot detect rapid signal changes needed for high-speed infrared systems. Some of the applications which require a fast detector (tau < 30 msec) are: freespace communication, active infrared countermeasure, non-invasive medical monitoring, and LIDARs. Although photon detectors have frequency responses in the megahertz range, their high temperature detectivity is severely degraded due to high Auger recombination rates. Bandgap engineering was used in order to suppress Auger recombination at room temperature in type-II superlattices. Our experimental results demonstrated nearly one order of magnitude lower Auger recombination rate at room temperature in these type-II superlattices compared to typical intrinsic detectors, such as HgCdTe, with similar bandgap. Uncooled detectors based on the engineered superlattices showed a detectivity of 1.3 x 108g cmHz 1/2/W at 11 Et m, which is comparable to microbolometers. However, the measured response time of the detectors was more than five orders of magnitude faster than microbolometers. In parallel, devices for operation in the VLWIR were developed. High-performance infrared detectors with cutoff wavelength above 14 mum are highly needed for many space-based applications. Commonly used detectors are extrinsic silicon and Hg

  15. Extraordinary photocurrent harvesting at type-II heterojunction interfaces: toward high detectivity carbon nanotube infrared detectors.

    PubMed

    Lu, Rongtao; Christianson, Caleb; Kirkeminde, Alec; Ren, Shenqiang; Wu, Judy

    2012-12-12

    Despite the potentials and the efforts put in the development of uncooled carbon nanotube infrared detectors during the past two decades, their figure-of-merit detectivity remains orders of magnitude lower than that of conventional semiconductor counterparts due to the lack of efficient exciton dissociation schemes. In this paper, we report an extraordinary photocurrent harvesting configuration at a semiconducting single-walled carbon nanotube (s-SWCNT)/polymer type-II heterojunction interface, which provides highly efficient exciton dissociation through the intrinsic energy offset by designing the s-SWCNT/polymer interface band alignment. This results in significantly enhanced near-infrared detectivity of 2.3 × 10(8) cm·Hz(1/2)/W, comparable to that of the many conventional uncooled infrared detectors. With further optimization, the s-SWCNT/polymer nanohybrid uncooled infrared detectors could be highly competitive for practical applications.

  16. HST NICMOS snapshot survey of faint galaxies at z < 1

    NASA Astrophysics Data System (ADS)

    Hinkley, S.; Im, M.; DEEP Team

    2000-12-01

    During Cycle 7 HST observations, we have obtained NICMOS H-band images of faint field galaxies for which both HST morphological information (in V and/or I) and spectroscopic redshifts are available. The purpose of the NICMOS observation is to provide their morphology in rest frame NIR wavelengths (8000 - 16000 Å), where the effect of dust extinction is less severe, and to obtain their near infrared (NIR) colors. The objects in our field are partly contained in the Groth Strip being studied in detail by the DEEP team. In addition, we have made use of a software package called GIM2D (Simard et al. 2001). This package is designed to perform detailed 2-dimensional decompositions for images of distant galaxies. Using this software, we have obtained structural parameters for the objects in the H-band to complement those parameters in V and I. We will present: i) color gradients inside elliptical galaxies to test models of their formation; ii) the effect of dust extinction on the properties of field galaxies at 0 < z < 1; iii) evolution of V-H, and V-I colors of bulges as well as the B/T ratio of spiral galaxies as a function of redshift; iv) morphological k-correction. The median redshift of our sample is z ~ 0.5 and this corresponds to about one half of the current age of the universe. This work is supported by the STScI grant GO-07895.02-96A.

  17. Infrared Extraction Change for the NSLS-II Storage Ring

    SciTech Connect

    Blednykh,A.; Carr, L.; Coburn, D.; Krinsky, S.

    2009-05-04

    The short- and long-range wakepotentials have been studied for the design of the infrared (IR) extraction chamber with large full aperture: 67mm vertical and 134mm horizontal. The IR-chamber will be installed within a 2.6m long wide-gap bending magnet with 25m bend radius. Due to the large bend radius it is difficult to separate the light from the electron trajectory. The required parameters of the collected IR radiation at the extraction mirror are {approx}50mrad horizontal and {approx}25mrad vertical (full radiation opening angles). If the extraction mirror is seen by the beam, resonant modes are generated in the chamber. In this paper, we present the detailed calculated impedance for the design of the far-IR chamber, and show that placing the extraction mirror in the proper position eliminates the resonances. In this case, the impedance reduces to that of a simple tapered structure, which is acceptable in regard to its impact on the electron beam.

  18. Hα kinematics of the Spitzer Infrared Nearby Galaxies Survey - II

    NASA Astrophysics Data System (ADS)

    Dicaire, I.; Carignan, C.; Amram, P.; Hernandez, O.; Chemin, L.; Daigle, O.; de Denus-Baillargeon, M.-M.; Balkowski, C.; Boselli, A.; Fathi, K.; Kennicutt, R. C.

    2008-04-01

    This is the second part of an Hα kinematics follow-up survey of the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample. The aim of this paper is to shed new light on the role of baryons and their kinematics and on the dark/luminous matter relation in the star-forming regions of galaxies, in relation with studies at other wavelengths. The data for 37 galaxies are presented. The observations were made using Fabry-Perot interferometry with the photon-counting camera FaNTOmM on four different telescopes, namely the Canada-France-Hawaii 3.6-m, the ESO La Silla 3.6-m, the William Herschel 4.2-m and the Observatoire du mont Mégantic 1.6-m telescopes. The velocity fields are computed using custom IDL routines designed for an optimal use of the data. The kinematical parameters and rotation curves are derived using the GIPSY software. It is shown that non-circular motions associated with galactic bars affect the kinematical parameters fitting and the velocity gradient of the rotation curves. This leads to incorrect determinations of the baryonic and dark matter distributions in the mass models derived from those rotation curves. Based on observations made with the ESO 3.60-m telescope at La Silla Observatories under programme ID 076.B-0859 and on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France and the University of Hawaii. E-mail: isabelle@astro.umontreal.ca (ID);claude.carignan@umontreal.ca (CC) ‡ Visiting Astronomer, Canada-France-Hawaii Telescope, operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France and the University of Hawaii.

  19. Kinematics of faint white dwarfs.

    PubMed

    Luyten, W J

    1978-10-01

    An analysis has been made for solar motion for 128 very faint white dwarfs of color class b or a. While about 40% of these stars may be high-velocity objects, it seems definitely indicated that the luminosity of all of them is considerably lower than that for the "normal" white dwarf of the same color.

  20. THE COSMIC NEAR-INFRARED BACKGROUND. II. FLUCTUATIONS

    SciTech Connect

    Fernandez, Elizabeth R.; Komatsu, Eiichiro; Shapiro, Paul R.; Iliev, Ilian T.

    2010-02-20

    The near-infrared background (NIRB) is one of a few methods that can be used to observe the redshifted light from early stars at a redshift of 6 and above, and thus it is imperative to understand the significance of any detection or nondetection of the NIRB. Fluctuations of the NIRB can provide information on the first structures, such as halos and their surrounding ionized regions in the intergalactic medium (IGM). We combine, for the first time, N-body simulations, radiative transfer code, and analytic calculations of luminosity of early structures to predict the angular power spectrum (C{sub l} ) of fluctuations in the NIRB. We study in detail the effects of various assumptions about the stellar mass, the initial mass spectrum of stars, the metallicity, the star formation efficiency (f{sub *}), the escape fraction of ionizing photons (f{sub esc}), and the star formation timescale (t{sub SF}), on the amplitude as well as the shape of C{sub l} . The power spectrum of NIRB fluctuations is maximized when f{sub *} is the largest (as C{sub l} {proportional_to} f {sup 2}{sub *}) and f{sub esc} is the smallest (as more nebular emission is produced within halos). A significant uncertainty in the predicted amplitude of C{sub l} exists due to our lack of knowledge of t{sub SF} of these early populations of galaxies, which is equivalent to our lack of knowledge of the mass-to-light ratio of these sources. We do not see a turnover in the NIRB angular power spectrum of the halo contribution, which was claimed to exist in the literature, and explain this as the effect of high levels of nonlinear bias that was ignored in the previous calculations. This is partly due to our choice of the minimum mass of halos contributing to NIRB ({approx}2 x 10{sup 9} M{sub sun}), and a smaller minimum mass, which has a smaller nonlinear bias, may still exhibit a turnover. Therefore, our results suggest that both the amplitude and shape of the NIRB power spectrum provide important information

  1. The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs

    NASA Astrophysics Data System (ADS)

    Liu, Michael C.; Dupuy, Trent J.; Allers, Katelyn N.

    2016-12-01

    We present a large, uniform analysis of young (≈10-150 Myr) ultracool dwarfs, based on new high-precision infrared (IR) parallaxes for 68 objects. We find that low-gravity (vl-g) late-M and L dwarfs form a continuous sequence in IR color-magnitude diagrams, separate from the field population and from current theoretical models. These vl-g objects also appear distinct from young substellar (brown dwarf and exoplanet) companions, suggesting that the two populations may have a different range of physical properties. In contrast, at the L/T transition, young, old, and spectrally peculiar objects all span a relatively narrow range in near-IR absolute magnitudes. At a given spectral type, the IR absolute magnitudes of young objects can be offset from ordinary field dwarfs, with the largest offsets occurring in the Y and J bands for late-M dwarfs (brighter than the field) and mid-/late-L dwarfs (fainter than the field). Overall, low-gravity (vl-g) objects have the most uniform photometric behavior, while intermediate gravity (int-g) objects are more diverse, suggesting a third governing parameter beyond spectral type and gravity class. We examine the moving group membership for all young ultracool dwarfs with parallaxes, changing the status of 23 objects (including 8 previously identified planetary-mass candidates) and fortifying the status of another 28 objects. We use our resulting age-calibrated sample to establish empirical young isochrones and show a declining frequency of vl-g objects relative to int-g objects with increasing age. Notable individual objects in our sample include high-velocity (≳100 km s-1) int-g objects, very red late-L dwarfs with high surface gravities, candidate disk-bearing members of the MBM20 cloud and β Pic moving group, and very young distant interlopers. Finally, we provide a comprehensive summary of the absolute magnitudes and spectral classifications of young ultracool dwarfs, using a combined sample of 102 objects found in the field

  2. Faint Submillimeter Galaxies Behind the Frontier Field Clusters

    NASA Astrophysics Data System (ADS)

    Hsu, Li-Yen; Cowie, Lennox; Barger, Amy; Wang, Wei-Hao; Chen, Chian-Chou

    2015-08-01

    Faint submillimeter galaxies are the major contributors to the submillimeter extragalactic background light and hence the dominant star-forming population in the dusty universe. Determining how much these galaxies overlap the optically selected samples is critical to fully account for the cosmic star formation history. To explore this faint submillimeter population, we have been observing nine galaxy clusters with the SCUBA-2 camera on the James Clerk Maxwell Telescope, including five of the clusters in the HST Frontier Fields program. We have also been using the Submillimeter Array to determine the positions of our detected sources precisely. Our recent observations have discovered several high-redshift dusty galaxies with far-infrared luminosities similar to that of the Milky Way or luminous infrared galaxies but which are undetected in current deep radio, optical and near-infrared images. These remarkable results suggest that a substantial amount of star formation in even the faint submillimeter population may be hidden from rest-frame optical surveys.

  3. PESSTO monitoring of SN 2012hn: further heterogeneity among faint Type I supernovae

    NASA Astrophysics Data System (ADS)

    Valenti, S.; Yuan, F.; Taubenberger, S.; Maguire, K.; Pastorello, A.; Benetti, S.; Smartt, S. J.; Cappellaro, E.; Howell, D. A.; Bildsten, L.; Moore, K.; Stritzinger, M.; Anderson, J. P.; Benitez-Herrera, S.; Bufano, F.; Gonzalez-Gaitan, S.; McCrum, M. G.; Pignata, G.; Fraser, M.; Gal-Yam, A.; Le Guillou, L.; Inserra, C.; Reichart, D. E.; Scalzo, R.; Sullivan, M.; Yaron, O.; Young, D. R.

    2014-01-01

    We present optical and infrared monitoring data of SN 2012hn collected by the Public European Southern Observatory Spectroscopic Survey for Transient Objects. We show that SN 2012hn has a faint peak magnitude (MR ˜ -15.65) and shows no hydrogen and no clear evidence for helium in its spectral evolution. Instead, we detect prominent Ca II lines at all epochs, which relates this transient to previously described `Ca-rich' or `gap' transients. However, the photospheric spectra (from -3 to +32 d with respect to peak) of SN 2012hn show a series of absorption lines which are unique and a red continuum that is likely intrinsic rather than due to extinction. Lines of Ti II and Cr II are visible. This may be a temperature effect, which could also explain the red photospheric colour. A nebular spectrum at +150 d shows prominent Ca II, O I, C I and possibly Mg I lines which appear similar in strength to those displayed by core-collapse supernovae (SNe). To add to the puzzle, SN 2012hn is located at a projected distance of 6 kpc from an E/S0 host and is not close to any obvious star-forming region. Overall SN 2012hn resembles a group of faint H-poor SNe that have been discovered recently and for which a convincing and consistent physical explanation is still missing. They all appear to explode preferentially in remote locations offset from a massive host galaxy with deep limits on any dwarf host galaxies, favouring old progenitor systems. SN 2012hn adds heterogeneity to this sample of objects. We discuss potential explosion channels including He-shell detonations and double detonations of white dwarfs as well as peculiar core-collapse SNe.

  4. Chandra Observations of Faint LMXB's

    NASA Technical Reports Server (NTRS)

    Wilson, Colleen A.; Patel, S. K.; Kouveliotou, C.; vanderKlis, M.; Belloni, T.; Lewin, W. H. G.; Six, N. Frank (Technical Monitor)

    2002-01-01

    There exists a group of persistently faint galactic X-ray sources that based on their location in the galaxy, high Lx/Lopt, association with X-ray bursts, and absence of X-ray pulsations are thought to be low-mass X-ray binaries (LMXBs). We present results from Chandra observations for 7 of these systems: 1708-409, 1711-339, 1735-269, 1736-297, 1746-331, 1746.7-3224, and 1812-12. Improved locations for all sources, excluding 1736-297 and 1746-331 (which were not detected) are presented. Our observations are consistent with previously reported transient behavior of 1736-297, 1746-331, and 1711-339 (which we detect in one of two observations). Energy and power spectra are presented for 1735-269, 1711-339, and 1746.7-3224. The energy spectra are hard, consistent with typical faint LMXB spectra. Further, we present a newly discovered source, a very faint, soft, source, separated by 2.7' from 1746.7-3224.

  5. Faint radio sources and gravitational lensing

    SciTech Connect

    Langston, G.I.; Conner, S.R.; Heflin, M.B.; Lehar, J.; Burke, B.F. MIT, Cambridge, MA )

    1990-04-01

    Measurements of the surface density of radio sources resulting from a deep VLA integration at 5 GHz and the MIT-Green Bank (MG) II 5 GHz survey are summarized. The faint source counts are combined with previous observations and fitted to a power-law function of surface density vs. limiting flux density. The surface density of radio sources brighter than 1 mJy is k = 0.019 + or - 0.004/arcmin. The power-law exponent is best fit by -0.93 + or - 0.14. Between 15 and 100 mJy, the surface density of radio sources varies nearly as predicted by Euclidian models of the universe. Estimates are given for the number of chance alignments of radio sources in the VLA snapshot observations of the MIT-Princeton-Caltech gravitational lens search. The probability of lens candidate configurations occurring by chance alignment is calculated. 28 refs.

  6. Faintness

    MedlinePlus

    ... yourself? About Stephen J. Schueler, M.D News Advertising How It Works FAQ for Consumers FAQ for Physicians Testimonials Site Map Terms of Use Contact Us FreeMD is provided for information purposes only and should not be used as a ...

  7. Fainting

    MedlinePlus

    ... usually because changes in the nervous system and circulatory_system cause a temporary drop in the amount of ... a lot of changes, including changes in the circulatory system. This leads to low blood pressure that may ...

  8. High-resolution mid-infrared spectra of Co II, Ni I, and Fe II in SN 1987A

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.; Boyle, R. J.; Wiedemann, G. R.; Moseley, S. H.

    1993-01-01

    Ground-based infrared observations of SN 1987A on day 612 after the explosion have yielded resolved line profiles of Co II, Ni I, Fe II at 10.52, 11.31, and 17.94 micron, respectively. The spectra were taken at a resolving power of about 1000 with an array grating spectrometer on the 4 m telescope of Cerro Tololo Inter-American Observatory. Based on the observed line intensities we have estimated the minimum mass of each ion: M(Co II) = (6.0 +/- 1.8) x 10 exp -5 solar mass; M(Ni I) = (1.1 +/- 0.1) x 10 exp -3 solar mass; and M(Fe II) = (8.0 +/- 1.5) x 10 exp -3 solar mass. From these we infer total masses for cobalt, nickel, and iron in the ejecta. The nickel and iron line profiles are markedly asymmetric. We interpret these as arising from two components, one centered on the stellar rest velocity with an approximately 3250 km/s full width, and the second at about +1200 km/s with an approximately 1100 km/s full width. The asymmetry may represent a large-scale fracturing of the ejecta by Rayleigh-Taylor instabilities.

  9. High-resolution mid-infrared spectra of Co II, Ni I, and Fe II in SN 1987A

    NASA Astrophysics Data System (ADS)

    Jennings, D. E.; Boyle, R. J.; Wiedemann, G. R.; Moseley, S. H.

    1993-05-01

    Ground-based infrared observations of SN 1987A on day 612 after the explosion have yielded resolved line profiles of Co II, Ni I, Fe II at 10.52, 11.31, and 17.94 micron, respectively. The spectra were taken at a resolving power of about 1000 with an array grating spectrometer on the 4 m telescope of Cerro Tololo Inter-American Observatory. Based on the observed line intensities we have estimated the minimum mass of each ion: M(Co II) = (6.0 +/- 1.8) x 10 exp -5 solar mass; M(Ni I) = (1.1 +/- 0.1) x 10 exp -3 solar mass; and M(Fe II) = (8.0 +/- 1.5) x 10 exp -3 solar mass. From these we infer total masses for cobalt, nickel, and iron in the ejecta. The nickel and iron line profiles are markedly asymmetric. We interpret these as arising from two components, one centered on the stellar rest velocity with an approximately 3250 km/s full width, and the second at about +1200 km/s with an approximately 1100 km/s full width. The asymmetry may represent a large-scale fracturing of the ejecta by Rayleigh-Taylor instabilities.

  10. Near-infrared (Fe II) and Pa Beta imaging and spectroscopy of Arp 220

    NASA Technical Reports Server (NTRS)

    Armus, L.; Shupe, D. L.; Matthews, K.; Soifer, B. T.; Neugebauer, G.

    1995-01-01

    We have imaged the ultraluminous infrared galaxy Arp 220 in light of the near-infrared (Fe II) 1.257 micron and Pa-beta lines, and have obtained spectra in the J- and H-band atmospheric windows. Arp 220 is a strong source of (Fe II) and Pa-beta emission, with luminosities of 1.3 x 10(exp 41) and 9.2 x 10(exp 40) ergs/s, respectively. The (Fe II) and Pa-beta emission are both extended over the central 2 sec-3 sec, but with different morphologies. We suggest that the extended (Fe II) emission is produced through the interaction of fast shocks with ambient gas in the interstellar medium (ISM) at the base of the outflowing, supernovae-driven superwind mapped by Heckman et al. (1987). The bolometric luminosity of the starburst required to power this wind is estimated to be at least 2 x 10(exp 11) solar luminosity. If the spatially unresolved (Fe II) emission is produced via a large number of supernova remnants, the implied rate is approximately 0.6/yr. The overall luminosity of such a starburst could account for a large fraction (1/2-1/3) of the Arp 220 energy budget, but the large deficit of ionizing photons (as counted by the Pa-beta luminosity) requires that the starburst be rapidly declining and/or have a low upper mass cutoff. Alternatively, dust may effectively compete with the gas for ionizing photons, or much of the ionizing radiation may escape through 'holes' in the ISM. It is also possible that a buried active galactic nuclei (AGN) produces a large fraction of the unresolved (Fe II) and Pa-beta emission. We briefly discuss these possibilities in light of these new imaging and spectroscopic data.

  11. Large Magellanic Cloud Near-infrared Synoptic Survey. IV. Leavitt Laws for Type II Cepheid Variables

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Anupam; Macri, Lucas M.; Rejkuba, Marina; Kanbur, Shashi M.; Ngeow, Chow-Choong; Singh, Harinder P.

    2017-04-01

    We present time-series observations of Population II Cepheids in the Large Magellanic Cloud at near-infrared (JHK s ) wavelengths. Our sample consists of 81 variables with accurate periods and optical (VI) magnitudes from the OGLE survey, covering various subtypes of pulsators (BL Herculis, W Virginis, and RV Tauri). We generate light-curve templates using high-quality I-band data in the LMC from OGLE and K s -band data in the Galactic bulge from VISTA Variables in Via Láctea survey and use them to obtain robust mean magnitudes. We derive period–luminosity (P–L) relations in the near-infrared and Period–Wesenheit (P–W) relations by combining optical and near-infrared data. Our P–L and P–W relations are consistent with published work when excluding long-period RV Tauris. We find that Pop II Cepheids and RR Lyraes follow the same P–L relations in the LMC. Therefore, we use trigonometric parallax from the Gaia DR1 for VY Pyx and the Hubble Space Telescope parallaxes for k Pav and 5 RR Lyrae variables to obtain an absolute calibration of the Galactic K s -band P–L relation, resulting in a distance modulus to the LMC of {μ }{LMC}=18.54+/- 0.08 mag. We update the mean magnitudes of Pop II Cepheids in Galactic globular clusters using our light-curve templates and obtain distance estimates to those systems, anchored to a precise late-type eclipsing binary distance to the LMC. We find that the distances to these globular clusters based on Pop II Cepheids are consistent (within 2σ ) with estimates based on the {M}V-[{Fe}/{{H}}] relation for horizontal branch stars.

  12. CASSIS: The Cornell Atlas of Spitzer/Infrared Spectrograph Sources. II. High-resolution Observations

    NASA Astrophysics Data System (ADS)

    Lebouteiller, V.; Barry, D. J.; Goes, C.; Sloan, G. C.; Spoon, H. W. W.; Weedman, D. W.; Bernard-Salas, J.; Houck, J. R.

    2015-06-01

    The Infrared Spectrograph (IRS) on board the Spitzer Space Telescope observed about 15,000 objects during the cryogenic mission lifetime. Observations provided low-resolution (R=λ /{Δ }λ ≈ 60-127) spectra over ≈ 5-38 μm and high-resolution (R≈ 600) spectra over 10-37 μm. The Cornell Atlas of Spitzer/IRS Sources (CASSIS) was created to provide publishable quality spectra to the community. Low-resolution spectra have been available in CASSIS since 2011, and here we present the addition of the high-resolution spectra. The high-resolution observations represent approximately one-third of all staring observations performed with the IRS instrument. While low-resolution observations are adapted to faint objects and/or broad spectral features (e.g., dust continuum, molecular bands), high-resolution observations allow more accurate measurements of narrow features (e.g., ionic emission lines) as well as a better sampling of the spectral profile of various features. Given the narrow aperture of the two high-resolution modules, cosmic ray hits and spurious features usually plague the spectra. Our pipeline is designed to minimize these effects through various improvements. A super-sampled point-spread function was created in order to enable the optimal extraction in addition to the full aperture extraction. The pipeline selects the best extraction method based on the spatial extent of the object. For unresolved sources, the optimal extraction provides a significant improvement in signal-to-noise ratio over a full aperture extraction. We have developed several techniques for optimal extraction, including a differential method that eliminates low-level rogue pixels (even when no dedicated background observation was performed). The updated CASSIS repository now includes all the spectra ever taken by the IRS, with the exception of mapping observations.

  13. Enhanced infrared detectors using resonant structures combined with thin type-II superlattice absorbers

    SciTech Connect

    Goldflam, Michael D.; Kadlec, Emil Andrew; Olson, Ben V.; Klem, John F.; Hawkins, Samuel D.; Parameswaran, S.; Coon, Wesley Thomas; Keeler, Gordon Arthur; Fortune, Torben Ray; Tauke-Pedretti, Anna; Wendt, Joel R.; Shaner, Eric A.; Davids, Paul S.; Kim, Jin K.; Peters, David W.

    2016-12-22

    Here we examined the spectral responsivity of a 1.77μm thick type-II superlattice based long-wave infrared detector in combination with metallic nanoantennas. Coupling between the Fabry-Pérot cavity formed by the semiconductor layer and the resonant nanoantennas on its surface enables spectral selectivity, while also increasing peak quantum efficiency to over 50%. Electromagnetic simulations reveal that this high responsivity is a direct result of field-enhancement in the absorber layer, enabling significant absorption in spite of the absorber’s subwavelength thickness. Notably, thinning of the absorbing material could ultimately yield lower photodetector noise through a reduction in dark current while improving photocarrier collection efficiency. The temperature- and incident-angle-independent spectral response observed in these devices allows for operation over a wide range of temperatures and optical systems. This detector paradigm demonstrates potential benefits to device performance with applications throughout the infrared.

  14. Enhanced infrared detectors using resonant structures combined with thin type-II superlattice absorbers

    DOE PAGES

    Goldflam, Michael D.; Kadlec, Emil Andrew; Olson, Ben V.; ...

    2016-12-22

    Here we examined the spectral responsivity of a 1.77μm thick type-II superlattice based long-wave infrared detector in combination with metallic nanoantennas. Coupling between the Fabry-Pérot cavity formed by the semiconductor layer and the resonant nanoantennas on its surface enables spectral selectivity, while also increasing peak quantum efficiency to over 50%. Electromagnetic simulations reveal that this high responsivity is a direct result of field-enhancement in the absorber layer, enabling significant absorption in spite of the absorber’s subwavelength thickness. Notably, thinning of the absorbing material could ultimately yield lower photodetector noise through a reduction in dark current while improving photocarrier collection efficiency.more » The temperature- and incident-angle-independent spectral response observed in these devices allows for operation over a wide range of temperatures and optical systems. This detector paradigm demonstrates potential benefits to device performance with applications throughout the infrared.« less

  15. Enhanced infrared detectors using resonant structures combined with thin type-II superlattice absorbers

    NASA Astrophysics Data System (ADS)

    Goldflam, M. D.; Kadlec, E. A.; Olson, B. V.; Klem, J. F.; Hawkins, S. D.; Parameswaran, S.; Coon, W. T.; Keeler, G. A.; Fortune, T. R.; Tauke-Pedretti, A.; Wendt, J. R.; Shaner, E. A.; Davids, P. S.; Kim, J. K.; Peters, D. W.

    2016-12-01

    We examined the spectral responsivity of a 1.77 μm thick type-II superlattice based long-wave infrared detector in combination with metallic nanoantennas. Coupling between the Fabry-Pérot cavity formed by the semiconductor layer and the resonant nanoantennas on its surface enables spectral selectivity, while also increasing peak quantum efficiency to over 50%. Electromagnetic simulations reveal that this high responsivity is a direct result of field-enhancement in the absorber layer, enabling significant absorption in spite of the absorber's subwavelength thickness. Notably, thinning of the absorbing material could ultimately yield lower photodetector noise through a reduction in dark current while improving photocarrier collection efficiency. The temperature- and incident-angle-independent spectral response observed in these devices allows for operation over a wide range of temperatures and optical systems. This detector paradigm demonstrates potential benefits to device performance with applications throughout the infrared.

  16. The infrared emission of G333.6-0.2 - An extremely nonspherical H II region

    NASA Technical Reports Server (NTRS)

    Hyland, A. R.; Mcgregor, P. J.; Robinson, G.; Thomas, J. A.; Becklin, E. E.; Gatley, I.; Werner, M. W.

    1980-01-01

    The southern H II region G333.6-0.2, which has a total luminosity of 3.3 million solar luminosities (for an assumed distance of 4 kpc) was mapped at 2.2, 10, 30, 50, and 100 microns. At all wavelengths, the surface brightness of the infrared radiation is unusually high and the structure of the source is compact and symmetrical. The present observations, along with previous data, suggest that G333.6-0.2 is excited by a single luminous object or a very compact cluster, which has formed on the front surface of a dense molecular cloud as seen from the earth. It is shown that the spectral and spatial characteristics of the infrared radiation can be understood in terms of this blister model.

  17. The [C II] 158 Micron Line in Ultraluminous Infrared Galaxies Revisited

    NASA Technical Reports Server (NTRS)

    Luhman, M. L.; Satyapal, S.; Fischer, J.; Wolfire, M. G.; Sturm, E.; Dudley, C. C.; Lutz, D.; Genzel, R.

    2003-01-01

    We present a study of the [C II] 157.74 micron fine-structure line in a sample of 15 ultraluminous infrared (IR) galaxies (IR luminosity L(sub IR greater than or equal to 10(exp 12)L.; ULIRGs) using the Long Wavelength Spectrometer (LWS) on the Infrared Space Observatory (ISO). We confirm the observed order of magnitude deficit (compared to normal and starburst galaxies) in the strength of the [C II] line relative to the far-infrared (FIR) dust continuum emission found in our initial report, but here with a sample that is twice as large. This result suggests that the deficit is a general phenomenon affecting 4 out of 5 ULIRGs. We present an analysis using observations of generally acknowledged photodissociation region (PDR) tracers ([C II], [OI] 63 and 145 micron, and FIR continuum emission), which suggests that a high ultraviolet flux G(sub 0) incident on a moderate density n PDR could explain the deficit. However, comparisons with other ULIRG observations, including CO (1-0), [C I] (1-0), and 6.2 micron polycyclic aromatic hydrocarbon (PAH) emission, suggest that high G(sub 0)/n PDRs alone cannot produce a self-consistent solution that is compatible with all of the observations. We propose that non-PDR contributions to the FIR continuum can explain the apparent [C II] deficiency. Here, unusually high G(sub 0) and/ or n physical conditions in ULIRGs as compared to those in normal and starburst galaxies are not required to explain the [C II] deficit. Dust-bounded photoionization regions, which generate much of the FIR emission but do not contribute significant [C II] emission, offer one possible physical origin for this additional non-PDR component. Such environments may also contribute to the observed suppression of FIR fine-structure emission from ionized gas and PAHs, as well as the warmer FIR colors found in ULIRGs. The implications for observations at higher redshifts are also revisited.

  18. Fourier transform infrared spectrum of the radical cation of beta-carotene photoinduced in photosystem II.

    PubMed

    Noguchi, T; Mitsuka, T; Inoue, Y

    1994-12-19

    A Fourier-transform infrared (FTIR) spectrum of the radical cation of beta-carotene photoinduced in photosystem II (PSII) membranes was obtained at 80K under oxidizing conditions, by utilizing the light-induced FTIR difference technique. Formation of the beta-carotene cation was monitored with the electronic absorption band at 993 nm. An FTIR spectrum of a chemically-generated beta-carotene cation in chloroform was also measured and compared with the spectrum of PSII. Since the FTIR bands of carotenoid cation have characteristic features with strong intensities, they can be useful markers in studying the reaction of carotenoid in PSII.

  19. The [C II] 158 Micron Line Deficit in Ultraluminous Infrared Galaxies Revisited

    DTIC Science & Technology

    2003-09-10

    THE [C ii] 158 MICRON LINE DEFICIT IN ULTRALUMINOUS INFRARED GALAXIES REVISITED1 M. L. Luhman ,2,3 S. Satyapal,4,5,6 J. Fischer,2 M. G.Wolfire,7 E...INTRODUCTION In a previous study ( Luhman et al. 1998, hereafter Paper I), we reported measurements of the 157.74 lm 2P3=2 2P1=2 fine-structure line of C+ in...4945, NGC 1068, and Circinus), in order to compare the ULIRG distribution with that of normal and starburst galaxies only. 762 LUHMAN ET AL. Vol. 594

  20. Ultrafast infrared observation of exciton equilibration from oriented single crystals of photosystem II

    NASA Astrophysics Data System (ADS)

    Kaucikas, Marius; Maghlaoui, Karim; Barber, Jim; Renger, Thomas; van Thor, Jasper J.

    2016-12-01

    In oxygenic photosynthesis, two photosystems work in series. Each of them contains a reaction centre that is surrounded by light-harvesting antennae, which absorb the light and transfer the excitation energy to the reaction centre where electron transfer reactions are driven. Here we report a critical test for two contrasting models of light harvesting by photosystem II cores, known as the trap-limited and the transfer-to-the trap-limited model. Oriented single crystals of photosystem II core complexes of Synechococcus elongatus are excited by polarized visible light and the transient absorption is probed with polarized light in the infrared. The dichroic amplitudes resulting from photoselection are maintained on the 60 ps timescale that corresponds to the dominant energy transfer process providing compelling evidence for the transfer-to-the-trap limitation of the overall light-harvesting process. This finding has functional implications for the quenching of excited states allowing plants to survive under high light intensities.

  1. The appearance of dusty H II blisters at radio and infrared wavelengths

    NASA Technical Reports Server (NTRS)

    Icke, V.; Gatley, I.; Israel, F. P.

    1980-01-01

    Detailed calculations for the observational appearance of nonspherical Stromgren regions at radio and infrared wavelengths are presented. The computations are made feasible by two assumptions, namely (1) no stellar photon leaves the solid angle within which it was emitted, and (2) the radiation spectrum can be represented by three delta functions corresponding to Lyman continuum, Lyman alpha, and softer radiation. These calculations are used to develop models for the H II blisters M17 A and 30 Doradus, and also first order parameters for a sample of other well-studied galactic H II regions. It is concluded that the observations are well explained by an ionizing object in a density gradient, without the need for peculiar dust properties or distribution.

  2. Effect of hole transport on performance of infrared type-II superlattice light emitting diodes

    SciTech Connect

    Lin, Youxi; Suchalkin, Sergey; Kipshidze, Gela; Hosoda, Takashi; Westerfeld, David; Shterengas, Leon; Belenky, Gregory; Laikhtman, Boris

    2015-04-28

    The effect of hole transport on the performance of infrared light emitting diodes (LED) was investigated. The active area of the LEDs comprised two type-II superlattices with different periods and widths connected in series. Electroluminescence spectra of the devices with different positions of long wave and mid wave superlattice sections were mostly contributed by the superlattice closest to the p-contact. The experimental results indicate that due to suppressed vertical hole transport, the recombination of electrically injected electrons and holes in a type II superlattice LED active region takes place within a few superlattice periods near p-barrier. Possible reason for the effect is reduction of hole diffusion coefficient in an active area of a superlattice LED under bias.

  3. Optically faint radio sources: reborn AGN?

    NASA Astrophysics Data System (ADS)

    Filho, M. E.; Brinchmann, J.; Lobo, C.; Antón, S.

    2011-12-01

    We present our discovery of several relatively strong radio sources in the field-of-view of SDSS galaxy clusters that have no optical counterparts down to the magnitude limits of the SDSS. The optically faint radio sources appear as double-lobed or core-jet objects in the FIRST radio images and have projected angular sizes ranging from 0.5 to 1.0 arcmin. We followed-up these sources with near-infrared imaging using the wide-field imager HAWK-I on the VLT. We detected Ks-band emitting regions, about 1.5 arcsec in size and coincident with the centers of the radio structures, in all sources, with magnitudes in the range 17-20 mag. We used spectral modelling to characterize the sample sources. In general, the radio properties are similar to those observed in 3CRR sources but the optical-radio slopes are consistent with those of moderate to high redshift (z < 4) gigahertz-peaked spectrum sources. Our results suggest that these unusual objects are galaxies whose black hole has been recently re-ignited but that retain large-scale radio structures, which are signatures of previous AGN activity.

  4. Faint dwarfs in nearby groups

    SciTech Connect

    Speller, Ryan; Taylor, James E. E-mail: taylor@uwaterloo.ca

    2014-06-20

    The number and distribution of dwarf satellite galaxies remain a critical test of cold dark matter-dominated structure formation on small scales. Until recently, observational information about galaxy formation on these scales has been limited mainly to the Local Group. We have searched for faint analogues of Local Group dwarfs around nearby bright galaxies, using a spatial clustering analysis of the photometric catalog of the Sloan Digital Sky Survey (SDSS) Data Release 8. Several other recent searches of SDSS have detected clustered satellite populations down to Δm{sub r} ≡ (m{sub r,} {sub sat} – m{sub r,} {sub main}) ∼ 6-8, using photometric redshifts to reduce background contamination. SDSS photometric redshifts are relatively imprecise, however, for faint and nearby galaxies. Instead, we use angular size to select potential nearby dwarfs and consider only the nearest isolated bright galaxies as primaries. As a result, we are able to detect an excess clustering signal from companions down to Δm{sub r} = 12, 4 mag fainter than most recent studies. We detect an overdensity of objects at separations <400 kpc, corresponding to about 4.6 ± 0.5 satellites per central galaxy, consistent with the satellite abundance expected from the Local Group, given our selection function. Although the sample of satellites detected is incomplete by construction, since it excludes the least and most compact dwarfs, this detection provides a lower bound on the average satellite luminosity function, down to luminosities corresponding to the faintest ''classical'' dwarfs of the Local Group.

  5. Multifunctional in vivo vascular imaging using near-infrared II fluorescence

    PubMed Central

    Hong, Guosong; Lee, Jerry C.; Robinson, Joshua T.; Raaz, Uwe; Xie, Liming; Huang, Ngan F.; Cooke, John P.; Dai, Hongjie

    2013-01-01

    In vivo real-time epifluorescence imaging of mouse hindlimb vasculatures in the second near-infrared region (NIR-II, 1.1–1.4 µm) is performed using single-walled carbon nanotubes (SWNTs) as fluorophores. Both high spatial resolution (~30 µm) and temporal resolution (<200 ms/frame) for small vessel imaging are achieved 1~3 mm deep in the tissue owing to the beneficial NIR-II optical window that affords deep anatomical penetration and low scattering. This spatial resolution is unattainable by traditional NIR imaging (NIR-I, 0.75–0.9 µm) or microscopic computed tomography (micro-CT), while the temporal resolution far exceeds scanning microscopic imaging techniques. Arterial and venous vessels are unambiguously differentiated using a dynamic contrast-enhanced NIR-II imaging technique based on their distinct hemodynamics. Further, the deep tissue penetration, high spatial and temporal resolution of NIR-II imaging allow for precise quantifications of blood velocity in both normal and ischemic femoral arteries, which are beyond the capability of ultrasonography at lower blood velocity. PMID:23160236

  6. The ISO-IRAS Faint Galaxy Survey

    NASA Technical Reports Server (NTRS)

    Smith, Harding E.

    1999-01-01

    As part of the ISO-IRAS Faint Galaxy Survey ISO Satellite observations of over 600 IRAS sources have been obtained with the ISOCAM instrument. Because our survey strategy involved relatively short integrations, great care was required in developing analysis software including cosmic-ray and transient removal and calibration. These observations have now been through final pipeline processing at IPAC and ground-based follow-up is ongoing. The observations are for sources from two samples: a " Filler' sample selected to be at z greater than 0.1 and a fainter sample which selected for the highest redshift galaxies in the IRAS survey, with redshifts 0.2 less than z less than 1.0. I now have obtained ground-based follow-up spectrophotometry at Lick and Palomar observatories for 100 LFIRGs with 0.1 less than z less than 0.7. Our observations have confirmed that these systems are comparable to nearby LFIRGs such as Arp 220, with L (sub -)(fir) greater than 10(exp 11) L(sub -) sun and typically HII/Liner optical excitation. About 10% of the galaxies show true AGN (Sy2) excitation. Based on our work on a nearby complete sample of LFIRGS, we believe that the majority of these systems are luminous Starbursts, thus this project is tracing the luminous end of the galaxy star-forming luminosity function - the (infrared) star-formation history of the Universe to z approx. 1, a topic of some considerable recent interest. A by-product of these ISOCAM observations is approximately 1 square degree of deep 2 microns pointings outside the IRAS error boxes, allowing us an independent estimate of the mid-infrared log N - log S relation. Ground-based observations of this sample are continuing.

  7. Development status of Type-II superlattice infrared detector in JAXA

    NASA Astrophysics Data System (ADS)

    Sakai, Michito; Murooka, Junpei; Kumeta, Ayaka; Katayama, Haruyoshi; Kimura, Toshiyoshi; Inada, Hiroshi; Iguchi, Yasuhiro; Hiroe, Yuta; Kimata, Masafumi

    2016-09-01

    One of JAXA's future missions, using an imaging Fourier Transform Spectrometer (FTS), require the focal plane array (FPA) that has high sensitivity and a very long-wavelength infrared (VLWIR) cutoff wavelength. Since a Type-II superlattice (T2SL) is the only known infrared material to have a theoretically predicted performance superior to that of HgCdTe and the cutoff wavelength can be tailored in the wavelength region of 3-30 μm, we started the research and development of the T2SL detector in 2009. In order to confirm our final goal which is to realize an FPA with a cutoff wavelength of 15 μm, we fabricated InAs/GaInSb T2SL infrared detectors with a cutoff wavelength of 15 μm. We show the results of the dark current and responsivity measurement of single pixel detectors and the development status of FPAs including the image taken by a 320 × 256 InAs/GaInSb T2SL FPA with a cutoff wavelength of 15 μm.

  8. The infrared echo of Type II supernovae with circumstellar dust shells. II - A probe into the presupernova evolution of the progenitor star

    NASA Technical Reports Server (NTRS)

    Dwek, E.

    1985-01-01

    This paper studies the spectral appearance and evolution of the infrared light curve, also referred to as the infrared echo, of Type II supernovae embedded in carbon- or oxygen-rich circumstellar dust shells. The distinct spectral signature of the echo and its temporal evolution can be used to estimate the mass of the shell and identify the composition of the dust. Since the shell mass and dust composition are determined by the combined effect of stellar mass loss and the dredging of newly synthesized heavy elements to the stellar surface, observations of the infrared echo may provide useful clues to the presupernova evolution of the progenitor star.

  9. Interpretation of colors of faint galaxies

    SciTech Connect

    Kron, R.G.

    1980-10-01

    We present new calculations for evolving light in galaxies which allow the color distribution expected for faint field galaxies to be computed. We normalize the expected counts to data in catalogs of bright galaxies, and find that an excellent fit to Kron's faint photometry can be achieved with a Friedmann model and no other special assumptions.

  10. J-Band Infrared Spectroscopy of a Sample of Brown Dwarfs Using NIRSPEC on Keck II.

    PubMed

    McLean; Wilcox; Becklin; Figer; Gilbert; Graham; Larkin; Levenson; Teplitz; Kirkpatrick

    2000-04-10

    Near-infrared spectroscopic observations of a sample of very cool, low-mass objects are presented with higher spectral resolution than in any previous studies. Six of the objects are L dwarfs, ranging in spectral class from L2 to L8/9, and the seventh is a methane or T dwarf. These new observations were obtained during commissioning of the near-infrared spectrometer (NIRSPEC), the first high-resolution near-infrared cryogenic spectrograph for the Keck II 10 m telescope on Mauna Kea, Hawaii. Spectra with a resolving power of R approximately 2500 from 1.135 to 1.360 µm (approximately J band) are presented for each source. At this resolution, a rich spectral structure is revealed, much of which is due to blending of unresolved molecular transitions. Strong lines due to neutral potassium (K i) and bands due to iron hydride (FeH) and steam (H2O) change significantly throughout the L sequence. Iron hydride disappears between L5 and L8, the steam bands deepen, and the K i lines gradually become weaker but wider because of pressure broadening. An unidentified feature occurs at 1.22 µm that has a temperature dependence like FeH but has no counterpart in the available FeH opacity data. Because these objects are 3-6 mag brighter in the near-infrared compared with the I band, spectral classification is efficient. One of the objects studied (2MASSW J1523+3014) is the coolest L dwarf discovered so far by the 2 Micron All-Sky Survey (2MASS), but its spectrum is still significantly different from the methane-dominated objects such as Gl 229B or SDSS 1624+0029.

  11. An Infrared Spectroscopy Study Of Pb(II) And Siderophore Sorption To Montmorillonite

    NASA Astrophysics Data System (ADS)

    Maurice, P. A.; Hunter, E. L.; Quicksall, A. N.; Haack, E.; Johnston, C. T.

    2010-12-01

    Aerobic microorganisms exude low molecular weight organic ligands known as siderophores in order to acquire nutrient Fe. Because siderophores can also bind other metals such as Pb, Zn, and Cd, they may affect metal sorption, fate, and transport. This study combined batch sorption experiments, thermodynamic modeling, X-ray diffraction (XRD), and spectroscopic analysis, to investigate Pb(II) and desferrioxamine B (DFOB) sorption to montmorillonite, alone and in combination, at pH 3-9, ~22 C, and in 0.1 M NaCl. Samples at pH 3, 5.5, and 7.5 were analyzed by XRD and Fourier-Transform Infrared Spectroscopy (FTIR) and samples at pH5.5 were analyzed by in-situ Attenuated Total Reflection Infrared Spectroscopy (ATR-FTIR). DFOB does not bind Pb substantially at pH 3, and sorption results showed that the ligand only minimally affects Pb sorption at this pH. However, combination of batch sorption experiments with XRD, FTIR, and ATR-FTIR analysis suggested that Pb(II)/DFOB (co)absorption in the interlayer is likely an important sorption mechanism at pH 5.5 and 7.5 under both air-dried and aqueous conditions. The precise structure of the sorption complex(es) could not be determined by these methods. Some adsorption of Pb(II)/DFOB to the external clay surface is also possible. In the absence of DFOB, a Pb-carbonate complex or precipitate (perhaps hydrocerrusite) was detected by FTIR. Overall, results showed that a microbial siderophore may affect Pb sorption to montmorillonite, that (co)absorption in the interlayer region can be important, and that sorption effects can vary substantially depending upon solution conditions.

  12. Platinum (II) azatetrabenzoporphyrins for near-infrared organic light emitting diodes

    NASA Astrophysics Data System (ADS)

    Huang, L.; Park, C. D.; Fleetham, T.; Li, J.

    2016-12-01

    This article describes a series of platinum (II) azatetrabenzoporphyrin emitters for near-infrared (NIR) organic light emitting diode (OLED) applications. Platinum (II) aza-triphenyltetrabenzoporphyrin (PtNTBP) results in a 72 nm shift in the photoluminescent (PL) emission spectrum to 842 nm compared to 770 nm of the platinum (II) tetraphenyltetrabenzoporphyrin (PtTPTBP). Also, the full width at half maximum of the emission spectrum of PtNTBP was significantly narrowed to 27 nm compared to 40 nm for PtTPTBP. The multilayer devices fabricated by thermal vacuum evaporation process employing PtTPTBP, PtNTBP, and cis-PtN2TBP exhibit electroluminescent (EL) emission peak at 770 nm, 848 nm, and 846 nm with the peak external quantum efficiency (EQE) of 8.0%, 2.8%, and 1.5%, respectively. Even with the decrease in EQE of devices employing PtNTBP and cis-PtN2TBP compared with those employing PtTPTBP, the combination of the spectral narrowing and the bathochromic shift to lower energy EL emission demonstrates the promise of PtNTBP for NIR applications. In the meanwhile, the solution-processed single-layer device using PtNTBP demonstrates the EQE of 0.33% and the peak EL emission at 844 nm.

  13. HUBBLE'S SEARCH FOR FAINT FIELD STARS IN GALACTIC HALO

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Left A NASA Hubble Space Telescope image of a randomly selected area of sky taken to search for faint red stars that might constitute dark matter in our Milky Way Galaxy. (Dark matter is material of an unknown type that makes up most of the mass of our galaxy). If the dark matter in our Galaxy was made of faint red stars -- as many scientists have previously conjectured -- then about 38 such stars should have been visible in this HST image. The simulated stars (diamond-shaped symbols), based on theoretical calculations, illustrate what scientists would have seen if the dark matter were locked-up in faint red stars. These surprising results rule out dim stars as an explanation for dark matter in our Galaxy. Right The unmodified HST image shows the region is actually so devoid of stars that far more distant background galaxies can easily be seen. The field is in the constellation Eridanus, far outside the plane of our Milky Way Galaxy. This region was chosen to highlight stars in the galactic halo, where dark matter exists, and to avoid the contribution of faint stars in the plane of the Galaxy. Technical Information: The image was constructed from seven exposures totaling almost three hours of searching by HST. The field shown is about 1.5 arc-minutes across. The image was taken in near-infrared light (814 nm) with the Wide Field Planetary Camera 2, on Feb 8, 1994. This observation is part of the HST parallel observing program. Credit: J Bahcall, Institute for Advance Study, Princeton and NASA

  14. Faint High-Latitude Carbon Stars

    NASA Astrophysics Data System (ADS)

    Green, Paul J.

    1992-10-01

    Since carbon giants are ideal for study of the structure and kinematics of the outer galactic halo, we have undertaken a wide-area survey to search for faint high-latitude carbon (FHLC) stars. We use two-color photometric selection with large format CCDs to cover 52 deg^2 of sky to a depth of about V=18. Below this limit, we find good (< 20%) agreement between our object counts as a function of magnitude and the galactic models of Bahcall and Coneira (1984) at a variety of latitudes and longitudes. Our spectroscopic followup began with low-resolution spectra of 19 unconfirmed C-star candidates from the Case objective-prism photographic survey of Sanduleak and Pesch (1988). Four of these we find to be M stars. The 15 C stars we classify on the two-parameter Keenan-Morgan (1941) system as warm (color class < 4), with moderate to weak carbon band strengths (C class < 3). Of 94 faint C-star candidates from our own CCD survey, one highly ranked V=17 candidate was found to have strong carbon and CN bands. We estimate that to a depth of V=18, the surface density of FHLC stars is 0.019^0.044_-0.016 deg^-2. We identify two FHLC stars with previously cataloged high-proper-motion objects. These objects are thus inferred to be dwarf carbon (dC) stars, supplementing the one previously known case, G 77-61. Not all dC stars will have detectable proper motions, so other luminosity/distance indicators are needed: we find that C dwarfs all have similar JHK colors, and possibly an unusually strong lambda-6191 bandhead of carbon. By comparing positions of the HST Guide Star Catalog and the original Palomar Observatory Sky Survey, we detect proper motions in two additional FHLC stars. Our proper-motion survey, spanning a 30-yr base line, thus identifies four new dC's, and provides proper-motion upper limits for another 44 FHLC stars. Kinematic simulations suggest that virtually all Population II dCs will have detectable proper motions in a survey as sensitive as our own, and that to a

  15. Strain-balanced Si/SiGe type-II superlattices for near-infrared photodetection

    SciTech Connect

    Ali, Dyan; Richardson, Christopher J. K.

    2014-07-21

    Strain balanced silicon-silicon germanium type-II superlattice p-i-n photodetectors grown on a silicon germanium relaxed buffer layer are shown to exhibit an absorption band that extends beyond 0.7 eV (λ = 1.77 μm) with dark current densities of 27 μA cm{sup −2}. Simulations of the absorption edge, which are based on x-ray diffraction characterization, low observed dark current densities, and low dislocation densities, are consistent with fully strained heterostructures. Potential applications for devices made from this heterostructure design could include integrated silicon detectors, or low-noise absorption regions for infrared-extended silicon based avalanche photodiodes.

  16. Infrared and optical studies of the Chamaeleon II and Lupus low-mass star forming regions .

    NASA Astrophysics Data System (ADS)

    Spezzi, L.; Alcalá, J. M.; Chapman, N.; Covino, E.; Evans, N. J., II; Frasca, A.; Gandolfi, D.; Huard, T. L.; Oliveira, I.; Jørgensen, J. K.; Merín, B.; Stapelfeldt, K. R.

    The Spitzer Legacy survey ``From Molecular Cores to Planet-forming Disks'' \\citep[c2d][]{Eva03} provided infrared observations of sources that span the evolutionary sequence from molecular cores to proto-planetary disks, encompassing a wide range of star-forming environments. These overall observations allowed to study crucial steps in the formation of stars and planets with unprecedented sensitivity. We present some results from the Spitzer observations and complementary data in the low-mass star forming regions in Chamaeleon II and Lupus. We focus, in particular, on the star-formation history and activity of these clouds, the low-mass end of their IMF and the envelope/disk properties of their young populations.

  17. The infrared CA II triplet - A luminosity indicator for stellar population synthesis

    NASA Astrophysics Data System (ADS)

    Jones, J. E.; Alloin, D. M.; Jones, B. J. T.

    1984-08-01

    The authors study the properties of the Ca II infrared triplet (Ca T) from a sample of Reticon spectra of 62 stars. The stars range over spectral types B though mid-M, and the sample spans some four orders of magnitude in gravity g, and almost a factor of 10 in metallicity. It is found that, over all spectral types, from F to mid-M, and over this large gravity interval, the equivalent width of Ca T correlates strongly with log g. This is an almost one-valued relation, being relatively insensitive to metallicity. Thus, since most of the light from galaxies is thought to come from G and K stars, the Ca T feature should be a useful tool for constraining the dwarf: giant ratio of the light-dominant stellar population. Existing measurements of Ca T are applied in an analysis of the stellar content in the nucleus of M31.

  18. Far Infrared Spectroscopy of H II Regions. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Ward, D. B.

    1975-01-01

    The far infrared spectra of H II regions are investigated. A liquid helium cooled grating spectrometer designed to make observations from the NASA Lear Jet is described along with tests of the instrument. The observing procedure on the Lear Jet telescope is described and the method of data analysis is discussed. Results are presented from a search for the (O III) 88.16 micron line. An upper limit on the emission in this line is obtained and line detection is described. Results are compared to theoretical predictions, and future applications of fine structure line observations are discussed. Coarse resolution results are given along with calibration problems. The spectra obtained are compared to models for dust emission.

  19. Hole effective masses and subband splitting in type-II superlattice infrared detectors

    NASA Astrophysics Data System (ADS)

    Ting, David Z.; Soibel, Alexander; Gunapala, Sarath D.

    2016-05-01

    We explore band structure effects to help determine the suitability of n-type type-II superlattice (T2SL) absorbers for infrared detectors. It is often assumed that the exceedingly large growth-direction band-edge curvature hole effective mass in n-type long wavelength infrared (LWIR) T2SL would lead to low hole mobility and therefore low detector collection quantum efficiency. We computed the thermally averaged conductivity effective mass and show that the LWIR T2SL hole conductivity effective mass along the growth direction can be orders of magnitude smaller than the corresponding band-edge effective mass. LWIR InAs/GaSb T2SL can have significantly smaller growth-direction hole conductivity effective mass than its InAs/InAsSb counterpart. For the InAs/InAsSb T2SL, higher Sb fraction is more favorable for hole transport. Achieving long hole diffusion length becomes progressively more difficult for the InAs/InAsSb T2SL as the cutoff wavelength increases, since its growth-direction hole conductivity effective mass increases significantly with decreasing band gap. However, this is mitigated by the fact that the splitting between the top valence subbands also increases with the cutoff wavelength, leading to reduced inter-subband scattering and increased relaxation time.

  20. Ultrafast infrared observation of exciton equilibration from oriented single crystals of photosystem II

    PubMed Central

    Kaucikas, Marius; Maghlaoui, Karim; Barber, Jim; Renger, Thomas; van Thor, Jasper J.

    2016-01-01

    In oxygenic photosynthesis, two photosystems work in series. Each of them contains a reaction centre that is surrounded by light-harvesting antennae, which absorb the light and transfer the excitation energy to the reaction centre where electron transfer reactions are driven. Here we report a critical test for two contrasting models of light harvesting by photosystem II cores, known as the trap-limited and the transfer-to-the trap-limited model. Oriented single crystals of photosystem II core complexes of Synechococcus elongatus are excited by polarized visible light and the transient absorption is probed with polarized light in the infrared. The dichroic amplitudes resulting from photoselection are maintained on the 60 ps timescale that corresponds to the dominant energy transfer process providing compelling evidence for the transfer-to-the-trap limitation of the overall light-harvesting process. This finding has functional implications for the quenching of excited states allowing plants to survive under high light intensities. PMID:28008915

  1. 450 d of Type II SN 2013ej in optical and near-infrared

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Jerkstrand, A.; Valenti, S.; Sollerman, J.; Seitenzahl, I. R.; Pastorello, A.; Schulze, S.; Chen, T.-W.; Childress, M. J.; Fraser, M.; Fremling, C.; Kotak, R.; Ruiter, A. J.; Schmidt, B. P.; Smartt, S. J.; Taddia, F.; Terreran, G.; Tucker, B. E.; Barbarino, C.; Benetti, S.; Elias-Rosa, N.; Gal-Yam, A.; Howell, D. A.; Inserra, C.; Kankare, E.; Lee, M. Y.; Li, K. L.; Maguire, K.; Margheim, S.; Mehner, A.; Ochner, P.; Sullivan, M.; Tomasella, L.; Young, D. R.

    2016-09-01

    We present optical and near-infrared photometric and spectroscopic observations of SN 2013ej, in galaxy M74, from 1 to 450 d after the explosion. SN 2013ej is a hydrogen-rich supernova, classified as a Type IIL due to its relatively fast decline following the initial peak. It has a relatively high peak luminosity (absolute magnitude MV = -17.6) but a small 56Ni production of ˜0.023 M⊙. Its photospheric evolution is similar to other Type II SNe, with shallow absorption in the Hα profile typical for a Type IIL. During transition to the radioactive decay tail at ˜100 d, we find the SN to grow bluer in B - V colour, in contrast to some other Type II supernovae. At late times, the bolometric light curve declined faster than expected from 56Co decay and we observed unusually broad and asymmetric nebular emission lines. Based on comparison of nebular emission lines most sensitive to the progenitor core mass, we find our observations are best matched to synthesized spectral models with a MZAMS = 12-15 M⊙ progenitor. The derived mass range is similar to but not higher than the mass estimated for Type IIP progenitors. This is against the idea that Type IIL are from more massive stars. Observations are consistent with the SN having a progenitor with a relatively low-mass envelope.

  2. Food for the photometrists - Faint galaxies revealed

    NASA Astrophysics Data System (ADS)

    Malin, D. F.

    The advantages of photographic plates over CCD detectors for some types of astronomical photometry (uniformity over large areas and information-storage capacity) are discussed, and illustrated using images of faint galaxies and faint galactic structures. It is pointed out that the photographic amplification technique (Malin, 1978), although at present only qualitative, is much more time-efficient than digital scanning. Consideration is also given to the production of full-color images by superimposition of B, V, and R plates.

  3. Infrared

    NASA Astrophysics Data System (ADS)

    Vollmer, M.

    2013-11-01

    'Infrared' is a very wide field in physics and the natural sciences which has evolved enormously in recent decades. It all started in 1800 with Friedrich Wilhelm Herschel's discovery of infrared (IR) radiation within the spectrum of the Sun. Thereafter a few important milestones towards widespread use of IR were the quantitative description of the laws of blackbody radiation by Max Planck in 1900; the application of quantum mechanics to understand the rotational-vibrational spectra of molecules starting in the first half of the 20th century; and the revolution in source and detector technologies due to micro-technological breakthroughs towards the end of the 20th century. This has led to much high-quality and sophisticated equipment in terms of detectors, sources and instruments in the IR spectral range, with a multitude of different applications in science and technology. This special issue tries to focus on a few aspects of the astonishing variety of different disciplines, techniques and applications concerning the general topic of infrared radiation. Part of the content is based upon an interdisciplinary international conference on the topic held in 2012 in Bad Honnef, Germany. It is hoped that the information provided here may be useful for teaching the general topic of electromagnetic radiation in the IR spectral range in advanced university courses for postgraduate students. In the most general terms, the infrared spectral range is defined to extend from wavelengths of 780 nm (upper range of the VIS spectral range) up to wavelengths of 1 mm (lower end of the microwave range). Various definitions of near, middle and far infrared or thermal infrared, and lately terahertz frequencies, are used, which all fall in this range. These special definitions often depend on the scientific field of research. Unfortunately, many of these fields seem to have developed independently from neighbouring disciplines, although they deal with very similar topics in respect of the

  4. Big Fish, Little Fish: Two New Ultra-faint Satellites of the Milky Way

    NASA Astrophysics Data System (ADS)

    Belokurov, V.; Walker, M. G.; Evans, N. W.; Gilmore, G.; Irwin, M. J.; Just, D.; Koposov, S.; Mateo, M.; Olszewski, E.; Watkins, L.; Wyrzykowski, L.

    2010-03-01

    We report the discovery of two new Milky Way satellites in the neighboring constellations of Pisces and Pegasus identified in data from the Sloan Digital Sky Survey. Pisces II, an ultra-faint dwarf galaxy lies at the distance of ~180 kpc, some 15° away from the recently detected Pisces I. Segue 3, an ultra-faint star cluster lies at the distance of 16 kpc. We use deep follow-up imaging obtained with the 4-m Mayall Telescope at Kitt Peak National Observatory to derive their structural parameters. Pisces II has a half-light radius of ~60 pc, while Segue 3 is 20 times smaller at only 3 pc.

  5. A single prolific r-process event preserved in an ultra-faint dwarf galaxy

    NASA Astrophysics Data System (ADS)

    Ji, Alexander; Frebel, Anna; Chiti, Anirudh; Simon, Joshua

    2016-03-01

    The heaviest elements in the periodic table are synthesized through the r-process, but the astrophysical site for r-process nucleosynthesis is still unknown. Ultra-faint dwarf galaxies contain a simple fossil record of early chemical enrichment that may determine this site. Previous measurements found very low levels of neutron-capture elements in ultra-faint dwarfs, preferring supernovae as the r-process site. I present high-resolution chemical abundances of nine stars in the recently discovered ultra-faint dwarf Reticulum II, which display extremely enhanced r-process abundances 2-3 orders of magnitude higher than the other ultra-faint dwarfs. Stars with such extreme r-process enhancements are only rarely found in the Milky Way halo. The r-process abundances imply that the neutron-capture material in Reticulum II was synthesized in a single prolific event that is incompatible with r-process yields from ordinary core-collapse supernovae. Reticulum II provides an opportunity to discriminate whether the source of this pure r-process signature is a neutron star merger or magnetorotationally driven supernova. The single event is also a uniquely stringent constraint on the metal mixing and star formation history of this ultra-faint dwarf galaxy.

  6. THE COORDINATED RADIO AND INFRARED SURVEY FOR HIGH-MASS STAR FORMATION. II. SOURCE CATALOG

    SciTech Connect

    Purcell, C. R.; Hoare, M. G.; Lumsden, S. L.; Urquhart, J. S.; Cotton, W. D.; Chandler, C.; Churchwell, E. B.; Diamond, P.; Fuller, G.; Garrington, S. T.; Dougherty, S. M.; Fender, R. P.; Gledhill, T. M.; Goldsmith, P. F.; Hindson, L.; Jackson, J. M.; Kurtz, S. E.; Marti, J. [Departamento de Fisica, EPSJ, Universidad de Jaen, Campus Las Lagunillas s and others

    2013-03-01

    The CORNISH project is the highest resolution radio continuum survey of the Galactic plane to date. It is the 5 GHz radio continuum part of a series of multi-wavelength surveys that focus on the northern GLIMPSE region (10 Degree-Sign < l < 65 Degree-Sign ), observed by the Spitzer satellite in the mid-infrared. Observations with the Very Large Array in B and BnA configurations have yielded a 1.''5 resolution Stokes I map with a root mean square noise level better than 0.4 mJy beam{sup -1}. Here we describe the data-processing methods and data characteristics, and present a new, uniform catalog of compact radio emission. This includes an implementation of automatic deconvolution that provides much more reliable imaging than standard CLEANing. A rigorous investigation of the noise characteristics and reliability of source detection has been carried out. We show that the survey is optimized to detect emission on size scales up to 14'' and for unresolved sources the catalog is more than 90% complete at a flux density of 3.9 mJy. We have detected 3062 sources above a 7{sigma} detection limit and present their ensemble properties. The catalog is highly reliable away from regions containing poorly sampled extended emission, which comprise less than 2% of the survey area. Imaging problems have been mitigated by down-weighting the shortest spacings and potential artifacts flagged via a rigorous manual inspection with reference to the Spitzer infrared data. We present images of the most common source types found: H II regions, planetary nebulae, and radio galaxies. The CORNISH data and catalog are available online at http://cornish.leeds.ac.uk.

  7. THE SPATIAL EXTENT OF (U)LIRGS IN THE MID-INFRARED. II. FEATURE EMISSION

    SciTech Connect

    DIaz-Santos, T.; Charmandaris, V.; Armus, L.; Stierwalt, S.; Haan, S.; Howell, J. H.; Petric, A. O.; Surace, J. A.; Mazzarella, J. M.; Veilleux, S.; Murphy, E. J.; Appleton, P.; Evans, A. S.; Sanders, D. B.

    2011-11-01

    We present results from the second part of our analysis of the extended mid-infrared (MIR) emission of the GOALS sample based on 5-14 {mu}m low-resolution spectra obtained with the Infrared Spectrograph on Spitzer. We calculate the fraction of extended emission (FEE) as a function of wavelength for all galaxies in the sample, FEE{sub {lambda}}, defined as the fraction of the emission that originates outside of the unresolved central component of a source, and spatially separate the MIR spectrum of a galaxy into its nuclear and extended components. We find that the [Ne II]12.81 {mu}m emission line is as compact as the hot dust MIR continuum, while the polycyclic aromatic hydrocarbon (PAH) emission is more extended. In addition, the 6.2 and 7.7 {mu}m PAH emission is more compact than that of the 11.3 {mu}m PAH, which is consistent with the formers being enhanced in a more ionized medium. The presence of an active galactic nucleus (AGN) or a powerful nuclear starburst increases the compactness and the luminosity surface density of the hot dust MIR continuum, but has a negligible effect on the spatial extent of the PAH emission on kpc-scales. Furthermore, it appears that both processes, AGN and/or nuclear starburst, are indistinguishable in terms of how they modify the integrated PAH-to-continuum ratio of the FEE in (ultra)luminous infrared galaxies ((U)LIRGs). Globally, the 5-14 {mu}m spectra of the extended emission component are homogeneous for all galaxies in the GOALS sample. This suggests that, independently of the spatial distribution of the various MIR features, the physical properties of star formation occurring at distances farther than 1.5 kpc from the nuclei of (U)LIRGs are very similar, resembling local star-forming galaxies with L{sub IR} < 10{sup 11} L{sub sun}, as well as star-formation-dominated ULIRGs at z {approx} 2. In contrast, the MIR spectra of the nuclear component of local ULIRGs and LIRGs are very diverse. These results imply that the observed

  8. Observational studies on the near-infrared unidentified emission bands in galactic H II regions

    SciTech Connect

    Mori, Tamami I.; Onaka, Takashi; Sakon, Itsuki; Ohsawa, Ryou; Bell, Aaron C.; Ishihara, Daisuke; Shimonishi, Takashi

    2014-03-20

    Using a large collection of near-infrared spectra (2.5-5.4 μm) of Galactic H II regions and H II region-like objects, we perform a systematic investigation of astronomical polycyclic aromatic hydrocarbon (PAH) features. Thirty-six objects were observed using the infrared camera on board the AKARI satellite as a part of a director's time program. In addition to the well known 3.3-3.6 μm features, most spectra show a relatively weak emission feature at 5.22 μm with sufficient signal-to-noise ratios, which we identify as the PAH 5.25 μm band (previously reported). By careful analysis, we find good correlations between the 5.25 μm band and both the aromatic hydrocarbon feature at 3.3 μm and the aliphatic hydrocarbon features at around 3.4-3.6 μm. The present results give us convincing evidence that the astronomical 5.25 μm band is associated with C-H vibrations, as suggested by previous studies, and show its potential to probe the PAH size distribution. The analysis also shows that the aliphatic-to-aromatic ratio of I {sub 3.4-3.6} {sub μm}/I {sub 3.3} {sub μm} decreases against the ratio of the 3.7 μm continuum intensity to the 3.3 μm band, I {sub cont,} {sub 3.7} {sub μm}/I {sub 3.3} {sub μm}, which is an indicator of the ionization fraction of PAHs. The midinfrared color of I {sub 9} {sub μm}/I {sub 18} {sub μm} also declines steeply against the ratio of the hydrogen recombination line Brα at 4.05 μm to the 3.3 μm band, I {sub Brα}/I {sub 3.3} {sub μm}. These facts indicate possible dust processing inside or at the boundary of ionized gas.

  9. On the clustering of faint red galaxies

    NASA Astrophysics Data System (ADS)

    Xu, Haojie; Zheng, Zheng; Guo, Hong; Zhu, Ju; Zehavi, Idit

    2016-08-01

    Faint red galaxies in the Sloan Digital Sky Survey show a puzzling clustering pattern in previous measurements. In the two-point correlation function (2PCF), they appear to be strongly clustered on small scales, indicating a tendency to reside in massive haloes as satellite galaxies. However, their weak clustering on large scales suggests that they are more likely to be found in low-mass haloes. The interpretation of the clustering pattern suffers from the large sample variance in the 2PCF measurements, given the small volume of the volume-limited sample of such faint galaxies. We present improved clustering measurements of faint galaxies by making a full use of a flux-limited sample to obtain volume-limited measurements with an increased effective volume. In the improved 2PCF measurements, the fractional uncertainties on large scales drop by more than 40 per cent, and the strong contrast between small-scale and large-scale clustering amplitudes seen in previous work is no longer prominent. From halo occupation distribution modelling of the measurements, we find that a considerable fraction of faint red galaxies to be satellites in massive haloes, a scenario supported by the strong covariance of small-scale 2PCF measurements and the relative spatial distribution of faint red galaxies and luminous galaxies. However, the satellite fraction is found to be degenerate with the slope of the distribution profile of satellites in inner haloes. We compare the modelling results with semi-analytic model predictions and discuss the implications.

  10. Mass fainting in garment factories in Cambodia.

    PubMed

    Eisenbruch, Maurice

    2017-04-01

    This paper reports an ethnographic study of mass fainting among garment factory workers in Cambodia. Research was undertaken in 2010-2015 in 48 factories in Phnom Penh and 8 provinces. Data were collected in Khmer using nonprobability sampling. In participant observation with monks, factory managers, health workers, and affected women, cultural understandings were explored. One or more episodes of mass fainting occurred at 34 factories, of which 9 were triggered by spirit possession. Informants viewed the causes in the domains of ill-health/toxins and supernatural activities. These included "haunting" ghosts at factory sites in the wake of Khmer Rouge atrocities or recent fatal accidents and retaliating guardian spirits at sites violated by foreign owners. Prefigurative dreams, industrial accidents, or possession of a coworker heralded the episodes. Workers witnessing a coworker fainting felt afraid and fainted. When taken to clinics, some showed signs of continued spirit influence. Afterwards, monks performed ritual ceremonies to appease spirits, extinguish bonds with ghosts, and prevent recurrence. Decoded through its cultural motifs of fear and protest, contagion, forebodings, the bloody Khmer Rouge legacy, and trespass, mass fainting in Cambodia becomes less enigmatic.

  11. Optical Spectroscopy of Luminous Infrared Galaxies. II. Analysis of the Nuclear and Long-Slit Data

    NASA Astrophysics Data System (ADS)

    Veilleux, S.; Kim, D.-C.; Sanders, D. B.; Mazzarella, J. M.; Soifer, B. T.

    1995-05-01

    A spectroscopic survey of a sample of 200 luminous IRAS galaxies (LIGs: L_ir_^7^ > 3 x 10^10^ L_sun_; H_0_ = 75 km s^-1^ Mpc^-1^) was carried out using the Palomar 5 meter and University of Hawaii 2.2 m telescopes. Kim et al. (1995) described the data-taking and data-reduction procedures and presented line and continuum measurements extracted from the nucleus of these objects. In this paper, the nuclear data are combined with circumnuclear measurements on 23 of these galaxies to investigate the properties of the line-emitting gas and underlying stellar population in and out of the nucleus. The nuclear spectra of these galaxies were classified as H II region-like" or "AGN-like" using a large number of line-ratio diagnostics corrected for the underlying stellar absorption features. This correction is an important source of errors in some previous studies. The emission-line spectra of many AGNs were found to-be of relatively low ionization level and were therefore classified as LINER. We confirm that both the fraction of LIGs with AGN spectra and the fraction of Seyferts among the AGN increase with infrared luminosity, reaching values of 62% and 54% at the highest observed luminosities, respectively. The fraction of LINERs, on the other hand, is relatively constant at ~27%. The source of the ionization of the emission-line gas often is a function of the distance from the nucleus. Based on the emission-line ratios and the strengths of the stellar absorption features, circumnuclear starburst activity is a common feature of LIGs, regardless of their nuclear spectral types. The emission-line, absorption-line, continuum, radio, and IRAS properties of the LINERs suggest that most of the LINER emission in these infrared-selected galaxies is produced through shock ionization rather than photoionization by a genuine active nucleus. The nuclear region of Seyfert LIGs is found to be slightly less reddened than that of the LINERs and H II galaxies. The dust distribution generally

  12. 77 FR 27081 - II-VI, Incorporated, Infrared Optics-Saxonburg Division, Saxonburg, Pennsylvania; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-08

    ... employment related to the production of infrared and CO 2 laser optics, and related materials. The initial... experienced a decline in the sales or production of infrared and CO 2 laser optics, and related materials... production of infrared and CO 2 laser optics, and related materials (or like or directly competitive...

  13. A NEAR-INFRARED TEMPLATE DERIVED FROM I Zw 1 FOR THE Fe II EMISSION IN ACTIVE GALAXIES

    SciTech Connect

    Garcia-Rissmann, A.; Rodriguez-Ardila, A.; Sigut, T. A. A.; Pradhan, A. K.

    2012-05-20

    In active galactic nucleus spectra, a series of Fe II multiplets form a pseudo-continuum that extends from the ultraviolet to the near-infrared (NIR). This emission is believed to originate in the broad-line region, and it has been known for a long time that pure photoionization fails to reproduce it in the most extreme cases, as does the collisional excitation alone. The most recent models by Sigut and Pradhan include details of the Fe II ion microphysics and cover a wide range in the ionization parameter log U{sub ion} = (- 3.0 {yields} -1.3) and density log n{sub H} = (9.6 {yields} 12.6). With the aid of such models and a spectral synthesis approach, we studied for the first time in detail the NIR emission of I Zw 1. The main goals were to confirm the role played by Ly{alpha} fluorescence mechanisms in the production of the Fe II spectrum and to construct the first semi-empirical NIR Fe II template that best represents this emission, consequently allowing its clean subtraction in other sources. A good overall match between the observed Fe II+Mg II features with those predicted by the best-fitted model was obtained, corroborating the Ly{alpha} fluorescence as a key process to understand the Fe II spectrum. The best model was fine-tuned by applying a deconvolution method to the observed Fe II+Mg II spectrum. This derived semi-empirical template was then fitted to the spectrum of Ark 564, showing that it nicely reproduced its observed Fe II+Mg II emission. Our work extends the current set of available Fe II templates into the NIR region.

  14. A femtosecond visible/visible and visible/mid-infrared transient absorption study of the light harvesting complex II.

    PubMed

    Stahl, Andreas D; Di Donato, Mariangela; van Stokkum, Ivo; van Grondelle, Rienk; Groot, Marie Louise

    2009-12-16

    Light harvesting complex II (LHCII) is the most abundant protein in the thylakoid membrane of higher plants and green algae. LHCII acts to collect solar radiation, transferring this energy mainly toward photosystem II, with a smaller amount going to photosystem I; it is then converted into a chemical, storable form. We performed time-resolved femtosecond visible pump/mid-infrared probe and visible pump/visible probe absorption difference spectroscopy on purified LHCII to gain insight into the energy transfer in this complex occurring in the femto-picosecond time regime. We find that information derived from mid-infrared spectra, together with structural and modeling information, provides a unique visualization of the flow of energy via the bottleneck pigment chlorophyll a604.

  15. Interlayer Transition and Infrared Photodetection in Atomically Thin Type-II MoTe₂/MoS₂ van der Waals Heterostructures.

    PubMed

    Zhang, Kenan; Zhang, Tianning; Cheng, Guanghui; Li, Tianxin; Wang, Shuxia; Wei, Wei; Zhou, Xiaohao; Yu, Weiwei; Sun, Yan; Wang, Peng; Zhang, Dong; Zeng, Changgan; Wang, Xingjun; Hu, Weida; Fan, Hong Jin; Shen, Guozhen; Chen, Xin; Duan, Xiangfeng; Chang, Kai; Dai, Ning

    2016-03-22

    We demonstrate the type-II staggered band alignment in MoTe2/MoS2 van der Waals (vdW) heterostructures and an interlayer optical transition at ∼1.55 μm. The photoinduced charge separation between the MoTe2/MoS2 vdW heterostructure is verified by Kelvin probe force microscopy (KPFM) under illumination, density function theory (DFT) simulations and photoluminescence (PL) spectroscopy. Photoelectrical measurements of MoTe2/MoS2 vdW heterostructures show a distinct photocurrent response in the infrared regime (1550 nm). The creation of type-II vdW heterostructures with strong interlayer coupling could improve our fundamental understanding of the essential physics behind vdW heterostructures and help the design of next-generation infrared optoelectronics.

  16. High-pressure infrared and Raman studies of polymorphism in pharmaceutical compounds: Spironolactone, Forms I and II

    NASA Astrophysics Data System (ADS)

    Pisegna, Gisia L.; Gilson, Denis F. R.; Butler, Ian S.

    2014-12-01

    The infrared and Raman spectra of the two polymorphic forms, I and II, of the synthetic steroid spironolactone (C24H32O4S) have been examined under high pressures up to about 50 kbar with the aid of a diamond-anvil cell. While the differences in peak wavenumbers between the two polymorphs are small, the difference in the pressure dependence is dramatic. Both forms undergo structural transformations under pressure, but over different pressure ranges.

  17. DISCOVERY OF A FAINT QUASAR AT z ∼ 6 AND IMPLICATIONS FOR COSMIC REIONIZATION

    SciTech Connect

    Kim, Yongjung; Im, Myungshin; Jeon, Yiseul; Choi, Changsu; Hong, Jueun; Hyun, Minhee; Jun, Hyunsung David; Kim, Dohyeong; Kim, Duho; Kim, Jae-Woo; Lee, Seong-Kook; Taak, Yoon Chan; Yoon, Yongmin; Kim, Minjin; Park, Won-Kee; Karouzos, Marios; Kim, Ji Hoon; Pak, Soojong E-mail: mim@astro.snu.ac.kr

    2015-11-10

    Recent studies suggest that faint active galactic nuclei may be responsible for the reionization of the universe. Confirmation of this scenario requires spectroscopic identification of faint quasars (M{sub 1450} > −24 mag) at z ≳ 6, but only a very small number of such quasars have been spectroscopically identified so far. Here, we report the discovery of a faint quasar IMS J220417.92+011144.8 at z ∼ 6 in a 12.5 deg{sup 2} region of the SA22 field of the Infrared Medium-deep Survey (IMS). The spectrum of the quasar shows a sharp break at ∼8443 Å, with emission lines redshifted to z = 5.944 ± 0.002 and rest-frame ultraviolet continuum magnitude M{sub 1450} = −23.59 ± 0.10 AB mag. The discovery of IMS J220417.92+011144.8 is consistent with the expected number of quasars at z ∼ 6 estimated from quasar luminosity functions based on previous observations of spectroscopically identified low-luminosity quasars. This suggests that the number of M{sub 1450} ∼ −23 mag quasars at z ∼ 6 may not be high enough to fully account for the reionization of the universe. In addition, our study demonstrates that faint quasars in the early universe can be identified effectively with a moderately wide and deep near-infrared survey such as the IMS.

  18. Mid-infrared properties of luminous infrared galaxies. II. Probing the dust and gas physics of the goals sample

    SciTech Connect

    Stierwalt, S.; Armus, L.; Diaz-Santos, T.; Marshall, J.; Haan, S.; Howell, J.; Murphy, E. J.; Inami, H.; Petric, A. O.; Charmandaris, V.; Evans, A. S.; Iwasawa, K.; Kim, D. C.; Rich, J. A.; Spoon, H. W. W.; U, V.

    2014-08-01

    The Great Observatories All-sky LIRG Survey (GOALS) is a comprehensive, multiwavelength study of luminous infrared galaxies (LIRGs) in the local universe. Here, we present the results of a multi-component, spectral decomposition analysis of the low-resolution mid-infrared (MIR) Spitzer Infrared Spectrograph spectra from 5-38 μm of 244 LIRG nuclei. The detailed fits and high-quality spectra allow for characterization of the individual polycyclic aromatic hydrocarbon (PAH) features, warm molecular hydrogen emission, and optical depths for both silicate dust grains and water ices. We find that starbursting LIRGs, which make up the majority of the GOALS sample, are very consistent in their MIR properties (i.e., τ{sub 9.7μm}, τ{sub ice}, neon line ratios, and PAH feature ratios). However, as their EQW{sub 6.2{sub μm}} decreases, usually an indicator of an increasingly dominant active galactic nucleus (AGN), LIRGs cover a larger spread in these MIR parameters. The contribution from PAH emission to the total IR luminosity (L(PAH)/L(IR)) in LIRGs varies from 2%-29% and LIRGs prior to their first encounter show significantly higher L(PAH)/L(IR) ratios on average. We observe a correlation between the strength of the starburst (represented by IR8 = L{sub IR}/L{sub 8{sub μm}}) and the PAH fraction at 8 μm but no obvious link between IR8 and the 7.7 to 11.3 PAH ratio, suggesting that the fractional photodissociation region (PDR) emission, and not the overall grain properties, is associated with the rise in IR8 for galaxies off the starburst main sequence. We detect crystalline silicate features in ∼6% of the sample but only in the most obscure sources (s{sub 9.7{sub μm}} < –1.24). Ice absorption features are observed in ∼11% (56%) of GOALS LIRGs (ULIRGs) in sources with a range of silicate depths. Most GOALS LIRGs have L(H{sub 2})/L(PAH) ratios elevated above those observed for normal star-forming galaxies and exhibit a trend for increasing L(H{sub 2})/L

  19. Faint detection of exoplanets in microlensing surveys

    SciTech Connect

    Brown, Robert A.

    2014-06-20

    We propose a new approach to discovering faint microlensing signals below traditional thresholds, and for estimating the binary-lens mass ratio and the apparent separation from such signals. The events found will be helpful in accurately estimating the true distribution of planetary semimajor axes, which is an important goal of space microlensing surveys.

  20. Infrared environment of 6 Cephei

    NASA Astrophysics Data System (ADS)

    Abraham, P.; Kun, M.; Balazs, L. G.; Holl, A.; Fronto, A.

    1993-02-01

    This paper deals with the study of various features in the interstellar environment of the Be star 6 Cephei analyzing IRAS maps and optical data. We suggest that the conspicuous nearly circular arc on the IRAS maps is a stellar wind bubble (SWB). It has been shown that the faint H II region S 133 is probably a part of a chain of ionized arcs surrounding the older group of the Cepheus OB2 association. The relationship of 6 Cephei to a giant infrared ring (Cepheus Bubble) indicates a distance of about 800 pc and an unusually high absolute brightness of -5 mag for the star. 21 H alpha emission stars have been found in the 6 Cep area. We constructed a model for the infrared point source associated with 6 Cephei in terms of the infrared emission of the surrounding reflection nebula, and modeled the extended infrared emission of the reflection nebula adopting the dust model of Desert et al. (1990). The model resulted in a significant underabundance of very small grains and a normal abundance of PAH's with respect to the big grains. The model gives 0.23 solar mass for the dust mass of the reflection nebula which is not sufficient to account for the measured reddening of the star.

  1. MID-INFRARED EXTINCTION MAPPING OF INFRARED DARK CLOUDS. II. THE STRUCTURE OF MASSIVE STARLESS CORES AND CLUMPS

    SciTech Connect

    Butler, Michael J.; Tan, Jonathan C.

    2012-07-20

    We develop the mid-infrared extinction (MIREX) mapping technique of Butler and Tan (Paper I), presenting a new method to correct for the Galactic foreground emission based on observed saturation in independent cores. Using Spitzer GLIMPSE 8 {mu}m images, this allows us to accurately probe mass surface densities, {Sigma}, up to {approx_equal} 0.5 g cm{sup -2} with 2'' resolution and mitigate one of the main sources of uncertainty associated with Galactic MIREX mapping. We then characterize the structure of 42 massive starless and early-stage cores and their surrounding clumps, selected from 10 infrared dark clouds, measuring {Sigma}{sub cl}(r) from the core/clump centers. We first assess the properties of the core/clump at a scale where the total enclosed mass as projected on the sky is M{sub cl} = 60 M{sub Sun }. We find that these objects have a mean radius of R{sub cl} {approx_equal} 0.1 pc, mean {Sigma}{sub cl} = 0.3 g cm{sup -} and, if fitted by a power-law (PL) density profile {rho}{sub cl}{proportional_to}r{sup -k{sub {rho}}{sub ,}{sub c}{sub l}}, a mean value of k{sub {rho},cl} = 1.1. If we assume a core is embedded in each clump and subtract the surrounding clump envelope to derive the core properties, then we find a mean core density PL index of k{sub {rho},c} = 1.6. We repeat this analysis as a function of radius and derive the best-fitting PL plus uniform clump envelope model for each of the 42 core/clumps. The cores have typical masses of M{sub c} {approx} 100 M{sub Sun} and {Sigma}-bar{sub c} {approx} 0.1 g cm{sup -2}, and are embedded in clumps with comparable mass surface densities. We also consider Bonnor-Ebert density models, but these do not fit the observed {Sigma} profiles as well as PLs. We conclude that massive starless cores exist and are well described by singular polytropic spheres. Their relatively low values of {Sigma} and the fact that they are IR dark may imply that their fragmentation is inhibited by magnetic fields rather than

  2. Infrared, Raman, 1H NMR, thermal and positron annihilation lifetime studies of Pb(II), Sn(II), Sb(III), Bi(III)-barbital complexes

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Sharshar, T.

    2012-05-01

    Metal complexes of Pb(II), Sn(II), Sb(III) and Bi(III) with a barbital sodium were synthesized and characterized by several techniques, including elemental analysis (C, H and N), molar conductance measurements, infrared, Raman, 1H NMR, positron annihilation lifetime and thermogravimetric analysis. Reactions of barbital sodium (NaL) with salts of Pb(NO3)2, SnCl2ṡ2H2O, SbCl3 and BiCl3 affords four novel mononuclear complexes [Pb(HL)2], [Sn(L)(H2O)], [Sb(HL)(L)] and [Bi(HL)(L)]. In complexes of Pb(II), Sb(III) and Bi(III), the molar ratio of metal-to-ligand is 1:2. Both of Sb(III) and Bi(III) complexes have six coordination via two molecules of barbital (HL and L), one of them deprotonated NH. The Pb(II) complex has a central metal ion adopts tetradentate fashion which surrounded by two (HL) barbital moieties. The elemental analysis shows that Sn(II) complex is tetradentate 1:1 ratio, chelated through oxygen sbnd O of (ONa), deprotonated (sbnd NH) and one coordinated water molecule. The positron annihilation lifetime parameters were found to be dependent on the structure, electronic configuration and molecular weight of metal complexes.

  3. Deriving remote sensing reflectance from turbid Case II waters using green-shortwave infrared bands based model

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Yin, Shoujing; Xiao, Rulin; Xu, Qianxiang; Lin, Changsong

    2014-04-01

    The objectives of this study are to validate the applicability of a shortwave infrared atmospheric correction model (SWIR-based model) in deriving remote sensing reflectance in turbid Case II waters, and to improve that model using a proposed green-shortwave infrared model (GSWIR-based model). In a GSWIR-based model, the aerosol type is determined by a SWIR-based model and the reflectance due to aerosol scattering is calculated using spectral slope technology. In this study, field measurements collected from three independent cruises from two different Case II waters were used to compare models. The results indicate that both SWIR- and GSWIR-based models can be used to derive the remote sensing reflectance at visible wavelengths in turbid Case II waters, but GSWIR-based models are superior to SWIR-based models. Using the GSWIR-based model decreases uncertainty in remote sensing reflectance retrievals in turbid Case II waters by 2.6-12.1%. In addition, GSWIR-based model’s sensitivity to user-supplied parameters was determined using the numerical method, which indicated that the GSWIR-based model is more sensitive to the uncertainty of spectral slope technology than to that of aerosol type retrieval methodology. Due to much lower noise tolerance of GSWIR-based model in the blue and near-infrared regions, the GSWIR-based model performs poorly in determining remote sensing reflectance at these wavelengths, which is consistent with the GSWIR-based model’s accuracy evaluation results.

  4. An Infrared Study of the Dust Properties and Geometry of the Arched Filaments H ii Region with SOFIA/FORCAST

    NASA Astrophysics Data System (ADS)

    Hankins, M. J.; Lau, R. M.; Morris, M. R.; Herter, T. L.

    2017-03-01

    Massive stellar clusters provide radiation (∼ {10}7{--}{10}8 {L}ȯ ) and winds (∼1000 km s‑1) that act to heat dust and shape their surrounding environment. In this paper, the Arched Filaments in the Galactic center were studied to better understand the influence of the Arches cluster on its nearby interstellar medium (ISM). The Arched Filaments were observed with the Faint Object InfraRed CAMera for the SOFIA Telescope at 19.7, 25.2, 31.5, and 37.1 μm. Color–temperature maps of the region created with the 25.2 and 37.1 μm data reveal relatively uniform dust temperatures (70–100 K) over the extent of the filaments (∼25 pc). Distances between the cluster and the filaments were calculated assuming equilibrium heating of standard-size ISM dust grains (∼0.1 μm). The distances inferred by this method are in conflict with the projected distance between the filaments and the cluster, although this inconsistency can be explained if the characteristic grain size in the filaments is smaller (∼0.01 μm) than typical values. DustEM models of selected locations within the filaments show evidence of depleted abundances of polycyclic aromatic hydrocarbons (PAHs) by factors of ∼1.6–10 by mass compared to the diffuse ISM. The evidence for both PAH depletion and a smaller characteristic grain size points to processing of the ISM within the filaments. We argue that the eroding of dust grains within the filaments is not likely attributable to the radiation or winds from the Arches cluster, but may be related to the physical conditions in the Galactic center.

  5. Cerebral near infrared spectroscopy oximetry in extremely preterm infants: phase II randomised clinical trial

    PubMed Central

    Pellicer, Adelina; Alderliesten, Thomas; Austin, Topun; van Bel, Frank; Benders, Manon; Claris, Olivier; Dempsey, Eugene; Franz, Axel R; Fumagalli, Monica; Gluud, Christian; Grevstad, Berit; Hagmann, Cornelia; Lemmers, Petra; van Oeveren, Wim; Pichler, Gerhard; Plomgaard, Anne Mette; Riera, Joan; Sanchez, Laura; Winkel, Per; Wolf, Martin; Greisen, Gorm

    2015-01-01

    Objective To determine if it is possible to stabilise the cerebral oxygenation of extremely preterm infants monitored by cerebral near infrared spectroscopy (NIRS) oximetry. Design Phase II randomised, single blinded, parallel clinical trial. Setting Eight tertiary neonatal intensive care units in eight European countries. Participants 166 extremely preterm infants born before 28 weeks of gestation: 86 were randomised to cerebral NIRS monitoring and 80 to blinded NIRS monitoring. The only exclusion criterion was a decision not to provide life support. Interventions Monitoring of cerebral oxygenation using NIRS in combination with a dedicated treatment guideline during the first 72 hours of life (experimental) compared with blinded NIRS oxygenation monitoring with standard care (control). Main outcome measures The primary outcome measure was the time spent outside the target range of 55-85% for cerebral oxygenation multiplied by the mean absolute deviation, expressed in %hours (burden of hypoxia and hyperoxia). One hour with an oxygenation of 50% gives 5%hours of hypoxia. Secondary outcomes were all cause mortality at term equivalent age and a brain injury score assessed by cerebral ultrasonography. Randomisation Allocation sequence 1:1 with block sizes 4 and 6 in random order concealed for the investigators. The allocation was stratified for gestational age (<26 weeks or ≥26 weeks). Blinding Cerebral oxygenation measurements were blinded in the control group. All outcome assessors were blinded to group allocation. Results The 86 infants randomised to the NIRS group had a median burden of hypoxia and hyperoxia of 36.1%hours (interquartile range 9.2-79.5%hours) compared with 81.3 (38.5-181.3) %hours in the control group, a reduction of 58% (95% confidence interval 35% to 73%, P<0.001). In the experimental group the median burden of hypoxia was 16.6 (interquartile range 5.4-68.1) %hours, compared with 53.6 (17.4-171.3) %hours in the control group (P=0.0012). The

  6. An infrared spectroscopic based method for mercury(II) detection in aqueous solutions.

    PubMed

    Chandrasoma, Asela; Hamid, Amer Al Abdel; Bruce, Alice E; Bruce, Mitchell R M; Tripp, Carl P

    2012-05-30

    A new method that uses solid phase extraction (SPE) coupled with FTIR spectroscopy to detect Hg(II) in aqueous samples is described. The technique is envisioned for on-site, field evaluation rather than lab-based techniques. This paper presents the "proof of principle" of this new approach toward measurements of Hg(II) in water and identifies mass transport issues that would need to be overcome in order to migrate from a lab based method to field operation. The SPE material supported on a Si wafer is derivatized with an acylthiosemicarbazide, which undergoes a reaction in the presence of aqueous Hg(II) to form an oxadiazole ring. The progress of the reaction is monitored by IR spectroscopy. Following EPA guidelines, the method of detection limit (MDL) for the SPE/IR was 5 μg of Hg(II)cm(-2). In a 1L sample and a 1cm(2) Si wafer, this translates to a detection limit of 5 ppb. This system shows a high selectivity toward aqueous Hg(II) over other thiophilic heavy metal ions such as Pb(II), Cd(II), Fe(III), and Zn(II) and other metal ions such as Ni(II), Mn(II), Co(II), Cu(II), In(III), Ru(III), Na(I), and Ag(I) in aqueous solutions.

  7. Extreme Faint Flux Imaging with an EMCCD

    NASA Astrophysics Data System (ADS)

    Daigle, Olivier; Carignan, Claude; Gach, Jean-Luc; Guillaume, Christian; Lessard, Simon; Fortin, Charles-Anthony; Blais-Ouellette, Sébastien

    2009-08-01

    An EMCCD camera, designed from the ground up for extreme faint flux imaging, is presented. CCCP, the CCD Controller for Counting Photons, has been integrated with a CCD97 EMCCD from e2v technologies into a scientific camera at the Laboratoire d’Astrophysique Expérimentale (LAE), Université de Montréal. This new camera achieves subelectron readout noise and very low clock-induced charge (CIC) levels, which are mandatory for extreme faint flux imaging. It has been characterized in laboratory and used on the Observatoire du Mont Mégantic 1.6 m telescope. The performance of the camera is discussed and experimental data with the first scientific data are presented.

  8. Charting the Winds that Change the Universe, II: The Single Aperture Far Infrared Observatory (SAFIR)

    NASA Technical Reports Server (NTRS)

    Rieke, G. H.; Benford, D. J.; Harvey, P. M.; Lawrence, C. R.; Leisawitz, D. T.; Lester, D. F.; Mather, J. C.; Stacey, G. J.; Werner, M. W.; Yorke, H. W.

    2004-01-01

    SAFIR will study the birth and evolution of stars and planetary systems so young that they are invisible to optical and near-infrared telescopes such as NGST. Not only does the far-infrared radiation penetrate the obscuring dust clouds that surround these systems, but the protoplanetary disks also emit much of their radiation in the far infrared. Furthermore, the dust reprocesses much of the optical emission from the newly forming stars into this wavelength band. Similarly, the obscured central regions of galaxies, which harbor massive black holes and huge bursts of star formation, can be seen and analyzed in the far infrared. SAFIR will have the sensitivity to see the first dusty galaxies in the universe. For studies of both star-forming regions in our galaxy and dusty galaxies at high redshifts, SAFIR will be essential in tying together information that NGST will obtain on these systems at shorter wavelengths and that ALMA will obtain at longer wavelengths.

  9. Auger recombination in long-wave infrared InAs/InAsSb type-II superlattices

    SciTech Connect

    Olson, B. V.; Grein, C. H.; Kim, J. K.; Kadlec, E. A.; Klem, J. F.; Hawkins, S. D.; Shaner, E. A.

    2015-12-29

    The Auger lifetime is a critical intrinsic parameter for infrared photodetectors as it determines the longest potential minority carrier lifetime and consequently the fundamental limitations to their performance. Here, Auger recombination is characterized in a long-wave infrared InAs/InAsSb type-II superlattice. Auger coefficients as small as 7.1×10–26 cm6/s are experimentally measured using carrier lifetime data at temperatures in the range of 20 K–80 K. The data are compared to Auger-1 coefficients predicted using a 14-band K•p electronic structure model and to coefficients calculated for HgCdTe of the same bandgap. In conclusion, the experimental superlattice Auger coefficients are found to be an order-of-magnitude smaller than HgCdTe.

  10. Auger recombination in long-wave infrared InAs/InAsSb type-II superlattices

    DOE PAGES

    Olson, B. V.; Grein, C. H.; Kim, J. K.; ...

    2015-12-29

    The Auger lifetime is a critical intrinsic parameter for infrared photodetectors as it determines the longest potential minority carrier lifetime and consequently the fundamental limitations to their performance. Here, Auger recombination is characterized in a long-wave infrared InAs/InAsSb type-II superlattice. Auger coefficients as small as 7.1×10–26 cm6/s are experimentally measured using carrier lifetime data at temperatures in the range of 20 K–80 K. The data are compared to Auger-1 coefficients predicted using a 14-band K•p electronic structure model and to coefficients calculated for HgCdTe of the same bandgap. In conclusion, the experimental superlattice Auger coefficients are found to be anmore » order-of-magnitude smaller than HgCdTe.« less

  11. The subarcsecond mid-infrared view of local active galactic nuclei - II. The mid-infrared-X-ray correlation

    NASA Astrophysics Data System (ADS)

    Asmus, D.; Gandhi, P.; Hönig, S. F.; Smette, A.; Duschl, W. J.

    2015-11-01

    We present an updated mid-infrared (MIR) versus X-ray correlation for the local active galactic nuclei (AGN) population based on the high angular resolution 12 and 18μm continuum fluxes from the AGN subarcsecond MIR atlas and 2-10 keV and 14-195 keV data collected from the literature. We isolate a sample of 152 objects with reliable AGN nature and multi-epoch X-ray data and minimal MIR contribution from star formation. Although the sample is not homogeneous or complete, we show that our results are unlikely to be affected by significant biases. The MIR-X-ray correlation is nearly linear and within a factor of 2 independent of the AGN type and the wavebands used. The observed scatter is <0.4 dex. A possible flattening of the correlation slope at the highest luminosities probed (˜1045 erg s-1) towards low MIR luminosities for a given X-ray luminosity is indicated but not significant. Unobscured objects have, on average, an MIR-X-ray ratio that is only ≤0.15 dex higher than that of obscured objects. Objects with intermediate X-ray column densities (22 < log NH < 23) actually show the highest MIR-X-ray ratio on average. Radio-loud objects show a higher mean MIR-X-ray ratio at low luminosities while the ratio is lower than average at high luminosities. This may be explained by synchrotron emission from the jet contributing to the MIR at low luminosities and additional X-ray emission at high luminosities. True Seyfert 2 candidates do not show any deviation from the general behaviour suggesting that they possess a dusty obscurer as in other AGN. Double AGN also do not deviate. Finally, we show that the MIR-X-ray correlation can be used to investigate the AGN nature of uncertain objects. Specifically, we give equations that allow us to determine the intrinsic 2-10 keV luminosities and column densities for objects with complex X-ray properties to within 0.34 dex. These techniques are applied to the uncertain objects of the remaining AGN MIR atlas, demonstrating the

  12. Constraints on MACHO Dark Matter from Compact Stellar Systems in Ultra-Faint Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Brandt, Timothy

    2017-01-01

    I show that a recently discovered star cluster near the center of the ultra-faint dwarf galaxy Eridanus II provides strong constraints on massive compact halo objects (MACHOs) of >5 M⊙ as the main component of dark matter. MACHO dark matter will dynamically heat the cluster, driving it to larger sizes and higher velocity dispersions until it dissolves into its host galaxy. The stars in compact ultra-faint dwarf galaxies themselves will be subject to the same dynamical heating; the survival of at least ten such galaxies places independent limits on MACHO dark matter of masses >10 M⊙. Both Eri II's cluster and the compact ultra-faint dwarfs are characterized by stellar masses of just a few thousand M⊙ and half-light radii of 13 pc (for the cluster) and 30 pc (for the ultra-faint dwarfs). These systems close the 20 -100 M⊙ window of allowed MACHO dark matter and combine with existing constraints from microlensing, wide binaries, and disk kinematics to rule out dark matter composed entirely of MACHOs from 10-7 M⊙ up to arbitrarily high masses. NASA Sagan Fellow.

  13. Charting the Winds that Change the Universe, II The Single Aperture Far Infrared Observatory (SAFIR)

    NASA Technical Reports Server (NTRS)

    Leisawitz, David

    2003-01-01

    The Single Aperture Far Infrared Observatory (SAFIR) will study the birth and evolution of stars and planetary systems so young that they are invisible to optical and near-infrared telescopes such as NGST. Not only does the far-infrared radiation penetrate the obscuring dust clouds that surround these systems, but the protoplanetary disks also emit much of their radiation in the far infrared. Furthermore, the dust reprocesses much of the optical emission from the newly forming stars into this wavelength band. Similarly, the obscured central regions of galaxies, which harbor massive black holes and huge bursts of star formation, can be seen and analyzed in the far infrared. SAFIR will have the sensitivity to see the first dusty galaxies in the universe. For studies of both star-forming regions in our galaxy and dusty galaxies at high redshifts, SAFIR will be essential in tying together information that NGST will obtain on these systems at shorter wavelengths and that ALMA will obtain at longer wavelengths.

  14. DUST AROUND R CORONAE BOREALIS STARS. II. INFRARED EMISSION FEATURES IN AN H-POOR ENVIRONMENT

    SciTech Connect

    Garcia-Hernandez, D. A.; Lambert, D. L. E-mail: nkrao@iiap.res.in

    2013-08-20

    Residual Spitzer/Infrared Spectrograph spectra for a sample of 31 R Coronae Borealis (RCB) stars are presented and discussed in terms of narrow emission features superimposed on the quasi-blackbody continuous infrared emission. A broad {approx}6-10 {mu}m dust emission complex is seen in the RCBs showing an extreme H-deficiency. A secondary and much weaker {approx}11.5-15 {mu}m broad emission feature is detected in a few RCBs with the strongest {approx}6-10 {mu}m dust complex. The Spitzer infrared spectra reveal for the first time the structure within the {approx}6-10 {mu}m dust complex, showing the presence of strong C-C stretching modes at {approx}6.3 and 8.1 {mu}m as well as of other dust features at {approx}5.9, 6.9, and 7.3 {mu}m, which are attributable to amorphous carbonaceous solids with little or no hydrogen. The few RCBs with only moderate H-deficiencies display the classical ''unidentified infrared bands (UIRs)'' and mid-infrared features from fullerene-related molecules. In general, the characteristics of the RCB infrared emission features are not correlated with the stellar and circumstellar properties, suggesting that the RCB dust features may not be dependent on the present physical conditions around RCB stars. The only exception seems to be the central wavelength of the 6.3 {mu}m feature, which is blueshifted in those RCBs showing also the UIRs, i.e., the RCBs with the smallest H deficiency.

  15. THE WIRED SURVEY. II. INFRARED EXCESSES IN THE SDSS DR7 WHITE DWARF CATALOG

    SciTech Connect

    Debes, John H.; Leisawitz, David T.; Hoard, D. W.; Wachter, Stefanie; Cohen, Martin

    2011-12-01

    With the launch of the Wide-field Infrared Survey Explorer (WISE), a new era of detecting planetary debris and brown dwarfs (BDs) around white dwarfs (WDs) has begun with the WISE InfraRed Excesses around Degenerates (WIRED) Survey. The WIRED Survey is sensitive to substellar objects and dusty debris around WDs out to distances exceeding 100 pc, well beyond the completeness level of local WDs. In this paper, we present a cross-correlation of the preliminary Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) WD catalog between the WISE, Two-Micron All Sky Survey (2MASS), UKIRT Infrared Deep Sky Survey (UKIDSS), and SDSS DR7 photometric catalogs. From {approx}18,000 input targets, there are WISE detections comprising 344 'naked' WDs (detection of the WD photosphere only), 1020 candidate WD+M dwarf binaries, 42 candidate WD+BD systems, 52 candidate WD+dust disk systems, and 69 targets with indeterminate infrared excess. We classified all of the detected targets through spectral energy distribution model fitting of the merged optical, near-IR, and WISE photometry. Some of these detections could be the result of contaminating sources within the large ( Almost-Equal-To 6'') WISE point-spread function; we make a preliminary estimate for the rates of contamination for our WD+BD and WD+disk candidates and provide notes for each target of interest. Each candidate presented here should be confirmed with higher angular resolution infrared imaging or infrared spectroscopy. We also present an overview of the observational characteristics of the detected WDs in the WISE photometric bands, including the relative frequencies of candidate WD+M, WD+BD, and WD+disk systems.

  16. Star formation rates from [C II] 158 μm and mid-infrared emission lines for starbursts and active galactic nuclei

    SciTech Connect

    Sargsyan, L.; Lebouteiller, V.; Weedman, D.; Barry, D.; Spoon, H.; Samsonyan, A.; Bernard-Salas, J.; Houck, J. E-mail: dweedman@isc.astro.cornell.edu

    2014-07-20

    A summary is presented for 130 galaxies observed with the Herschel Photodetector Array Camera and Spectrometer instrument to measure fluxes for the [C II] 158 μm emission line. Sources cover a wide range of active galactic nucleus to starburst classifications, as derived from polycyclic aromatic hydrocarbon strength measured with the Spitzer Infrared Spectrograph. Redshifts from [C II] and line to continuum strengths (equivalent width (EW) of [C II]) are given for the full sample, which includes 18 new [C II] flux measures. Calibration of L([C II)]) as a star formation rate (SFR) indicator is determined by comparing [C II] luminosities with mid-infrared [Ne II] and [Ne III] emission line luminosities; this gives the same result as determining SFR using bolometric luminosities of reradiating dust from starbursts: log SFR = log L([C II)]) – 7.0, for SFR in M{sub ☉} yr{sup –1} and L([C II]) in L{sub ☉}. We conclude that L([C II]) can be used to measure SFR in any source to a precision of ∼50%, even if total source luminosities are dominated by an active galactic nucleus (AGN) component. The line to continuum ratio at 158 μm, EW([C II]), is not significantly greater for starbursts (median EW([C II]) = 1.0 μm) compared to composites and AGNs (median EW([C II]) = 0.7 μm), showing that the far-infrared continuum at 158 μm scales with [C II] regardless of classification. This indicates that the continuum at 158 μm also arises primarily from the starburst component within any source, giving log SFR = log νL{sub ν}(158 μm) – 42.8 for SFR in M{sub ☉} yr{sup –1} and νL{sub ν}(158 μm) in erg s{sup –1}.

  17. Near-infrared spectra and intrinsic luminosities of candidate type II quasars at 2 < z < 3.4

    SciTech Connect

    Greene, Jenny E.; Strauss, Michael A.; Pattarakijwanich, Petchara; Alexandroff, Rachael; Zakamska, Nadia L.; Liu, Guilin; Lang, Dustin; Hamann, Frederick; Ross, Nicholas P.; Myers, Adam D.; Brandt, W. Niel; Schneider, Donald P.; York, Donald

    2014-06-10

    We present JHK near-infrared (NIR) spectroscopy of 25 candidate Type II quasars selected from the Sloan Digital Sky Survey (SDSS), using Triplespec on the Apache Point Observatory 3.5 m telescope, the Folded-port InfraRed Echellette at the Magellan/Baade 6.5 m telescope, and the Gemini Near-Infrared Spectrograph on Gemini. At redshifts of 2 < z < 3.4, our NIR spectra probe the rest-frame optical region of these targets, which were initially selected to have strong lines of C IV and Ly α, with FWHM < 2000 km s{sup –1} from the SDSS pipeline. We use the [O III] λ5007 line shape as a model for the narrow-line region emission and find that Hα consistently requires a broad component with FWHMs ranging from 1000 to 7500 km s{sup –1}. Interestingly, the C IV lines also require broad bases, but with considerably narrower widths of 1000-4500 km s{sup –1}. Estimating the extinction using the Balmer decrement and also the relationship in lower-z quasars between rest equivalent width and luminosity in the [O III] line, we find typical A{sub V} values of 0-2 mag, which naturally explains the attenuated C IV lines relative to Hα. We propose that our targets are moderately obscured quasars. We also describe one unusual object with three distinct velocity peaks in its [O III] spectrum.

  18. An ultra-faint galaxy candidate discovered in early data from the Magellanic Satellites Survey

    DOE PAGES

    Drlica-Wagner, A.; Bechtol, Keith; Allam, S.; ...

    2016-11-30

    Here, we report a new ultra-faint stellar system found in Dark Energy Camera data from the first observing run of the Magellanic Satellites Survey (MagLiteS). MagLiteS J0644–5953 (Pictor II or Pic II) is a low surface brightness (more » $$\\mu ={28.5}_{-1}^{+1}\\,\\mathrm{mag}\\,\\,\\mathrm{arcsec}{}^{-2}$$ within its half-light radius) resolved overdensity of old and metal-poor stars located at a heliocentric distance of $${45}_{-4}^{+5}\\,\\mathrm{kpc}$$. The physical size ($${r}_{1/2}={46}_{-11}^{+15}\\,\\mathrm{pc}\\,$$) and low luminosity ($${M}_{V}=-{3.2}_{-0.5}^{+0.4}\\,\\mathrm{mag}\\,$$) of this satellite are consistent with the locus of spectroscopically confirmed ultra-faint galaxies. MagLiteS J0644–5953 (Pic II) is located $${11.3}_{-0.9}^{+3.1}\\,\\mathrm{kpc}\\,$$ from the Large Magellanic Cloud (LMC), and comparisons with simulation results in the literature suggest that this satellite was likely accreted with the LMC. The close proximity of MagLiteS J0644–5953 (Pic II) to the LMC also makes it the most likely ultra-faint galaxy candidate to still be gravitationally bound to the LMC.« less

  19. An Ultra-faint Galaxy Candidate Discovered in Early Data from the Magellanic Satellites Survey

    NASA Astrophysics Data System (ADS)

    Drlica-Wagner, A.; Bechtol, K.; Allam, S.; Tucker, D. L.; Gruendl, R. A.; Johnson, M. D.; Walker, A. R.; James, D. J.; Nidever, D. L.; Olsen, K. A. G.; Wechsler, R. H.; Cioni, M. R. L.; Conn, B. C.; Kuehn, K.; Li, T. S.; Mao, Y.-Y.; Martin, N. F.; Neilsen, E.; Noel, N. E. D.; Pieres, A.; Simon, J. D.; Stringfellow, G. S.; van der Marel, R. P.; Yanny, B.

    2016-12-01

    We report a new ultra-faint stellar system found in Dark Energy Camera data from the first observing run of the Magellanic Satellites Survey (MagLiteS). MagLiteS J0644-5953 (Pictor II or Pic II) is a low surface brightness (μ ={28.5}-1+1 {mag} {arcsec}{}-2 within its half-light radius) resolved overdensity of old and metal-poor stars located at a heliocentric distance of {45}-4+5 {kpc}. The physical size ({r}1/2={46}-11+15 {pc} ) and low luminosity ({M}V=-{3.2}-0.5+0.4 {mag} ) of this satellite are consistent with the locus of spectroscopically confirmed ultra-faint galaxies. MagLiteS J0644-5953 (Pic II) is located {11.3}-0.9+3.1 {kpc} from the Large Magellanic Cloud (LMC), and comparisons with simulation results in the literature suggest that this satellite was likely accreted with the LMC. The close proximity of MagLiteS J0644-5953 (Pic II) to the LMC also makes it the most likely ultra-faint galaxy candidate to still be gravitationally bound to the LMC.

  20. An ultra-faint galaxy candidate discovered in early data from the Magellanic Satellites Survey

    SciTech Connect

    Drlica-Wagner, A.; Bechtol, Keith; Allam, S.; Tucker, D. L.; Gruendl, R. A.; Johnson, M. D.; Walker, A. R.; James, D. J.; Nidever, D. L.; Olsen, K. A. G.; Wechsler, R. H.; Cioni, M. R. L.; Conn, B. C.; Kuehn, K.; Li, T. S.; Mao, Y. -Y.; Martin, N. F.; Neilsen, E.; Noel, N. E. D.; Pieres, A.; Simon, J. D.; Stringfellow, G. S.; Marel, R. P. van der; Yanny, B.

    2016-11-30

    Here, we report a new ultra-faint stellar system found in Dark Energy Camera data from the first observing run of the Magellanic Satellites Survey (MagLiteS). MagLiteS J0644–5953 (Pictor II or Pic II) is a low surface brightness ($\\mu ={28.5}_{-1}^{+1}\\,\\mathrm{mag}\\,\\,\\mathrm{arcsec}{}^{-2}$ within its half-light radius) resolved overdensity of old and metal-poor stars located at a heliocentric distance of ${45}_{-4}^{+5}\\,\\mathrm{kpc}$. The physical size (${r}_{1/2}={46}_{-11}^{+15}\\,\\mathrm{pc}\\,$) and low luminosity (${M}_{V}=-{3.2}_{-0.5}^{+0.4}\\,\\mathrm{mag}\\,$) of this satellite are consistent with the locus of spectroscopically confirmed ultra-faint galaxies. MagLiteS J0644–5953 (Pic II) is located ${11.3}_{-0.9}^{+3.1}\\,\\mathrm{kpc}\\,$ from the Large Magellanic Cloud (LMC), and comparisons with simulation results in the literature suggest that this satellite was likely accreted with the LMC. The close proximity of MagLiteS J0644–5953 (Pic II) to the LMC also makes it the most likely ultra-faint galaxy candidate to still be gravitationally bound to the LMC.

  1. The Population of Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Barker, Ed; Buckalew, Brent; Burkhardt, Andrew; Cowardin, Heather; Frith, James; Gomez, Juan; Kaleida, Catherine; Lederer, Susan M.; Lee, Chris H.

    2016-01-01

    The 6.5-m Magellan telescope 'Walter Baade' at the Las Campanas Observatory in Chile has been used for spot surveys of the GEO orbital regime to study the population of optically faint GEO debris. The goal is to estimate the size of the population of GEO debris at sizes much smaller than can be studied with 1-meter class telescopes. Despite the small size of the field of view of the Magellan instrument (diameter 0.5-degree), a significant population of objects fainter than R = 19th magnitude have been found with angular rates consistent with circular orbits at GEO. We compare the size of this population with the numbers of GEO objects found at brighter magnitudes by smaller telescopes. The observed detections have a wide range in characteristics starting with those appearing as short uniform streaks. But there are a substantial number of detections with variations in brightness, flashers, during the 5-second exposure. The duration of each of these flashes can be extremely brief: sometimes less than half a second. This is characteristic of a rapidly tumbling object with a quite variable projected size times albedo. If the albedo is of the order of 0.2, then the largest projected size of these objects is around 10-cm. The data in this paper was collected over the last several years using Magellan's IMACS camera in f/2 mode. The analysis shows the brightness bins for the observed GEO population as well as the periodicity of the flashers. All objects presented are correlated with the catalog: the focus of the paper will be on the uncorrelated, optically faint, objects. The goal of this project is to better characterize the faint debris population in GEO that access to a 6.5-m optical telescope in a superb site can provide.

  2. Conversion of the spin state of the manganese complex in photosystem II induced by near-infrared light.

    PubMed

    Boussac, A; Girerd, J J; Rutherford, A W

    1996-06-04

    The manganese complex (Mn4) which is responsible for water oxidation in photosystem II is EPR detectable in the S2 state, one of the five redox states of the enzyme cycle. The S2 state is observable at 10 K either as a multiline signal (spin 1/2) or as a signal at g = 4.1 (spin 3/2 or spin 5/2). It is shown here that at around 150 K the state responsible for the multiline signal is converted to that responsible for the g = 4.1 signal upon the absorption of infrared light. This conversion is fully reversible at 200 K. The action spectrum of this conversion has its maximum at 820 nm (12 200 cm-1) and is similar to the intervalence charge transfer band in di-mu-oxo-(MnIIIMnIV) model systems. It is suggested that the conversion of the multiline signal to the g = 4.1 signal results from absorption of infrared light by the Mn cluster itself, resulting in electron transfer from MnIII to MnIV. The g = 4.1 signal is thus proposed to arise from a state which differs from that which gives rise to the multiline signal only in terms of this change in its valence distribution. The near-infrared light effect was observed in the S2 state of Sr(2+)-reconstituted photosystem II and in Ca(2+)-depleted, EGTA (or citrate-)-treated photosystem II but not in ammonia-treated photosystem II. Earlier results in the literature which showed that the g = 4.1 state was preferentially formed by illumination at 130 K are reinterpreted as being the result of two photochemical events: the first being photosynthetic charge separation resulting in an S2 state which gives rise to the multiline signal and the second being the conversion of this state to the g = 4.1 state due to the simultaneous and inadvertent presence of 820 nm light in the broad-band illumination given. There is therefore no reason to consider the state responsible for the g = 4.1 signal as a precursor of that which gives rise to the multiline signal.

  3. The formation of Jupiter's faint rings

    PubMed

    Burns; Showalter; Hamilton; Nicholson; de Pater I; Ockert-Bell; Thomas

    1999-05-14

    Observations by the Galileo spacecraft and the Keck telescope showed that Jupiter's outermost (gossamer) ring is actually two rings circumscribed by the orbits of the small satellites Amalthea and Thebe. The gossamer rings' unique morphology-especially the rectangular end profiles at the satellite's orbit and the enhanced intensities along the top and bottom edges of the rings-can be explained by collisional ejecta lost from the inclined satellites. The ejecta evolves inward under Poynting-Robertson drag. This mechanism may also explain the origin of Jupiter's main ring and suggests that faint rings may accompany all small inner satellites of the other jovian planets.

  4. BIG FISH, LITTLE FISH: TWO NEW ULTRA-FAINT SATELLITES OF THE MILKY WAY

    SciTech Connect

    Belokurov, V.; Walker, M. G.; Evans, N. W.; Gilmore, G.; Irwin, M. J.; Koposov, S.; Watkins, L.; Wyrzykowski, L.; Just, D.; Olszewski, E.; Mateo, M. E-mail: walker@ast.cam.ac.uk

    2010-03-20

    We report the discovery of two new Milky Way satellites in the neighboring constellations of Pisces and Pegasus identified in data from the Sloan Digital Sky Survey. Pisces II, an ultra-faint dwarf galaxy lies at the distance of {approx}180 kpc, some 15 deg. away from the recently detected Pisces I. Segue 3, an ultra-faint star cluster lies at the distance of 16 kpc. We use deep follow-up imaging obtained with the 4-m Mayall Telescope at Kitt Peak National Observatory to derive their structural parameters. Pisces II has a half-light radius of {approx}60 pc, while Segue 3 is 20 times smaller at only 3 pc.

  5. Infrared Spectra and Optical Constants of Astronomical Ices: II. Ethane and Ethylene

    NASA Technical Reports Server (NTRS)

    Hudson, Reggie L.; Gerakines, Perry A.; Moore, M. H.

    2014-01-01

    Infrared spectroscopic observations have established the presence of hydrocarbon ices on Pluto and other TNOs, but the abundances of such molecules cannot be deduced without accurate optical constants (n, k) and reference spectra. In this paper we present our recent measurements of near- and mid-infrared optical constants for ethane (C2H6) and ethylene (C2H4) in multiple ice phases and at multiple temperatures. As in our recent work on acetylene (C2H2), we also report new measurements of the index of refraction of each ice at 670 nm. Comparisons are made to earlier work where possible, and electronic versions of our new results are made available.

  6. AGN Obscuration Through Dusty Infrared Dominated Flows. II. Multidimensional, Radiation-Hydrodynamics Modeling

    NASA Technical Reports Server (NTRS)

    Dorodnitsyn, Anton; Kallman, Tim; Bisno\\vatyiI-Kogan, Gennadyi

    2011-01-01

    We explore a detailed model in which the active galactic nucleus (AGN) obscuration results from the extinction of AGN radiation in a global ow driven by the pressure of infrared radiation on dust grains. We assume that external illumination by UV and soft X-rays of the dusty gas located at approximately 1pc away from the supermassive black hole is followed by a conversion of such radiation into IR. Using 2.5D, time-dependent radiation hydrodynamics simulations in a ux-limited di usion approximation we nd that the external illumination can support a geometrically thick obscuration via out ows driven by infrared radiation pressure in AGN with luminosities greater than 0:05 L(sub edd) and Compton optical depth, Tau(sub T) approx > & 1.

  7. Understanding Active Galactic Nuclei using near-infrared high angular resolution polarimetry II: Preliminary results

    NASA Astrophysics Data System (ADS)

    Marin, F.; Grosset, L.; Goosmann, R.; Gratadour, D.; Rouan, D.; Clénet, Y.; Pelat, D.; Rojas Lobos, P. A.

    2016-12-01

    In this second research note of a series of two, we present the first near-infrared results we obtained when modeling Active Galactic Nuclei (AGN). Our first proceedings showed the comparison between the MontAGN and STOKES Monte Carlo codes. Now we use our radiative transfer codes to simulate the polarization maps of a prototypical, NGC 1068-like, type-2 radio-quiet AGN. We produced high angular resolution infrared (1 μm) polarization images to be compared with recent observations in this wavelength range. Our preliminary results already show a good agreement between the models and observations but cannot account for the peculiar linear polarization angle of the torus such as observed. tet{Gratadour2015} found a polarization position angle being perpendicular to the bipolar outflows axis. Further work is needed to improve the models by adding physical phenomena such as dichroism and clumpiness.

  8. Prediction of potential mushroom yield by visible and near-infrared spectroscopy using fresh phase II compost.

    PubMed

    Sharma, H S S; Kilpatrick, M; Lyons, G

    2005-08-01

    Potential mushroom (Agaricus bisporus) yield of phase II compost is determined by interactions of key quality parameters including dry matter, nitrogen dry matter, ammonia, pH, conductivity, thermophilic microorganisms, C : N ratio, fiber fractions, ash, and certain minerals. This study was aimed at generating robust visible and near-infrared (Vis-NIR) calibrations for predicting potential yield, using spectra from fresh phase II compost. Four compost comparative trials were carried out during the winter and summer months of 2001-2003, under controlled experimental conditions employing six commercially prepared composts, with eight replicate (8 bag) plots per treatment (48 x 8 = 384). The substrates were prepared by windrow or bunker phase I, followed by phase II production. The fresh samples were scanned for Vis-NIR (400-2498 nm) spectra, averaged, transformed, and regressed against the recorded yield by employing a modified partial least squares algorithm. The best calibration model generated from the database explained 84% of yield variation within the data set with a standard error of calibration of 13.75 kg/tonne of fresh compost. The model was successfully tested for robustness with yield results obtained from a validation trial, carried out under similar experimental conditions in early 2004, and the standard error of prediction was 18.21 kg/tonne, which was slightly higher than the mean experimental error (17.94 kg/tonne) of the trial. The accuracy of the model is acceptable for estimating potential yield by classifying phase II substrate as poor (180-220 kg), medium (220-260 kg), and high (260-300 kg) yielding compost. The yield prediction model is being transferred to a new instrument based at Loughgall for routine evaluation of commercial phase II samples.

  9. Demonstration of dual-band infrared thermal imaging for bridge inspection. Phase II, final report

    SciTech Connect

    Durbin, P.F.; Del Grande, N.K.; Schaich, P.C.

    1996-03-01

    Developing and implementing methods of effective bridge rehabilitation is a major issue for the Federal Highway Administration (FHWA). The nation spends $5 billion annually to replace, rehabilitate or construct new bridges. According to the National Bridge Inventory, over 100,000 U.S. bridges are structurally deficient. About 40,000 of these bridges have advanced deck deterioration. The most common causes of serious deck deterioration is delamination. Delaminations result when steel reinforcements within the bridge deck corrode, creating gaps that separate the concrete into layers. A reliable inspection technology, capable of identifying delaminations, would represent a power new tool in bridge maintenance. To date, most bridge inspections rely on human interpretation of surface visual features of chain dragging. These methods are slow, disruptive, unreliable and raise serious safety concerns. Infrared thermal imaging detects subsurface delaminations and surface clutter, which is introduced by foreign material on the roadway. Typically, foreign material which is not always evident on a video tape image, produces a unique IR reflectance background unlike the thermal response of a subsurface delamination. Lawrence Livermore National Laboratory (LLNL) uses dual-band infrared (DBIR) thermal imaging to identify and remove nonthermal IR reflectance backgrounds from foreign material on the roadway. DBIR methods improve the performance of IR thermal imaging by a factor of ten, compared to single-band infrared (SBIR) methods. DBIR thermal imaging allows precise temperature measurement to reliably locate bridge deck delaminations and remove wavelength-dependent emissivity variations due to foreign material on the roadway.

  10. Cold H I in faint dwarf galaxies

    NASA Astrophysics Data System (ADS)

    Patra, Narendra Nath; Chengalur, Jayaram N.; Karachentsev, Igor D.; Kaisin, Serafim S.; Begum, Ayesha

    2016-03-01

    We present the results of a study of the amount and distribution of cold atomic gas, as well its correlation with recent star formation in a sample of extremely faint dwarf irregular galaxies. Our sample is drawn from the Faint Irregular Galaxy GMRT Survey (FIGGS) and its extension, FIGGS2. We use two different methods to identify cold atomic gas. In the first method, line-of-sight H I spectra were decomposed into multiple Gaussian components and narrow Gaussian components were identified as cold H I. In the second method, the brightness temperature (TB ) is used as a tracer of cold H I. We find that the amount of cold gas identified using the TB method is significantly larger than the amount of gas identified using Gaussian decomposition. We also find that a large fraction of the cold gas identified using the TB method is spatially coincident with regions of recent star formation, although the converse is not true. That is only a small fraction of the regions with recent star formation are also covered by cold gas. For regions where the star formation and the cold gas overlap, we study the relationship between the star formation rate density and the cold H I column density. We find that the star formation rate density has a power-law dependence on the H I column density, but that the slope of this power law is significantly flatter than that of the canonical Kennicutt-Schmidt relation.

  11. A multifrequency radio continuum and IRAS faint source survey of markarian galaxies

    NASA Technical Reports Server (NTRS)

    Bicay, M. D.; Kojoian, G.; Seal, J.; Dickinson, D. F.; Malkan, M. A.

    1995-01-01

    Results are presented from a multifrequency radio continumm survey of Markarian galaxies (MRKs) and are supplemented by IRAS infrared data from the Faint Source Survey. Radio data are presented for 899 MRKs observed at nu = 4.755 GHz with the National Radio Astronomy Observatory (NRAO)-Green Bank 300 foot (91 m) telescope, including nearly 88% of those objects in Markarian lists VI-XIV. In addition, 1.415 GHz measurements of 258 MRKs, over 30% of the MRKs accessible from the National Aeronomy and Ionosphere Center (NAIC)-Arecibo, are reported. Radio continuum observations of smaller numbers of MRKs were made at 10.63 GHz and at 23.1 GHz and are also presented. Infrared data from the IRAS Faint Source Survey (Ver. 2) are presented for 944 MRKs, with reasonably secure identifications extracted from the NASA/IPAC Extragalactic Database. MRKs exhibit the same canonical infrared characteristics as those reported for various other galaxy samples, that is well-known enhancement of the 25 micrometer/60 micrometer color ratio among Seyfert MRKs, and a clear tendency for MRKs with warmer 60 micrometer/100 micrometer colors to also possess cooler 12 micrometer/25 micrometer colors. In addition, non-Seyfert are found to obey the well-documented infrared/radio luminosity correlation, with the tightest correlation seen for starburst MRKs.

  12. Highly efficient near-infrared light-emitting diodes by using type-II CdTe/CdSe core/shell quantum dots as a phosphor.

    PubMed

    Shen, Huaibin; Zheng, Ying; Wang, Hongzhe; Xu, Weiwei; Qian, Lei; Yang, Yixing; Titov, Alexandre; Hyvonen, Jake; Li, Lin Song

    2013-11-29

    In this paper, we present an innovative method for the synthesis of CdTe/CdSe type-II core/shell structure quantum dots (QDs) using 'greener' chemicals. The PL of CdTe/CdSe type-II core/shell structure QDs ranges from 600 to 820 nm, and the as-synthesized core/shell structures show narrow size distributions and stable and high quantum yields (50–75%). Highly efficient near-infrared light-emitting diodes (LEDs) have been demonstrated by employing the CdTe/CdSe type-II core/shell QDs as emitters. The devices fabricated based on these type-II core/shell QDs show color-saturated near-infrared emission from the QD layers, a low turn-on voltage of 1.55 V, an external quantum efficiency (EQE) of 1.59%, and a current density and maximum radiant emittance of 2.1 × 10(3) mA cm−2 and 17.7 mW cm−2 at 8 V; it is the first report to use type-II core/shell QDs as near-infrared emitters and these results may offer a practicable platform for the realization of near-infrared QD-based light-emitting diodes, night-vision-readable displays, and friend/foe identification system.

  13. Helium shells and faint emission lines from slitless flash spectra

    PubMed Central

    Bazin, Cyril; Koutchmy, Serge

    2013-01-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence. PMID:25685435

  14. Helium shells and faint emission lines from slitless flash spectra.

    PubMed

    Bazin, Cyril; Koutchmy, Serge

    2013-05-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence.

  15. A Search for Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Lederer, Susan M.; Barker, Edwin S.; Cowardin, Heather; Abercromby, Kira J.; ilha, Jiri

    2011-01-01

    Existing optical surveys for debris at geosynchronous orbit (GEO) have been conducted with meter class telescopes, which have detection limits in the range of 18th-19th magnitude. We report on a new search for optically faint debris at GEO using the 6.5-m Magellan 1 telescope Walter Baade at Las Campanas Observatory in Chile. Our goal is to go as faint as possible and characterize the brightness distribution of debris fainter than R = 20th magnitude, corresponding to a size smaller than 10 cm assuming an albedo of 0.175. We wish to compare the inferred size distribution for GEO debris with that for LEO debris. We describe results obtained during 9.4 hours of observing time during 25-27 March 2011. We used the IMACS f/2 instrument, which has a mosaic of 8 CCDs, and a field of view of 30 arc-minutes in diameter. This is the widest field of view of any instrument on either Magellan telescope. All observations were obtained through a Sloan r filter. The limiting magnitude for 5 second exposures is estimated to be fainter than 22. With this small field of view and the limited observing time, our objective was to search for optically faint objects from the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris (SSN # 25001 and 33519) with the 6.5-m telescope, followed by a survey for objects on similar orbits but with a spread in mean anomaly. To detect bright objects over a wider field of view (1.6x1.6 degrees), we observed the same field centers at the same time through a similar filter with the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will describe our experiences using Magellan, a telescope never used previously for orbital debris research, and our initial results.

  16. A Search For Optically Faint GEO Debris

    NASA Astrophysics Data System (ADS)

    Seitzer, P.; Lederer, S.; Barker, E.; Cowardin, H.; Abercromby, K.; Silha, J.; Burkhardt, A.

    2011-09-01

    Existing optical surveys for debris at geosynchronous orbit (GEO) have been conducted with meter class telescopes, which have detection limits in the range of 18th-19th magnitude. We report on a new search for optically faint debris at GEO using the 6.5-m Magellan telescope ‘Walter Baade’ at Las Campanas Observatory in Chile. Our goal is to go as faint as possible and characterize the brightness distribution of debris fainter than R = 20th magnitude, corresponding to a size smaller than 10 cm assuming an albedo of 0.175. We wish to compare the inferred size distribution for GEO debris with that for LEO debris. We describe preliminary results obtained during 9.4 hours of observing time during 25-27 March 2011. We used the IMACS f/2 instrument, which has a mosaic of 8 CCDs, and a field of view of 30 arc-minutes in diameter. This is the widest field of view of any instrument on either Magellan telescope. All observations were obtained through a Sloan r’ filter. The limiting magnitude for 5 second exposures is measured to be fainter tan R = 21. With this small field of view and the limited observing time, our objective was to search for optically faint objects from the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris (SSN # 25001 and 33519) with the 6.5-m telescope, followed by a survey for objects on similar orbits but with a spread in mean anomaly. To detect bright objects over a wider field of view (1.6x1.6 degrees), we observed the same field centers at the same time through a similar filter with the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will describe our experiences using Magellan, a telescope never used previously for orbital debris research, and our initial results.

  17. Luminosity function of [O II] emission-line galaxies in the MassiveBlack-II simulation

    NASA Astrophysics Data System (ADS)

    Park, KwangHo; Di Matteo, Tiziana; Ho, Shirley; Croft, Rupert; Wilkins, Stephen M.; Feng, Yu; Khandai, Nishikanta

    2015-11-01

    We examine the luminosity function (LF) of [O II] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at 0.06 ≤ z ≤ 3.0 using the [O II] emission line luminosity L([O II]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [O II] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([O II]) = 1043.0 erg s-1 while the low redshifts (z ≤ 0.3) show an excess in the prediction of bright [O II] galaxies, but still displaying a good match with observations below L([O II]) = 1041.6 erg s-1. Based on the validity in reproducing the properties of [O II] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [O II] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from -3 to -2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)-1 at z ≤ 2 while the faint end evolves as ˜3(z + 1)-1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [O III] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. Finally, we show that the auto-correlation function of [O II] and [O III] emitting galaxies shows a rapid evolution from z = 2 to 1.

  18. CCD time-resolved photometry of faint cataclysmic variables. II

    SciTech Connect

    Szkody, P.; Howell, S.B.; Mateo, M.; Kreidl, T.J. Planetary Science Institute, Tucson, AZ Mount Wilson and Las Campanas Observatories, Pasadena, CA Lowell Observatory, Flagstaff, AZ )

    1989-10-01

    Time-resolved optical broad-band light curves obtained from differential photometry on sequential CCD frames of the known or suspected cataclysmic variable FO And, EH Aqr, WX Cet, XX Cet, AL Com, V503 Cyg, AH Eri, CP Eri, IR Gem, RW UMi, PG0134+070, and US 3215 are presented. The analysis of the light curves with coverage of greater than 2 hrs shows repeatable periodicity in five objects. PG0134+070 exhibits eclipses of 1.3-1.8 mag depth with a period of 313 min. V503 Cyg has a 0.7-1.0 mag peak-to-peak modulation with a period of 109 min. IR Gem shows a large modulation at the orbital period of 99 min, and comparison with previous data indicates that this modulation may have an amplitude dependent on outburst phase. AH Eri reveals a 0.1-0.3 mag modulation, at a period of 42 min. Better time-resolved data on AL Com confirm the 0.4-mag variation reported by Howell and Szkody (1988) at a period of 42 min. These latter two short periods likely indicate magnetic systems. There is also some evidence of periodicity in RW UMi and WX Cet which must be confirmed with further data. 25 refs.

  19. Infrared Multiple-Photon Dissociation spectroscopy of group II metal complexes with salicylate

    SciTech Connect

    Ryan P. Dain; Gary Gresham; Gary S. Groenewold; Jeffrey D. Steill; Jos Oomens; Michael J. van Stipdonk

    2011-07-01

    Ion-trap tandem mass spectrometry with collision-induced dissociation, and the combination of infrared multiple-photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) calculations were used to characterize singly-charged, 1:1 complexes of Ca2+, Sr2+ and Ba2+ with salicylate. For each metal-salicylate complex, the CID pathways are: (a) elimination of CO2 and (b) formation of [MOH]+ where M=Ca2+, Sr2+ or Ba2+. DFT calculations predict three minima for the cation-salicylate complexes which differ in the mode of metal binding. In the first, the metal ion is coordinated by O atoms of the (neutral) phenol and carboxylate groups of salicylate. In the second, the cation is coordinated by phenoxide and (neutral) carboxylic acid groups. The third mode involves coordination by the carboxylate group alone. The infrared spectrum for the metal-salicylate complexes contains a number of absorptions between 1000 – 1650 cm-1, and the best correlation between theoretical and experimental spectra for the structure that features coordination of the metal ion by phenoxide and the carbonyl group of the carboxylic acid group, consistent with calculated energies for the respective species.

  20. First Detection of Mid-infrared Variability from an Ultraluminous X-Ray Source Holmberg II X-1

    NASA Astrophysics Data System (ADS)

    Lau, R. M.; Heida, M.; Kasliwal, M. M.; Walton, D. J.

    2017-04-01

    We present mid-infrared (IR) light curves of the Ultraluminous X-ray Source (ULX) Holmberg II X-1 from observations taken between 2014 January 13 and 2017 January 5 with the Spitzer Space Telescope at 3.6 and 4.5 μm in the Spitzer Infrared Intensive Transients Survey. The mid-IR light curves, which reveal the first detection of mid-IR variability from a ULX, is determined to arise primarily from dust emission rather than from a jet or an accretion disk outflow. We derived the evolution of the dust temperature ({T}{{d}}∼ 600{--}800 {{K}}), IR luminosity ({L}{IR}∼ 3× {10}4 {L}ȯ ), mass ({M}{{d}}∼ 1{--}3× {10}-6 {M}ȯ ), and equilibrium temperature radius ({R}{eq}∼ 10{--}20 {au}). A comparison of X-1 with a sample of spectroscopically identified massive stars in the Large Magellanic Cloud on a mid-IR color–magnitude diagram suggests that the mass donor in X-1 is a supergiant (sg) B[e]-star. The sgB[e]-interpretation is consistent with the derived dust properties and the presence of the [Fe ii] (λ =1.644 μ {{m}}) emission line revealed from previous near-IR studies of X-1. We attribute the mid-IR variability of X-1 to the increased heating of dust located in a circumbinary torus. It is unclear what physical processes are responsible for the increased dust heating; however, it does not appear to be associated with the X-ray flux from the ULX, given the constant X-ray luminosities provided by serendipitous, near-contemporaneous X-ray observations around the first mid-IR variability event in 2014. Our results highlight the importance of mid-IR observations of luminous X-ray sources traditionally studied at X-ray and radio wavelengths.

  1. Searching for Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Lederer, Susan M.; Abercromby, Kira J.; Barker, Edwin S.; Burkhardt, Andrew; Cowardin, Heather; Krisko, Paula; Silha, Jiri

    2012-01-01

    We report on results from a search for optically faint debris (defined as R > 20th magnitude, or smaller than 10 cm assuming an albedo of 0.175)) at geosynchronous orbit (GEO) using the 6.5-m Magellan telescope "Walter Baade" at Las Campanas Observatory in Chile. Our goal is to characterize the brightness distribution of debris to the faintest limiting magnitude possible. Our data was obtained during 6 hours of observing time during the photometric nights of 26 and 27 March 2011 with the IMACS f/2 instrument, which has a field of view (fov) of 0.5 degrees in diameter. All observations were obtained through a Sloan r filter, and calibrated by observations of Landolt standard stars. Our primary objective was to search for optically faint objects from one of the few known fragmentations at GEO: the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris with the 6.5-m telescope, followed by a survey for unknown objects on similar orbits but with different mean anomalies. To establish the bright end of the debris population, calibrated observations were acquired on the same field centers, telescope rates, and time period with a similar filter on the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will show the calibrated brightness distributions from both telescopes, and compare the observed brightness distributions with that predicted for various population models of debris of different sizes.

  2. Spectrum from Faint Galaxy IRAS F00183-7111

    NASA Technical Reports Server (NTRS)

    2003-01-01

    NASA's Spitzer Space Telescope has detected the building blocks of life in the distant universe, albeit in a violent milieu. Training its powerful infrared eye on a faint object located at a distance of 3.2 billion light-years, Spitzer has observed the presence of water and organic molecules in the galaxy IRAS F00183-7111. With an active galactic nucleus, this is one of the most luminous galaxies in the universe, rivaling the energy output of a quasar. Because it is heavily obscured by dust (see visible-light image in the inset), most of its luminosity is radiated at infrared wavelengths.

    The infrared spectrograph instrument onboard Spitzer breaks light into its constituent colors, much as a prism does for visible light. The image shows a low-resolution spectrum of the galaxy obtained by the spectrograph at wavelengths between 4 and 20 microns. Spectra are graphical representations of a celestial object's unique blend of light. Characteristic patterns, or fingerprints, within the spectra allow astronomers to identify the object's chemical composition and to determine such physical properties as temperature and density.

    The broad depression in the center of the spectrum denotes the presence of silicates (chemically similar to beach sand) in the galaxy. An emission peak within the bottom of the trough is the chemical signature for molecular hydrogen. The hydrocarbons (orange) are organic molecules comprised of carbon and hydrogen, two of the most common elements on Earth. Since it has taken more than three billion years for the light from the galaxy to reach Earth, it is intriguing to note the presence of organics in a distant galaxy at a time when life is thought to have started forming on our home planet.

    Additional features in the spectrum reveal the presence of water ice (blue), carbon dioxide ice (green) and carbon monoxide (purple) in both gas and solid forms. The magenta peak corresponds to singly ionized neon gas, a spectral line often used by

  3. An Interferometric Study of the Fomalhaut Inner Debris Disk. II. Keck Nuller Mid-infrared Observations

    NASA Astrophysics Data System (ADS)

    Mennesson, B.; Absil, O.; Lebreton, J.; Augereau, J.-C.; Serabyn, E.; Colavita, M. M.; Millan-Gabet, R.; Liu, W.; Hinz, P.; Thébault, P.

    2013-02-01

    We report on high-contrast mid-infrared observations of Fomalhaut obtained with the Keck Interferometer Nuller (KIN) showing a small resolved excess over the level expected from the stellar photosphere. The measured null excess has a mean value of 0.35% ± 0.10% between 8 and 11 μm and increases from 8 to 13 μm. Given the small field of view of the instrument, the source of this marginal excess must be contained within 2 AU of Fomalhaut. This result is reminiscent of previous VLTI K-band (sime2μm) observations, which implied the presence of a ~0.88% excess, and argued that thermal emission from hot dusty grains located within 6 AU from Fomalhaut was the most plausible explanation. Using a parametric two-dimensional radiative transfer code and a Bayesian analysis, we examine different dust disk structures to reproduce both the near- and mid-infrared data simultaneously. While not a definitive explanation of the hot excess of Fomalhaut, our model suggests that the most likely inner few AU disk geometry consists of a two-component structure, with two different and spatially distinct grain populations. The 2-11 μm data are consistent with an inner hot ring of very small (sime10-300 nm) carbon-rich grains concentrating around 0.1 AU. The second dust population—inferred from the KIN data at longer mid-infrared wavelengths—consists of larger grains (size of a few microns to a few tens of microns) located further out in a colder region where regular astronomical silicates could survive, with an inner edge around 0.4 AU-1 AU. From a dynamical point of view, the presence of the inner concentration of submicron-sized grains is surprising, as such grains should be expelled from the inner planetary system by radiation pressure within only a few years. This could either point to some inordinate replenishment rates (e.g., many grazing comets coming from an outer reservoir) or to the existence of some braking mechanism preventing the grains from moving out.

  4. Are the Faint Structures Ahead of Solar Coronal Mass Ejections Real Signatures of Driven Shocks?

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Ok; Moon, Y.-J.; Lee, Jin-Yi; Lee, Kyoung-Sun; Kim, Sujin; Lee, Kangjin

    2014-11-01

    Recently, several studies have assumed that the faint structures ahead of coronal mass ejections (CMEs) are caused by CME-driven shocks. In this study, we have conducted a statistical investigation to determine whether or not the appearance of such faint structures depends on CME speeds. For this purpose, we use 127 Solar and Heliospheric Observatory/Large Angle Spectroscopic COronagraph (LASCO) front-side halo (partial and full) CMEs near the limb from 1997 to 2011. We classify these CMEs into two groups by visual inspection of CMEs in the LASCO-C2 field of view: Group 1 has the faint structure ahead of a CME and Group 2 does not have such a structure. We find the following results. (1) Eighty-seven CMEs belong to Group 1 and 40 CMEs belong to Group 2. (2) Group 1 events have much higher speeds (average = 1230 km s-1 and median = 1199 km s-1) than Group 2 events (average = 598 km s-1 and median = 518 km s-1). (3) The fraction of CMEs with faint structures strongly depends on CME speeds (V): 0.93 (50/54) for fast CMEs with V >= 1000 km s-1, 0.65 (34/52) for intermediate CMEs with 500 km s-1 <= V < 1000 km s-1, and 0.14 (3/21) for slow CMEs with V < 500 km s-1. We also find that the fraction of CMEs with deca-hecto metric type II radio bursts is consistent with the above tendency. Our results indicate that the observed faint structures ahead of fast CMEs are most likely an enhanced density manifestation of CME-driven shocks.

  5. ARE THE FAINT STRUCTURES AHEAD OF SOLAR CORONAL MASS EJECTIONS REAL SIGNATURES OF DRIVEN SHOCKS?

    SciTech Connect

    Lee, Jae-Ok; Moon, Y.-J.; Lee, Kangjin; Lee, Jin-Yi; Lee, Kyoung-Sun; Kim, Sujin E-mail: moonyj@khu.ac.kr

    2014-11-20

    Recently, several studies have assumed that the faint structures ahead of coronal mass ejections (CMEs) are caused by CME-driven shocks. In this study, we have conducted a statistical investigation to determine whether or not the appearance of such faint structures depends on CME speeds. For this purpose, we use 127 Solar and Heliospheric Observatory/Large Angle Spectroscopic COronagraph (LASCO) front-side halo (partial and full) CMEs near the limb from 1997 to 2011. We classify these CMEs into two groups by visual inspection of CMEs in the LASCO-C2 field of view: Group 1 has the faint structure ahead of a CME and Group 2 does not have such a structure. We find the following results. (1) Eighty-seven CMEs belong to Group 1 and 40 CMEs belong to Group 2. (2) Group 1 events have much higher speeds (average = 1230 km s{sup –1} and median = 1199 km s{sup –1}) than Group 2 events (average = 598 km s{sup –1} and median = 518 km s{sup –1}). (3) The fraction of CMEs with faint structures strongly depends on CME speeds (V): 0.93 (50/54) for fast CMEs with V ≥ 1000 km s{sup –1}, 0.65 (34/52) for intermediate CMEs with 500 km s{sup –1} ≤ V < 1000 km s{sup –1}, and 0.14 (3/21) for slow CMEs with V < 500 km s{sup –1}. We also find that the fraction of CMEs with deca-hecto metric type II radio bursts is consistent with the above tendency. Our results indicate that the observed faint structures ahead of fast CMEs are most likely an enhanced density manifestation of CME-driven shocks.

  6. InAs/Ga(In)Sb type-II superlattices short/middle dual color infrared detectors

    NASA Astrophysics Data System (ADS)

    Shi, Yanli; Hu, Rui; Deng, Gongrong; He, Wenjing; Feng, Jiangmin; Fang, Mingguo; Li, Xue; Deng, Jun

    2015-06-01

    Short wavelength and middle wavelength dual color infrared detector were designed and prepared with InAs/Ga(In)Sb type-II superlattices materials. The Crosslight software was used to calculate the relation between wavelength and material parameter such as thickness of InAs, GaSb, then energy strucutre of 100 periods 8ML/8ML InAs/GaSb and the absorption wavelength was calculated. After fixing InAs/GaSb thickness parameter, devices with nBn and pin structure were designed and prepared to compare performance of these two structures. Comparison results showed both structure devices were available for high temperature operation which black detectivity under 200K were 7.9×108cmHz1/2/W for nBn and 1.9×109cmHz1/2/W for pin respectively. Considering the simultaneous readout requirement for further FPAs application the NIP/PIN InAs/GaSb dual-color structure was grown by MBE method. Both two mesas and one mesa devices structure were designed and prepared to appreciate the short/middle dual color devices. Cl2-based ICP etching combined with phosphoric acid based chemicals were utilized to form mesas, silicon dioxide was deposited via PECVD as passivation layer. Ti/Au was used as metallization. Once the devices were finished, the electro-optical performance was measured. Measurement results showed that optical spectrum response with peak wavelength of 2.7μm and 4.3μm under 77K temperature was gained, the test results agree well with calculated results. Peak detectivity was measured as 2.08×1011cmHz1/2/W and 6.2×1010cmHz1/2/W for short and middle wavelength infrared detector respectively. Study results disclosed that InAs/Ga(In)Sb type-II SLs is available for both short and middle wavelength infrared detecting with good performance by simply altering the thickness of InAs layer and GaSb layer.

  7. Nuclear Infrared Spectral Energy Distribution of Type II Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Videla, Liza; Lira, Paulina; Andrews, Heather; Alonso-Herrero, Almudena; Alexander, David M.; Ward, Martin

    2013-02-01

    We present near- and mid-IR observations of a sample of Seyfert II galaxies drawn from the 12 μm Galaxy sample. The sample was observed in the J, H, K, L, M and N bands. Galaxy surface brightness profiles are modeled using nuclear, bulge, bar (when necessary), and disk components. To check the reliability of our findings, the procedure was tested using Spitzer observations of M 31. Nuclear spectral energy distributions (SEDs) are determined for 34 objects, and optical spectra are presented for 38, including analysis of their stellar populations using the STARLIGHT spectral synthesis code. Emission line diagnostic diagrams are used to discriminate between genuine active galactic nuclei (AGNs) and H II nuclei. Combining our observations with those found in the literature, we have a total of 40 SEDs. It is found that about 40% of the SEDs are characterized by an upturn in the near-IR, which we have quantified as a NIR slope α < 1 for an SED characterized as λf λvpropλα. The three objects with an H II nucleus and two Seyfert nuclei with strong contamination from a circumnuclear also show an upturn. For genuine AGNs, this component could be explained as emission from the accretion disk, a jet, or from a very hot dust component leaking from the central region through a clumpy obscuring structure. The presence of a very compact nuclear starburst as the origin for this NIR excess emission is not favored by our spectroscopic data for these objects.

  8. The infrared medium-deep survey. II. How to trigger radio AGNs? Hints from their environments

    SciTech Connect

    Karouzos, Marios; Im, Myungshin; Kim, Jae-Woo; Lee, Seong-Kook; Jeon, Yiseul; Choi, Changsu; Hong, Jueun; Hyun, Minhee; Jun, Hyunsung David; Kim, Dohyeong; Kim, Yongjung; Kim, Ji Hoon; Kim, Duho; Park, Won-Kee; Taak, Yoon Chan; Yoon, Yongmin; Chapman, Scott; Pak, Soojong; Edge, Alastair

    2014-12-10

    Activity at the centers of galaxies, during which the central supermassive black hole is accreting material, is nowadays accepted to be rather ubiquitous and most probably a phase of every galaxy's evolution. It has been suggested that galactic mergers and interactions may be the culprits behind the triggering of nuclear activity. We use near-infrared data from the new Infrared Medium-Deep Survey and the Deep eXtragalactic Survey of the VIMOS-SA22 field and radio data at 1.4 GHz from the FIRST survey and a deep Very Large Array survey to study the environments of radio active galactic nuclei (AGNs) over an area of ∼25 deg{sup 2} and down to a radio flux limit of 0.1 mJy and a J-band magnitude of 23 mag AB. Radio AGNs are predominantly found in environments similar to those of control galaxies at similar redshift, J-band magnitude, and (M{sub u} – M{sub r} ) rest-frame color. However, a subpopulation of radio AGNs is found in environments up to 100 times denser than their control sources. We thus preclude merging as the dominant triggering mechanism of radio AGNs. By fitting the broadband spectral energy distribution of radio AGNs in the least and most dense environments, we find that those in the least dense environments show higher radio-loudness, higher star formation efficiencies, and higher accretion rates, typical of the so-called high-excitation radio AGNs. These differences tend to disappear at z > 1. We interpret our results in terms of a different triggering mechanism for these sources that is driven by mass loss through winds of young stars created during the observed ongoing star formation.

  9. EVOLVING STARBURST MODELING OF FAR-INFRARED/SUBMILLIMETER/MILLIMETER LINE EMISSION. II. APPLICATION TO M 82

    SciTech Connect

    Yao Lihong

    2009-11-01

    We present starburst models for far-infrared/sub-millimeter/millimeter line emission of molecular and atomic gas in an evolving starburst region, which is treated as an ensemble of noninteracting hot bubbles that drive spherical shells of swept-up gas into a surrounding uniform gas medium. These bubbles and shells are driven by stellar winds and supernovae within massive star clusters formed during an instantaneous starburst. The underlying stellar radiation from the evolving clusters affects the properties and structure of photodissociation regions (PDRs) in the shells, and hence the spectral energy distributions (SEDs) of the molecular and atomic line emission from these swept-up shells and the associated parent giant molecular clouds contain a signature of the stage of evolution of the starburst. The physical and chemical properties of the shells and their structure are computed using a simple, well-known similarity solution for the shell expansion, a stellar population synthesis code, and a time-dependent PDR chemistry model. The SEDs for several molecular and atomic lines ({sup 12}CO and its isotope {sup 13}CO, HCN, HCO{sup +}, C, O, and C{sup +}) are computed using a nonlocal thermodynamic equilibrium line radiative transfer model. By comparing our models with the available observed data of nearby infrared bright galaxies, especially M 82, we constrain the models and in the case of M 82, we provide estimates for the ages (5-6 Myr, 10 Myr) of recent starburst activity. We also derive a total H{sub 2} gas mass of approx(2-3.4) x 10{sup 8} M {sub sun} for the observed regions of the central 1 kpc starburst disk of M 82.

  10. Characterizing ultraviolet and infrared observational properties for galaxies. II. Features of attenuation law

    SciTech Connect

    Mao, Ye-Wei; Kong, Xu; Lin, Lin E-mail: xkong@ustc.edu.cn

    2014-07-01

    Variations in the attenuation law have a significant impact on observed spectral energy distributions for galaxies. As one important observational property for galaxies at ultraviolet and infrared wavelength bands, the correlation between infrared-to-ultraviolet luminosity ratio and ultraviolet color index (or ultraviolet spectral slope), i.e., the IRX-UV relation (or IRX-β relation), offered a widely used formula for correcting dust attenuation in galaxies, but the usability appears to be in doubt now because of considerable dispersion in this relation found by many studies. In this paper, on the basis of spectral synthesis modeling and spatially resolved measurements of four nearby spiral galaxies, we provide an interpretation of the deviation in the IRX-UV relation with variations in the attenuation law. From both theoretical and observational viewpoints, two components in the attenuation curve, the linear background and the 2175 Å bump, are suggested to be the parameters in addition to the stellar population age (addressed in the first paper of this series) in the IRX-UV function; different features in the attenuation curve are diagnosed for the galaxies in our sample. Nevertheless, it is often difficult to ascertain the attenuation law for galaxies in actual observations. Possible reasons for preventing the successful detection of the parameters in the attenuation curve are also discussed in this paper, including the degeneracy of the linear background and the 2175 Å bump in observational channels, the requirement for young and dust-rich systems to study, and the difficulty in accurate estimates of dust attenuations at different wavelength bands.

  11. Polarizer mechanism for the space telescope faint object spectrograph

    NASA Technical Reports Server (NTRS)

    Thulson, M. D.

    1983-01-01

    The polarizer mechanism for the Space Telescope Faint Object Spectrograph is described. This device will allow spectropolarimetric measurements of faint astronomical objects. The mechanism employs a unique arrangement to meet functional requirements in a compact package and with only one actuator. Detailed tolerance analysis and a variety of tests indicate that the polarizer is capable of accurate and reliable performance.

  12. First Results from the ISO-IRAS Faint Galaxy Survey

    NASA Technical Reports Server (NTRS)

    Wolstencroft, R. D.; Wehrle, A. E.; Levine, D. A.

    1997-01-01

    We present the first result from the ISO-IRAS Faint Galaxy Survey (IIFGS), a program designed to obtain ISO observations of the most distant and luminous galaxies in the IRAS Faint Source Survey by filling short gaps in the ISO observing schedule with pairs of 12um ISOCAM AND 90um ISOPHOT observation.

  13. Optical and near-IR observations of the faint and fast 2008ha-like supernova 2010ae

    NASA Astrophysics Data System (ADS)

    Stritzinger, M. D.; Hsiao, E.; Valenti, S.; Taddia, F.; Rivera-Thorsen, T. J.; Leloudas, G.; Maeda, K.; Pastorello, A.; Phillips, M. M.; Pignata, G.; Baron, E.; Burns, C. R.; Contreras, C.; Folatelli, G.; Hamuy, M.; Höflich, P.; Morrell, N.; Prieto, J. L.; Benetti, S.; Campillay, A.; Haislip, J. B.; LaClutze, A. P.; Moore, J. P.; Reichart, D. E.

    2014-01-01

    A comprehensive set of optical and near-infrared (NIR) photometry and spectroscopy is presented for the faint and fast 2008ha-like supernova (SN) 2010ae. Contingent on the adopted value of host extinction, SN 2010ae reached a peak brightness of -13.8 > MV > -15.3 mag, while modeling of the UVOIR light curve suggests it produced 0.003-0.007 M⊙ of 56Ni, ejected 0.30-0.60 M⊙ of material, and had an explosion energy of 0.04-0.30 × 1051 erg. The values of these explosion parameters are similar to the peculiar SN 2008ha -for which we also present previously unpublished early phase optical and NIR light curves - and places these two transients at the faint end of the 2002cx-like SN population. Detailed inspection of the post-maximum NIR spectroscopic sequence indicates the presence of a multitude of spectral features, which are identified through SYNAPPS modeling to be mainly attributed to Co ii. Comparison with a collection of published and unpublished NIR spectra of other 2002cx-like SNe, reveals that a Co ii footprint is ubiquitous to this subclass of transients, providing a link to Type Ia SNe. A visual-wavelength spectrum of SN 2010ae obtained at +252 days past maximum shows a striking resemblance to a similar epoch spectrum of SN 2002cx. However, subtle differences in the strength and ratio of calcium emission features, as well as diversity among similar epoch spectra of other 2002cx-like SNe indicates a range of physical conditions of the ejecta, highlighting the heterogeneous nature of thispeculiar class of transients. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile (ESO Programs 082.A-0526, 084.D-0719, 088.D-0222, 184.D-1140, and 386.D-0966); the Gemini Observatory, Cerro Pachon, Chile (Gemini Programs GS-2010A-Q-14 and GS-2010A-Q-38); the Magellan 6.5 m telescopes at Las Campanas Observatory; and the SOAR telescope.Tables 1-5 and Appendix A are available in electronic form at http

  14. Radial velocities and metallicities from infrared Ca ii triplet spectroscopy of open clusters. II. Berkeley 23, King 1, NGC 559, NGC 6603, and NGC 7245

    NASA Astrophysics Data System (ADS)

    Carrera, R.; Casamiquela, L.; Ospina, N.; Balaguer-Núñez, L.; Jordi, C.; Monteagudo, L.

    2015-06-01

    Context. Open clusters are key to studying the formation and evolution of the Galactic disc. However, there is a deficiency of radial velocity and chemical abundance determinations for open clusters in the literature. Aims: We intend to increase the number of determinations of radial velocities and metallicities from spectroscopy for open clusters. Methods: We acquired medium-resolution spectra (R ~ 8000) in the infrared region Ca ii triplet lines (~8500 Å) for several stars in five open clusters with the long-slit IDS spectrograph on the 2.5 m Isaac Newton Telescope (Roque de los Muchachos Observatory, Spain). Radial velocities were obtained by cross-correlation fitting techniques. The relationships available in the literature between the strength of infrared Ca ii lines and metallicity were also used to derive the metallicity for each cluster. Results: We obtain ⟨Vr⟩ = 48.6 ± 3.4, -58.4 ± 6.8, 26.0 ± 4.3, and -65.3 ± 3.2 km s-1 for Berkeley 23, NGC 559, NGC 6603, and NGC 7245, respectively. We found [ Fe/H ] = -0.25 ± 0.14 and -0.15 ± 0.18 for NGC 559 and NGC 7245, respectively. Berkeley 23 has low metallicity, [ Fe/H ] = -0.42 ± 0.13, which is similar to other open clusters in the outskirts of the Galactic disc. In contrast, we derived high metallicity ([ Fe/H ] = +0.43 ± 0.15) for NGC 6603, which places this system among the most metal-rich known open clusters. To our knowledge, this is the first determination of radial velocities and metallicities from spectroscopy for these clusters, except NGC 6603, for which radial velocities had been previously determined. We have also analysed ten stars in the line of sight to King 1. Because of the large dispersion obtained in both radial velocity and metallicity, we cannot be sure that we have sampled true cluster members. Based on observations made with the 2.5 m Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the

  15. Visible and near-infrared calibrations for quality assessment of fresh phase I and II mushroom (Agaricus bisporus) compost.

    PubMed

    Sharma, H S S; Kilpatrick, M; Lyons, G; Sturgeon, S; Archer, J; Moore, S; Cheung, L; Finegan, K

    2005-11-01

    Previous studies have shown that visible and near-infrared spectra (Vis-NIR) of dry and milled compost can be used for generating partial least squares (PLS) calibrations of phase II compost parameters including ammonia, nitrogen dry matter (NDM), dry matter (DM), pH, conductivity, carbon, microbial population, and potential productivity. The objective of this study was to develop robust calibrations for some of the key parameters from the spectra of fresh phase I and II composts. Samples of substrates from six commercial production yards were obtained during winter and summer months of 2000-2004 to monitor changes in quality and were analyzed for the test factors. Vis-NIR reflectance measurements of fresh samples (740) were made over the range of 400-2500 nm. After mathematical pretreatments, PLS calibrations of the key parameters were developed using the NIR (1100-2500 nm) and visible and NIR (400-2500 nm) regions and subsequently validated using an independent sample set of 123 phase I and II samples obtained during 2004-2005. The phase I and II standard errors of laboratory measurements of ammonia, pH, conductivity, DM, NDM, and ash were lower than the standard error of predictions of the same parameters, respectively, by the best NIR or Vis-NIR models. The degree of precision for some of the calibrations, especially ammonia, NDM, and DM, is suitable for composters to monitor changes in quality parameters during production. The laboratory measurement errors for phase I samples were greater than those of the phase II samples, except for ash, due to a higher degree of heterogeneity in the substrate. The calibrations, especially for pH, conductivity, and ash, need to be improved with new sample sets. A major advantage of NIR spectroscopy is the ability to assess substrate quality for a range of target parameters simultaneously, within a few hours of receiving the samples. The main drawbacks are the expensive instrumentation, expertise, and training necessary for

  16. Near-infrared absorbing and emitting Ru(II)-Pt(II) heterodimetallic complexes of dpdpz (dpdpz = 2,3-di(2-pyridyl)-5,6-diphenylpyrazine).

    PubMed

    Wu, Si-Hai; Burkhardt, Stephen E; Yao, Jiannian; Zhong, Yu-Wu; Abruña, Héctor D

    2011-05-02

    The reaction of 2,3-di(2-pyridyl)-5,6-diphenylpyrazine (dpdpz) with K(2)PtCl(4) in a mixture of acetonitrile and water afforded mono-Pt complex (dpdpz)PtCl(2)4 in good yield, with two lateral pyridine nitrogen atoms binding to the metal center. Two types of Ru(II)-Pt(II) heterodimetallic complexes bridged by dpdpz, namely, [(bpy)(2)Ru(dpdpz)Pt(C≡CC(6)H(4)R)](2+) (7-9, R = H, NMe(2), or Cl, respectively) and [(tpy)Ru(dpdpz)Pt(C≡CPh)] (+) (12), were then designed and prepared, where bpy = 2,2'-bipyridine and tpy = 2,2';6',2''-terpyridine. In both cases, the platinum atom binds to dpdpz with a C(∧)N(∧)N tridentate mode. However, the coordination of the ruthenium atom with dpdpz could either be noncyclometalated (N(∧)N bidentate) or cyclometalated (C(∧)N(∧)N tridentate). The electronic properties of these complexes were subsequently studied and compared by spectroscopic and electrochemical analyses and theoretical calculations. These complexes exhibit substantial absorption in the visible to NIR (near-infrared) region because of mixed MLCT (metal-to-ligand-charge-tranfer) transitions from both the ruthenium and the platinum centers. Complexes 7 and 9 were found to emit NIR light with higher quantum yields than those of the mono-Ru complex [(bpy)(2)Ru(dpdpz)](2+) (5) and bis-Ru complex [(bpy)(2)Ru(dpdpz)Ru(bpy)(2)](4+) (13). However, no emission was detected from complex 8 or 12 at room temperature in acetonitrile.

  17. The Kondo problem. II. Crossover from asymptotic freedom to infrared slavery

    NASA Astrophysics Data System (ADS)

    Schlottmann, P.

    1982-04-01

    In the preceding paper we transformed the s-d Hamiltonian onto a resonance level with a large perturbation and derived the scaling equations for the vertices, the invariant coupling, and the resonance width. The scaling equations are integrated under the assumption that the energy dependence of the resonance width can be neglected. The transcendental equation obtained in this way for the renormalized resonance width is solved in the relevant limits and allows a calculation of the static and dynamical susceptibility. At high temperatures the perturbation expansion for the relaxation rate and the susceptibility is reproduced up to third order in Jρ. At low temperatures the lifetime and χ0 remain finite and vary according to a Fermi-liquid theory. The approximation scheme interpolates in this way between the asymptotic freedom and the infrared slavery, yielding a smooth crossover. The present results are in quantitative agreement with previous ones obtained with the relaxation-kernel method by Götze and Schlottmann. The advantages and drawbacks of the method are discussed. The calculation of the dynamical susceptibility is extended to nonzero external magnetic fields. The quasielastic peak of χ''(ω)ω is suppressed at low temperatures and large magnetic fields and shoulders develop at ω=+/-B.

  18. DEEP NEAR-INFRARED SURVEY OF THE PIPE NEBULA. II. DATA, METHODS, AND DUST EXTINCTION MAPS

    SciTech Connect

    Roman-Zuniga, Carlos G.; Lada, Charles J.; Lombardi, Marco

    2010-12-20

    We present a new set of high-resolution dust extinction maps of the nearby and essentially starless Pipe Nebula molecular cloud. The maps were constructed from a concerted deep near-infrared imaging survey with the ESO-VLT, ESO-NTT, CAHA 3.5 m telescopes, and 2MASS data. The new maps have a resolution three times higher than the previous extinction map of this cloud by Lombardi et al. and are able to resolve structures down to 2600 AU. We detect 244 significant extinction peaks across the cloud. These peaks have masses between 0.1 and 18.4 M{sub sun}, diameters between 1.2 and 5.7 x 10{sup 4} AU (0.06 and 0.28 pc), and mean densities of about 10{sup 4} cm{sup -3}, all in good agreement with previous results. From the analysis of the mean surface density of companions we find a well-defined scale near 1.4 x 10{sup 4} AU below which we detect a significant decrease in structure of the cloud. This scale is smaller than the Jeans length calculated from the mean density of the peaks. The surface density of peaks is not uniform but instead it displays clustering. Extinction peaks in the Pipe Nebula appear to have a spatial distribution similar to the stars in Taurus, suggesting that the spatial distribution of stars evolves directly from the primordial spatial distribution of high-density material.

  19. Hot Young Solution to Faint Sun Paradox

    NASA Astrophysics Data System (ADS)

    Riofrio, L.

    2006-12-01

    The "Faint Young Sun" has been a paradox of astrophysics. The standard solar model predicts that 4 billion years ago Earth was too cold to support life. Geology and the fossil record contradict this prediction. The paradox and possible solution are a fascinating combination of astrophysics, relativity and the Earth sciences. Models predict that 4 billion years ago the Sun shone with only 70 % of its present luminosity. Since power P is related to temperature T by the Stefan-Boltzmann Law P ∝ T4, Earth temperature would have been only 91 % of its present value. That temperature is approximately 283K, so temperature in the past would have been only 258K. Earth's surface would have frozen solid, making evolution of life very unlikely. Geology shows evidence of extensive sedimentation 4 billion years ago. Other geological markers corroborate the presence of liquid water on Earth during this period. Paleontology dates the earliest organisms at least 3.4 to 4 billion years old. Clearly liquid water and life both existed when the model predicts Earth was frozen solid. This conflict with observations is the Faint Young Sun paradox. Fortunately, Relativity and Space/Time can help save the standard solar model. The Sun converts its fuel to energy according to E=mc2. Unified Space/Time predicts that c is given by: GM=tc3. Where t is age of the Universe, GM combines its mass and gravitational constant. Solving, we have c(t)=(GM)^{1/3} t^{-1/3}. Billions of years ago, solar output and temperature were therefore higher than originally calculated. Earth is estimated to be 4.6 billion years and the Universe 13.7 billion years old, 1.5 times its age at the time of Earth's formation. Energy e=mc2 is adjusted by (1.5)^{2/3} = 1.31 times the initial estimate. Multiplying by that estimate of 70 %, the Sun's actual output was 0.917 of the present value. Temperature was then (0.917)^{1/4} = 98 % of today's value. If we start with an estimate of 76 %, the Sun's true output was exactly

  20. Is the faint young Sun paradox solved?

    NASA Astrophysics Data System (ADS)

    Wolf, E. T.; Toon, O. B.

    2013-12-01

    How did the early Earth remain warm despite weak solar luminosity? The faint young Sun paradox has stubbornly resisted a self-consistent solution since it was first introduced by Sagan and Mullen [1] over four decades ago. However, recent revisions to expected paleo-ocean temperatures [2, 3] along with new results from three-dimensional climate models [4] may allow this long standing problem to be finally put to rest. Here we use a modified version of the Community Atmosphere Model version 3 from the National Center for Atmospheric Research to study early climate. We find that resolving the faint young Sun paradox becomes less problematic when viewing a full representation of the climate system. For the late Archean climate (80% solar constant), relatively modest amounts of CO2 (≤0.02 bar) and CH4 (0.001 bar) yield surface temperatures equal to the present day with no other alterations to climate. Cooler climates with large ice caps but with temperate tropical regions can be supported with considerably smaller greenhouse gas burdens. The incorporation of systematic climate system elements expected for the Archean such as fewer cloud condensation nuclei (CCN) [5], reduced land albedos [5], and an increased atmospheric inventory of N2 [6], can provide a combined 10 to 20 K of additional surface warming given reasonable assumptions. With the inclusion of 0.001 bar of CH4, 2 PAL of N2, reduced land albedos, and reduced CCN, present day mean surface temperatures can be maintained for the earliest Archean (75% solar constant) with only ~0.01 bar of CO2. However, lower requirements for atmospheric CO2 may imply that photochemical hazes were frequent during the Archean. [1] Sagan, C., & Mullen, G. Science 177, 52 (1972) [2] Hren, M.T., Tice, M.M., & Chamberlin, C.P. Nature 462, 205 (2009) [3] Blake. R.E., Chang, S.J., & Lepland, A. Nature 464, 1029 (2010) [4] Wolf, E.T., & Toon, O.B. Astrobiology 13(7), 1 (2013) [5] Rosing, M.T., Bird, D.K., Sleep, N.H., & Bjerrum, C

  1. Faint high-latitude carbon stars

    NASA Astrophysics Data System (ADS)

    Green, Paul Jonathan

    We have undertaken a wide area survey to search for faint high latitude carbon (FHLC) stars. Carbon giants are ideal for study of the structure and kinematics of the outer galactic halo. We use two color photometric selection with large format charge-coupled devices (CCD's) to cover 52 deg2 of sky to a depth of about V = 18. Below this limit, we find good (approximately less than 20 percent) agreement between our object counts as a function of magnitude and the galactic models of Bahcall and Soneira at a variety of latitudes and longitudes. Our spectroscopic followup began with low-resolution spectra of 19 unconfirmed C star candidates from the Case objective-prism photographic survey of Sanduleak and Pesch. Four of these we find to be M stars. The 15 C stars we classify on the two-parameter Keenan-Morgan system as warm (color class less than 3). Of 94 faint C star candidates from our own CCD survey, one highly ranked V = 17 candidate was found to have strong carbon and CN bands. We estimate that to a depth of V = 18, the surface density FHLC stars is 0.019+0.044-.016 deg-2. We identify two FHLC stars with previously catalogued high proper motion objects. These objects are thus inferred to be dwarf carbon (dC) stars, supplementing the one previously known case, G77-61. Not all dC stars will have detectable proper motions, so other luminosity/distance indicators are needed: we find that C dwarfs all have similar JHK colors, and possibly an unusually strong lambda-6191 bandhead of carbon. By comparing positions in the HST Guide Star Catalog and the original Palomar Observatory Sky Survey, we detect proper motions in two additional FHLC stars. Our proper motion survey, spanning a 30 year baseline, thus identifies two new dC's, and provides proper motion upper limits for another 44 FHLC stars. Kinematic simulations suggest that virtually all Population 2 dC's will have detectable proper motions in a survey as sensitive as our own, and that to a limit of V approximately

  2. SUBARU MID-INFRARED IMAGING OF THE QUADRUPLE LENSES. II. UNVEILING LENS STRUCTURE OF MG0414+0534 AND Q2237+030

    SciTech Connect

    Minezaki, Takeo; Chiba, Masashi; Kashikawa, Nobunari; Inoue, Kaiki Taro; Kataza, Hirokazu E-mail: chiba@astr.tohoku.ac.jp E-mail: kinoue@phys.kindai.ac.jp

    2009-05-20

    We present mid-infrared imaging at 11.7 {mu}m for the quadruple lens systems, MG0414+0534 and Q2237+030, using the cooled mid-infrared camera and spectrometer attached on the Subaru telescope. MG0414+0534 is characterized by a bright pair of lensed images (A1, A2) and their optical flux ratio A2/A1 deviates significantly from the prediction of a smooth-lens model. Q2237+030 is 'the Einstein Cross' being comprised of four lensed images, which are significantly affected by microlensing in a foreground lensing galaxy. Our mid-infrared observations of these lensed images have revealed that the mid-infrared flux ratio for A2/A1 of MG0414+0534 is nearly unity (0.90 {+-} 0.04). We find that this flux ratio is systematically small, at 4-5{sigma} level, compared with the prediction of a best smooth-lens model (1.09) represented by a singular isothermal ellipsoid and external shear. The smooth-lens model, which also considers the additional lensing effect of the possible faint satellite, object X, still provides a large flux ratio of A2/A1=1.06, thereby suggesting the presence of more substructures that can explain our observational result. In contrast, for Q2237+030, our high signal-to-noise observation indicates that the mid-infrared flux ratios between all the four images of Q2237+030 are virtually consistent with the prediction of a smooth-lens model. Based on the size estimate of the dust torus surrounding the nuclei of these QSOs, we set limits on the mass of a substructure in these lens systems, which can cause anomalies in the flux ratios. For MG0414+0534, since the required mass of a substructure inside its Einstein radius is {approx}>360 M {sub sun}, millilensing by a cold dark matter substructure is most likely. If it is modeled as a singular isothermal sphere, the mass inside a radius of 100 pc is given as {approx}>1.0 x 10{sup 5} M {sub sun}. For Q2237+030, there is no significant evidence of millilensing, so the reported anomalous flux ratios in shorter

  3. No climate paradox under the faint early Sun.

    PubMed

    Rosing, Minik T; Bird, Dennis K; Sleep, Norman H; Bjerrum, Christian J

    2010-04-01

    Environmental niches in which life first emerged and later evolved on the Earth have undergone dramatic changes in response to evolving tectonic/geochemical cycles and to biologic interventions, as well as increases in the Sun's luminosity of about 25 to 30 per cent over the Earth's history. It has been inferred that the greenhouse effect of atmospheric CO(2) and/or CH(4) compensated for the lower solar luminosity and dictated an Archaean climate in which liquid water was stable in the hydrosphere. Here we demonstrate, however, that the mineralogy of Archaean sediments, particularly the ubiquitous presence of mixed-valence Fe(II-III) oxides (magnetite) in banded iron formations is inconsistent with such high concentrations of greenhouse gases and the metabolic constraints of extant methanogens. Prompted by this, and the absence of geologic evidence for very high greenhouse-gas concentrations, we hypothesize that a lower albedo on the Earth, owing to considerably less continental area and to the lack of biologically induced cloud condensation nuclei, made an important contribution to moderating surface temperature in the Archaean eon. Our model calculations suggest that the lower albedo of the early Earth provided environmental conditions above the freezing point of water, thus alleviating the need for extreme greenhouse-gas concentrations to satisfy the faint early Sun paradox.

  4. Theoretical Design and Material Growth of Type-II Antimonide-based Superlattices for Infrared Detection and Imaging

    NASA Astrophysics Data System (ADS)

    Nguyen, Binh-Minh

    The goal of this PhD thesis is to investigate quantum properties of the superlattice system, design appropriate device architectures and experimentally fabricate infrared detectors which can outperform currently existing devices. In parallel, efforts in material growth using molecular beam epitaxy (MBE) have resulted in higher material quality and vastly improved growth conditions of III-V compounds as compared to previous work. Superlattices as thick as 15mum were realized without growth defects or dislocations, narrow X-ray diffraction peaks and small surface roughness. Many ternary and quaternary layers such as InAsSb, AlAsSb, GaAlAsSb were routinely used in new design architectures to enhance the electrical performance of the devices. Advances in theoretical calculations and material growth have allowed this work to continue with comprehensive studies of photodetector device architectures. Fundamental parameters affecting the performance of infrared detectors were investigated. We have experimentally pointed out the difference in the collection of photocurrent generated in the n-type and p-type regions. By forcing the device's active region to have an appropriate p-doped concentration, and by assuring long diffusion carrier lengths with high material quality, the quantum efficiency of Type-II superlattice photodiodes have been demonstrated in excess 50% in front side illumination configuration and 75% in back side illumination configuration. In an attempt to optimize the electrical performance, basic mechanisms of the dark current have been thoroughly analyzed. By intentionally doping the active region, the diffusion and generation-recombination currents were reduced until they were overwhelmed by the tunneling current. The device performance was then further enhanced due to the suppression of the tunneling current using the hetero-design of the M-structure superlattice. This optimization scheme can be repeated iteratively to lower all bulk-components of the

  5. THE SPITZER INFRARED SPECTROGRAPH DEBRIS DISK CATALOG. II. SILICATE FEATURE ANALYSIS OF UNRESOLVED TARGETS

    SciTech Connect

    Mittal, Tushar; Chen, Christine H.; Jang-Condell, Hannah; Manoj, P.; Sargent, Benjamin A.; Watson, Dan M.; Lisse, Carey M.

    2015-01-10

    During the Spitzer Space Telescope cryogenic mission, astronomers obtained Infrared Spectrograph (IRS) observations of hundreds of debris disk candidates that have been compiled in the Spitzer IRS Debris Disk Catalog. We have discovered 10 and/or 20 μm silicate emission features toward 120 targets in the catalog and modeled the IRS spectra of these sources, consistent with MIPS 70 μm observations, assuming that the grains are composed of silicates (olivine, pyroxene, forsterite, and enstatite) and are located either in a continuous disk with power-law size and surface density distributions or thin rings that are well-characterized using two separate dust grain temperatures. For systems better fit by the continuous disk model, we find that (1) the dust size distribution power-law index is consistent with that expected from a collisional cascade, q = 3.5-4.0, with a large number of values outside this range, and (2) the minimum grain size, a {sub min}, increases with stellar luminosity, L {sub *}, but the dependence of a {sub min} on L {sub *} is weaker than expected from radiation pressure alone. In addition, we also find that (3) the crystalline fraction of dust in debris disks evolves as a function of time with a large dispersion in crystalline fractions for stars of any particular stellar age or mass, (4) the disk inner edge is correlated with host star mass, and (5) there exists substantial variation in the properties of coeval disks in Sco-Cen, indicating that the observed variation is probably due to stochasticity and diversity in planet formation.

  6. GALAXY CLUSTERS IN THE IRAC DARK FIELD. II. MID-INFRARED SOURCES

    SciTech Connect

    Krick, J. E.; Surace, J. A.; Yan, L.; Thompson, D.; Ashby, M. L. N.; Hora, J. L.; Gorjian, V.

    2009-07-20

    We present infrared (IR) luminosities, star formation rates (SFR), colors, morphologies, locations, and active galactic nuclei (AGNs) properties of 24 {mu}m detected sources in photometrically detected high-redshift clusters in order to understand the impact of environment on star formation (SF) and AGN evolution in cluster galaxies. We use three newly identified z = 1 clusters selected from the IRAC dark field; the deepest ever mid-IR survey with accompanying, 14 band multiwavelength data including deep Hubble Space Telescope imaging and deep wide-area Spitzer MIPS 24 {mu}m imaging. We find 90 cluster members with MIPS detections within two virial radii of the cluster centers, of which 17 appear to have spectral energy distributions dominated by AGNs and the rest dominated by SF. We find that 43% of the star-forming sample have IR luminosities L{sub IR} > 10{sup 11} L{sub sun} (luminous IR galaxies). The majority of sources (81%) are spirals or irregulars. A large fraction (at least 25%) show obvious signs of interactions. The MIPS-detected member galaxies have varied spatial distributions as compared to the MIPS-undetected members with one of the three clusters showing SF galaxies being preferentially located on the cluster outskirts, while the other two clusters show no such trend. Both the AGN fraction and the summed SFR of cluster galaxies increase from redshift zero to one, at a rate that is a few times faster in clusters than over the same redshift range in the field. Cluster environment does have an effect on the evolution of both AGN fraction and SFR from redshift one to the present, but does not affect the IR luminosities or morphologies of the MIPS sample. SF happens in the same way regardless of environment making MIPS sources look the same in the cluster and field, however the cluster environment does encourage a more rapid evolution with time as compared to the field.

  7. COMPARATIVE STUDY OF ASYMMETRY ORIGIN OF GALAXIES IN DIFFERENT ENVIRONMENTS. II. NEAR-INFRARED OBSERVATIONS

    SciTech Connect

    Plauchu-Frayn, I.; Coziol, R. E-mail: rcoziol@astro.ugto.m

    2010-08-15

    In this second paper of two analyses, we present near-infrared (NIR) morphological and asymmetry studies performed in a sample of 92 galaxies found in different density environments: galaxies in compact groups (CGs; HCGs in the Hickson Catalog of Compact Groups of Galaxies), isolated pairs of galaxies (KPGs in Karachentsev's list of isolated pairs of galaxies), and isolated galaxies (KIGs in Karachentseva's Catalog of Isolated Galaxies). Both studies have proved useful for identifying the effect of interactions on galaxies. In the NIR, the properties of the galaxies in HCGs, KPGs, and KIGs are more similar than they are in the optical. This is because the NIR band traces the older stellar populations, which formed earlier and are more relaxed than the younger populations. However, we found asymmetries related to interactions in both KPG and HCG samples. In HCGs, the fraction of asymmetric galaxies is even higher than what we found in the optical. In the KPGs the interactions look like very recent events, while in the HCGs galaxies are more morphologically evolved and show properties suggesting they suffered more frequent interactions. The key difference seems to be the absence of star formation in the HCGs; while interactions produce intense star formation in the KPGs, we do not see this effect in the HCGs. This is consistent with the dry merger hypothesis; the interaction between galaxies in CGs is happening without the presence of gas. If the gas was spent in stellar formation (to build the bulge of the numerous early-type galaxies), then the HCGs possibly started interacting sometime before the KPGs. On the other hand, the dry interaction condition in CGs suggests that the galaxies are on merging orbits, and consequently such system cannot be that much older either. Cosmologically speaking, the difference in formation time between pairs of galaxies and CGs may be relatively small. The two phenomena are typical of the formation of structures in low

  8. Supermassive black holes and their host galaxies. II. The correlation with near-infrared luminosity revisited

    SciTech Connect

    Läsker, Ronald; Van de Ven, Glenn; Ferrarese, Laura; Shankar, Francesco

    2014-01-01

    We present an investigation of the scaling relations between supermassive black hole (SMBH) masses, M {sub •}, and their host galaxies' K-band bulge (L {sub bul}) and total (L {sub tot}) luminosities. The wide-field WIRCam imager at the Canada-France-Hawaii-Telescope was used to obtain the deepest and highest resolution near-infrared images available for a sample of 35 galaxies with securely measured M {sub •}, selected irrespective of Hubble type. For each galaxy, we derive bulge and total magnitudes using a two-dimensional image decomposition code that allows us to account, if necessary, for large- and small-scale disks, cores, bars, nuclei, rings, envelopes, and spiral arms. We find that the present-day M {sub •}-L {sub bul} and M {sub •}-L {sub tot} relations have consistent intrinsic scatter, suggesting that M {sub •} correlates equally well with bulge and total luminosity of the host. Our analysis provides only mild evidence of a decreased scatter if the fit is restricted to elliptical galaxies. The log-slopes of the M {sub •}-L {sub bul} and M {sub •}-L {sub tot} relations are 0.75 ± 0.10 and 0.92 ± 0.14, respectively. However, while the slope of the M {sub •}-L {sub bul} relation depends on the detail of the image decomposition, the characterization of M {sub •}-L {sub tot} does not. Given the difficulties and ambiguities of decomposing galaxy images into separate components, our results indicate that L {sub tot} is more suitable as a tracer of SMBH mass than L {sub bul}, and that the M {sub •}-L {sub tot} relation should be used when studying the co-evolution of SMBHs and galaxies.

  9. Accurate shear measurement with faint sources

    SciTech Connect

    Zhang, Jun; Foucaud, Sebastien; Luo, Wentao E-mail: walt@shao.ac.cn

    2015-01-01

    For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.

  10. The Population of Optically Faint GEO Debris

    NASA Astrophysics Data System (ADS)

    Seitzer, P.; Barker, E.; Buckalew, B.; Burkhardt, A.; Cowardin, H.; Frith, J.; Kaleida, C.; Lederer, S.; Lee, C.

    2016-09-01

    The 6.5-m Magellan telescope, 'Walter Baade', at the Las Campanas Observatory in Chile has been used for spot surveys of the geosynchronous Earth orbit (GEO) regime to study the population of optically faint GEO debris. The goal is to estimate the population of GEO debris at sizes much smaller than can be studied with 1-meter class telescopes. Despite the small field of view of the Magellan instrument (diameter 0.5-degree), a significant population of objects fainter than R = 19th magnitude has been found with angular rates consistent with circular orbits at GEO. We compare the size of this population with the numbers of GEO objects found at brighter magnitudes by smaller telescopes. The detections have a wide range of characteristics starting with those appearing as short uniform streaks. But there are a substantial number of detections that vary in brightness ("flashers") during the 5-second exposure. The duration of each of these flashes can be extremely brief: sometimes less than half a second. This is characteristic of a rapidly tumbling object with a quite variable projected product of size * albedo. If the albedo is of the order of 0.2, then the largest projected size of these objects is around 10-cm.

  11. Detection of Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, P.; Lederer, S.; Barker, E.; Cowardin, H.; Abercromby, K.; Silha, J.; Burkhardt, A.

    2014-01-01

    There have been extensive optical surveys for debris at geosynchronous orbit (GEO) conducted with meter-class telescopes, such as those conducted with MODEST (the Michigan Orbital DEbris Survey Telescope, a 0.6-m telescope located at Cerro Tololo in Chile), and the European Space Agency's 1.0-m space debris telescope (SDT) in the Canary Islands. These surveys have detection limits in the range of 18th or 19th magnitude, which corresponds to sizes larger than 10 cm assuming an albedo of 0.175. All of these surveys reveal a substantial population of objects fainter than R = 15th magnitude that are not in the public U.S. Satellite Catalog. To detect objects fainter than 20th magnitude (and presumably smaller than 10 cm) in the visible requires a larger telescope and excellent imaging conditions. This combination is available in Chile. NASA's Orbital Debris Program Office has begun collecting orbital debris observations with the 6.5-m (21.3-ft diameter) "Walter Baade" Magellan telescope at Las Campanas Observatory. The goal is to detect objects as faint as possible from a ground-based observatory and begin to understand the brightness distribution of GEO debris fainter than R = 20th magnitude.

  12. Infrared spectroscopy of methanol-hexane liquid mixtures. II. The strength of hydrogen bonding

    NASA Astrophysics Data System (ADS)

    Max, Jean-Joseph; Chapados, Camille

    2009-03-01

    The study by Fourier transform infrared attenuated total reflectance spectroscopy at 27 °C of methanol (MeOH) and hexane mixtures is presented. In the 0-0.25 and 0.75-1.00 molar fractions, the mixtures form homogeneous solutions, whereas from 0.25 to 0.75, the mixtures are inhomogeneous forming two phases. These mixtures have the near 3300 cm-1 OH stretch band only slightly displaced throughout the whole concentration range indicating very little variation in the H-bonding condition. This result is very different from that of MeOH in CCl4 where the OH stretch bands are scattered in a wide frequency range. Factor analysis applied to the MeOH/hexane spectra gave seven principal factors (one hexane and six methanol factors) and retrieved their principal spectra and abundances. In the inhomogeneous region, the two phase volumes changed inversely with concentration, but their factor compositions are invariable at 1:3 and 3:1 molar ratios. Five of the six principal methanol factors have the O-H and the C-O stretch bands situated near, respectively, 3310 and 1025 cm-1 with little displacement in the whole concentration range. The sixth factor observed at 3654 cm-1 (full width at half height<40 cm-1) was assigned to free methanol OH by Max and Chapados [J. Chem. Phys. 128, 224512 (2008)]. This species concentration is very low but constant at around 0.01M in the methanol range of 0.5-2.5M. The main OH stretch bands (˜3300 cm-1) were simulated with six Gaussian components that were assigned to different hydrogen-bonding situations. These form reverse micelles at low methanol concentrations and micelles at high concentrations that persist in pure methanol. A very different state of affairs exists in MeOH in CCl4 where free OH groups are formed in almost all mixtures except in pure MeOH. Since hexane is a better model of a lipidic milieu than CCl4, the results for MeOH/hexane give a better representation of the fate of alcoholic OH groups in such a milieu.

  13. Infrared spectroscopy of acetone-water liquid mixtures. II. Molecular model

    NASA Astrophysics Data System (ADS)

    Max, Jean-Joseph; Chapados, Camille

    2004-04-01

    In aqueous acetone solutions, the strong bathochromic shifts observed on the OH and CO stretch infrared (IR) bands are due to hydrogen bonds between these groups. These shifts were evaluated by factor analysis (FA) that separated the band components from which five water and five acetone principal factors were retrieved [J. Chem. Phys. 119, 5632 (2003)]. However, these factors were abstract making them difficult to interpret. To render them real an organization model of molecules is here developed whose abundances are compared to the experimental ones. The model considers that the molecules are randomly organized limited by the hydrogen bond network formed between the water hydrogen atoms and the acetone or water oxygen atoms, indifferently. Because the oxygen of water has two covalent hydrogen atoms which are hydrogen-bonded and may receive up to two hydrogen atoms from neighbor molecules hydrogen-bonded to it, three types of water molecules are found: OH2, OH3, and OH4 (covalent and hydrogen bonds). In the OH stretch region these molecules generate three absorption regimes composed of ν3, ν1, and their satellites. The strength of the H-bond given increases with the number of H-bonds accepted by the oxygen atom of the water H-bond donor, producing nine water situations. Since FA cannot separate those species that evolve concomitantly the nine water situations are regrouped into five factors, the abundance of which compared exactly to that retrieved by FA. From the factors' real spectra the OH stretch absorption are simulated to, respectively, give for the ν3 and ν1 components the mean values for OH2, 3608, 3508; OH3, 3473, 3282 and OH4, 3391, 3223 cm-1. The mean separations from the gas-phase position which are respectively about 150, 330, and 400 cm-1 are related to the vacancy of the oxygen electron doublets: two, one, and zero, respectively. No acetone hydrate that sequesters water molecules is formed. Similarly, acetone produces ten species, two of which

  14. Faint spatial object classifier construction based on data mining technology

    NASA Astrophysics Data System (ADS)

    Lou, Xin; Zhao, Yang; Liao, Yurong; Nie, Yong-ming

    2016-11-01

    Data mining can effectively obtain the faint spatial object's patterns and characteristics, the universal relations and other implicated data characteristics, the key of which is classifier construction. Faint spatial object classifier construction with spatial data mining technology for faint spatial target detection is proposed based on theoretical analysis of design procedures and guidelines in detail. For the one-sidedness weakness during dealing with the fuzziness and randomness using this method, cloud modal classifier is proposed. Simulating analyzing results indicate that this method can realize classification quickly through feature combination and effectively resolve the one-sidedness weakness problem.

  15. a Faint and Lonely Brown Dwarf in the Solar Vicinity

    NASA Astrophysics Data System (ADS)

    1997-04-01

    La Silla, each covering a sky area of 5 o.5 x 5 o.5. When comparing plates of the same sky field obtained at time intervals of several years [1] , she was able to detect, among the hundreds of thousands of stellar images on the plates, a few faint ones whose positions had changed a little in the meantime. The search technique is based on the fact that such a shift is a good indicator of the object being relatively nearby. It must therefore also be intrinsically faint, i.e. a potential White Dwarf candidate. On every pair of plates, approximately twenty faint moving objects were detected with proper motions [2] of more than 0.25 arcsec per year. Indeed, follow-up spectroscopic observations showed that about 20 percent of these or about four per plate were White Dwarfs. Until now, a total of forty new White Dwarfs have been discovered during this very successful project, i.e. over ten times more than originally expected. And then - a Brown Dwarf! Caption to ESO PR Photo 11/97 [JPEG, 144k] ESO Press Photo 11/97 When checking two plates with a time inverval of 11 years, Maria Teresa Ruiz earlier this year discovered a very faint object in the southern constellation of Hydra (The Water-Snake), moving at 0.35 arcsec per year (cf. ESO Press Photo 11/97). In order to establish its true nature, she obtained its spectrum (in the visual to near-infrared region from wavelengths 450-1000 nm) on March 15 using the ESO 3.6-m telescope and the EFOSC1 spectrograph. Caption to ESO PR Photo 12/97 [GIF, 35k] ESO Press Photo 12/97 To her great surprise, the spectrum was of a type never seen before and certainly not that of a White Dwarf or any other easily identifiable type of star (cf. ESO Press Photo 12/97). In particular, there were no signs of spectral bands of titanium oxide (TiO) or vanadium oxide (VO) which are common in very cool stars, nor of the spectral lines seen in White Dwarfs. On the other hand, an absorption line of the short-lived element lithium was identified, as well

  16. Structure of selected basic zinc/copper (II) phosphate minerals based upon near-infrared spectroscopy - Implications for hydrogen bonding

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Reddy, B. Jagannadha; Palmer, Sara J.; Keeffe, Eloise C.

    2011-03-01

    The NIR spectra of reichenbachite, scholzite and parascholzite have been studied at 298 K. The spectra of the minerals are different, in line with composition and crystal structural variations. Cation substitution effects are significant in their electronic spectra and three distinctly different electronic transition bands are observed in the near-infrared spectra at high wavenumbers in the 12,000-7600 cm -1 spectral region. Reichenbachite electronic spectrum is characterised by Cu(II) transition bands at 9755 and 7520 cm -1. A broad spectral feature observed for ferrous ion in the 12,000-9000 cm -1 region both in scholzite and parascholzite. Some what similarities in the vibrational spectra of the three phosphate minerals are observed particularly in the OH stretching region. The observation of strong band at 5090 cm -1 indicates strong hydrogen bonding in the structure of the dimorphs, scholzite and parascholzite. The three phosphates exhibit overlapping bands in the 4800-4000 cm -1 region resulting from the combinations of vibrational modes of (PO 4) 3- units.

  17. Star formation in the inner Galaxy - a far-infrared and radio study of two H II regions

    SciTech Connect

    Lester, D.F.; Dinerstein, H.L.; Harvey, P.M.; Evans, N.J. II; Werner, M.W.

    1985-09-01

    Far-infrared and radio continuum maps have been made of two inner-Galaxy H II region complexes, G30.8-0.0 and G25.4-0.2, along with radio and molecular line measurements at selected positions. The far-IR emission from each region is dominated by two sources. For both G25.4 and G30.8, the distribution of the emission is similar to that of the radio emission, indicating that OB stars provide most of the heating. There is evidence that extinction plays an important role in G30.8, even in the far-IR. A near-IR point source has been detected in G30.8 at the position of peak far-IR color temperature. This source may be the ionizing star for the core of G30.8. Measurement of forbidden S III 9532 A from G25.4SE indicates that the extinction toward this source is very low, which is difficult to reconcile with previously determined distance measurements to this source. 49 references.

  18. 77 FR 21586 - II-VI, Incorporated, Infrared Optics-Saxonburg Division, Saxonburg, PA; Notice of Affirmative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-10

    ... employment related to the production of infrared and CO 2 laser optics, and related materials. The initial... experienced a decline in the sales or production of infrared and CO 2 laser optics, and related materials... production of infrared and CO 2 laser optics, and related materials (or like or directly competitive...

  19. Faint solar radio structures from decametric observations

    NASA Astrophysics Data System (ADS)

    Briand, C.; Zaslavsky, A.; Maksimovic, M.; Zarka, P.; Lecacheux, A.; Rucker, H. O.; Konovalenko, A. A.; Abranin, E. P.; Dorovsky, V. V.; Stanislavsky, A. A.; Melnik, V. N.

    2008-10-01

    Aims: Decameter radio observations of the solar corona reveal the presence of numerous faint frequency drifting emissions, similar to “solar S bursts” which are reported in the literature. We present a statistical analysis of the characteristics of these emissions and propose a mechanism to excite the Langmuir waves thought to be at the origin of these emissions. Methods: The observations were performed between 1998 and 2002 with the Digital Spectro Polarimeter (DSP) receivers operated at the UTR-2 and Nançay decameter radio telescopes in the frequency range 15-30 MHz. Our theoretical explanation is based on Vlasov-Ampère simulations. Results: Based on the frequency drift rate, three populations of structures can be identified. The largest population presents an average negative frequency drift of -0.9 MHz s-1 and a lifetime up to 11 s (median value of 2.72 s). A second population shows a very small frequency drift of -0.1 MHz s-1 and a short lifetime of about 1 s. The third population presents an average positive frequency drift of +0.95 MHz s-1 and a lifetime of up to 3 s. Also, the frequency drift as a function of frequency is consistent with the former results, which present results in higher frequency range. No specific relationship was found between the occurrence of these emissions and the solar cycle or presence of flares. Assuming that these emissions are produced by “electron clouds” propagating the solar corona, we deduce electron velocities of about 3-5 times the electron thermal velocity. As previously shown, a localized, time-dependent modulation of the electron distribution function (heating) leads to low velocity electron clouds (consistent with observations), which, in turn, can generate Langmuir waves and electromagnetic signals by nonlinear processes.

  20. Faint CV Monitoring at CBA Pretoria

    NASA Astrophysics Data System (ADS)

    Monard, L. A. G. B.

    2006-05-01

    The regular monitoring of faint cataclysmic variables (CV) is one of five observing programs that are run at CBA Pretoria. It started off in 2002 with about 120 CVs and related objects in the program. The intention was to observe those targets as often as possible with unfiltered CCD. There were continuous additions of more CVs by digging deeper in the CV atlas, new finds, and reclassified stars while some were taken off the list. At the end of 2004 the number of CVs in the observing program exceeded 200. With only one telescope and one observer and so many other things to observe, the actual number of snapshot CV observations have been much less than hoped. Despite this, the program has shown to be very successful. Publications have been referring to reported findings from this program while even more publications resulted from observing campaigns (time resolved photometry) dedicated to CVs that were found in outburst by observations at CBA Pretoria. In most cases they were the first real-time outburst detection of that CV. The present paper will not deal with those published or alerted finds but will show observing results of other CVs from the list just to give an indication of the broader meaningfulness of such a program. A selection of fifteen light curves obtained after three years of monitoring will be shown and discussed. The choice of the 15 stars was based on their possible interest and the fact that they have been positively observed on most occasions, since they were mostly brighter than magnitude 18 CR (unfiltered with red zero-point).

  1. NASA Researches the 'FaINT' Side of Sonic Booms

    NASA Video Gallery

    As the latest in a continuing progression of NASA supersonics research projects aimed at reducing or mitigating the effect of sonic booms, the Farfield Investigation of No Boom Threshold, or FaINT,...

  2. Star formation in infrared bright and infrared faint starburst interacting galaxies

    NASA Technical Reports Server (NTRS)

    Lamb, Susan A.; Bushouse, Howard A.; Towns, John W.

    1990-01-01

    Short wavelength IUE spectra of Arp 248b and UGC 8315N are combined with optical spectra and interpreted using a combination of spectrum synthesis and spectral diagnostics to place constraints on the massive star populations of the central regions of these galaxies and to deduce information about the star formation histories in the last 10(exp 8) years. The authors find that both galaxies have substantial fractions of their optical light coming from massive stars and that Arp 248b may be dominated in the UV by WR stars. The UV spectra are dominated by radiation from evolved massive stars and the authors place and age on the burst in Arp 248b of a few tens of millions of years.

  3. HST observations of faint Cold Classical KBOs

    NASA Astrophysics Data System (ADS)

    Penteado, Paulo F.; Trilling, David E.; Grundy, Will

    2016-10-01

    The size distribution of the known Kuiper Belt Objects has been described by a double power law, with a break at R magnitude 25. There are two leading interpretations to this break: 1) It is the result of the collisional evolution, with the objects smaller than the break being the population most affected by collisional erosion. 2) The size distribution break is primordial, set during the Kuiper Belt formation.The low inclination KBOs, the Cold Classical population, is thought to have been dynamically isolated since the formation of the Solar System, and thus only collisions between Cold Classicals would have affected their size distribution. If the distribution is collisional, it probes parameters of the Kuiper Belt history: strengths of the bodies, impact energies and frequency, and the the number of objects. If the distribution is primordial, it reveals parameters of the Kuiper Belt accretion, as well as limits on its subsequent collisional history.We obtained HST observations of 16 faint Cold Classicals, which we combine with archival HST observations of 20 others, to examine the distribution of two properties of the smallest KBOs: colors and binary fraction. These properties can differentiate between a primordial and a collisional origin of the size distribution break. If the smaller bodies have been through extensive collisional evolution, they will have exposed materials from their interiors, which has not been exposed to weathering, and thus should be bluer than the old surfaces of the larger bodies. Another constraint can be derived from the fraction of binary objects: the angular momentum of the observed binaries is typically too high to result from collisions, thus a collisionally-evolved population would have a lower binary fraction, due to the easier separation of binaries, compared to the disruption of similar-sized bodies, and the easier disruption of the binary components, due to the smaller size.We present the constraints to the color and binary

  4. Is Solar Activity Once More Fainting?

    NASA Astrophysics Data System (ADS)

    Mares Aguilar, C. E.; Schröder, K.-P.; Song, G.

    2013-04-01

    After an anomalously long and deep minimum, will the Sun now once again reach a period of weaker activity cycles, which would affect northern hemisphere winter climate? We here discuss the current state and outlook of solar activity, and we propose to monitor the solar Ca II K line emission “as a star”, as part of the regular observing schedule of the Hamburg robotic telescope, which is bound to move to Guanajuato this year (2012). In fact, the chromospheric Ca II K line emission is a good proxy for the solar far-ultraviolet flux, as both are generated at about the same plasma temperatures (12-15,000 K) and both originate from the same active regions (plages). The solar ultraviolet flux, in turn, warms the stratosphere by photo dissociation of ozone and other molecules and, consequently, affects the strength of the North Atlantic Oscillation (NOA).

  5. FAINT SUBMILLIMETER GALAXY COUNTS AT 450 {mu}m

    SciTech Connect

    Chen, Chian-Chou; Cowie, Lennox L.; Barger, Amy J.; Casey, Caitlin M.; Lee, Nicholas; Sanders, David B.; Williams, Jonathan P.; Wang, Wei-Hao

    2013-01-10

    We present the results of SCUBA-2 observations at 450 {mu}m and 850 {mu}m of the field lensed by the massive cluster A370. With a total survey area >100 arcmin{sup 2} and 1{sigma} sensitivities of 3.92 and 0.82 mJy beam{sup -1} at 450 and 850 {mu}m, respectively, we find a secure sample of 20 sources at 450 {mu}m and 26 sources at 850 {mu}m with a signal-to-noise ratio (S/N) > 4. Using the latest lensing model of A370 and Monte Carlo simulations, we derive the number counts at both wavelengths. The 450 {mu}m number counts probe a factor of four deeper than the counts recently obtained from the Herschel Space Telescope at similar wavelengths, and we estimate that {approx}47%-61% of the 450 {mu}m extragalactic background light resolved into individual sources with 450 {mu}m fluxes greater than 4.5 mJy. The faint 450 {mu}m sources in the 4{sigma} sample have positional accuracies of 3 arcsec, while brighter sources (S/N >6{sigma}) are good to 1.4 arcsec. Using a deep radio map (1{sigma} {approx} 6 {mu}Jy) we find that the percentage of submillimeter sources having secure radio counterparts is 85% for 450 {mu}m sources with intrinsic fluxes >6 mJy and 67% for 850 {mu}m sources with intrinsic fluxes >4 mJy. We also find that 67% of the >4{sigma} 450 {mu}m sources are detected at 850 {mu}m, while the recovery rate at 450 {mu}m of >4{sigma} 850 {mu}m sources is 54%. Combined with the source redshifts estimated using millimetric flux ratios, the recovered rate is consistent with the scenario where both 450 {mu}m and 20 cm emission preferentially select lower redshift dusty sources, while 850 {mu}m emission traces a higher fraction of dusty sources at higher redshifts. We identify potential counterparts in various wavelengths from X-ray to mid-infrared and measure the multiwavelength photometry, which we then use to analyze the characteristics of the sources. We find three X-ray counterparts to our robust submillimeter sample (S/N > 5), giving an active galactic nucleus

  6. Enhanced faint companion photometry and astrometry using wavelength diversity.

    PubMed

    Burke, Daniel; Devaney, Nicholas

    2010-11-01

    In this paper we examine approaches to faint companion detection and estimation in multi-spectral images. We will employ the Hotelling observer, which is the optimal linear algorithm for signal detection. We have shown how to use this observer to estimate faint object position and brightness in the presence of residual speckle, which usually limits astrometric and photometric techniques. These speckles can be reduced by differential imaging techniques such as Angular Differential Imaging and Spectral Differential Imaging. Here we present results based on simulations of adaptive-optics-corrected images from an Extremely Large Telescope (ELT) that contain quasi-static speckle noise. The simulation includes Angular Differential Imaging and Spectral Differential Imaging to reduce the residual speckle and subsequent multi-wavelength processing. We examine the feasibility of this approach on simulated ELT observations of faint companions.

  7. The nature of faint emission-line galaxies

    NASA Technical Reports Server (NTRS)

    Smetanka, John J.

    1993-01-01

    One of the results of faint galaxy redshift surveys is the increased fraction of galaxies which have strong emission-line spectra. These faint surveys find that roughly 50 percent of the galaxies have an equivalent width of (OII), W sub 3727, greater than 20 A while this fraction is less than 20 percent in the DARS survey. This has been interpreted as evidence for strong evolution in the galaxy population at redshifts less than 0.5. In order to further investigate the properties of the galaxies in faint redshift surveys, two important factors must be addressed. The first is the observed correlation between color, luminosity, and W sub 3727. There is a correlation between color and the strength of emission lines, bluer galaxies having stronger emission features, as evident for Markarian galaxies and for galaxies in Kennicutt's spectrophotometric atlas. This correlation also applies galaxies in faint redshift surveys. In addition, low luminosity galaxies have a larger average W sub 3727 (and bluer colors) than higher luminosity galaxies. This is illustrated for Kennicutt's low z late-type galaxies, for the Durham Faint Surveys, and for galaxies in SA68. The second factor which must be incorporated into any interpretation of the faint emission galaxies is the different luminosity functions for galaxies depending on color. This is usually modeled by varying M* for different color classes (or morphological types); however, the shape of the luminosity function is different for galaxies with different colors. Low luminosity, blue galaxies have a much larger number density than low luminosity, red galaxies. Furthermore, the low luminosity end of the blue galaxy luminosity function is not well fit by a Schechter function. These two factors have been included in a very simple, no-evolution, model for the galaxy population. This model uses the luminosity functions from Shanks (1990) and spectral energy distributions (SED's) from Bruzual (1988). W sub 3727 is predicted using

  8. On the source of the late-time infrared luminosity of SN 1998S and other Type II supernovae

    NASA Astrophysics Data System (ADS)

    Pozzo, M.; Meikle, W. P. S.; Fassia, A.; Geballe, T.; Lundqvist, P.; Chugai, N. N.; Sollerman, J.

    2004-08-01

    We present late-time near-infrared (NIR) and optical observations of the Type IIn SN 1998S. The NIR photometry spans 333-1242 d after explosion, while the NIR and optical spectra cover 333-1191 and 305-1093 d, respectively. The NIR photometry extends to the M' band (4.7 μm), making SN 1998S only the second ever supernova for which such a long IR wavelength has been detected. The shape and evolution of the Hα and HeI 1.083-μm line profiles indicate a powerful interaction with a progenitor wind, as well as providing evidence of dust condensation within the ejecta. The latest optical spectrum suggests that the wind had been flowing for at least 430 yr. The intensity and rise of the HK continuum towards longer wavelengths together with the relatively bright L' and M' magnitudes show that the NIR emission was due to hot dust newly formed in the ejecta and/or pre-existing dust in the progenitor circumstellar medium (CSM). The NIR spectral energy distribution (SED) at about 1 yr is well described by a single-temperature blackbody spectrum at about 1200 K. The temperature declines over subsequent epochs. After ~2 yr, the blackbody matches are less successful, probably indicating an increasing range of temperatures in the emission regions. Fits to the SEDs achieved with blackbodies weighted with λ-1 or λ-2 emissivity are almost always less successful. Possible origins for the NIR emission are considered. Significant radioactive heating of ejecta dust is ruled out, as is shock/X-ray-precursor heating of CSM dust. More plausible sources are (a) an IR echo from CSM dust driven by the ultraviolet/optical peak luminosity, and (b) emission from newly-condensed dust which formed within a cool, dense shell produced by the ejecta shock/CSM interaction. We argue that the evidence favours the condensing dust hypothesis, although an IR echo is not ruled out. Within the condensing-dust scenario, the IR luminosity indicates the presence of at least 10-3 Msolar of dust in the ejecta

  9. Raman, infrared, photoluminescence and theoretical studies of the II-VI-VI ternary CdSeTe

    NASA Astrophysics Data System (ADS)

    Feng, Z. C.; Becla, P.; Kim, L. S.; Perkowitz, S.; Feng, Y. P.; Poon, H. C.; Williams, K. P.; Pitt, G. D.

    1994-04-01

    We have examined Bridgman-grown zincblende CdSe xTe 1- x ( x < 0.36) by Raman scattering, Fourier transform infrared reflectivity, photoluminescence and theoretical analysis. The Raman data showed evidence of surface structural improvement by long-term room temperature annealing. The combined Raman and infrared data confirmed the interpretation that a third infrared mode besides the CdTe- and CdSe-like transverse optical phonon modes, arose from non-random atomic clustering. Room temperature photoluminescence spectra were obtained and compared with pseudopotential calculations.

  10. Intercomparison of stratospheric water vapor observed by satellite experiments: Stratospheric Aerosol and Gas Experiment II versus Limb Infrared Monitor of the Stratosphere and Atmospheric Trace Molecule Spectroscopy

    SciTech Connect

    Chiou, E.W.; Larsen, J.C. ); McCormick, M.P.; McMaster, L.R.; Chu, W.P. ); Rind, D. ); Oltmans, S. )

    1993-03-20

    This paper presents a comparison of the stratospheric water vapor measurements made by the satellite-borne sensors the Stratospheric Aerosol and Gas Experiment II (SAGE II), the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS), and the Spacelab 3 Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment. LIMS obtained data for 7 months between November 1978 and May 1979; ATMOS was carried on Shuttle and observed eight profiles from April 30 to May 6, 1985 at approximately 30[degrees]N and 50[degrees]S; and, SAGE II continues to make measurements since its launch in October 1984. For both 30[degrees]N and 50[degrees]S in May, the comparisons between SAGE II and ATMOS show agreement within the estimated combined uncertainty of the two experiments. Several important features identified by LIMS observations have been confirmed by SAGE II: a well-developed hygropause in the lower stratosphere at low- to mid-latitudes, a poleward latitudinal gradient, increasing water vapor mixing ratios with altitude in the tropics, and the transport of dry lower stratospheric water vapor upward and southward in May, and upward and northward in November. A detailed comparative study also indicates that the two previously suggested corrections for LIMS, a correction in tropical lower stratosphere due to a positive temperature bias and the correction above 28 km based on improved emissivities will bring LIMS measurements much closer to those of SAGE II. The only significant difference occurs at high southern latitudes in May below 18 km, where LIMS measurements are 2-3 ppmv greater. It should be noted that LIMS observations are from 16 to 50 km, ATMOS from 14 to 86 km, and SAGE II from mid-troposphere to 40 km. With multiyear coverage, SAGE II observations should be useful for studying tropospheric-stratospheric exchange, for stratospheric transport, and for preparing water vapor climatologies for the stratosphere and the upper troposphere. 32 refs., 14 figs., 2 tabs.

  11. Intercomparison of stratospheric water vapor observed by satellite experiments: Stratospheric Aerosol and Gas Experiment II versus Limb Infrared Monitor of the Stratosphere and Atmospheric Trace Molecule Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chiou, E. W.; McCormick, M. P.; McMaster, L. R.; Chu, W. P.; Larsen, J. C.; Rind, D.; Oltmans, S.

    1993-03-01

    This paper presents a comparison of the stratospheric water vapor measurements made by the satellite-borne sensors the Stratospheric Aerosol and Gas Experiment II (SAGE II), the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS), and the Spacelab 3 Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment. LIMS obtained data for 7 months between November 1978 and May 1979; ATMOS was carried on Shuttle and observed eight profiles from April 30 to May 6, 1985 at approximately 30°N and 50°S; and, SAGE II continues to make measurements since its launch in October 1984. For both 30°N and 50°S in May, the comparisons between SAGE II and ATMOS show agreement within the estimated combined uncertainty of the two experiments. Several important features identified by LIMS observations have been confirmed by SAGE II: a well-developed hygropause in the lower stratosphere at low- to mid-latitudes, a poleward latitudinal gradient, increasing water vapor mixing ratios with altitude in the tropics, and the transport of dry lower stratospheric water vapor upward and southward in May, and upward and northward in November. A detailed comparative study also indicates that the two previously suggested corrections for LIMS, a correction in tropical lower stratosphere due to a positive temperature bias and the correction above 28 km based on improved emissivities will bring LIMS measurements much closer to those of SAGE II. The only significant difference occurs at high southern latitudes in May below 18 km, where LIMS measurements are 2-3 ppmv greater. It should be noted that LIMS observations are from 16 to 50 km, ATMOS from 14 to 86 km, and SAGE II from mid-troposphere to 40 km. With multiyear coverage, SAGE II observations should be useful for studying tropospheric-stratospheric exchange, for stratospheric transport, and for preparing water vapor climatologies for the stratosphere and the upper troposphere.

  12. Theoretical design and material growth of Type-II Antimonide-based superlattices for multi-spectral infrared detection and imaging

    NASA Astrophysics Data System (ADS)

    Hoang, Anh Minh

    Infrared detectors find applications in many aspects of life, from night vision, target tracking for homeland security and defense, non-destructive failure detection in industry, chemical sensing in medicine, and free-space communication. Currently, the dominant technologies of photodetectors based upon HgCdTe and InSb are experiencing many limitations. Under this circumstance, the Type-II InAs/GaSb/AlSb superlattices which have been intensively studied recently appear to be an excellent candidate to give breakthroughs in the infrared technology. The Type-II SLs with theirs advantages such as great flexibility in bandgap engineering, high carrier effective mass, Auger recombination suppression and high uniformity have shown excellent device performance from MWIR to VLWIR. In the era of the third generation for infrared cameras, Type-II SLs are entering the new phase of development with high performance and multi-spectral detection. The goal of this work is to investigate quantum properties of the superlattice system, design appropriate device architectures and experimentally fabricate infrared detectors which can push further the limit of this material system and outperform existing competing technologies. The binary-binary InAs/GaSb superlattice has gone through much transformation over the years. Incorporating compounds lattice matched to the 6.1A family has invited more possibilities to band engineer the Type-II SLs. For the first time, by employing all three members of this material system, we have designed a new superlattice structure and demonstrated shortwavelength infrared (SWIR) photodiodes based on Type-II InAs/GaSb/AlSb with high electrical and optical performance. The photodiodes exhibited a quantum efficiency of 60% with very low dark current, can be operated at room temperature. In addition to the range of MWIR to VLWIR, a new channel of detection has been added to the GaSb based type-II SL material system. The new realization of SWIR photodiodes has

  13. A Newly Developed Model for Fluorescence of C2H6 ν5 in Comets and Application to Infrared Spectra Acquired with NIRSPEC at Keck II

    NASA Astrophysics Data System (ADS)

    Radeva, Yana L.; Mumma, M. J.; Villanueva, G. L.; A'Hearn, M. F.

    2010-01-01

    Exploring the compositional diversity of cometary nuclei is key to understanding the formation and evolution of the Solar System, and the origin of water and prebiotic organics on the Earth. For most polyatomic gases, a production rate can be obtained from measured ro-vibrational intensities if an accurate rotational temperature is available, and the comparison of temperatures displayed by individual molecular species can reveal additional insights into physics in the cometary inner coma. Until now, accurate temperatures could be derived for HCN, CO, and H2O, but not for ethane (C2H6). As a symmetric hydrocarbon, C2H6 is uniquely sampled in the infrared, but the fine rotational structure of the ν7 Q-branches at 3.3 μm cannot be resolved by current infrared spectrometers, ultimately limiting the retrievals of rotational temperatures from these lines. However, the complex ro-vibrational structure (P- and R-branches) of the ν5 band at 3.5 μm is resolved by the Near Infrared Echelle Spectrograph on the Keck II telescope (NIRSPEC). We developed a fluorescence model for the infrared ν5 band of C2H6, and applied it to interpret high-resolution infrared spectra acquired with NIRSPEC. We present rotational temperatures and production rates for C2H6 in multiple comets. We compare the extracted rotational temperatures for ethane with those obtained from simultaneous measurements of other species (H2O and HCN). We also compare mixing ratios derived from the C2H6 ν5 band with those derived from the previously analyzed (by NASA GSFC team members) ν7 band. This work now establishes a robust method for quantifying additional physical parameters for ethane in comets.

  14. LIFTING THE DUSTY VEIL WITH NEAR- AND MID-INFRARED PHOTOMETRY. II. A LARGE-SCALE STUDY OF THE GALACTIC INFRARED EXTINCTION LAW

    SciTech Connect

    Zasowski, G.; Majewski, S. R.; Indebetouw, R. E-mail: srm4n@virginia.ed

    2009-12-10

    We combine near-infrared (Two Micron All Sky Survey) and mid-infrared (Spitzer-IRAC) photometry to characterize the IR extinction law (1.2-8 mum) over nearly 150 deg. of contiguous Milky Way midplane longitude. The relative extinctions in five passbands across these wavelength and longitude ranges are derived by calculating color excess ratios for G and K giant red clump stars in contiguous midplane regions and deriving the wavelength dependence of extinction in each one. Strong, monotonic variations in the extinction law shape are found as a function of angle from the Galactic center, symmetric on either side of it. These longitudinal variations persist even when dense interstellar regions, known a priori to have a shallower extinction curve, are removed. The increasingly steep extinction curves toward the outer Galaxy indicate a steady decrease in the absolute-to-selective extinction ratio (R{sub V} ) and in the mean dust grain size at greater Galactocentric angles. We note an increasing strength of the 8 mum extinction inflection at high Galactocentric angles and, using theoretical dust models, show that this behavior is consistent with the trend in R{sub V} . Along several lines of sight where the solution is most feasible, A {sub l}ambda/A{sub K{sub s}} as a function of Galactic radius (R {sub GC}) is estimated and shown to have a Galactic radial dependence. Our analyses suggest that the observed relationship between extinction curve shape and Galactic longitude is due to an intrinsic dependence of the extinction law on Galactocentric radius.

  15. The CFHT (MOS/PUMA) faint quasar survey

    NASA Astrophysics Data System (ADS)

    Schade, David

    A multi-aperture spectroscopic survey for faint quasars has been carried out at Canada-France-Hawaii telescope. The survey is capable of reaching two magnitudes deeper into the luminosity function at redshifts greater than 3 than the deepest existing surveys. The technique is discussed and preliminary results are presented.

  16. 1. Dyea Dock looking south. Note faint evenly spaced circular ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Dyea Dock looking south. Note faint evenly spaced circular dark pieces of grass up through the middle of the picture indicating posts making up the pier. Photograph made from park service cherry picker. - Dyea Dock & Association (Ruins), Skagway, Skagway, AK

  17. Secondary Structure and Pd(II) Coordination in S-Layer Proteins from Bacillus sphaericus Studied by Infrared and X-Ray Absorption Spectroscopy

    PubMed Central

    Fahmy, Karim; Merroun, Mohamed; Pollmann, Katrin; Raff, Johannes; Savchuk, Olesya; Hennig, Christoph; Selenska-Pobell, Sonja

    2006-01-01

    The S-layer of Bacillus sphaericus strain JG-A12, isolated from a uranium-mining site, exhibits a high metal-binding capacity, indicating that it may provide a protective function by preventing the cellular uptake of heavy metals and radionuclides. This property has allowed the use of this and other S-layers as self-assembling organic templates for the synthesis of nanosized heavy metal cluster arrays. However, little is known about the molecular basis of the metal-protein interactions and their impact on secondary structure. We have studied the secondary structure, protein stability, and Pd(II) coordination in S-layers from the B. sphaericus strains JG-A12 and NCTC 9602 to elucidate the molecular basis of their biological function and of the metal nanocluster growth. Fourier transform infrared spectroscopy reveals similar secondary structures, containing ∼35% β-sheets and little helical structure. pH-induced infrared absorption changes of the side-chain carboxylates evidence a remarkably low pK < 3 in both strains and a structural stabilization when Pd(II) is bound. The COO−-stretching absorptions reveal a predominant Pd(II) coordination by chelation/bridging by Asp and Glu residues. This agrees with XANES and EXAFS data revealing oxygens as coordinating atoms to Pd(II). The additional participation of nitrogen is assigned to side chains rather than to the peptide backbone. The topology of nitrogen- and carboxyl-bearing side chains appears to mediate heavy metal binding to the large number of Asp and Glu in both S-layers at particularly low pH as an adaptation to the environment from which the strain JG-A12 has been isolated. These side chains are thus prime targets for the design of engineered S-layer-based nanoclusters. PMID:16698775

  18. The VISTA Carina Nebula Survey. II. Spatial distribution of the infrared-excess-selected young stellar population

    NASA Astrophysics Data System (ADS)

    Zeidler, P.; Preibisch, T.; Ratzka, T.; Roccatagliata, V.; Petr-Gotzens, M. G.

    2016-01-01

    We performed a deep wide-field (6.76 sq. deg) near-infrared survey with the VISTA telescope that covers the entire extent of the Carina nebula complex (CNC). The point-source catalog created from these data contains around four million individual objects down to masses of 0.1 M⊙. We present a statistical study of the large-scale spatial distribution and an investigation of the clustering properties of infrared-excesses objects, which are used to trace disk-bearing young stellar objects (YSOs). A selection based on a near-infrared (J-H) versus (H-Ks) color-color diagram shows an almost uniform distribution over the entire observed area. We interpret this as a result of the very high degree of background contamination that arises from the Carina Nebula's location close to the Galactic plane. Complementing the VISTA near-infrared catalog with Spitzer IRAC mid-infrared photometry improves the situation of the background contamination considerably. We find that a (J-H) versus (Ks- [4.5]) color-color diagram is well suited to tracing the population of YSO-candidates (cYSOs) by their infrared excess. We identify 8781 sources with strong infrared excess, which we consider as cYSOs. This sample is used to investigate the spatial distribution of the cYSOs with a nearest-neighbor analysis. The surface density distribution of cYSOs agrees well with the shape of the clouds as seen in our Herschel far-infrared survey. The strong decline in the surface density of excess sources outside the area of the clouds supports the hypothesis that our excess-selected sample consists predominantly of cYSOs with a low level of background contamination. This analysis allows us to identify 14 groups of cYSOs outside the central area.Our results suggest that the total population of cYSOs in the CNC comprises about 164 000 objects, with a substantial fraction (~35%) located in the northern, still not well studied parts. Our cluster analysis suggests that roughly half of the cYSOs constitute a

  19. Homo- and Heterobimetallic Ruthenium(II) and Osmium(II) Complexes Based on a Pyrene-Biimidazolate Spacer as Efficient DNA-Binding Probes in the Near-Infrared Domain.

    PubMed

    Mardanya, Sourav; Karmakar, Srikanta; Mondal, Debiprasad; Baitalik, Sujoy

    2016-04-04

    We report in this work a new family of homo- and heterobimetallic complexes of the type [(bpy)2M(Py-Biimz)M'(II)(bpy)2](2+) (M = M' = Ru(II) or Os(II); M = Ru(II) and M' = Os(II)) derived from a pyrenyl-biimidazole-based bridge, 2-imidazolylpyreno[4,5-d]imidazole (Py-BiimzH2). The homobimetallic Ru(II) and Os(II) complexes were found to crystallize in monoclinic form with space group P21/n. All the complexes exhibit strong absorptions throughout the entire UV-vis region and also exhibit luminescence at room temperature. For osmium-containing complexes (2 and 3) both the absorption and emission band stretched up to the NIR region and thus afford more biofriendly conditions for probable applications in infrared imaging and phototherapeutic studies. Detailed luminescence studies indicate that the emission originates from the respective (3)MLCT excited state mainly centered in the [M(bpy)2](2+) moiety of the complexes and is only slightly affected by the pyrene moiety. The bimetallic complexes show two successive one-electron reversible metal-centered oxidations in the positive potential window and several reduction processes in the negative potential window. An efficient intramolecular electronic energy transfer is found to occur from the Ru center to the Os-based component in the heterometallic dyad. The binding studies of the complexes with DNA were thoroughly studied through different spectroscopic techniques such as UV-vis absorption, steady-state and time-resolved emission, circular dichroism, and relative DNA binding study using ethidium bromide. The intercalative mode of binding was suggested to be operative in all cases. Finally, computational studies employing DFT and TD-DFT were also carried out to interpret the experimentally observed absorption and emission bands of the complexes.

  20. AN IN-DEPTH VIEW OF THE MID-INFRARED PROPERTIES OF POINT SOURCES AND THE DIFFUSE ISM IN THE SMC GIANT H II REGION, N66

    SciTech Connect

    Whelan, David G.; Johnson, Kelsey E.; Indebetouw, Remy; Lebouteiller, Vianney; Bernard-Salas, Jeronimo; Brandl, Bernhard R. E-mail: kej7a@virginia.edu E-mail: vianney.lebouteiller@cea.fr E-mail: epeeters@uwo.ca E-mail: brandl@strw.leidenuniv.nl

    2013-07-01

    The focus of this work is to study mid-infrared point sources and the diffuse interstellar medium (ISM) in the low-metallicity ({approx}0.2 Z{sub Sun }) giant H II region N66 in order to determine properties that may shed light on star formation in these conditions. Using the Spitzer Space Telescope's Infrared Spectrograph, we study polycyclic aromatic hydrocarbon (PAH), dust continuum, silicate, and ionic line emission from 14 targeted infrared point sources as well as spectra of the diffuse ISM that is representative of both the photodissociation regions (PDRs) and the H II regions. Among the point source spectra, we spectroscopically confirm that the brightest mid-infrared point source is a massive embedded young stellar object, we detect silicates in emission associated with two young stellar clusters, and we see spectral features of a known B[e] star that are commonly associated with Herbig Be stars. In the diffuse ISM, we provide additional evidence that the very small grain population is being photodestroyed in the hard radiation field. The 11.3 {mu}m PAH complex emission exhibits an unexplained centroid shift in both the point source and ISM spectra that should be investigated at higher signal-to-noise and resolution. Unlike studies of other regions, the 6.2 {mu}m and 7.7 {mu}m band fluxes are decoupled; the data points cover a large range of I{sub 7.7}/I{sub 11.3} PAH ratio values within a narrow band of I{sub 6.2}/I{sub 11.3} ratio values. Furthermore, there is a spread in PAH ionization, being more neutral in the dense PDR where the radiation field is relatively soft, but ionized in the diffuse ISM/PDR. By contrast, the PAH size distribution appears to be independent of local ionization state. Important to unresolved studies of extragalactic low-metallicity star-forming regions, we find that emission from the infrared-bright point sources accounts for only 20%-35% of the PAH emission from the entire region. These results make a comparative data set to

  1. Room-temperature vibrational difference spectrum for S2QB-/S1QB of photosystem II determined by time-resolved Fourier transform infrared spectroscopy.

    PubMed

    Zhang, H; Fischer, G; Wydrzynski, T

    1998-04-21

    Time-resolved FTIR spectroscopy has been used to kinetically characterize the vibrational properties of intact photosystem II-enriched membrane samples undergoing the S1QB-to-S2QB- transition at room temperature. To optimize the experimental conditions for the FTIR measurements, oxygen polarographic and variable chlorophyll a fluorescence measurements were used to define the decay of S2 and QA-, respectively. The flash-induced S2QB-/S1QB difference spectra were measured at a temporal resolution of 4.44 s and a spectral resolution of 4 cm-1. An intense positive band is observed at 1480 cm-1 in the difference spectrum and shows a slow decay with a half time of approximately 13 s. Based on its decay kinetics and analogy to the infrared absorption of QA- of photosystem II and QB- in bacterial reaction centers, we conclude that the 1480 cm-1 band arises from QB- of PSII and tentatively assign it to the upsilon(CO) mode of the semiquinone anion QB-. The infrared spectral features attributed to the S1-to-S2 transition of the Mn cluster at room temperature show striking similarity to the S2/S1 difference spectrum measured at cryogenic temperatures (Noguchi, T., Ono, T.-A., and Inoue, Y. (1995) Biochim. Biophys. Acta 1228, 189-200).

  2. Polarization-modulated infrared spectroscopy and x-ray reflectivity of photosystem II core complex at the gas-water interface.

    PubMed Central

    Gallant, J; Desbat, B; Vaknin, D; Salesse, C

    1998-01-01

    The state of photosystem II core complex (PS II CC) in monolayer at the gas-water interface was investigated using in situ polarization-modulated infrared reflection absorption spectroscopy and x-ray reflectivity techniques. Two approaches for preparing and manipulating the monolayers were examined and compared. In the first, PS II CC was compressed immediately after spreading at an initial surface pressure of 5.7 mN/m, whereas in the second, the monolayer was incubated for 30 min at an initial surface pressure of 0.6 mN/m before compression. In the first approach, the protein complex maintained its native alpha-helical conformation upon compression, and the secondary structure of PS II CC was found to be stable for 2 h. The second approach resulted in films showing stable surface pressure below 30 mN/m and the presence of large amounts of beta-sheets, which indicated denaturation of PS II CC. Above 30 mN/m, those films suffered surface pressure instability, which had to be compensated by continuous compression. This instability was correlated with the formation of new alpha-helices in the film. Measurements at 4 degreesC strongly reduced denaturation of PS II CC. The x-ray reflectivity studies indicated that the spread film consists of a single protein layer at the gas-water interface. Altogether, this study provides direct structural and molecular information on membrane proteins when spread in monolayers at the gas-water interface. PMID:9826610

  3. Predictive modeling of infrared radiative heating in tomato dry-peeling process: Part II. Model validation and sensitivity analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A predictive mathematical model was developed to simulate heat transfer in a tomato undergoing double sided infrared (IR) heating in a dry-peeling process. The aims of this study were to validate the developed model using experimental data and to investigate different engineering parameters that mos...

  4. Theoretical investigation of InAs/GaSb type-II pin superlattice infrared detector in the mid wavelength infrared range

    NASA Astrophysics Data System (ADS)

    Kaya, U.; Hostut, M.; Kilic, A.; Sakiroglu, S.; Sokmen, I.; Ergun, Y.; Aydinli, A.

    2013-02-01

    In this study, we present the theoretical investigation of type-II InAs/GaSb superlattice p-i-n detector. Kronig-Penney and envelope function approximation is used to calculate band gap energy and superlattice minibands. Variational method is also used to calculate exciton binding energies. Our results show that carriers overlap increases at GaSb/InAs interface on the higher energy side while it decreases at InAs/GaSb interface on the lower energy side with increasing reverse bias due to shifting the hole wavefunction toward to the GaSb/InAs interface decisively. Binding energies increase with increasing electric field due to overall overlap of electron and hole wave functions at the both interfaces in contrast with type I superlattices. This predicts that optical absorption is enhanced with increasing electric field.

  5. STELLAR ARCHEOLOGY IN THE GALACTIC HALO WITH ULTRA-FAINT DWARFS. VII. HERCULES

    SciTech Connect

    Musella, Ilaria; Ripepi, Vincenzo; Marconi, Marcella E-mail: ripepi@na.astro.it; and others

    2012-09-10

    We present the first time-series study of the ultra-faint dwarf galaxy Hercules. Using a variety of telescope/instrument facilities we secured about 50 V and 80 B epochs. These data allowed us to detect and characterize 10 pulsating variable stars in Hercules. Our final sample includes six fundamental-mode (ab-type) and three first-overtone (c-type) RR Lyrae stars, and one Anomalous Cepheid. The average period of the ab-type RR Lyrae stars, (P{sub ab}) = 0.68 days ({sigma} = 0.03 days), places Hercules in the Oosterhoff II group, as found for almost the totality of the ultra-faint dwarf galaxies investigated so far for variability. The RR Lyrae stars were used to obtain independent estimates of the metallicity, reddening, and distance to Hercules, for which we find [Fe/H] = -2.30 {+-} 0.15 dex, E(B - V) = 0.09 {+-} 0.02 mag, and (m - M){sub 0} = 20.6 {+-} 0.1 mag, in good agreement with the literature values. We have obtained a V, B - V color-magnitude diagram (CMD) of Hercules that reaches V {approx} 25 mag and extends beyond the galaxy's half-light radius over a total area of 40' Multiplication-Sign 36'. The CMD and the RR Lyrae stars indicate the presence of a population as old and metal-poor as (at least) the Galactic globular cluster M68.

  6. Superconductivity applications for infrared and microwave devices II; Proceedings of the Meeting, Orlando, FL, Apr. 4, 5, 1991

    NASA Technical Reports Server (NTRS)

    Heinen, Vernon O. (Editor); Bhasin, Kul B. (Editor)

    1991-01-01

    Topics discussed include thin-film technology, microwave transmission lines and resonators, microwave devices and circuits, infrared detectors and bolometers, and superconducting junctions. Papers are presented on possible enhancement in bolometric response using free-standing film of YBa2Cu3O(x), aging and surface instability in high-Tc superconductors, epitaxial Tl2Ba2CaCu2O8 thin films on LaAlO3 and their microwave device properties, the performance of stripline resonators using sputtered YBCO films, and a coplanar waveguide microwave filter of YBa2Cu3O7. Attention is also given to the performance characteristics of Y-Ba-Cu-O microwave superconducting detectors, high-Tc bolometer developments for planetary missions, infrared detectors from YBaCuO thin films, high-temperature superconductor junction technology, and submillimeter receiver components using superconducting tunnel junctions.

  7. Faint High Orbit Debris Observations with ISON Optical Network

    NASA Astrophysics Data System (ADS)

    Molotov, I.; Agapov, V.

    New cooperation for global monitoring of space objects at high orbits, International Scientific Optical Network (ISON), is appeared under auspices of the Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences. ISON provides the observations of faint deep space debris in cooperation with team of the Astronomical Institute of the University of Bern (AIUB) since 2004. It is jointly discovered already about 500 faint space debris fragments at high orbits and almost 200 of them are continuously tracked with ISON. Presence of space debris clouds created in earlier suspected fragmentations of GEO objects is proved by long deterministic observations of individual members of the clouds. For the first time, a large amount of data on long time intervals is obtained for objects with high area-to-mass ratio (AMR). Till present, the uncatalogued faint deep debris are discovering mainly with Teide ESA OGS telescope and Crimean observatory in Nauchny, while object tracking is providing by cooperation of the 0.5-2.6-m class telescopes including Zimmerwald, Gissar, Mondy, Abastumany, Arkhyz, Mayaki, Andrushivka and Terskol. During 2009 it is planned to join several telescopes with large field of view (1.3 - 2.3 degree) in Ussuriysk, Krasnojarsk, Mondy, Nauchniy, Andrushivka, Abastumani, Mayaki and Kitab into semi-automatic network in order to try to establish the faint debris quasi continuous orbit maintenance. It is planned to use survey mode for this purpose as it is adjusted now for brighter GEO objects with ISON survey subsystem of 22-cm telescopes. Along with sensors development, it is elaborated and tested a few survey modes and algorithm permitting to find correlation between short arc tracks of non-correlated objects in order to discovery of new objects and to establish their orbits.

  8. The Orion HII Region and the Orion Bar in the Mid-infrared

    NASA Astrophysics Data System (ADS)

    Salgado, F.; Berné, O.; Adams, J. D.; Herter, T. L.; Keller, L. D.; Tielens, A. G. G. M.

    2016-10-01

    We present mid-infrared photometry of the Orion bar obtained with the Faint Object infraRed Camera for the SOFIA Telescope (FORCAST) on board SOFIA at 6.4, 6.6, 7.7, 19.7, 31.5, and 37.1 μm. By complementing this observation with archival FORCAST and Herschel/PACS images, we are able to construct a complete infrared spectral energy distribution of the Huygens region in the Orion nebula. Comparing the infrared images with gas tracers, we find that PACS maps trace the molecular cloud, while the FORCAST data trace the photodissociation region (PDR) and the H ii region. Analysis of the energetics of the region reveal that the PDR extends for 0.28 pc along the line of sight and that the bar is inclined at an angle of 4°. The infrared and submillimeter images reveal that the Orion bar represents a swept-up shell with a thickness of 0.1 pc. The mass of the shell implies a shock velocity of ≃3 km s-1 and an age of ≃105 years for the H ii region. Our analysis shows that the UV and infrared dust opacities in the H ii region and the PDR are a factor 5 to 10 lower than in the diffuse interstellar medium. In the ionized gas, Lyα photons are a major source of dust heating at distances larger than ≃0.06 pc from θ 1 Ori C. Dust temperatures can be explained if the size of the grains is between 0.1 and 1 μm. We derive the photoelectric heating efficiency of the atomic gas in the Orion bar. The results are in good qualitative agreement with models and the quantitative differences indicate a decreased polycyclic aromatic hydrocarbon abundance in this region.

  9. The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. II. Framework, Strategy, and First Result

    NASA Astrophysics Data System (ADS)

    Wright, J. T.; Griffith, R. L.; Sigurdsson, S.; Povich, M. S.; Mullan, B.

    2014-09-01

    We describe the framework and strategy of the Ĝ infrared search for extraterrestrial civilizations with large energy supplies, which will use the wide-field infrared surveys of WISE and Spitzer to search for these civilizations' waste heat. We develop a formalism for translating mid-infrared photometry into quantitative upper limits on extraterrestrial energy supplies. We discuss the likely sources of false positives, how dust can and will contaminate our search, and prospects for distinguishing dust from alien waste heat. We argue that galaxy-spanning civilizations may be easier to distinguish from natural sources than circumstellar civilizations (i.e., Dyson spheres), although GAIA will significantly improve our capability to identify the latter. We present a zeroth order null result of our search based on the WISE all-sky catalog: we show, for the first time, that Kardashev Type III civilizations (as Kardashev originally defined them) are very rare in the local universe. More sophisticated searches can extend our methodology to smaller waste heat luminosities, and potentially entirely rule out (or detect) both Kardashev Type III civilizations and new physics that allows for unlimited "free" energy generation.

  10. the Ĝ infrared search for extraterrestrial civilizations with large energy supplies. II. Framework, strategy, and first result

    SciTech Connect

    Wright, J. T.; Griffith, R. L.; Sigurdsson, S.; Povich, M. S.; Mullan, B.

    2014-09-01

    We describe the framework and strategy of the Ĝ infrared search for extraterrestrial civilizations with large energy supplies, which will use the wide-field infrared surveys of WISE and Spitzer to search for these civilizations' waste heat. We develop a formalism for translating mid-infrared photometry into quantitative upper limits on extraterrestrial energy supplies. We discuss the likely sources of false positives, how dust can and will contaminate our search, and prospects for distinguishing dust from alien waste heat. We argue that galaxy-spanning civilizations may be easier to distinguish from natural sources than circumstellar civilizations (i.e., Dyson spheres), although GAIA will significantly improve our capability to identify the latter. We present a zeroth order null result of our search based on the WISE all-sky catalog: we show, for the first time, that Kardashev Type III civilizations (as Kardashev originally defined them) are very rare in the local universe. More sophisticated searches can extend our methodology to smaller waste heat luminosities, and potentially entirely rule out (or detect) both Kardashev Type III civilizations and new physics that allows for unlimited 'free' energy generation.

  11. A Wide Area Survey for High-Redshift Massive Galaxies. II. Near-Infrared Spectroscopy of BzK-Selected Massive Star-Forming Galaxies

    NASA Astrophysics Data System (ADS)

    Onodera, Masato; Arimoto, Nobuo; Daddi, Emanuele; Renzini, Alvio; Kong, Xu; Cimatti, Andrea; Broadhurst, Tom; Alexander, Dave M.

    2010-05-01

    Results are presented from near-infrared spectroscopic observations of a sample of BzK-selected, massive star-forming galaxies (sBzKs) at 1.5 < z < 2.3 that were obtained with OHS/CISCO at the Subaru telescope and with SINFONI at the Very Large Telescope. Among the 28 sBzKs observed, Hα emission was detected in 14 objects, and for 11 of them the [N II] λ6583 flux was also measured. Multiwavelength photometry was also used to derive stellar masses and extinction parameters, whereas Hα and [N II] emissions have allowed us to estimate star formation rates (SFRs), metallicities, ionization mechanisms, and dynamical masses. In order to enforce agreement between SFRs from Hα with those derived from rest-frame UV and mid-infrared, additional obscuration for the emission lines (that originate in H II regions) was required compared to the extinction derived from the slope of the UV continuum. We have also derived the stellar mass-metallicity relation, as well as the relation between stellar mass and specific SFR (SSFR), and compared them to the results in other studies. At a given stellar mass, the sBzKs appear to have been already enriched to metallicities close to those of local star-forming galaxies of similar mass. The sBzKs presented here tend to have higher metallicities compared to those of UV-selected galaxies, indicating that near-infrared selected galaxies tend to be a chemically more evolved population. The sBzKs show SSFRs that are systematically higher, by up to ~2 orders of magnitude, compared to those of local galaxies of the same mass. The empirical correlations between stellar mass and metallicity, and stellar mass and SSFR are then compared with those of evolutionary population synthesis models constructed either with the simple closed-box assumption, or within an infall scenario. Within the assumptions that are built-in such models, it appears that a short timescale for the star formation (sime100 Myr) and large initial gas mass appear to be required

  12. Photometric and spectroscopic study of the ultra-faint Milky Way satellite Pegasus III

    NASA Astrophysics Data System (ADS)

    Kim, Dongwon; Jerjen, Helmut; Geha, Marla C.; Chiti, Anirudh; Milone, Antonino; Da Costa, Gary S.; Mackey, Dougal; Frebel, Anna; Conn, Blair

    2017-01-01

    Pegasus III (Peg III) is one of the few known ultra-faint dwarf (UFD) satellite galaxies in the outer halo (R >150 kpc) of the Milky Way (MW). We present results from a recent study of Peg III using Magellan/IMACS and Keck/DEIMOS. Our newly-measured structural parameters confirm that Peg III is large (rh = 53±14pc), elongated (∈ = 0.38+0.22-0.38 ), and faint (MV=-3.4±0.4 mag) — indicative of its nature as a dwarf rather than a globular cluster. In the color-magnitude diagram, Peg III is well described by an old (>12Gyr) and metal-poor ([Fe/H]<-2.0 dex) stellar population at a heliocentric distance of 215±12 kpc. Using spectroscopic measurements of individual stars, we identify seven kinematic members of Peg III. The Ca II triplet lines of the brightest members verify that Peg III indeed contains stars with metallicity as low as [Fe/H]=-2.55±0.15 dex. The systemic velocity and velocity dispersion of Peg III are -222.9±2.6 km/s and 5.4+3.0-2.5 km/s, respectively. The inferred dynamical mass within the half-light radius of 1.4+3.0-1.1×106M⊙, and the mass-to-light ratio of M/LV = 1470+5660-1240M⊙/L⊙ provide further evidence that Peg III is a bona fide UFD. Peg III and another distant UFD Pisces II lie relatively close to each other (△dspatial=43±19 kpc) and share similar systemic radial velocities (△vGSR=12.3±3.7 km/s), which suggests that they may share a common origin.

  13. The gas-rich circumbinary disk of HR 4049. II. A detailed study of the near-infrared spectrum

    SciTech Connect

    Malek, S. E.; Cami, J. E-mail: jcami@uwo.ca

    2014-10-20

    HR 4049 is a peculiar evolved binary surrounded by a circumbinary disk. Mid-infrared observations show that the disk is rich in molecular gas and radially extended. To study the properties of this disk, we re-analyzed a set of near-infrared observations at high spectral resolution obtained with Gemini-Phoenix. These data cover absorption lines originating from the first overtone of CO and from H{sub 2}O in the 2.3 μm region as well as more complex emission-absorption profiles from H{sub 2}O and the fundamental mode of CO near 4.6 μm. By using an excitation diagram and from modeling the spectrum, we find that most of the CO overtone and H{sub 2}O absorption originates from hot gas (T {sub ex} ≈ 1000 K) with high column densities, consistent with the mid-infrared data. The strong emission in the wavelength range of the CO fundamental furthermore suggests that there is a significant quantity of gas in the inner cavity of the disk. In addition, there is a much colder component in the line of sight to the disk. A detailed analysis of the overtone line profiles reveals variations in the line widths that are consistent with a radially extended disk in Keplerian rotation with hotter gas closer to the central star. We estimate the mass of the primary to be ∼0.34 M {sub ☉} and discuss the implications for its evolutionary status.

  14. Determination of anesthetic molecule environments by infrared spectroscopy. II. Multiple sites for nitrous oxide in proteins, lipids, and brain tissue.

    PubMed

    Hazzard, J H; Gorga, J C; Caughey, W S

    1985-08-01

    The presence of molecules of the general anesthetic nitrous oxide (N2O) in oils, esters, proteins, red cells, cream, lipid vesicles, and brain tissue upon exposure to the gas was observed by infrared spectroscopy. Analysis of the N-N-O antisymmetric stretch band reveals a distribution of N2O molecules among several sites of differing polarity in these solutions and tissues. The sensitivity of the band intensity and frequency to the number and strength of the dipoles in the solvating molecules is demonstrated by the resolution of N2O-ester and N2O-alkane interactions in acetic acid ethyl ester and oleic acid methyl ester. In all aqueous solutions and in all tissues a population of N2O molecules in water is observed. At least two sites of N2O-protein interaction are observed in purified hemoglobin A and packed red cells; multiple N2O sites may also be present in bovine serum albumin. Two sites of N2O-lipid interaction are observed in whipping cream and in an aqueous suspension of phosphatidylcholine vesicles. The sites providing the least polar immediate environment to N2O in hemoglobin, cream, and vesicles give similar band frequencies to those found in pure alkane solvents. Infrared spectra of bovine brain tissue, upon exposure to N2O, show N2O molecules present in water and in two less-polar environments. Analysis of spectra of N2O in cerebellum tissue removed from a dog under halothane-N2O anesthesia reveals, in addition to N2O in water, a single population of N2O molecules in an alkane-like environment. Infrared spectroscopy provides a unique means of probing the structure of the environment of N2O and should prove useful in correlating anesthetic potency with anesthetic environment under physiological conditions.

  15. Herschel Discovery of a New Class of Cold, Faint Debris Discs

    NASA Technical Reports Server (NTRS)

    Eiroal, C.; Marshall, J. P.; Mora, A.; Krivov, A. V.; Montesinos, B.; Absil, O.; Ardila, D.; Arevalo, M.; Augereau, J.-Ch.; Bayo, A.; Danchi, W.; del Burgo, C.; Ertel, S.; Fridlund, M.; Gonzalez-Garcia, B. M.; Heras, A. M.; Lebreton, J.; Liseau, R.; Maldonado, J.; Meeus, G.; Montes, D.; Pilbratt, G. L.; Roberge, A.; Sanz-Forcada, J.; Stapelfeldt, K.

    2011-01-01

    We present Herschel PACS 100 and 160 micron observations of the solar-type stars alpha Men, HD 88230 and HD 210277, which form part of the FGK stars sample of the Herschel Open Time Key Programme (OTKP) DUNES (DUst around NEarby Stars). Our observations show small infrared excesses at 160 m for all three stars. HD 210277 also shows a small excess at 100 micron, while the 100 micron fluxes of alpha Men and HD 88230 agree with the stellar photospheric predictions. We attribute these infrared excesses to a new class of cold, faint debris discs. alpha Men and HD 88230 are spatially resolved in the PACS 160 m images, while HD 210277 is point-like at that wavelength. The projected linear sizes of the extended emission lie in the range from approx 115 to <= 250 AU. The estimated black body temperatures from the 100 and 160 micron fluxes are approx < 22 K, while the fractional luminosity of the cold dust is L(sub dust) / L(*) approx 10 (exp 6) close to the luminosity of the Solar-System's Kuiper belt. These debris discs are the coldest and faintest discs discovered so far around mature stars and cannot easily be explained by invoking "classical" debris disc models.

  16. Herschel discovery of a new class of cold, faint debris discs

    NASA Astrophysics Data System (ADS)

    Eiroa, C.; Marshall, J. P.; Mora, A.; Krivov, A. V.; Montesinos, B.; Absil, O.; Ardila, D.; Arévalo, M.; Augereau, J.-Ch.; Bayo, A.; Danchi, W.; Del Burgo, C.; Ertel, S.; Fridlund, M.; González-García, B. M.; Heras, A. M.; Lebreton, J.; Liseau, R.; Maldonado, J.; Meeus, G.; Montes, D.; Pilbratt, G. L.; Roberge, A.; Sanz-Forcada, J.; Stapelfeldt, K.; Thébault, P.; White, G. J.; Wolf, S.

    2011-12-01

    We present Herschel PACS 100 and 160 μm observations of the solar-type stars α Men, HD 88230 and HD 210277, which form part of the FGK stars sample of the Herschel open time key programme (OTKP) DUNES (DUst around NEarby Stars). Our observations show small infrared excesses at 160 μm for all three stars. HD 210277 also shows a small excess at 100 μm, while the 100 μm fluxes of α Men and HD 88230 agree with the stellar photospheric predictions. We attribute these infrared excesses to a new class of cold, faint debris discs. Both α Men and HD 88230 are spatially resolved in the PACS 160 μm images, while HD 210277 is point-like at that wavelength. The projected linear sizes of the extended emission lie in the range from ~115 to ≤ 250 AU. The estimated black body temperatures from the 100 and 160 μm fluxes are ≲22 K, and the fractional luminosity of the cold dust is Ldust/L ⋆ ~ 10-6, close to the luminosity of the solar-system's Kuiper belt. These debris discs are the coldest and faintest discs discovered so far around mature stars, so they cannot be explained easily invoking "classical" debris disc models. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  17. Herschel Discovery of a New class of Cold, Faint Debris Discs

    NASA Technical Reports Server (NTRS)

    Eiroa, C.; Marshall, J. P.; Mora, A.; Krivov, A. V.; Montesinos, B.; Absil, O.; Ardila, D.; Arevalo, M.; Augereau, J. -Ch.; Bayo, A.; Danchi, W.; del Burgo, C.; Ertel, S.; Fridlund, M.; Gonzalez-Garcia, B. M.; Heras, A. M.; Lebreton, J.; Liseau, R.; Maldonado, J.; Meeus, G.; Montes, D.; Pilbratt, G. L.; Roberge, A.; Sanz-Forcada, J.; Stapelfeldt, K.

    2012-01-01

    We present Herschel PACS 100 and 160 micron observations of the solar-type stars alpha Men, HD 88230 and HD 210277, which form part of the FGK stars sample of the Herschel Open Time Key Programme (OTKP) DUNES (DUst around NEarby Stars). Our observations show small infrared excesses at 160 micron for all three stars. HD 210277 also shows a small excess at 100 micron. while the 100 micron fluxes of a Men and HD 88230 agree with the stellar photospheric predictions. We attribute these infrared excesses to a new class of cold, faint debris discs. alpha Men and HD 88230 are spatially resolved in the PACS 160 micron images, while HD 210277 is point-like at that wavelength. The projected linear sizes of the extended emission lie in the range from approximately 115 to <= 250 AU. The estimated black body temperatures from the 100 and 160 micron fluxes are approximately < 22 K, while the fractional luminosity of the cold dust is L(dust)/ L(star) approximates 10(exp -6), close to the luminosity of the Solar-System's Kuiper belt. These debris discs are the coldest and faintest discs discovered so far around mature stars and cannot easily be explained by invoking "classical" debris disc models.

  18. Infrared analysis of clustering in the II-VI-VI compound CdSexTe1-x

    NASA Astrophysics Data System (ADS)

    Perkowitz, S.; Kim, L. S.; Becla, P.

    1991-03-01

    Infrared reflectivity spectra at 82 K for Bridgman-grown CdSexTe1-x crystals (x=0.05-0.35) show the two expected transverse-optical phonon modes and an unexpected third mode. Analysis of the data, using the cluster model of Verleur and Barker, shows that these spectra represent substantial nonrandom clustering of the anions around the cations. The magnitude and x dependence of the clustering is similar to that seen in the related compound CdSexS1-x grown at the same temperature, although by a different growth method.

  19. Adsorption and coadsorption of molecular hydrogen isotopes in zeolites. II. Infrared analyses of H2, HD, and D2 in NaA

    NASA Astrophysics Data System (ADS)

    Stéphanie-Victoire, Françoise; de Lara, Evelyne Cohen

    1998-10-01

    The infrared analysis of the induced bands of molecular hydrogen isotopes, adsorbed in NaA zeolite, shows several features; (i) when the amount of adsorbed molecules increases, the bands become complex, showing three components, which can be related to different energetic situation of the molecules in the cavity; (ii) the band frequency is lower than the gas frequency; for each species the shifts are proportional to the inverse square root of the mass (same interaction with the crystal); (iii) the absolute intensity increases when the temperature decreases, this is due to the fact that the molecule remains longer in the vicinity of the adsorption site where the electric field is the highest. Its amplitude is deduced from the absolute intensities measured at the lowest temperature (˜1010 V/m, in agreement with other results).

  20. Background-limited long wavelength infrared InAs/InAs1- xSbx type-II superlattice-based photodetectors operating at 110 K

    NASA Astrophysics Data System (ADS)

    Haddadi, Abbas; Dehzangi, Arash; Adhikary, Sourav; Chevallier, Romain; Razeghi, Manijeh

    2017-03-01

    We report the demonstration of high-performance long-wavelength infrared (LWIR) nBn photodetectors based on InAs/InAs1- xSbx type-II superlattices. A new saw-tooth superlattice design was used to implement the electron barrier of the photodetectors. The device exhibited a cut-off wavelength of ˜10 μ m at 77 K. The photodetector exhibited a peak responsivity of 2.65 A/W, corresponding to a quantum efficiency of 43%. With an R × A of 664 Ω . cm2 and a dark current density of 8 × 10-5 A/cm2, under -80 mV bias voltage at 77 K, the photodetector exhibited a specific detectivity of 4.72 × 1011 cm.√{Hz }/W and a background-limited operating temperature of 110 K.

  1. Collision-induced infrared spectra of H2-He pairs at temperatures from 18 to 7000 K. II. Overtone and hot bands

    SciTech Connect

    Borysow, A.; Frommhold, L.; Texas Univ., Austin )

    1989-06-01

    The three lowest spectral moments of the collision induced absorption (CIA) spectra of H2-He pairs have been computed from first principles for temperatures T from 18 to 7000 K for a number of hydrogen overtone and hot bands involving vibrational quantum numbers nu = 0, 1, 2, 3 yields nu-prime = 0, 1, 2, 3. The data are given in a form suitable for the computation of CIA spectra of H2-He as function of frequency and temperature, using simple computer codes and model line shapes. The work is of interest for the spectroscopy of the atmospheres of the outer planets and of stars that contain neutral molecular hydrogen and helium (late stars, white dwarfs, and Population II stars) in the infrared and visible region of the spectrum. 13 refs.

  2. Fourier-transform infrared and Raman spectra of cysteine dichloride cadmium(II) anion DFT: B3LYP/3-21G(d) structural and vibrational calculations.

    PubMed

    Faget, Grisset; Felcman, Judith; Giannerini, Tiago; Téllez, Claudio A

    2005-07-01

    The cysteine dichloride cadmium(II) potassium was synthesized and the structural analysis was carried out through the following methods: determination of the C, H, N, S and O contents, thermogravimetry, infrared and Raman spectra. Assuming Cd-S, Cd-O (O-carboxilate) and Cd-N bonds, several hypothetical structures were calculated by means DFT: B3LYP/3-21G(d) quantum mechanical method. The calculations shows that the Cd-S and Cd-N central bonds are favoured in the anion complex formation [Cd(Cys)Cl2]-, being the stabilization energy 55.52 kcal mol(-1) lower than isotopomers with Cd-S and Cd-O central bonds. Features of the infrared and Raman spectra confirm the theoretical structural prediction. Full assignment of the vibrational spectra is proposed based on the DFT procedure, and in order to confirm the C-H, N-H, C-C, C-N, Cd-N, Cd-S and Cd-Cl stretching and the HNH and HCH bending, a normal coordinate analysis based on local symmetry force field for -SC(H2)C-, -CdN(H2)C- and -SCd(Cl2)N- fragments was carried out.

  3. Direct measurement of excited-state intervalence transfer in [(tpy)Ru(III)(tppz(*-))Ru(II)(tpy)](4+) by time-resolved near-infrared spectroscopy.

    PubMed

    Dattelbaum, Dana M; Hartshorn, Chris M; Meyer, Thomas J

    2002-05-08

    Extension of time-resolved infrared (TRIR) measurements into the near-infrared region has allowed the first direct measurement of a mixed-valence band in the metal-to-ligand charge transfer (MLCT) excited state of a symmetrical ligand-bridged complex. Visible laser flash excitation of [(tpy)Ru(tppz)Ru(tpy)]4+ (tppz is 2,3,5,6-tetrakis(2-pyridyl)pyrazine; tpy is 2,2':6',6' '-terpyridine) produces the mixed-valence, MLCT excited state [(tpy)RuIII(tppz*-)RuII(tpy)]4+* with the excited electron localized on the bridging tppz ligand. A mixed-valence band appears at numax = 6300 cm-1 with a bandwidth-at-half- maximum, Deltanu1/2 = 1070 cm-1. In the analogous ground-state complex, [(tpy)Ru(tppz)Ru(tpy)]5+, a mixed-valence band appears at numax = 6550 cm-1 with Deltanu1/2 = 970 cm-1 which allows a comparison to be made of electronic coupling across tppz0 and tppz*- as bridging ligands.

  4. Near-infrared spectral monitoring of Triton with IRTF/SpeX II: Spatial distribution and evolution of ices

    NASA Astrophysics Data System (ADS)

    Grundy, W. M.; Young, L. A.; Stansberry, J. A.; Buie, M. W.; Olkin, C. B.; Young, E. F.

    2010-02-01

    This report arises from an ongoing program to monitor Neptune's largest moon Triton spectroscopically in the 0.8 to 2.4 μm range using IRTF/SpeX. Our objective is to search for changes on Triton's surface as witnessed by changes in the infrared absorption bands of its surface ices N,CH,HO, CO, and CO. We have recorded infrared spectra of Triton on 53 nights over the ten apparitions from 2000 to 2009. The data generally confirm our previously reported diurnal spectral variations of the ice absorption bands (Grundy and Young, 2004). Nitrogen ice shows a large amplitude variation, with much stronger absorption on Triton's Neptune-facing hemisphere. We present evidence for seasonal evolution of Triton's N ice: the 2.15 μm absorption band appears to be diminishing, especially on the Neptune-facing hemisphere. Although it is mostly dissolved in N ice, Triton's CH ice shows a very different longitudinal variation from the N ice, challenging assumptions of how the two ices behave. Unlike Triton's CH ice, the CO ice does exhibit longitudinal variation very similar to the N ice, implying that CO and N condense and sublimate together, maintaining a consistent mixing ratio. Absorptions by HO and CO ices show negligible variation as Triton rotates, implying very uniform and/or high latitude spatial distributions for those two non-volatile ices.

  5. Proper motions of young stellar outflows in the mid-infrared with Spitzer II HH 377/Cep E

    NASA Astrophysics Data System (ADS)

    Noriega-Crespo, A.; Raga, A. C.; Moro-Martín, A.; Flagey, N.; Carey, S. J.

    2014-10-01

    We have used multiple mid-infrared observations at 4.5 μm obtained with the infrared array camera, of the compact (˜ 1.4\\prime ) young stellar bipolar outflow Cep E to measure the proper motion of its brightest condensations. The images span a period of ˜ 6 yr and have been reprocessed to achieve a higher angular resolution (˜ 0.8\\prime\\prime ) than their normal beam (˜ 2\\prime\\prime ). We found that for a distance of 730 pc, the tangential velocities of the north and south outflow lobes are 62+/- 29 and 94+/- 26 km {{s}-1} respectively, and moving away from the central source roughly along the major axis of the flow. A simple 3D hydrodynamical simulation of the H2 gas in a precessing outflow supports this idea. Observations and models confirm that the molecular hydrogen gas, traced by the pure rotational transitions, moves at highly supersonic velocities without being dissociated. This suggests either a very efficient mechanism to reform H2 molecules along these shocks or the presence of some other mechanism (e.g. strong magnetic field) that shields the H2 gas.

  6. Application of Infrared Multiphoton Dissociation Spectroscopy for the Study of Chiral Recognition in the Protonated Serine Clusters: Part II

    NASA Astrophysics Data System (ADS)

    Sunahori, Fumie X.; Kitova, Elena N.; Klassen, John S.; Xu, Yunjie; Yang, Guochun

    2011-06-01

    Serine is an amino acid which has long been known to form the magic-number serine octamer [Ser_8 + H]^+. It has been shown that the serine octamer exhibits strong preference for homochirality. Although a few possible structures for the homochiral serine octamer have been proposed, no definite conclusion has so far been drawn. Last year at this conference, we reported on the study of the protonated serine octamer and dimer as well as the chiral recognition in these clusters using infrared multiphoton dissociation (IRMPD) spectroscopic technique coupled with a Fourier transform ion cyclotron (FTICR) mass spectrometer. Here we present our latest results on the search for the infrared signatures of chiral recognition in the serine octamer and the dimer using a mixture of the deuterated 2,3,3-d_3-L-serine and normal D-serine solution. Using the isotopic labeled species, we could isolate the heterochiral species and obtain their IRMPD spectra which can be directly compared with those of the homochiral species. As an aid to interpret the observed spectra, molecular structures and vibrational frequencies of both homochiral and heterochiral octamer and dimer have been predicted by ab initio calculations. New insights into the hitherto undetermined structure of the serine octamer will be discussed. S. C. Nanita and R. G. Cooks Angew. Chem. Int. Ed. 45, (554), 2006.

  7. Non-Gaussianity of the cosmic infrared background anisotropies - II. Predictions of the bispectrum and constraints forecast

    NASA Astrophysics Data System (ADS)

    Pénin, A.; Lacasa, F.; Aghanim, N.

    2014-03-01

    Using a full analytical computation of the bispectrum based on the halo model together with the halo occupation number, we derive the bispectrum of the cosmic infrared background (CIB) anisotropies that trace the clustering of dusty-star-forming galaxies. We focus our analysis on wavelengths in the far-infrared and the sub-millimeter typical of the Planck/HFI and Herschel/SPIRE instruments, 350, 550, 850 and 1380 μm. We explore the bispectrum behaviour as a function of several models of evolution of galaxies and show that it is strongly sensitive to that ingredient. Contrary to the power spectrum, the bispectrum, at the four wavelengths, seems dominated by low-redshift galaxies. Such a contribution can be hardly limited by applying low flux cuts. We also discuss the contributions of halo mass as a function of the redshift and the wavelength, recovering that each term is sensitive to a different mass range. Furthermore, we show that the CIB bispectrum is a strong contaminant of the cosmic microwave background bispectrum at 850 μm and higher. Finally, a Fisher analysis of the power spectrum, bispectrum alone and of the combination of both shows that degeneracies on the halo occupation distribution parameters are broken by including the bispectrum information, leading to tight constraints even when including foreground residuals.

  8. The faint source population at 15.7 GHz - III. A high-frequency study of HERGs and LERGs

    NASA Astrophysics Data System (ADS)

    Whittam, I. H.; Riley, J. M.; Green, D. A.; Jarvis, M. J.

    2016-10-01

    A complete sample of 96 faint (S > 0.5 mJy) radio galaxies is selected from the Tenth Cambridge (10C) survey at 15.7 GHz. Optical spectra are used to classify 17 of the sources as high-excitation or low-excitation radio galaxies (HERGs and LERGs, respectively), for the remaining sources three other methods are used; these are optical compactness, X-ray observations and mid-infrared colour-colour diagrams. 32 sources are HERGs and 35 are LERGs while the remaining 29 sources could not be classified. We find that the 10C HERGs tend to have higher 15.7-GHz flux densities, flatter spectra, smaller linear sizes and be found at higher redshifts than the LERGs. This suggests that the 10C HERGs are more core dominated than the LERGs. Lower-frequency radio images, linear sizes and spectral indices are used to classify the sources according to their radio morphology; 18 are Fanaroff and Riley type I or II sources, a further 13 show some extended emission, and the remaining 65 sources are compact and are referred to as FR0 sources. The FR0 sources are sub-divided into compact, steep-spectrum sources (13 sources) or gigahertz-peaked spectrum sources (10 sources) with the remaining 42 in an unclassified class. FR0 sources are more dominant in the subset of sources with 15.7-GHz flux densities <1 mJy, consistent with the previous result that the fainter 10C sources have flatter radio spectra. The properties of the 10C sources are compared to the higher-flux density Australia Telescope 20 GHz (AT20G) survey. The 10C sources are found at similar redshifts to the AT20G sources but have lower luminosities. The nature of the high-frequency selected objects changes as flux density decreases; at high flux densities the objects are primarily quasars, while at low flux densities radio galaxies dominate.

  9. High-Resolution Infrared Spectroscopy of Carbon-Sulfur Chains: II. C_5S and SC_5S

    NASA Astrophysics Data System (ADS)

    Thorwirth, Sven; Salomon, Thomas; Dudek, John B.

    2016-06-01

    Unbiased high-resolution infrared survey scans of the ablation products from carbon-sulfur targets in the 2100 to 2150 cm-1 regime reveal two bands previously not observed in the gas phase. On the basis of comparison against laboratory matrix-isolation work and new high-level quantum-chemical calculations these bands are attributed to the linear C_5S and SC_5S clusters. While polar C_5S was studied earlier using Fourier-transform microwave techniques, the present work marks the first gas-phase spectroscopic detection of SC_5S. H. Wang, J. Szczepanski, P. Brucat, and M. Vala 2005, Int. J. Quant. Chem. 102, 795 Y. Kasai, K. Obi, Y. Ohshima, Y. Hirahara, Y. Endo, K. Kawaguchi, and A. Murakami 1993, ApJ 410, L45 V. D. Gordon, M. C. McCarthy, A. J. Apponi, and P. Thaddeus 2001, ApJS 134, 311

  10. GROUND-BASED, NEAR-INFRARED EXOSPECTROSCOPY. II. TENTATIVE DETECTION OF EMISSION FROM THE EXTREMELY HOT JUPITER WASP-12b

    SciTech Connect

    Crossfield, Ian J. M.; Hansen, Brad M. S.; Barman, Travis

    2012-02-10

    We report the tentative detection of the near-infrared emission of the hot Jupiter WASP-12b with the low-resolution prism on Infrared Telescope Facility/SpeX. We find a K - H contrast color of 0.137% {+-} 0.054%, corresponding to a blackbody of temperature 2400{sup +1500}{sub -500} K and consistent with previous, photometric observations. We also revisit WASP-12b's energy budget on the basis of secondary eclipse observations: the dayside luminosity is a relatively poorly constrained (2.0-4.3) Multiplication-Sign 10{sup 30} erg s{sup -1}, but this still allows us to predict a day/night effective temperature contrast of 200-1000 K (assuming A{sub B} = 0). Thus, we conclude that WASP-12b probably does not have both a low albedo and low recirculation efficiency. Our results show the promise and pitfalls of using single-slit spectrographs for characterization of extrasolar planet atmospheres, and we suggest future observing techniques and instruments which could lead to further progress. Limiting systematic effects include the use of too narrow a slit on one night-which observers could avoid in the future-and chromatic slit losses (resulting from the variable size of the seeing disk) and variations in telluric transparency-which observers cannot control. Single-slit observations of the type we present remain the best option for obtaining {lambda} > 1.7 {mu}m spectra of transiting exoplanets in the brightest systems. Further and more precise spectroscopy is needed to better understand the atmospheric chemistry, structure, and energetics of this, and other, intensely irradiated planet.

  11. DISTRIBUTION OF FAINT ATOMIC GAS IN HICKSON COMPACT GROUPS

    SciTech Connect

    Borthakur, Sanchayeeta; Heckman, Timothy M.; Zhu, Guangtun; Yun, Min Su; Verdes-Montenegro, Lourdes; Braatz, James A.

    2015-10-10

    We present 21 cm H i observations of four Hickson Compact Groups (HCGs) with evidence for a substantial intragroup medium using the Robert C. Byrd Green Bank Telescope (GBT). By mapping H i emission in a region of 25′ × 25′ (140–650 kpc) surrounding each HCG, these observations provide better estimates of H i masses. In particular, we detected 65% more H i than that detected in the Karl G. Jansky Very Large Array (VLA) imaging of HCG 92. We also identify whether the diffuse gas has the same spatial distribution as the high surface brightness (HSB) H i features detected in the VLA maps of these groups by comparing the H i strengths between the observed and modeled masses based on VLA maps. We found that the H i observed with the GBT has a similar spatial distribution to the HSB structures in HCG 31 and HCG 68. Conversely, the observed H i distributions in HCG 44 and HCG 92 were extended and showed significant offsets from the modeled masses. Most of the faint gas in HCG 44 lies to the northeast–southwest region and in HCG 92 lies in the northwest region of their respective groups. The spatial and dynamical similarities between the total (faint+HSB) and the HSB H i indicate that the faint gas is of tidal origin. We found that the gas will survive ionization by the cosmic UV background and the escaping ionizing photons from the star-forming regions and stay primarily neutral for at least 500 Myr.

  12. The Value of Cloud Top and Surface Temperature Observations from the 1966 Nimbus II High Resolution Infrared Radiometer Historical Data Record

    NASA Astrophysics Data System (ADS)

    Moses, J. F.; Bedet, J. P.

    2008-12-01

    NASA's Nimbus II High Resolution Infrared Radiometer measured radiance temperatures of cloud tops, sea and land surfaces while in a polar, sun-synchronous orbit from May through November 1966. The instrument operated in the 3.5-4.1 micron atmospheric window region. Most HRIR observations were collected at night to avoid reflected solar radiation contributing to the emission from blackbody surfaces. At least two forms of the original observations have been retained by NASA, one in the form of 70mm film strips and a second containing digitized data on magnetic tape. In 2007, we began efforts to recover the historical record from the original 7-track tapes. The results provided a basis for understanding the instrument data and metadata structures, assessing calibration and geolocation information, and the mission's geographic and temporal coverage. This paper will examine the completeness and utility of this Nimbus II HRIR data record for consideration in future Earth science research studies. We will highlight an approach for making decisions about future recovery efforts, adding value for long term archive and data access strategies. Principle recovery and access concepts are offered for guiding preservation of this and similar sets of observations brought to you by EOSDIS.

  13. Intermediate-band photometry of faint standard stars

    NASA Technical Reports Server (NTRS)

    Dawson, D. W.

    1976-01-01

    The David Dunlap Observatory system uses six intermediate-band filters whose central wavelengths were chosen to cover important features in the spectrum of a late-type star. Calibrations of the color indices with physical parameters, allow one to estimate T sub eff, log g, Fe/H, M sub v and reddening directly from the photometry. Although a number of standards lists exist, only a small fraction of the stars is fainter than V=6. It is desirable to add to the numbers of faint standards. Results are presented of photometry of sixteen stars obtained during a program of variable-star photometry at Blue Mesa Observatory.

  14. A survey for faint variable objects in SA 57

    SciTech Connect

    Trevese, D.; Pittella, G.; Kron, R.G.; Koo, D.C.; Bershady, M.; Roma, Osservatorio Astronomico; ESA, European Space Research Institute, Frascati; Yerkes Observatory, Williams Bay, WI; Space Telescope Science Institute, Baltimore, MD; Lick Observatory, Santa Cruz, CA; Chicago Univ., IL )

    1989-07-01

    Nine Mayall 4 m prime-focus Kodak IIIa-J plates spanning an 11-yr baseline are analyzed in a uniform manner for the detection of variable objects to B = 22.6 at the level of Sigma of about 0.1 mag. Techniques are developed that succeed in independently finding objects already known to be variable, namely a sample of QSOs. Few additional objects were identified as variables with high certainty. The principal result, therefore, is an upper limit both to variable QSOs not previously identified by other techniques, and an upper limit at faint magnitudes on other classes of variable objects. 21 refs.

  15. Near infrared spectroscopy combined with multivariate analysis for monitoring the ethanol precipitation process of fraction I + II + III supernatant in human albumin separation

    NASA Astrophysics Data System (ADS)

    Li, Can; Wang, Fei; Zang, Lixuan; Zang, Hengchang; Alcalà, Manel; Nie, Lei; Wang, Mingyu; Li, Lian

    2017-03-01

    Nowadays, as a powerful process analytical tool, near infrared spectroscopy (NIRS) has been widely applied in process monitoring. In present work, NIRS combined with multivariate analysis was used to monitor the ethanol precipitation process of fraction I + II + III (FI + II + III) supernatant in human albumin (HA) separation to achieve qualitative and quantitative monitoring at the same time and assure the product's quality. First, a qualitative model was established by using principal component analysis (PCA) with 6 of 8 normal batches samples, and evaluated by the remaining 2 normal batches and 3 abnormal batches. The results showed that the first principal component (PC1) score chart could be successfully used for fault detection and diagnosis. Then, two quantitative models were built with 6 of 8 normal batches to determine the content of the total protein (TP) and HA separately by using partial least squares regression (PLS-R) strategy, and the models were validated by 2 remaining normal batches. The determination coefficient of validation (Rp2), root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP) and ratio of performance deviation (RPD) were 0.975, 0.501 g/L, 0.465 g/L and 5.57 for TP, and 0.969, 0.530 g/L, 0.341 g/L and 5.47 for HA, respectively. The results showed that the established models could give a rapid and accurate measurement of the content of TP and HA. The results of this study indicated that NIRS is an effective tool and could be successfully used for qualitative and quantitative monitoring the ethanol precipitation process of FI + II + III supernatant simultaneously. This research has significant reference value for assuring the quality and improving the recovery ratio of HA in industrialization scale by using NIRS.

  16. Near infrared spectroscopy combined with multivariate analysis for monitoring the ethanol precipitation process of fraction I+II+III supernatant in human albumin separation.

    PubMed

    Li, Can; Wang, Fei; Zang, Lixuan; Zang, Hengchang; Alcalà, Manel; Nie, Lei; Wang, Mingyu; Li, Lian

    2017-03-15

    Nowadays, as a powerful process analytical tool, near infrared spectroscopy (NIRS) has been widely applied in process monitoring. In present work, NIRS combined with multivariate analysis was used to monitor the ethanol precipitation process of fraction I+II+III (FI+II+III) supernatant in human albumin (HA) separation to achieve qualitative and quantitative monitoring at the same time and assure the product's quality. First, a qualitative model was established by using principal component analysis (PCA) with 6 of 8 normal batches samples, and evaluated by the remaining 2 normal batches and 3 abnormal batches. The results showed that the first principal component (PC1) score chart could be successfully used for fault detection and diagnosis. Then, two quantitative models were built with 6 of 8 normal batches to determine the content of the total protein (TP) and HA separately by using partial least squares regression (PLS-R) strategy, and the models were validated by 2 remaining normal batches. The determination coefficient of validation (Rp(2)), root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP) and ratio of performance deviation (RPD) were 0.975, 0.501g/L, 0.465g/L and 5.57 for TP, and 0.969, 0.530g/L, 0.341g/L and 5.47 for HA, respectively. The results showed that the established models could give a rapid and accurate measurement of the content of TP and HA. The results of this study indicated that NIRS is an effective tool and could be successfully used for qualitative and quantitative monitoring the ethanol precipitation process of FI+II+III supernatant simultaneously. This research has significant reference value for assuring the quality and improving the recovery ratio of HA in industrialization scale by using NIRS.

  17. What spectroscopy reveals concerning the Mn oxidation levels in the oxygen evolving complex of photosystem II: X-ray to near infra-red.

    PubMed

    Pace, Ron J; Jin, Lu; Stranger, Rob

    2012-08-28

    Photosystem II (PS II), found in oxygenic photosynthetic organisms, catalyses the most energetically demanding reaction in nature, the oxidation of water to molecular oxygen and protons. The water oxidase in PS II contains a Mn(4)Ca cluster (oxygen evolving complex, OEC), whose catalytic mechanism has been extensively investigated but is still unresolved. In particular the precise Mn oxidation levels through which the cluster cycles during functional turnover are still contentious. In this, the first of several planned parts, we examine a broad range of published data relating to this question, while considering the recent atomic resolution PS II crystal structure of Umena et al. (Nature, 2011, 473, 55). Results from X-ray, UV-Vis and NIR spectroscopies are considered, using an approach that is mainly empirical, by comparison with published data from known model systems, but with some reliance on computational or other theoretical considerations. The intention is to survey the extent to which these data yield a consistent picture of the Mn oxidation states in functional PS II - in particular, to test their consistency with two current proposals for the mean redox levels of the OEC during turnover; the so called 'high' and 'low' oxidation state paradigms. These systematically differ by two oxidation equivalents throughout the redox accumulating catalytic S state cycle (states S(0)···S(3)). In summary, we find that the data, in total, substantially favor the low oxidation proposal, particularly as a result of the new analyses we present. The low oxidation state scheme is able to resolve a number of previously 'anomalous' results in the observed UV-Visible S state turnover spectral differences and in the resonant inelastic X-ray spectroscopy (RIXS) of the Mn pre-edge region of the S(1) and S(2) states. Further, the low oxidation paradigm is able to provide a 'natural' explanation for the known sensitivity of the OEC Mn cluster to cryogenic near infra-red (NIR

  18. Fine structure of the age-chromospheric activity relation in solar-type stars. I. The Ca II infrared triplet: Absolute flux calibration

    NASA Astrophysics Data System (ADS)

    Lorenzo-Oliveira, D.; Porto de Mello, G. F.; Dutra-Ferreira, L.; Ribas, I.

    2016-10-01

    Context. Strong spectral lines are useful indicators of stellar chromospheric activity. They are physically linked to the convection efficiency, differential rotation, and angular momentum evolution and are a potential indicator of age. However, for ages > 2 Gyr, the age-activity relationship remains poorly constrained thus hampering its full application. Aims: The Ca II infrared triplet (IRT lines, λλ 8498, 8542, and 8662) has been poorly studied compared to classical chromospheric indicators. We report in this paper absolute chromospheric fluxes in the three Ca II IRT lines, based on a new calibration tied to up-to-date model atmospheres. Methods: We obtain the Ca II IRT absolute fluxes for 113 FGK stars from high signal-to-noise ratio (S/N) and high-resolution spectra covering an extensive domain of chromospheric activity levels. We perform an absolute continuum flux calibration for the Ca II IRT lines anchored in atmospheric models calculated as an explicit function of effective temperatures (Teff), metallicity ([Fe/H]), and gravities (log g) avoiding the degeneracy usually present in photometric continuum calibrations based solely on color indices. Results: The internal uncertainties achieved for continuum absolute flux calculations are ≈2% of the solar chromospheric flux, one order of magnitude lower than for photometric calibrations. Using Monte Carlo simulations, we gauge the impact of observational errors on the final chromospheric fluxes due to the absolute continuum flux calibration and find that Teffuncertainties are properly mitigated by the photospheric correction leaving [Fe/H] as the dominating factor in the chromospheric flux uncertainty. Conclusions: Across the FGK spectral types, the Ca II IRT lines are sensitive to chromospheric activity. The reduced internal uncertainties reported here enable us to build a new chromospheric absolute flux scale and explore the age-activity relation from the active regime down to very low activity levels and

  19. The black hole mass of NGC 4151. II. Stellar dynamical measurement from near-infrared integral field spectroscopy

    SciTech Connect

    Onken, Christopher A.; Ferrarese, Laura; Valluri, Monica; Brown, Jonathan S.; McGregor, Peter J.; Peterson, Bradley M.; Pogge, Richard W.; Bentz, Misty C.; Vestergaard, Marianne; Storchi-Bergmann, Thaisa; Riffel, Rogemar A. E-mail: mvalluri@umich.edu

    2014-08-10

    We present a revised measurement of the mass of the central black hole (M{sub BH} ) in the Seyfert 1 galaxy NGC 4151. The new stellar dynamical mass measurement is derived by applying an axisymmetric orbit-superposition code to near-infrared integral field data obtained using adaptive optics with the Gemini Near-infrared Integral Field Spectrograph (NIFS). When our models attempt to fit both the NIFS kinematics and additional low spatial resolution kinematics, our results depend sensitively on how χ{sup 2} is computed—probably a consequence of complex bar kinematics that manifest immediately outside the nuclear region. The most robust results are obtained when only the high spatial resolution kinematic constraints in the nuclear region are included in the fit. Our best estimates for the black hole mass and H-band mass-to-light ratio are M{sub BH} ∼ 3.76 ± 1.15 × 10{sup 7} M{sub ☉} (1σ error) and Y{sub H} ∼ 0.34 ± 0.03 M{sub ☉}/L{sub ☉} (3σ error), respectively (the quoted errors reflect the model uncertainties). Our black hole mass measurement is consistent with estimates from both reverberation mapping (3.57{sub −0.37}{sup +0.45}×10{sup 7} M{sub ⊙}) and gas kinematics (3.0{sub −2.2}{sup +0.75}×10{sup 7} M{sub ⊙}; 1σ errors), and our best-fit mass-to-light ratio is consistent with the photometric estimate of Y{sub H} = 0.4 ± 0.2 M{sub ☉}/L{sub ☉}. The NIFS kinematics give a central bulge velocity dispersion σ{sub c} = 116 ± 3 km s{sup –1}, bringing this object slightly closer to the M{sub BH}-σ relation for quiescent galaxies. Although NGC 4151 is one of only a few Seyfert 1 galaxies in which it is possible to obtain a direct dynamical black hole mass measurement—and thus, an independent calibration of the reverberation mapping mass scale—the complex bar kinematics makes it less than ideally suited for this purpose.

  20. A SPITZER SURVEY OF MID-INFRARED MOLECULAR EMISSION FROM PROTOPLANETARY DISKS. II. CORRELATIONS AND LOCAL THERMAL EQUILIBRIUM MODELS

    SciTech Connect

    Salyk, C.; Pontoppidan, K. M.; Blake, G. A.; Najita, J. R.; Carr, J. S.

    2011-04-20

    We present an analysis of Spitzer Infrared Spectrograph observations of H{sub 2}O, OH, HCN, C{sub 2}H{sub 2}, and CO{sub 2} emission, and Keck-NIRSPEC observations of CO emission, from a diverse sample of T Tauri and Herbig Ae/Be circumstellar disks. We find that detections and strengths of most mid-IR molecular emission features are correlated with each other, suggesting a common origin and similar excitation conditions for this mid-infrared line forest. Aside from the remarkable differences in molecular line strengths between T Tauri, Herbig Ae/Be, and transitional disks discussed in Pontoppidan et al., we note that the line detection efficiency is anti-correlated with the 13/30 {mu}m spectral slope, which is a measure of the degree of grain settling in the disk atmosphere. We also note a correlation between detection efficiency and H{alpha} equivalent width, and tentatively with accretion rate, suggesting that accretional heating contributes to line excitation. If detected, H{sub 2}O line fluxes are correlated with the mid-IR continuum flux, and other co-varying system parameters, such as L{sub *}. However, significant sample variation, especially in molecular line ratios, remains, and its origin has yet to be explained. Local thermal equilibrium (LTE) models of the H{sub 2}O emission show that line strength is primarily related to the best-fit emitting area, and this accounts for most source-to-source variation in H{sub 2}O emitted flux. Best-fit temperatures and column densities cover only a small range of parameter space, near {approx}10{sup 18} cm{sup -2} and 450 K for all sources, suggesting a high abundance of H{sub 2}O in many planet-forming regions. Other molecules have a range of excitation temperatures from {approx}500to1500 K, also consistent with an origin in planet-forming regions. We find molecular ratios relative to water of {approx}10{sup -3} for all molecules, with the exception of CO, for which n(CO)/n(H{sub 2}O) {approx} 1. However, LTE

  1. The Infrared Hunter

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

    This image composite compares infrared and visible views of the famous Orion nebula and its surrounding cloud, an industrious star-making region located near the hunter constellation's sword. The infrared picture is from NASA's Spitzer Space Telescope, and the visible image is from the National Optical Astronomy Observatory, headquartered in Tucson, Ariz.

    In addition to Orion, two other nebulas can be seen in both pictures. The Orion nebula, or M42, is the largest and takes up the lower half of the images; the small nebula to the upper left of Orion is called M43; and the medium-sized nebula at the top is NGC 1977. Each nebula is marked by a ring of dust that stands out in the infrared view. These rings make up the walls of cavities that are being excavated by radiation and winds from massive stars. The visible view of the nebulas shows gas heated by ultraviolet radiation from the massive stars.

    Above the Orion nebula, where the massive stars have not yet ejected much of the obscuring dust, the visible image appears dark with only a faint glow. In contrast, the infrared view penetrates the dark lanes of dust, revealing bright swirling clouds and numerous developing stars that have shot out jets of gas (green). This is because infrared light can travel through dust, whereas visible light is stopped short by it.

    The infrared image shows light captured by Spitzer's infrared array camera. Light with wavelengths of 8 and 5.8 microns (red and orange) comes mainly from dust that has been heated by starlight. Light of 4.5 microns (green) shows hot gas and dust; and light of 3.6 microns (blue) is from starlight.

  2. Large Magellanic Cloud Near-infrared Synoptic Survey. II. The Wesenheit Relations and Their Application to the Distance Scale

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Anupam; Kanbur, Shashi M.; Macri, Lucas M.; Singh, Harinder P.; Ngeow, Chow-Choong; Wagner-Kaiser, R.; Sarajedini, Ata

    2016-04-01

    We present new near-infrared (NIR) Cepheid period-Wesenheit (P-W) relations in the LMC using time-series observations from the Large Magellanic Cloud NIR Synoptic Survey. We also derive optical+NIR P-W relations using V and I magnitudes from the Optical Gravitational Lensing Experiment. We employ our new JHKs data to determine an independent distance to the LMC of {μ }{{LMC}}\\=\\18.47+/- 0.07(statistical) mag, using an absolute calibration of the Galactic relations based on several distance determination methods and accounting for the intrinsic scatter of each technique. We also derive new NIR period-luminosity and Wesenheit relations for Cepheids in M31 using observations from the Panchromatic Hubble Andromeda Treasury survey. We use the absolute calibrations of the Galactic and LMC {W}J,H relations to determine the distance modulus of M31, {μ }{{M31}}\\=\\24.46+/- 0.20 mag. We apply a simultaneous fit to Cepheids in several Local Group galaxies covering a range of metallicities (7.7\\lt 12+{log}[{{O}}/{{H}}]\\lt 8.6 dex) to determine a global slope of -3.244 ± 0.016 mag dex-1 for the {W}J,{Ks} relation and obtain robust distance estimates. Our distances are in good agreement with recent TRGB based distance estimates and we do not find any evidence for a metallicity dependence in the NIR P-W relations.

  3. Near-infrared spectroscopy of 3:1 Kirkwood Gap asteroids II: Probable and plausible parent bodies; primitive and differentiated

    NASA Astrophysics Data System (ADS)

    Fieber-Beyer, Sherry K.; Gaffey, Michael J.

    2014-02-01

    The 3:1 Kirkwood Gap asteroids are a mineralogically diverse set of asteroids located in a region that delivers meteoroids into Earth-crossing orbits. Mineralogical characterizations of asteroids in/near the 3:1 Kirkwood Gap can be used as a tool to “map” conditions and processes in the early Solar System. The chronological studies of the meteorite types provide a “clock” for the relative timing of those events and processes. By identifying the source asteroids of particular meteorite types, the “map” and “clock” can be combined to provide a much more sophisticated understanding of the history and evolution of the late solar nebula and the early Solar System. A mineralogical assessment of twelve 3:1 Kirkwood Gap asteroids has been carried out using near-infrared spectral data obtained from 2010 to 2011 combined with visible spectral data (when available) to cover the spectral interval of 0.4-2.5 μm. Eight of these asteroids have surfaces with basaltic-type silicate assemblages, indicating at least partial melting within their parent bodies. Although HED-like mineralogies are present these objects exhibit subdued features indicating the presence of an additional phase (e.g., NiFe metal) or process (e.g., space weathering). Four of these asteroids appear to be ordinary chondrite assemblages. Three of these are plausibly linked to the probable H-chondrite parent body, (6) Hebe.

  4. Near-infrared spectroscopic monitoring of the diffusion process of deuterium-labeled molecules in wood. Part II: hardwood.

    PubMed

    Tsuchikawa, Satoru; Siesler, H W

    2003-06-01

    Fourier transform near-infrared (FT-NIR) transmission spectroscopy was applied to monitor the diffusion process of deuterium-labeled molecules in hardwood (Beech). The results are compared with previous data obtained on softwood (Sitka spruce) in order to consistently understand the state of order in cellulose of wood. The saturation accessibility and diffusion rate varied characteristically with the OH groups in different states of order in the wood substance, the diffusants, and the wood species, respectively. The variation of saturation accessibility should be associated with the fundamental difference of the fine structure such as the microfibrils in the wood substance. The effect of the anatomical cellular structure on the accessibility was reflected in the variation of the diffusion rate with the wood species. The size effect of the diffusants also played an important role for the diffusion process in wood. Since the volumetric percentage of wood fibers and wood rays is relatively similar, the dichroic effects due to the anisotropy of the cellulose chains were apparently diminished. Finally, we proposed a new interpretation of the fine structure of the microfibrils in the cell wall by comparing a series of results from hardwood and softwood. Each elementary fibril in the hardwood has a more homogeneous arrangement in the microfibrils compared to that in the softwood.

  5. A Tool for Optimizing Observation Planning for Faint Moving Objects

    NASA Astrophysics Data System (ADS)

    Arredondo, Anicia; Bosh, Amanda S.; Levine, Stephen

    2016-10-01

    Observations of small solar system bodies such as trans-Neptunian objects and Centaurs are vital for understanding the basic properties of these small members of our solar system. Because these objects are often very faint, large telescopes and long exposures may be necessary, which can result in crowded fields in which the target of interest may be blended with a field star. For accurate photometry and astrometry, observations must be planned to occur when the target is free of background stars; this restriction results in limited observing windows. We have created a tool that can be used to plan observations of faint moving objects. Features of the tool include estimates of best times to observe (when the object is not too near another object), a finder chart output, a list of possible astrometric and photometric reference stars, and an exposure time calculator. This work makes use of the USNOFS Image and Catalogue Archive operated by the United States Naval Observatory, Flagstaff Station (S.E. Levine and D.G. Monet 2000), the JPL Horizons online ephemeris service (Giorgini et al. 1996), the Minor Planet Center's MPChecker (http://cgi.minorplanetcenter.net/cgi-bin/checkmp.cgi), and source extraction software SExtractor (Bertin & Arnouts 1996). Support for this work was provided by NASA SSO grant NNX15AJ82G.

  6. The faint radio AGN population in the spotlight

    NASA Astrophysics Data System (ADS)

    Herrera Ruiz, Noelia; Middelberg, Enno

    2016-08-01

    To determine the AGN component in the faint radio population is fundamental in galaxy evolution studies. A relatively easy and direct way to determine which galaxies do have a radio-active AGN is a detection using the Very Long Baseline Interferometry (VLBI) technique. The goal of this project is to study with statistically relevant numbers the faint radio source population using VLBI observations. To achieve this goal, the project is divided into two parts. In the first part, we have observed ~3000 radio sources in the COSMOS extragalactic field with the Very Long Baseline Array (VLBA) at 1.4GHz. We have detected 468 sources. In the second part, we have observed ~200 radio sources in the COSMOS field with extremely high sensitivity using the VLBA together with the Green Bank Telescope (GBT) at 1.4GHz, to explore an even fainter population in the flux density regime of tens of uJy. We are currently calibrating this data. In this overview I will present the survey design, observations, and calibration, along with some first results.

  7. Detectability of Ultra Faint Dwarf Galaxies with Gaia

    NASA Astrophysics Data System (ADS)

    Mateu, C.; Antoja, T.; Aguilar, L.; Figueras, F.; Brown, A.; Antiche, E.; Hernández-Pérez, F.; Valenzuela, O.; Aparicio, A.; Hidalgo, S.; Velázquez, H.

    2014-07-01

    We present a technique to detect Ultra-Faint Dwarf Galaxies (UFDs) in the Galactic Halo, using sky and proper motion information.The method uses wavelet transforms to detect peaks in the sky and proper motion planes, and to evaluate the probability of these being stochastic fluctuations. We aim to map thoroughly the detection limits of this technique. For this, we have produced a library of 15,000 synthetic UFDs, embedded in the Gaia Universe Model Snapshot (GUMS) background (Robin et al. 2012), each at a different distance, different luminosity, half-light radius, velocity dispersion and center-of-mass velocity, varying in ranges that extend well beyond those spanned by known classical and ultra-faint dSphs. We use these synthetic UFDs as a benchmark to characterize the completeness and detection limits of our technique, and present our results as a function of different physical and observable parameters of the UFDs (see full poster for more details at https://gaia.ub.edu/Twiki/pub/GREATITNFC/ProgramFinalconference/Poster_UFGX_Bcn_C_Mateu.pdf).

  8. A SPITZER SPACE TELESCOPE FAR-INFRARED SPECTRAL ATLAS OF COMPACT SOURCES IN THE MAGELLANIC CLOUDS. II. THE SMALL MAGELLANIC CLOUD

    SciTech Connect

    Van Loon, Jacco Th.; Oliveira, Joana M.; Gordon, Karl D.; Sloan, G. C.; Engelbracht, C. W.

    2010-04-15

    We present far-infrared spectra, {lambda} = 52-93 {mu}m, obtained with the Spitzer Space Telescope in the spectral energy distribution mode of its Multiband Imaging Photometer for Spitzer instrument, of a selection of luminous compact far-infrared sources in the Small Magellanic Cloud (SMC). These comprise nine young stellar objects (YSOs), the compact H II region N 81 and a similar object within N 84, and two red supergiants (RSGs). We use the spectra to constrain the presence and temperature of cool dust and the excitation conditions within the neutral and ionized gas, in the circumstellar environments and interfaces with the surrounding interstellar medium. We compare these results with those obtained in the Large Magellanic Cloud (LMC). The spectra of the sources in N 81 (of which we also show the Infrared Space Observatory-Long-wavelength Spectrograph spectrum between 50 and 170 {mu}m) and N 84 both display strong [O I] {lambda}63 {mu}m and [O III] {lambda}88 {mu}m fine-structure line emission. We attribute these lines to strong shocks and photo-ionized gas, respectively, in a 'champagne flow' scenario. The nitrogen content of these two H II regions is very low, definitely N(N)/N(O) < 0.04 but possibly as low as N(N)/N(O) < 0.01. Overall, the oxygen lines and dust continuum are weaker in star-forming objects in the SMC than in the LMC. We attribute this to the lower metallicity of the SMC compared to that of the LMC. While the dust mass differs in proportion to metallicity, the oxygen mass differs less; both observations can be reconciled with higher densities inside star-forming cloud cores in the SMC than in the LMC. The dust in the YSOs in the SMC is warmer (37-51 K) than in comparable objects in the LMC (32-44 K). We attribute this to the reduced shielding and reduced cooling at the low metallicity of the SMC. On the other hand, the efficiency of the photo-electric effect to heat the gas is found to be indistinguishable to that measured in the same manner

  9. Characterizing the Youngest Herschel-detected Protostars. II. Molecular Outflows from the Millimeter and the Far-infrared

    NASA Astrophysics Data System (ADS)

    Tobin, John J.; Stutz, Amelia M.; Manoj, P.; Megeath, S. Thomas; Karska, Agata; Nagy, Zsofia; Wyrowski, Friedrich; Fischer, William J.; Watson, Dan M.; Stanke, Thomas

    2016-11-01

    We present Combined Array for Research in Millimeter-wave Astronomy (CARMA) CO (J=1\\to 0) observations and Herschel PACS spectroscopy, characterizing the outflow properties toward extremely young and deeply embedded protostars in the Orion molecular clouds. The sample comprises a subset of the Orion protostars known as the PACS Bright Red Sources (PBRS; Stutz et al.). We observed 14 PBRS with CARMA and 8 of these 14 with Herschel, acquiring full spectral scans from 55 to 200 μm. Outflows are detected in CO (J=1\\to 0) from 8 of 14 PBRS, with two additional tentative detections; outflows are also detected from the outbursting protostar HOPS 223 (V2775 Ori) and the Class I protostar HOPS 68. The outflows have a range of morphologies; some are spatially compact, <10,000 au in extent, while others extend beyond the primary beam. The outflow velocities and morphologies are consistent with being dominated by intermediate inclination angles (80° ≥ i ≥ 20°). This confirms the interpretation of the very red 24-70 μm colors of the PBRS as a signpost of high envelope densities, with only one (possibly two) cases of the red colors resulting from edge-on inclinations. We detect high-J (J up > 13) CO lines and/or H2O lines from 5 of 8 PBRS and only for those with detected CO outflows. The far-infrared CO rotation temperatures of the detected PBRS are marginally colder (˜230 K) than those observed for most protostars (˜300 K), and only one of these five PBRS has detected [O i] 63 μm emission. The high envelope densities could be obscuring some [O i] emission and cause a ˜20 K reduction to the CO rotation temperatures. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  10. Spectral relationships for atmospheric correction. II. Improving NASA's standard and MUMM near infra-red modeling schemes.

    PubMed

    Goyens, C; Jamet, C; Ruddick, K G

    2013-09-09

    Spectral relationships, reflecting the spectral dependence of water-leaving reflectance, ρw(λ), can be easily implemented in current AC algorithms with the aim to improve ρw(λ) retrievals where the algorithms fail. The present study evaluates the potential of spectral relationships to improve the MUMM [Ruddick et al., 2006, Limnol. Oceanogr. 51, 1167-1179] and standard NASA [Bailey et al., 2010, Opt. Express 18, 7521-7527] near infra-red (NIR) modeling schemes included in the AC algorithm to account for non-zero ρw(λNIR), based on in situ coastal ρw(λ) and simulated Rayleigh corrected reflectance data. Two modified NIR-modeling schemes are investigated: (1) the standard NASA NIR-modeling scheme is forced with bounding relationships in the red spectral domain and with a NIR polynomial relationship and, (2) the constant NIR ρw(λ) ratio used in the MUMM NIR-modeling scheme is replaced by a NIR polynomial spectral relationship. Results suggest that the standard NASA NIR-modeling scheme performs better for all turbidity ranges and in particular in the blue spectral domain (percentage bias decreased by approximately 50%) when it is forced with the red and NIR spectral relationships. However, with these new constraints, more reflectance spectra are flagged due to non-physical Chlorophyll-a concentration estimations. The new polynomial-based MUMM NIR-modeling scheme yielded lower ρw(λ) retrieval errors and particularly in extremely turbid waters. However, including the polynomial NIR relationship significantly increased the sensitivity of the algorithm to errors on the selected aerosol model from nearby clear water pixels.

  11. Investigating the Near-Infrared Properties of Planetary Nebulae II. Medium Resolution Spectra. 2; Medium Resolution Spectra

    NASA Technical Reports Server (NTRS)

    Hora, Joseph L.; Latter, William B.; Deutsch, Lynne K.

    1998-01-01

    We present medium-resolution (R approximately 700) near-infrared (lambda = 1 - 2.5 micrometers) spectra of a sample of planetary nebulae (PNe). A narrow slit was used which sampled discrete locations within the nebulae; observations were obtained at one or more positions in the 41 objects included in the survey. The PN spectra fall into one of four general categories: H1 emission line-dominated PNe, H1 and H2 emission line PNe, H2 emission line-dominated PNe, and continuum-dominated PNe. These categories correlate with morphological type, with the elliptical PNe falling into the first group, and the bipolar PNe primarily in the H2 and continuum emission groups. The categories also correlate with C/O ratio, with the O-rich objects falling into the first group and the C-rich objects in the groups. Other spectral features were observed in all catagories, such as continuum emission from the central star, and warm dust continuum emission towards the long wavelength end of the spectra. H2 was detected in four PNe in this survey for the first time. An analysis was performed using the H2 line ratios in all of the PN spectra in the survey where a sufficient number of lines were observed to determine the ortho-to-para ratio and the rotational and vibrational excitation temperatures of the H-2 in those objects. One unexpected result from this analysis is that the H-2 is excited by absorption of ultraviolet photons in most of the PNe, although there are several PNe in which collisional excitation plays an important role. The correlation between bipolar morphology and H2 emission has been strengthened with the new detections of H2 in this survey.

  12. Ultra-light dark matter in ultra-faint dwarf galaxies

    NASA Astrophysics Data System (ADS)

    Calabrese, Erminia; Spergel, David N.

    2016-08-01

    Cold Dark Matter (CDM) models struggle to match the observations at galactic scales. The tension can be reduced either by dramatic baryonic feedback effects or by modifying the particle physics of CDM. Here, we consider an ultra-light scalar field DM particle manifesting a wave nature below a DM particle mass-dependent Jeans scale. For DM mass m ˜ 10-22 eV, this scenario delays galaxy formation and avoids cusps in the centre of the dark matter haloes. We use new measurements of half-light mass in ultra-faint dwarf galaxies Draco II and Triangulum II to estimate the mass of the DM particle in this model. We find that if the stellar populations are within the core of the density profile then the data are in agreement with a Wave Dark Matter model having a DM particle with m ˜ 3.7-5.6 × 10-22 eV. The presence of this extremely light particle will contribute to the formation of a central solitonic core replacing the cusp of a Navarro-Frenk-White profile and bringing predictions closer to observations of cored central density in dwarf galaxies.

  13. Spectrum of excess partial molar absorptivity. Part II: a near infrared spectroscopic study of aqueous Na-halides.

    PubMed

    Sebe, Fumie; Nishikawa, Keiko; Koga, Yoshikata

    2012-04-07

    Our earlier thermodynamic studies suggested that F(-) and Cl(-) form hydration shells with the hydration number 14 ± 2 and 2.3 ± 0.6, respectively, and leave the bulk H(2)O away from hydration shells unperturbed. Br(-) and I(-), on the other hand, form hydrogen bonds directly with the momentarily existing hydrogen bond network of H(2)O, and retard the degree of entropy-volume cross fluctuation inherent in liquid H(2)O. The effect of the latter is stronger for I(-) than Br(-). Here we seek additional information about this qualitative difference between Cl(-) and (Br(-) and I(-)) pair by near infrared (NIR) spectroscopy. We analyze the ν(2) + ν(3) band of H(2)O in the range 4600-5500 cm(-1) of aqueous solutions of NaCl, NaBr and NaI, by a new approach. From observed absorbance, we calculate excess molar absorptivity, ε(E), excess over the additive contributions of solute and solvent. ε(E) thus contains information about the effect of inter-molecular interactions in the ν(2) + ν(3) spectrum. The spectrum of ε(E) shows three bands; two negative ones at 5263 and 4873 cm(-1), and the positive band at 5123 cm(-1). We then define and calculate the excess partial molar absorptivity of each salt, ε(E)(salt). From the behaviour of ε(E)(salt) we suggest that the negative band at 5263 cm(-1) represents free H(2)O without much hydrogen bonding under the influence of local electric field of ions. Furthermore, from a sudden change in the x(salt) (mole fraction of salt) dependence of ε(E)(salt), we suggest that there is an ion-pairing in x(salt) > 0.032, 0.036, and 0.04 for NaCl, NaBr and NaI respectively. The positive band of ε(E) at 5123 cm(-1) is attributed to a modestly organized hydrogen bond network of H(2)O (or liquid-likeness), and the x(salt) dependence of ε indicated a qualitative difference in the effect of Cl(-) from those of Br(-) and I(-). Namely, the values of ε(E)(salt) stay constant for Cl(-) but those for Br(-) and I(-) decrease smoothly on

  14. Spatial distribution of far-infrared emission in spiral galaxies. II. Heating sources and gas-to-dust ratio.

    NASA Astrophysics Data System (ADS)

    Mayya, Y. D.; Rengarajan, T. N.

    1997-09-01

    . The flattened radial profiles indicate a global gas-to-dust ratio of around 300, which is within a factor of two of the local galactic value. keywords: dust - extinction - infrared radiation - heating sources - gas-to-dust ratio

  15. Near-infrared spectroscopy of M dwarfs. II. H2O molecule as an abundance indicator of oxygen†

    NASA Astrophysics Data System (ADS)

    Tsuji, Takashi; Nakajima, Tadashi; Takeda, Yoichi

    2015-04-01

    Based on the near-infrared spectra (R ≈ 20000) of M dwarfs, oxygen abundances are determined from the rovibrational lines of H2O. Although H2O lines in M dwarfs are badly blended with each other and the continuum levels are depressed appreciably by the collective effect of the numerous H2O lines themselves, quantitative analysis of H2O lines has been carried out by referring to the pseudo-continua, consistently defined on the observed and theoretical spectra. For this purpose, the pseudo-continuum on the theoretical spectrum has been evaluated accurately by the use of the recent high-precision H2O line-list. Then, we propose a simple and flexible method of analyzing the equivalent widths (EWs) of blended features (i.e., not necessarily limited to single lines) by the use of a mini-curve-of-growth (CG), which is a small portion of the usual CG around the observed EW. The mini-CG is generated by using the theoretical EWs evaluated from the synthetic spectrum in exactly the same way as the EWs are measured from the observed spectrum. The observed EW is converted to the abundance by the use of the mini-CG, and the process is repeated for all the observed EWs line-by-line or blend-by-blend. In cool M dwarfs, almost all the oxygen atoms left after CO formation are in stable H2O molecules, which suffer little change for the uncertainties due to imperfect modelling of the photospheres. Thus the numerous H2O lines are excellent abundance indicators of oxygen. The oxygen abundances are determined to be log AO (AO = NO/NH) between -3.5 and -3.0 in 38 M dwarfs, but cannot be determined in four early M dwarfs in which H2O lines are detected only marginally. The resulting log AO/AC values plotted against log AC appear to be systematically smaller in the carbon-rich M dwarfs, showing the different formation histories of oxygen and carbon in the chemical evolution of the Galactic disk. Also, AO/AFe ratios in most M dwarfs are closer to the solar AO/AFe ratio, based on the

  16. Dissymmetric Bis(dipyrrinato)zinc(II) Complexes: Rich Variety and Bright Red to Near-Infrared Luminescence with a Large Pseudo-Stokes Shift.

    PubMed

    Sakamoto, Ryota; Iwashima, Toshiki; Kögel, Julius F; Kusaka, Shinpei; Tsuchiya, Mizuho; Kitagawa, Yasutaka; Nishihara, Hiroshi

    2016-05-04

    Bis(dipyrrinato)metal(II) and tris(dipyrrinato)metal(III) complexes have been regarded as much less useful luminophores than their boron difluoride counterparts (4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes, BODIPYs), especially in polar solvent. We proposed previously that dissymmetry in such metal complexes (i.e., two different dipyrrinato ligands in one molecule) improves their fluorescence quantum efficiencies. In this work, we demonstrate the universality and utility of our methodology by synthesizing eight new dissymmetric bis(dipyrrinato)zinc(II) complexes and comparing them with corresponding symmetric complexes. Single-crystal X-ray diffraction analysis, (1)H and (13)C NMR spectroscopy, and high-resolution mass spectrometry confirm the retention of dissymmetry in both solution and solid states. The dissymmetric complexes all show greater photoluminescence (PL) quantum yields (ϕPL) than the corresponding symmetric complexes, allowing red to near-infrared emissions with large pseudo-Stokes shifts. The best performance achieves a maximum PL wavelength of 671 nm, a pseudo-Stokes shift of 5400 cm(-1), and ϕPL of 0.62-0.72 in toluene (dielectric constant εs = 2.4), dichloromethane (εs = 9.1), acetone (εs = 21.4), and ethanol (εs = 24.3). The large pseudo-Stokes shift is distinctive considering BODIPYs with small Stokes shifts (∼500 cm(-1)), and the ϕPL values are higher than or comparable to those of BODIPYs fluorescing at similar wavelengths. Electrochemistry and density functional theory calculations illustrate that frontier orbital ordering in the dissymmetric complexes meets the condition for efficient PL proposed in our theory.

  17. Faint UBVRI Standard Star Fields at +50° Declination

    NASA Astrophysics Data System (ADS)

    Clem, James L.; Landolt, Arlo U.

    2016-10-01

    Precise and accurate CCD-based UBVRI photometry is presented for ˜2000 stars distributed around the sky in a declination zone centered approximately at +50°. Their photometry has been calibrated to the standard Johnson UBV and Kron-Cousins RI systems through observations of the UBVRI standard stars presented in the various works of Landolt. The magnitude and color range for these stars are 12 ≲ V ≲ 22 and -0.3 ≲ (B - V) ≲ 1.8, respectively. Each star averages 13 measures in each UBVRI filter from data taken on 41 different photometric nights obtained over a 21 month period. Hence, there now exists a network of faint UBVRI photometric standard stars centered on the declination zones δ = -50°, 0°, and +50°.

  18. A sample of Swift/SDSS faint blazars

    NASA Astrophysics Data System (ADS)

    Fraga, Bernardo; Giommi, Paolo; Turriziani, Sara

    2015-12-01

    We aim here to provide a complete sample of faint (fr ≳ 1 mJy, fx ≳ 10-15 erg cm-2 s-1) blazars and blazar candidates serendipitously discovered in deep Swift images centered on Gamma-ray bursts (GRBs). By stacking all available images, we obtain exposures ranging from 104 to more than a million seconds. Since GRBs are thought to explode randomly across the sky, this set of deep fields can be considered as an unbiased survey of ≈ 12 square degrees of extragalactic sky, with sensitivities reaching a few 10-15 erg cm-2 s-1 in the 0.5-2 keV band. We then derive the x-ray Log N Log S and show that, considering that our sample may be contaminated by sources other than blazars, we are in agreement with previous estimations based on data and simulations.

  19. Clustering Effect on the Number Count of Faint Galaxies

    NASA Astrophysics Data System (ADS)

    Yamashita, K.

    1992-08-01

    We have tested the cosmological model of Ω0 = 1 and Λ = 0 against the faint galaxy number count taking the clustering effect of galaxies into account. The evolution of the large scale structure is simulated numerically by means of the particle mesh method in three dimensional space. We use 643 particles and the same number of mesh cells. We have found that the flat Friedmann-Robertson-Walker model without the cosmological constant does not explain the excess of the number count observed by Tyson even if the clustering effect is taken into account, provided the cluster size and the correlation length among clusters are less than the simulation box size of 128 h-1 Mpc. The clustering on scales larger than 128 h-1 Mpc is also considered.

  20. First results from the Faint Object Camera - SN 1987A

    NASA Technical Reports Server (NTRS)

    Jakobsen, P.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.

    1991-01-01

    The first images of SN 1987A taken on day 1278 after outburst with the Faint Object Camera on board the Hubble Space Telescope are presented. The supernova is well detected and resolved spatially in three broadband ultraviolet exposures spanning the 1500-3800 A range and in a narrow-band image centered on the forbidden O III 5007 line. Simple uniform disk fits to the profiles of SN 1987A yield an average angular diameter of 170 + or - 30 mas, corresponding to an average expansion velocity of 6000 km/s. The derived broadband ultraviolet fluxes, when corrected for interstellar absorption, indicate a blue ultraviolet spectrum corresponding to a color temperature near 13,000 K.

  1. MEASURING SIZES OF ULTRA-FAINT DWARF GALAXIES

    SciTech Connect

    Munoz, Ricardo R.; Padmanabhan, Nikhil; Geha, Marla

    2012-02-01

    The discovery of ultra-faint dwarf (UFD) galaxies in the halo of the Milky Way extends the faint end of the galaxy luminosity function to a few hundred solar luminosities. This extremely low luminosity regime poses a significant challenge for the photometric characterization of these systems. We present a suite of simulations aimed at understanding how different observational choices related to the properties of a low-luminosity system impact our ability to determine its true structural parameters such as half-light radius and central surface brightness. We focus on estimating half-light radii (on which mass estimates depend linearly) and find that these numbers can have up to 100% uncertainties when relatively shallow photometric surveys, such as the Sloan Digital Sky Survey, are used. Our simulations suggest that to recover structural parameters within 10% or better of their true values: (1) the ratio of the field of view to the half-light radius of the satellite must be greater than three, (2) the total number of stars, including background objects should be larger than 1000, and (3) the central to background stellar density ratio must be higher than 20. If one or more of these criteria are not met, the accuracy of the resulting structural parameters can be significantly compromised. In the context of future surveys such as Large Synoptic Survey Telescope, the latter condition will be closely tied to our ability to remove unresolved background galaxies. Assessing the reliability of measured structural parameters will become increasingly critical as the next generation of deep wide-field surveys detects UFDs beyond the reach of current spectroscopic limits.

  2. Hydrothermal synthesis of high-quality type-II CdTe/CdSe quantum dots with near-infrared fluorescence.

    PubMed

    Wang, Jing; Han, Heyou

    2010-11-01

    A simple hydrothermal method is developed for the synthesis of high-quality, water-soluble, and near-infrared (NIR)-emitting type-II core/shell CdTe/CdSe quantum dots (QDs) by employing thiol-capped CdTe QDs as core templates and CdCl(2) and Na(2)SeO(3) as shell precursors. Compared with the original CdTe core QDs, the core/shell CdTe/CdSe QDs exhibit an obvious red-shifted emission, whose color can be tuned between visible and NIR regions (620-740 nm) by controlling the thickness of the CdSe shell. The photoluminescence quantum yield (PL QY) of CdTe/CdSe QDs with an optimized thickness of the CdSe shell can reach up to 44.2% without any post-preparative treatment. Through a thorough study of the core/shell structure by high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible (UV-vis) absorption spectra, fluorescence spectra, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), the as-prepared CdTe/CdSe QDs demonstrate good monodispersity, hardened lattice structure and excellent photostability, offering a great potential for biological application.

  3. Evidence for a defect level above the conduction band edge of InAs/InAsSb type-II superlattices for applications in efficient infrared photodetectors

    SciTech Connect

    Prins, A. D.; Lewis, M. K.; Bushell, Z. L.; Sweeney, S. J.; Liu, S.; Zhang, Y.-H.

    2015-04-27

    We report pressure-dependent photoluminescence (PL) experiments under hydrostatic pressures up to 2.16 GPa on a mid-wave infrared InAs/InAs{sub 0.86}Sb{sub 0.14} type-II superlattice (T2SL) structure at different pump laser excitation powers and sample temperatures. The pressure coefficient of the T2SL transition was found to be 93 ± 2 meV·GPa{sup −1}. The integrated PL intensity increases with pressure up to 1.9 GPa then quenches rapidly indicating a pressure induced level crossing with the conduction band states at ∼2 GPa. Analysis of the PL intensity as a function of excitation power at 0, 0.42, 1.87, and 2.16 GPa shows a clear change in the dominant photo-generated carrier recombination mechanism from radiative to defect related. From these data, evidence for a defect level situated at 0.18 ± 0.01 eV above the conduction band edge of InAs at ambient pressure is presented. This assumes a pressure-dependent energy shift of −11 meV·GPa{sup −1} for the valence band edge and that the defect level is insensitive to pressure, both of which are supported by an Arrhenius activation energy analysis.

  4. Properties of galaxies at the faint end of the Hα luminosity function at z ~ 0.62

    NASA Astrophysics Data System (ADS)

    Gómez-Guijarro, Carlos; Gallego, Jesús; Villar, Víctor; Rodríguez-Muñoz, Lucía; Clément, Benjamin; Cuby, Jean-Gabriel

    2016-07-01

    Context. Studies measuring the star formation rate density, luminosity function, and properties of star-forming galaxies are numerous. However, it exists a gap at 0.5 < z < 0.8 in Hα-based studies. Aims: Our main goal is to study the properties of a sample of faint Hα emitters at z ~ 0.62. We focus on their contribution to the faint end of the luminosity function and derived star formation rate density, characterising their morphologies and basic photometric and spectroscopic properties. Methods: We use a narrow-band technique in the near-infrared, with a filter centred at 1.06 μm. The data come from ultra-deep VLT/HAWK-I observations in the GOODS-S field with a total of 31.9 h in the narrow-band filter. In addition to our survey, we mainly make use of ancillary data coming from the CANDELS and Rainbow Cosmological Surveys Database, from the 3D-HST for comparison, and also spectra from the literature. We perform a visual classification of the sample and study their morphologies from structural parameters available in CANDELS. In order to obtain the luminosity function, we apply a traditional V/Vmax method and perform individual extinction corrections for each object to accurately trace the shape of the function. Results: Our 28 Hα-selected sample of faint star-forming galaxies reveals a robust faint-end slope of the luminosity function α = - 1.46-0.08+0.16 . The derived star formation rate density at z ~ 0.62 is ρSFR = 0.036-0.008+0.012 M⊙ yr-1 Mpc-3 . The sample is mainly composed of disks, but an important contribution of compact galaxies with Sérsic indexes n ~ 2 display the highest specific star formation rates. Conclusions: The luminosity function at z ~ 0.62 from our ultra-deep data points towards a steeper α when an individual extinction correction for each object is applied. Compact galaxies are low-mass, low-luminosity, and starburst-dominated objects with a light profile in an intermediate stage from early to late types. Based on observations

  5. Freeze, flight, fight, fright, faint: adaptationist perspectives on the acute stress response spectrum.

    PubMed

    Bracha, H Stefan

    2004-09-01

    This article reviews the existing evolutionary perspectives on the acute stress response habitual faintness and blood-injection-injury type-specific phobia (BIITS phobia). In this article, an alternative evolutionary perspective, based on recent advances in evolutionary psychology, is proposed. Specifically, that fear-induced faintness (eg, fainting following the sight of a syringe, blood, or following a trivial skin injury) is a distinct Homo sapiens-specific extreme-stress survival response to an inescapable threat. The article suggests that faintness evolved in response to middle paleolithic intra-group and inter-group violence (of con-specifics) rather than as a pan-mammalian defense response, as is presently assumed. Based on recent literature, freeze, flight, fight, fright, faint provides a more complete description of the human acute stress response sequence than current descriptions. Faintness, one of three primary physiological reactions involved in BIITS phobia, is extremely rare in other phobias. Since heritability estimates are higher for faintness than for fears or phobias, the author suggests that trait-faintness may be a useful complement to trait-anxiety as an endophenotype in research on the human fear circuitry. Some implications for the forthcoming Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition as well as for clinical, health services, and transcriptomic research are briefly discussed.

  6. Investigation of Variability of Faint Galactic Early-Type Carbon Stars from the First Byurakan Spectral Sky Survey

    NASA Astrophysics Data System (ADS)

    Gigoyan, K. S.; Kostandyan, G. R.; Paronyan, G. M.

    2016-06-01

    In this poster, we discuss the nature of 66 faint carbon (C) stars which have been discovered by scrutinizing the plates of the First Byurakan Survey (FBS). These plates display low-resolution spectra of objects located at high Galactic latitudes and have a limiting magnitude of about V=16. Our sample of 66 confirmed spectroscopically to be C stars. These 66 objects are those which show early-type spectra. To better characterize these objects, medium-resolution CCD spectra were obtained and are exploited for them all, together with consideration of their 2MASS near-infrared (NIR) colors and their optical variability. We derive effective temperatures from photometry. Finally, the optical variability of our objects are studied by using the data of the Catalina Sky Survey (CSS). It is found that the vast majority does not display variability. However, for some of them, the phased light curve may indicate the presence of a secondary component.

  7. A NEW SYNTHETIC LIBRARY OF THE NEAR-INFRARED Ca II TRIPLET INDICES. I. INDEX DEFINITION, CALIBRATION, AND RELATIONS WITH STELLAR ATMOSPHERIC PARAMETERS

    SciTech Connect

    Du, W.; Luo, A. L.; Zhao, Y. H. E-mail: lal@nao.cas.cn

    2012-02-15

    Adopting the SPECTRUM package, which is a stellar spectral synthesis program, we have synthesized a comprehensive set of 2890 near-infrared (NIR) synthetic spectra with a resolution and wavelength sampling similar to the Sloan Digital Sky Survey (SDSS) and the forthcoming Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra. During the synthesis, we applied the 'New grids of ATLAS9 Model Atmosphere' to develop a grid of local thermodynamic equilibrium model atmospheres for effective temperatures (T{sub eff}) ranging from 3500 to 7500 K, for surface gravities (log g) from 0.5 to 5.0 dex, for metallicities ([Fe/H]) from -4.0 to 0.5 dex, and for solar ([{alpha}/Fe] = 0.0 dex) and non-solar ([{alpha}/Fe] = +0.4 dex) abundances. This synthetic stellar library is composed of 1350 solar scaled abundance (SSA) and 1530 non-solar scaled abundance (NSSA) spectra, grounding on which we have defined a new set of NIR Ca II triplet indices and an index CaT as the sum of the three. These defined indices were automatically measured on every spectrum of the synthetic stellar library and calibrated with the indices computed on the observational spectra from the INDO-U.S. stellar library. In order to check the effect of {alpha}-element enhancement on the so-defined Ca II indices, we compared indices measured on the SSA spectra with those on the NSSA ones at the same trine of stellar parameters (T{sub eff}, log g, [Fe/H]); luckily, little influences of {alpha}-element enhancement were found. Furthermore, comparisons of our synthetic indices with the observational ones from measurements on the INDO-U.S. stellar library, the SDSS-DR7 and SDSS-DR8 spectroscopic survey are presented, respectively, for dwarfs and giants in specific. For dwarfs, our synthetic indices could well reproduce the behaviors of the observational indices versus stellar parameters, which verifies the validity of our index definitions for dwarfs. For giants, the consistency between our synthetic

  8. SMA observations on faint submillimeter galaxies with S {sub 850} < 2 mJy: Ultra dusty low-luminosity galaxies at high redshift

    SciTech Connect

    Chen, Chian-Chou; Cowie, Lennox L.; Barger, Amy J.; Williams, Jonathan P.; Wang, Wei-Hao

    2014-07-01

    We obtained Submillimeter Array (SMA) observations of eight faint (intrinsic 850 μm fluxes < 2 mJy) submillimeter galaxies (SMGs) discovered in SCUBA images of the massive lensing cluster fields A370, A2390, and A1689 and detected five. In total, we obtain five SMA detections, all of which have de-lensed fluxes <1 mJy with estimated total infrared luminosities 10{sup 10}-10{sup 12} L {sub ☉}, comparable to luminous infrared galaxies and normal star-forming galaxies. Based on the latest number counts, these galaxies contribute ∼70% of the 850 μm extragalactic background light and represent the dominant star-forming galaxy population in the dusty universe. However, only 40{sub −16}{sup +30}% of our faint SMGs would be detected in deep optical or near-infrared surveys, which suggests many of these sources are at high redshifts (z ≳ 3) or extremely dusty, and they are not included in current star formation history estimates.

  9. Fourier transform infrared study of the cation radical of P680 in the photosystem II reaction center: evidence for charge delocalization on the chlorophyll dimer.

    PubMed

    Noguchi, T; Tomo, T; Inoue, Y

    1998-09-29

    A Fourier transform infrared (FTIR) difference spectrum of the primary electron donor (P680) of photosystem II upon its photooxidation (P680+/P680) was obtained in the frequency region of 1000-3000 cm-1. The reaction center (RC) complex (D1-D2-Cytb559) was used for the measurements in the presence of ferricyanide as an exogenous electron acceptor. Control measurements of electronic absorption (300-1200 nm) showed that illumination of the RC complex at 150 K induced major oxidation of P680 concomitant with oxidation of a carotenoid and an accessory chlorophyll (Chl). Illumination at 250 K also specifically bleached one of the two beta-carotene molecules bound to the RC complex, and the sample thus treated exhibited little formation of a carotenoid cation on subsequent illumination at 150 K. The P680+/P680 FTIR difference spectrum (with minor contamination of Chl+/Chl) was measured at 150 K using this partially carotenoid-deficient RC complex. The spectrum showed a broad positive band centered at approximately 1940 cm-1, which could be ascribed to an infrared electronic transition of P680+ analogous to that previously observed in various bacterial P+. This finding indicates that a positive charge is delocalized over (or hopping between) the two Chl molecules in P680+. The low intensity of this electronic band compared with that of the bacterial band could have three possible explanations: weak resonance interaction between the constituent Chl molecules, an asymmetric structure of P680+, and the difference in Chl species. Bands in the C=O stretching region (1600-1750 cm-1) were interpreted in comparison with resonance Raman spectra of the RC complex. The negative peaks at 1704 and 1679 cm-1 were proposed as candidates for the keto C9=O bands of P680. The observation that neither of these bands agreed with the main keto C9=O band at 1669 cm-1 in the previous 3P680/P680 FTIR spectrum [Noguchi et al. (1993) Biochemistry 32, 7186-7195] led to the idea that the triplet

  10. THE EXTENDED CHANDRA DEEP FIELD-SOUTH SURVEY: OPTICAL SPECTROSCOPY OF FAINT X-RAY SOURCES WITH THE VLT AND KECK

    SciTech Connect

    Silverman, J. D.; Mainieri, V.; Rosati, P.; Salvato, M.; Hasinger, G.; Bergeron, J.; Capak, P.; Szokoly, G.; Gilli, R.; Tozzi, P.; Vignali, C.; Alexander, D. M.; Brandt, W. N.; Luo, B.; Rafferty, D.; Xue, Y. Q.; Lehmer, B. D.; Bauer, F. E.

    2010-11-15

    We present the results of a program to acquire high-quality optical spectra of X-ray sources detected in the Extended-Chandra Deep Field-South (E-CDF-S) and its central 2 Ms area. New spectroscopic redshifts, up to z = 4, are measured for 283 counterparts to Chandra sources with deep exposures (t {approx} 2-9 hr per pointing) using multi-slit facilities on both VLT (VIMOS) and Keck (DEIMOS), thus bringing the total number of spectroscopically identified X-ray sources to over 500 in this survey field. Since our new spectroscopic identifications are mainly associated with X-ray sources in the shallower 250 ks coverage, we provide a comprehensive catalog of X-ray sources detected in the E-CDF-S including the optical and near-infrared counterparts, determined by a likelihood routine, and redshifts (both spectroscopic and photometric), that incorporate published spectroscopic catalogs, thus resulting in a final sample with a high fraction (80%) of X-ray sources having secure identifications. We demonstrate the remarkable coverage of the luminosity-redshift plane now accessible from our data while emphasizing the detection of active galactic nuclei (AGNs) that contribute to the faint end of the luminosity function (L {sub 0.5-8keV} {approx} 10{sup 43}-10{sup 44} erg s{sup -1}) at 1.5 {approx}< z {approx}< 3 including those with and without broad emission lines. Our redshift catalog includes 17 type-2 QSOs at 1 {approx}< z {approx}< 3.5 that significantly increases such samples (2x). Based on our deepest (9 hr) VLT/VIMOS observation, we identify 'elusive' optically faint galaxies (R {sub mag} {approx} 25) at z {approx} 2-3 based upon the detection of interstellar absorption lines (e.g., O II+Si IV, C II], C IV); we highlight one such case, an absorption-line galaxy at z = 3.208 having no obvious signs of an AGN in its optical spectrum. In addition, we determine accurate distances to eight galaxy groups with extended X-ray emission detected both by Chandra and XMM

  11. Serendipitous discovery of the faint solar twin Inti 1

    NASA Astrophysics Data System (ADS)

    Galarza, Jhon Yana; Meléndez, Jorge; Cohen, Judith G.

    2016-05-01

    Context. Solar twins are increasingly the subject of many studies owing to their wide range of applications from testing stellar evolution models to the calibration of fundamental observables; these stars are also of interest because high precision abundances could be achieved that are key to investigating the chemical anomalies imprinted by planet formation. Furthermore, the advent of photometric surveys with large telescopes motivates the identification of faint solar twins in order to set the zero point of fundamental calibrations. Aims: We intend to perform a detailed line-by-line differential analysis to verify whether 2MASS J23263267-0239363 (designated here as Inti 1) is indeed a solar twin. Methods: We determine the atmospheric parameters and differential abundances using high-resolution (R ≈ 50 000), high signal-to-noise (S/N ≈ 110-240 per pixel) Keck/HIRES spectra for our solar twin candidate, the previously known solar twin HD 45184, and the Sun (using reflected light from the asteroid Vesta). Results: For the bright solar twin HD 45184, we found Teff = 5864 ± 9 K, log g = 4.45 ± 0.03 dex, vt = 1.11 ± 0.02 km s-1, and [Fe/H] = 0.04 ± 0.01 dex, which are in good agreement with previous works. Our abundances are in excellent agreement with a recent high-precision work, with an element-to-element scatter of only 0.01 dex. The star Inti 1 has atmospheric parameters Teff = 5837 ± 11 K, log g = 4.42 ± 0.03 dex, vt = 1.04 ± 0.02 km s-1, and [Fe/H] = 0.07 ± 0.01 dex that are higher than solar. The age and mass of the solar twin HD 45184 (3 Gyr and 1.05 M⊙) and the faint solar twin Inti 1 (4 Gyr and 1.04 M⊙) were estimated using isochrones. The differential analysis shows that HD 45184 presents an abundance pattern that is similar to typical nearby solar twins; this means this star has an enhanced refractory relative to volatile elements, while Inti 1 has an abundance pattern closer to solar, albeit somewhat enhanced in refractories. The abundance

  12. Properties of Interstellar Medium In Infrared-bright QSOs Probed by [O i] 63 um and [C ii] 158 um Emission Lines

    NASA Astrophysics Data System (ADS)

    Zhao, Yinghe; Yan, Lin; Tsai, Chao-Wei

    2016-06-01

    We present a study of the interstellar medium (ISM) in the host galaxies of nine QSOs at 0.1 < z < 0.2 with black hole masses of 3× {10}7 {M}⊙ to 3× {10}9 {M}⊙ based on the far-IR spectroscopy taken with Herschel Space Observatory. We detect the [O i] 63 μm ([C ii] 158 μm) emission in 6 (8) out of 8 (9) sources. Our QSO sample has far-infrared luminosities ({L}{{FIR}}) ˜ several times {10}11{L}⊙ . The observed line-to-{L}{{FIR}} ratios ({L}[{{O}{{I}}]63μ {{m}}}/{L}{{FIR}} and {L}[{{C}{{II}}]}/{L}{{FIR}}) are in the ranges of 2.6 × 10-4 to 10-2 and 2.8 × 10-4 to 2 × 10-3, respectively (including upper limits). These ratios are comparable to the values found in local ULIRGs, but higher than the average value published so far for z\\gt 1 IR-bright QSOs. One target, W0752+19, shows an additional broad velocity component (˜720 km s-1) and exceptionally strong [O i] 63 μm emission with {L}[{{O}{{I}}]63μ {{m}}}/{L}{{FIR}} of 10-2, an order of magnitude higher than the average value found among local (U)LIRGs. Combining with the analyses of the Sloan Digital Sky Survey optical spectra, we conclude that the [O i] 63 μm emission in these QSOs is unlikely excited by shocks. We infer that the broad [O i] 63 μm emission in W0752+19 could arise from the warm and dense ISM in the narrow-line region of the central active galactic nucleus. Another possible explanation is the existence of a dense gas outflow with {n}{{H}}˜ {10}4 cm-3, where the corresponding broad [C ii] emission is suppressed. Based on the far-IR [O i] and [C ii] line ratios, we estimate constraints on the ISM density and UV radiation field intensity of {n}{{H}}≲ {10}3.3 cm-3 and {10}3\\lt {G}0≲ {10}4.2, respectively. These values are consistent with those found in local Seyfert 1 ULIRGs. In contrast, the gas with broad velocity width in W0752+19 has {n}{{H}}≳ {10}4.3 cm-3 and {G}0\\gt {10}4. Herschel is an ESA space observatory with science instruments provided by European-led Principal

  13. Deriving the Extinction to Young Stellar Objects using [Fe II] Near-infrared Emission Lines: Prescriptions from GIANO High-resolution Spectra

    NASA Astrophysics Data System (ADS)

    Pecchioli, T.; Sanna, N.; Massi, F.; Oliva, E.

    2016-07-01

    The near-infrared (NIR) emission lines of Fe+ at 1.257, 1.321, and 1.644 μm share the same upper level; their ratios can then be exploited to derive the extinction to a line emitting region once the relevant spontaneous emission coefficients are known. This is commonly done, normally from low-resolution spectra, in observations of shocked gas from jets driven by Young Stellar Objects. In this paper we review this method, provide the relevant equations, and test it by analyzing high-resolution (R ∼ 50,000) NIR spectra of two young stars, namely the Herbig Be star HD 200775 and the Be star V1478 Cyg, which exhibit intense emission lines. The spectra were obtained with the new GIANO echelle spectrograph at the Telescopio Nazionale Galileo. Notably, the high-resolution spectra allowed checking the effects of overlapping telluric absorption lines. A set of various determinations of the Einstein coefficients are compared to show how much the available computations affect extinction derivation. The most recently obtained values are probably good enough to allow reddening determination within 1 visual mag of accuracy. Furthermore, we show that [Fe ii] line ratios from low-resolution pure emission-line spectra in general are likely to be in error due to the impossibility to properly account for telluric absorption lines. If low-resolution spectra are used for reddening determinations, we advice that the ratio 1.644/1.257, rather than 1.644/1.321, should be used, being less affected by the effects of telluric absorption lines.

  14. A faint type of supernova from a white dwarf with a helium-rich companion.

    PubMed

    Perets, H B; Gal-Yam, A; Mazzali, P A; Arnett, D; Kagan, D; Filippenko, A V; Li, W; Arcavi, I; Cenko, S B; Fox, D B; Leonard, D C; Moon, D-S; Sand, D J; Soderberg, A M; Anderson, J P; James, P A; Foley, R J; Ganeshalingam, M; Ofek, E O; Bildsten, L; Nelemans, G; Shen, K J; Weinberg, N N; Metzger, B D; Piro, A L; Quataert, E; Kiewe, M; Poznanski, D

    2010-05-20

    Supernovae are thought to arise from two different physical processes. The cores of massive, short-lived stars undergo gravitational core collapse and typically eject a few solar masses during their explosion. These are thought to appear as type Ib/c and type II supernovae, and are associated with young stellar populations. In contrast, the thermonuclear detonation of a carbon-oxygen white dwarf, whose mass approaches the Chandrasekhar limit, is thought to produce type Ia supernovae. Such supernovae are observed in both young and old stellar environments. Here we report a faint type Ib supernova, SN 2005E, in the halo of the nearby isolated galaxy, NGC 1032. The 'old' environment near the supernova location, and the very low derived ejected mass ( approximately 0.3 solar masses), argue strongly against a core-collapse origin. Spectroscopic observations and analysis reveal high ejecta velocities, dominated by helium-burning products, probably excluding this as a subluminous or a regular type Ia supernova. We conclude that it arises from a low-mass, old progenitor, likely to have been a helium-accreting white dwarf in a binary. The ejecta contain more calcium than observed in other types of supernovae and probably large amounts of radioactive (44)Ti.

  15. Abundance ratios of red giants in low-mass ultra-faint dwarf spheroidal galaxies

    NASA Astrophysics Data System (ADS)

    François, P.; Monaco, L.; Bonifacio, P.; Moni Bidin, C.; Geisler, D.; Sbordone, L.

    2016-04-01

    Context. Low-mass dwarf spheroidal galaxies are key objects for our understanding of the chemical evolution of the pristine Universe and the Local Group of galaxies. Abundance ratios in stars of these objects can be used to better understand their star formation and chemical evolution. Aims: We report on the analysis of a sample of 11 stars belonging to five different ultra-faint dwarf spheroidal galaxies (UfDSph) that is based on X-Shooter spectra obtained at the VLT. Methods: Medium-resolution spectra have been used to determine the detailed chemical composition of their atmosphere. We performed a standard 1D LTE analysis to compute the abundances. Results: Considering all the stars as representative of the same population of low-mass galaxies, we found that the [α/Fe] ratios vs.s [Fe/H] decreases as the metallicity of the star increases in a way similar to that which is found for the population of stars that belong to dwarf spheroidal galaxies. The main difference is that the solar [α/Fe] is reached at a much lower metallicity for the UfDSph than for the dwarf spheroidal galaxies. We report for the first time the abundance of strontium in CVn II. The star we analyzed in this galaxy has a very high [Sr/Fe] and a very low upper limit of barium which makes it a star with an exceptionally high [Sr/Ba] ratio.

  16. STAR FORMATION IN ULTRA-FAINT DWARFS: CONTINUOUS OR SINGLE-AGE BURSTS?

    SciTech Connect

    Webster, David; Bland-Hawthorn, Joss; Sutherland, Ralph

    2015-01-30

    We model the chemical evolution of six ultra-faint dwarfs (UFDs): Bootes I, Canes Venatici II, Coma Berenices, Hercules, Leo IV, and Ursa Major I based on their recently determined star formation histories. We show that two single-age bursts cannot explain the observed [α/Fe] versus [Fe/H] distribution in these galaxies and that some self-enrichment is required within the first burst. An alternative scenario is modeled, in which star formation is continuous except for short interruptions when one or more supernovae temporarily blow the dense gas out from the center of the system. This model allows for self-enrichment and can reproduce the chemical abundances of the UFDs in which the second burst is only a trace population. We conclude that the most likely star formation history is one or two extended periods of star formation, with the first burst lasting for at least 100 Myr. As found in earlier work, the observed properties of UFDs can be explained by formation at a low mass (M{sub vir}∼10{sup 7} M{sub ⊙}), rather than being stripped remnants of much larger systems.

  17. The quenching of the ultra-faint dwarf galaxies in the reionization era

    SciTech Connect

    Brown, Thomas M.; Tumlinson, Jason; Kalirai, Jason S.; Avila, Roberto J.; Gennaro, Mario; Ferguson, Henry C. E-mail: tumlinson@stsci.edu E-mail: avila@stsci.edu E-mail: gennaro@stsci.edu; and others

    2014-12-01

    We present new constraints on the star formation histories of six ultra-faint dwarf galaxies: Bootes I, Canes Venatici II, Coma Berenices, Hercules, Leo IV, and Ursa Major I. Our analysis employs a combination of high-precision photometry obtained with the Advanced Camera for Surveys on the Hubble Space Telescope, medium-resolution spectroscopy obtained with the DEep Imaging Multi-Object Spectrograph on the W. M. Keck Observatory, and updated Victoria-Regina isochrones tailored to the abundance patterns appropriate for these galaxies. The data for five of these Milky Way satellites are best fit by a star formation history where at least 75% of the stars formed by z ∼ 10 (13.3 Gyr ago). All of the galaxies are consistent with 80% of the stars forming by z ∼ 6 (12.8 Gyr ago) and 100% of the stars forming by z ∼ 3 (11.6 Gyr ago). The similarly ancient populations of these galaxies support the hypothesis that star formation in the smallest dark-matter sub-halos was suppressed by a global outside influence, such as the reionization of the universe.

  18. Discovery of a faint, star-forming, multiply lensed, Lyman-α blob

    NASA Astrophysics Data System (ADS)

    Caminha, G. B.; Karman, W.; Rosati, P.; Caputi, K. I.; Arrigoni Battaia, F.; Balestra, I.; Grillo, C.; Mercurio, A.; Nonino, M.; Vanzella, E.

    2016-11-01

    We report the discovery of a multiply lensed Lyman-α blob (LAB) behind the galaxy cluster AS1063 using the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT). The background source is at z = 3.117 and is intrinsically faint compared to almost all previously reported LABs. We used our highly precise strong lensing model to reconstruct the source properties, and we find an intrinsic luminosity of LLyα = 1.9 × 1042 erg s-1, extending to 33 kpc. We find that the LAB is associated with a group of galaxies, and possibly a protocluster, in agreement with previous studies that find LABs in overdensities. In addition to Lyman-α (Lyα) emission, we find C iv, He ii, and O iii] ultraviolet (UV) emission lines arising from the centre of the nebula. We used the compactness of these lines in combination with the line ratios to conclude that the Lyα nebula is likely powered by embedded star formation. Resonant scattering of the Lyα photons then produces the extended shape of the emission. Thanks to the combined power of MUSE and strong gravitational lensing, we are now able to probe the circumgalatic medium of sub-L∗ galaxies at z ≈ 3.

  19. First results from the Faint Object Camera - Imaging the core of R Aquarii

    NASA Technical Reports Server (NTRS)

    Paresce, F.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.

    1991-01-01

    The Faint Object Camera on the HST was pointed toward the symbiotic long-period M7e Mira variable R Aquarii, and very high resolution images of the inner core, mainly in the ionized oxygen emission lines in the optical, are reported. Both images show bright arcs, knots, and filaments superposed on a fainter, diffuse nebulosity extending in a general SW-NE direction from the variable to the edge of the field at 10 arcsec distance. The core is resolved in forbidden O III 5007 A and forbidden O II 3727 A into at least two bright knots of emission whose positions and structures are aligned with PA = 50 deg. The central knots appear to be the source of a continuous, well-collimated, stream of material extending out to 3-4 arcsec in the northern sector corresponding to a linear distance of about 1000 AU. The northern stream seems to bend around an opaque obstacle and form a spiral before breaking up into wisps and knots. The southern stream is composed of smaller, discrete parcels of emitting gas curving to the SE.

  20. THE PRIMEVAL POPULATIONS OF THE ULTRA-FAINT DWARF GALAXIES

    SciTech Connect

    Brown, Thomas M.; Tumlinson, Jason; Kalirai, Jason S.; Avila, Roberto J.; Ferguson, Henry C. E-mail: tumlinson@stsci.edu E-mail: avila@stsci.edu; and others

    2012-07-01

    We present new constraints on the star formation histories of the ultra-faint dwarf (UFD) galaxies, using deep photometry obtained with the Hubble Space Telescope (HST). A galaxy class recently discovered in the Sloan Digital Sky Survey, the UFDs appear to be an extension of the classical dwarf spheroidals to low luminosities, offering a new front in efforts to understand the missing satellite problem. They are the least luminous, most dark-matter-dominated, and least chemically evolved galaxies known. Our HST survey of six UFDs seeks to determine if these galaxies are true fossils from the early universe. We present here the preliminary analysis of three UFD galaxies: Hercules, Leo IV, and Ursa Major I. Classical dwarf spheroidals of the Local Group exhibit extended star formation histories, but these three Milky Way satellites are at least as old as the ancient globular cluster M92, with no evidence for intermediate-age populations. Their ages also appear to be synchronized to within {approx}1 Gyr of each other, as might be expected if their star formation was truncated by a global event, such as reionization.

  1. Carbon Dioxide Cycling, Climate, Impacts, and the Faint Young Sun

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.; Sleep, H. H.

    1999-01-01

    Evidence for relatively mild climates on ancient Earth and Mars has been a puzzle in light of the faint early sun. The geologic evidence, although far from conclusive, would appear to indicate that the surfaces of both planets were, if anything, warmer ca. 3-4 Ga than they are now. The astrophysical argument that the sun ought to have brightened approx. 30% since it reached the main sequence is hard to refute. There results a paradox between the icehouse we expect and the greenhouse we think we see. The usual fix has been to posit massive CO2 atmospheres, although reduced gases (e.g., NH3 or CH4 ) have had their partisans. Evidence against siderite in paleosols dated 2.2-2.75 Ga sets a rough upper limit of 30 PAL (present atmospheric levels) on pCO2 at that time. This is an order of magnitude short of what is needed to defeat the fainter sun. We present here an independent argument against high pCO2 on early Earth that applies not only to the Archean but yet more forcefully to the Hadean era. Additional information is contained in the original extended abstract.

  2. SUPERNOVA 2003ie WAS LIKELY A FAINT TYPE IIP EVENT

    SciTech Connect

    Arcavi, Iair; Gal-Yam, Avishay; Sergeev, Sergey G.

    2013-04-15

    We present new photometric observations of supernova (SN) 2003ie starting one month before discovery, obtained serendipitously while observing its host galaxy. With only a weak upper limit derived on the mass of its progenitor (<25 M{sub Sun }) from previous pre-explosion studies, this event could be a potential exception to the ''red supergiant (RSG) problem'' (the lack of high-mass RSGs exploding as Type IIP SNe). However, this is true only if SN2003ie was a Type IIP event, something which has never been determined. Using recently derived core-collapse SN light-curve templates, as well as by comparison to other known SNe, we find that SN2003ie was indeed a likely Type IIP event. However, with a plateau magnitude of {approx} - 15.5 mag, it is found to be a member of the faint Type IIP class. Previous members of this class have been shown to arise from relatively low-mass progenitors (<12 M{sub Sun }). It therefore seems unlikely that this SN had a massive RSG progenitor. The use of core-collapse SN light-curve templates is shown to be helpful in classifying SNe with sparse coverage. These templates are likely to become more robust as large homogeneous samples of core-collapse events are collected.

  3. Serendipitous ALMA detections of faint submm galaxies in SERVS

    NASA Astrophysics Data System (ADS)

    Patil, Pallavi; Lacy, Mark; Nyland, Kristina

    2017-01-01

    We present a preliminary ALMA study of faint (<1mJy) submm galaxies with counterparts in the Spitzer Extragalactic Representative Volume Survey (SERVS). SERVS provides post-cryogenic IRAC imaging at 3.6 and 4.5 microns over an 18 deg2 area of the sky over five famous deep fields. The depth of the survey is ~ 2 µJy, and it provides a complete census of galaxies up to z ~ 5. While it is known that bright submm galaxies are associated with dusty, ultra-luminous starforming galaxies at z ~ 2, the sub-mJy population is still not well understood. A key missing piece of information is their morphologies at rest-frame optical wavelengths, which for high-redshift submm galaxies is only accessible through ALMA observations. The high sensitivity, spatial resolution, and positional accuracy of ALMA have enabled us to probe the nature of the sub-mJy population by resolving their spatial extents and improving constraints on their SEDS and photometric redshifts. We are building a catalog of sources by searching the ALMA archive for moderate to deep observations in the area covered by SERVS. This study will help us begin to understand the contribution of obscured star formation to the total star formation rate at high redshift and guide future wide-area surveys of submm galaxies with ALMA.

  4. Luminosity Function of Faint Globular Clusters in M87

    SciTech Connect

    Waters, Christopher Z.; Zepf, Stephen E.; Lauer, Tod R.; Baltz, Edward A.; Silk, Joseph; /Oxford U.

    2006-07-14

    We present the luminosity function to very faint magnitudes for the globular clusters in M87, based on a 30 orbit Hubble Space Telescope (HST) WFPC2 imaging program. The very deep images and corresponding improved false source rejection allow us to probe the mass function further beyond the turnover than has been done before. We compare our luminosity function to those that have been observed in the past, and confirm the similarity of the turnover luminosity between M87 and the Milky Way. We also find with high statistical significance that the M87 luminosity function is broader than that of the Milky Way. We discuss how determining the mass function of the cluster system to low masses can constrain theoretical models of the dynamical evolution of globular cluster systems. Our mass function is consistent with the dependence of mass loss on the initial cluster mass given by classical evaporation, and somewhat inconsistent with newer proposals that have a shallower mass dependence. In addition, the rate of mass loss is consistent with standard evaporation models, and not with the much higher rates proposed by some recent studies of very young cluster systems. We also find that the mass-size relation has very little slope, indicating that there is almost no increase in the size of a cluster with increasing mass.

  5. Near-infrared to near-infrared upconverting NaYF4:Yb3+,Tm3+ nanoparticles-aptamer-Au nanorods light resonance energy transfer system for the detection of mercuric(II) ions in solution.

    PubMed

    Chen, Hong-Qi; Yuan, Fei; Wang, Shao-Zhen; Xu, Juan; Zhang, Yi-Yan; Wang, Lun

    2013-04-21

    A new luminescence resonant energy transfer (LRET) system has been designed that utilizes near-infrared (NIR)-to-NIR upconversion lanthanide nanophosphors (UCNPs) as the donor, and Au nanorods (Au NRs) as the acceptor. The UCNPs were excited by a near-infrared (980 nm) wavelength and also emitted at a near-infrared wavelength (804 nm) using an inexpensive infrared continuous wave laser diode. The Au NRs showed a high absorption band around 806 nm, which provided large spectral overlap between the donor and the acceptor. Hg(2+) ions were added to an aqueous solution containing the UCNPs and Au NRs that were modified with a Hg(2+) aptamer. Then, a sandwich-type LRET system was developed for the detection of Hg(2+) ions that had high sensitivity and selectivity in the NIR region. The method was successfully applied to the sensing of Hg(2+) ions in water and human serum samples.

  6. A Deeper Look at Faint Hα Emission in Nearby Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Lee, Janice C.; Veilleux, Sylvain; McDonald, Michael; Hilbert, Bryan

    2016-02-01

    We present deep Hα imaging of three nearby dwarf galaxies, carefully selected to optimize observations with the Maryland-Magellan Tunable Filter (MMTF) on the Magellan 6.5 m telescope. An effective bandpass of ˜13 Å is used, and the images reach 3σ flux limits of ˜8 × 10-18 erg s-1 cm-2, which is about an order of magnitude lower than standard narrowband observations obtained by the most recent generation of local Hα galaxy surveys. The observations were originally motivated by the finding that the Hα/FUV flux ratio of galaxies systematically declines as global galactic properties such as the star formation rate (SFR) and stellar mass decrease. The three dwarf galaxies selected for study have SFRs that, when calculated from their Hα luminosities using standard conversion recipes, are ˜50% of those based on the FUV. Follow-up studies of many of the potential causes for the trends in the Hα/FUV flux ratio have been performed, but the possibility that previous observations have missed a non-negligible fraction of faint ionized emission in dwarf galaxies has not been investigated. The MMTF observations reveal both diffuse and structured Hα emission (filaments, shells, possible single-star H ii regions) spanning extents up to 2.5 times larger relative to previous observations. However, only up to an additional ˜5% of Hα flux is captured, which does not account for the trends in the Hα/FUV ratio. Beyond investigation of the Hα/FUV ratio, the impact of the newly detected extended flux on our understanding of star formation, the properties of H ii regions, and the propagation of ionizing photons warrant further investigation.

  7. THE DISTRIBUTION OF ALPHA ELEMENTS IN ULTRA-FAINT DWARF GALAXIES

    SciTech Connect

    Vargas, Luis C.; Geha, Marla; Kirby, Evan N.; Simon, Joshua D.

    2013-04-20

    The Milky Way ultra-faint dwarf (UFD) galaxies contain some of the oldest, most metal-poor stars in the universe. We present [Mg/Fe], [Si/Fe], [Ca/Fe], [Ti/Fe], and mean [{alpha}/Fe] abundance ratios for 61 individual red giant branch stars across eight UFDs. This is the largest sample of alpha abundances published to date in galaxies with absolute magnitudes M{sub V} > -8, including the first measurements for Segue 1, Canes Venatici II, Ursa Major I, and Leo T. Abundances were determined via medium-resolution Keck/DEIMOS spectroscopy and spectral synthesis. The sample spans the metallicity range -3.4 <[Fe/H] < -1.1. With the possible exception of Segue 1 and Ursa Major II, the individual UFDs show on average lower [{alpha}/Fe] at higher metallicities, consistent with enrichment from Type Ia supernovae. Thus, even the faintest galaxies have undergone at least a limited level of chemical self-enrichment. Together with recent photometric studies, this suggests that star formation in the UFDs was not a single burst, but instead lasted at least as much as the minimum time delay of the onset of Type Ia supernovae ({approx}100 Myr) and less than {approx}2 Gyr. We further show that the combined population of UFDs has an [{alpha}/Fe] abundance pattern that is inconsistent with a flat, Galactic halo-like alpha abundance trend, and is also qualitatively different from that of the more luminous CVn I dSph, which does show a hint of a plateau at very low [Fe/H].

  8. A DEEPER LOOK AT FAINT Hα EMISSION IN NEARBY DWARF GALAXIES

    SciTech Connect

    Lee, Janice C.; Hilbert, Bryan; Veilleux, Sylvain; McDonald, Michael

    2016-02-01

    We present deep Hα imaging of three nearby dwarf galaxies, carefully selected to optimize observations with the Maryland-Magellan Tunable Filter (MMTF) on the Magellan 6.5 m telescope. An effective bandpass of ∼13 Å is used, and the images reach 3σ flux limits of ∼8 × 10{sup −18} erg s{sup −1} cm{sup −2}, which is about an order of magnitude lower than standard narrowband observations obtained by the most recent generation of local Hα galaxy surveys. The observations were originally motivated by the finding that the Hα/FUV flux ratio of galaxies systematically declines as global galactic properties such as the star formation rate (SFR) and stellar mass decrease. The three dwarf galaxies selected for study have SFRs that, when calculated from their Hα luminosities using standard conversion recipes, are ∼50% of those based on the FUV. Follow-up studies of many of the potential causes for the trends in the Hα/FUV flux ratio have been performed, but the possibility that previous observations have missed a non-negligible fraction of faint ionized emission in dwarf galaxies has not been investigated. The MMTF observations reveal both diffuse and structured Hα emission (filaments, shells, possible single-star H ii regions) spanning extents up to 2.5 times larger relative to previous observations. However, only up to an additional ∼5% of Hα flux is captured, which does not account for the trends in the Hα/FUV ratio. Beyond investigation of the Hα/FUV ratio, the impact of the newly detected extended flux on our understanding of star formation, the properties of H ii regions, and the propagation of ionizing photons warrant further investigation.

  9. The Distribution of Alpha Elements in Ultra-faint Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Vargas, Luis C.; Geha, Marla; Kirby, Evan N.; Simon, Joshua D.

    2013-04-01

    The Milky Way ultra-faint dwarf (UFD) galaxies contain some of the oldest, most metal-poor stars in the universe. We present [Mg/Fe], [Si/Fe], [Ca/Fe], [Ti/Fe], and mean [α/Fe] abundance ratios for 61 individual red giant branch stars across eight UFDs. This is the largest sample of alpha abundances published to date in galaxies with absolute magnitudes MV > -8, including the first measurements for Segue 1, Canes Venatici II, Ursa Major I, and Leo T. Abundances were determined via medium-resolution Keck/DEIMOS spectroscopy and spectral synthesis. The sample spans the metallicity range -3.4 <[Fe/H] < -1.1. With the possible exception of Segue 1 and Ursa Major II, the individual UFDs show on average lower [α/Fe] at higher metallicities, consistent with enrichment from Type Ia supernovae. Thus, even the faintest galaxies have undergone at least a limited level of chemical self-enrichment. Together with recent photometric studies, this suggests that star formation in the UFDs was not a single burst, but instead lasted at least as much as the minimum time delay of the onset of Type Ia supernovae (~100 Myr) and less than ~2 Gyr. We further show that the combined population of UFDs has an [α/Fe] abundance pattern that is inconsistent with a flat, Galactic halo-like alpha abundance trend, and is also qualitatively different from that of the more luminous CVn I dSph, which does show a hint of a plateau at very low [Fe/H].

  10. DISCOVERY AND CHARACTERIZATION OF A FAINT STELLAR COMPANION TO THE A3V STAR zeta VIRGINIS

    SciTech Connect

    Hinkley, Sasha; Hillenbrand, Lynne; Oppenheimer, Ben R.; Brenner, Douglas; Zimmerman, Neil; Sivaramakrishnan, Anand; Roberts, Lewis C.; Roberts, Jennifer E.; Burruss, Rick; Shao, Michael; Vasisht, Gautam; Parry, Ian R.; King, David L.; Soummer, Remi; Simon, Michal; Perrin, Marshall D.; Lloyd, James P.; Bouchez, Antonin; Dekany, Richard; Beichman, Charles

    2010-03-20

    Through the combination of high-order adaptive optics and coronagraphy, we report the discovery of a faint stellar companion to the A3V star zeta Virginis. This companion is {approx}7 mag fainter than its host star in the H band, and infrared imaging spanning 4.75 years over five epochs indicates this companion has common proper motion with its host star. Using evolutionary models, we estimate its mass to be 0.168{sup +0.012}{sub -0.016} M{sub sun}, giving a mass ratio for this system q = 0.082{sup +0.007}{sub -0.008}. Assuming the two objects are coeval, this mass suggests an M4V-M7V spectral type for the companion, which is confirmed through {integral} field spectroscopic measurements. We see clear evidence for orbital motion from this companion and are able to constrain the semimajor axis to be {approx}>24.9 AU, the period {approx}>124 yr, and eccentricity {approx}>0.16. Multiplicity studies of higher mass stars are relatively rare, and binary companions such as this one at the extreme low end of the mass ratio distribution are useful additions to surveys incomplete at such a low mass ratio. Moreover, the frequency of binary companions can help to discriminate between binary formation scenarios that predict an abundance of low-mass companions forming from the early fragmentation of a massive circumstellar disk. A system such as this may provide insight into the anomalous X-ray emission from A stars, hypothesized to be from unseen late-type stellar companions. Indeed, we calculate that the presence of this M-dwarf companion easily accounts for the X-ray emission from this star detected by ROSAT.

  11. Multi-spectral Infrared Photodetectors and Focal Plane Arrays based on Band-engineered Type-II Indium-Arsenic / Gallium-Antimony Superlattices and its Variants

    NASA Astrophysics Data System (ADS)

    Huang, Edward Kwei-wei

    Type-II InAs/GaSb superlattices (T2SLs) is a quantum system that has recently garnered much attention for high performance infrared applications. Superlattices can be considered as an artificial bulk material with alternating heterojunctions at the atomic scale where electrons and holes are spatially separated into the InAs and GaSb wells respectively. The effective bandgaps are tailorable from 40meV to 400meV, making it highly suitable for imaging multiple wavebands in the infrared. With a high electron effective mass and energy bands that can also be optimized for the suppression of Auger recombination, T2SLs has drawn considerable interest in recent years and proves to be a prime candidate for third generation imaging. The general principles presented here are powerful and illustrate the flexibility of the T2SL system. The trends seen in the LWIR have also been applied to the MWIR regime resulting in impressive electrical performances at high operating temperatures. Combined with high quantum efficiencies typical of the T2SL material system, both the MWIR and LWIR detectors have reached 300K background-limited performances as demonstrated in this work. The bulk material improvements witnessed, however, make the manufacturability of the T2SL system more challenging, particularly in the aspect of mesa delineation. As the bulk material resistance is elevated, the delineated surface can become the path of least resistance and the result can be detrimental as semiconductor surfaces have been known to be a source of excess noise that could ultimately limit the detector's signal resolution. The difficulty of the problem is compounded by the fact that plasma etched diodes, where high energy ions are driven by an electric field toward the semiconductor to create anisotropic profiles, have been empirically evidenced to generate surface traps. Inductively coupled plasma etching techniques have been investigated in this work. This investigation found that the superlattice

  12. Chemical enrichment in Ultra-Faint Dwarf galaxies

    NASA Astrophysics Data System (ADS)

    Romano, Donatella

    2015-08-01

    The origin and evolution of galaxies is one of the great outstanding problems of astrophysics. The elusive, basic processes that govern galaxy formation can be advantageously studied in the simplest structures found orbiting the Milky Way, namely, the newly discovered Ultra-Faint Dwarf (UFD) galaxies. These low luminosity objects are the most dark matter-dominated galaxies known and likely the relics of the complex assembly processes that shaped the Galaxy over a Hubble time. They formed stars long (~12 Gyr) ago and have been quiescent ever since. Their present-day stellar masses are comparable to those of typical Milky Way globular clusters (GCs) but, at variance with GCs, they have large [Fe/H] spreads and average metallicities lower than those of the most metal-poor GCs, which clearly indicates they followed distinct evolutionary paths. The abundance ratios [α/Fe] measured in a few UFD giant stars closely resemble those of similarly metal-poor Galactic halo stars, suggesting that chemical evolution proceeded similarly in different systems at the earliest times. Despite their simplicity, a number of questions remain unanswered with regards to these systems: did they suffer 'one-shot' or extended star formation? what is the level and significance of chemical inhomogeneity inside these systems? was stellar feedback effective in removing all the gas left over from the star formation process, or did the interaction with the environment play a major role? In this contribution we discuss these issues basing on results we got from pure chemical evolution models, as well as three-dimensional hydrodynamical simulations run at subparsec resolution.

  13. Kinematics and chemistry of faint high latitude dwarf carbon stars

    NASA Astrophysics Data System (ADS)

    Yoon, Jinmi; Beers, Timothy C.; Dietz, Sarah; Lee, Young Sun; Placco, Vinicius M.

    2017-01-01

    The diffuse halo system of the Milky Way is complex, and has been shown to comprise at least two main components: a near-zero net rotation inner-halo and a more rapidly rotating outer-halo component. Studies of the ancient, very metal-poor stars in the Galactic halo system are crucial for understanding its early formation history. The so-called carbon-enhanced metal-poor (CEMP) stars are an important subset of the stars in the halo system, which exhibit distinctive kinematic and chemical signatures that can be used to constrain the star-formation histories and assembly of the various Galactic components.We have examined the sample of main-sequence dwarf and other faint high Galactic latitude carbon-enhanced stars from the Sloan Digital Sky Survey studied by Green (2013). As noted by Green, many of these starsexhibit high proper motions, which have been later claimed to be related to possible binary ejection models Plant et al. (2016). By use of the CEMP sub-classification approach of Yoon et al. (2016), we investigate whether the kinematics of these stars might instead result from their membership in the inner/outer halo populations of the Galaxy.ReferencesGreen, P. 2013, ApJ, 765, 12Plant, K. et al. 2016, AAS 227.34115Yoon, J. et al. 2016, ApJ, in pressAcknowledgementThis work was supported in part by the National Science Foundation under Grant No. PHY-1430152 (JINA Center for the Evolution of the Elements).

  14. On The Nature of Faint Galaxies with Strong UV Excess

    NASA Astrophysics Data System (ADS)

    Cruzen, S.; Weistrop, D.; Angione, R.

    1993-05-01

    Four faint galaxies identified in the Case Low-Dispersion Northern Sky Survey (Stephenson, Pesch, MacConnell 1992,ApJSS,82,471) show unusually strong UV excess in their objective prism spectra. We are currently investigating the nature of these galaxies (CG 1280, CG 1293, CG 1298, CG 1331). The preliminary results from the analysis of the spectra for galaxies CG 1293 (R.A.=15(h}22({m}00^{s)) .0, Decl.=+30deg 29(') .7 [1950]) and CG 1331 (R.A.=15(h}54({m}41^{s)) .9, Decl.=+29deg 57(') .4 [1950]) are presented. Stephenson, Pesch and MacConnell report that both galaxies have blue magnitudes of approximately 17. We obtained observations of these objects on 1992 July 2 and 3 with the CCD spectrograph on the 40-inch telescope at Mount Laguna Observatory. This CCD has an 800 x 800 format and covers an approximate wavelength range of 4000 Angstroms to 7000 Angstroms. Our analysis of the spectra reveals strong Hα emission with broad line profiles characteristic of Seyfert 1 galaxies. The spectrum of CG 1293 indicates a redshift of z = 0.1255 0.0003 and an Hα emission line width of 4180 km/sec (FWHM). The [SII] pair lambda 6717 and lambda 6731 have also been identified. We have determined a preliminary redshift for CG 1331 of z = 0.089 +/- 0.004. The Hα emission line width for CG 1331 is 7350 km/sec (FWHM). Lines corresponding to Hβ and Hγ have also been identified. This research has been supported in part by NASA through the Nevada Space Grant Consortium.

  15. Faint Object Camera imaging and spectroscopy of NGC 4151

    NASA Technical Reports Server (NTRS)

    Boksenberg, A.; Catchpole, R. M.; Macchetto, F.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Crane, P.; Deharveng, J. M.; Disney, M. J.; Jakobsen, P.

    1995-01-01

    We describe ultraviolet and optical imaging and spectroscopy within the central few arcseconds of the Seyfert galaxy NGC 4151, obtained with the Faint Object Camera on the Hubble Space Telescope. A narrowband image including (O III) lambda(5007) shows a bright nucleus centered on a complex biconical structure having apparent opening angle approximately 65 deg and axis at a position angle along 65 deg-245 deg; images in bands including Lyman-alpha and C IV lambda(1550) and in the optical continuum near 5500 A, show only the bright nucleus. In an off-nuclear optical long-slit spectrum we find a high and a low radial velocity component within the narrow emission lines. We identify the low-velocity component with the bright, extended, knotty structure within the cones, and the high-velocity component with more confined diffuse emission. Also present are strong continuum emission and broad Balmer emission line components, which we attribute to the extended point spread function arising from the intense nuclear emission. Adopting the geometry pointed out by Pedlar et al. (1993) to explain the observed misalignment of the radio jets and the main optical structure we model an ionizing radiation bicone, originating within a galactic disk, with apex at the active nucleus and axis centered on the extended radio jets. We confirm that through density bounding the gross spatial structure of the emission line region can be reproduced with a wide opening angle that includes the line of sight, consistent with the presence of a simple opaque torus allowing direct view of the nucleus. In particular, our modelling reproduces the observed decrease in position angle with distance from the nucleus, progressing initially from the direction of the extended radio jet, through our optical structure, and on to the extended narrow-line region. We explore the kinematics of the narrow-line low- and high-velocity components on the basis of our spectroscopy and adopted model structure.

  16. Astrometric observations of the faint outer satellites of Jupiter during the 1993 opposition

    NASA Technical Reports Server (NTRS)

    Shelus, Peter J.; Whipple, Arthur L.; Benedict, G. F.

    1993-01-01

    Astrometric positions for the faint outer Jovian satellites VI-XIII during the 1993 opposition have been obtained from the measurement of plates taken with the 2.1 m Otto Struve reflector at McDonald Observatory.

  17. Infrared Investigations.

    ERIC Educational Resources Information Center

    Lascours, Jean; Albe, Virginie

    2001-01-01

    Describes a series of simple and nontraditional experiments that enable students to discover the properties of infrared radiation by studying the propagation, reflection, diffusion, and refraction of infrared. The experiments rely on two modules, an infrared transmitter and an infrared receiver. (SAH)

  18. Spitzer ultra faint survey program (surfs up). I. An overview

    SciTech Connect

    Bradač, Maruša; Huang, Kuang-Han; Cain, Benjamin; Hall, Nicholas; Lubin, Lori; Ryan, Russell; Casertano, Stefano; Lemaux, Brian C.; Schrabback, Tim; Hildebrandt, Hendrik; Gonzalez, Anthony H.; Allen, Steve; Von der Linden, Anja; Gladders, Mike; Hinz, Joannah; Zaritsky, Dennis; Treu, Tommaso

    2014-04-20

    Spitzer UltRa Faint SUrvey Program is a joint Spitzer and Hubble Space Telescope Exploration Science program using 10 galaxy clusters as cosmic telescopes to study z ≳ 7 galaxies at intrinsically lower luminosities, enabled by gravitational lensing, than blank field surveys of the same exposure time. Our main goal is to measure stellar masses and ages of these galaxies, which are the most likely sources of the ionizing photons that drive reionization. Accurate knowledge of the star formation density and star formation history at this epoch is necessary to determine whether these galaxies indeed reionized the universe. Determination of the stellar masses and ages requires measuring rest-frame optical light, which only Spitzer can probe for sources at z ≳ 7, for a large enough sample of typical galaxies. Our program consists of 550 hr of Spitzer/IRAC imaging covering 10 galaxy clusters with very well-known mass distributions, making them extremely precise cosmic telescopes. We combine our data with archival observations to obtain mosaics with ∼30 hr exposure time in both 3.6 μm and 4.5 μm in the central 4' × 4' field and ∼15 hr in the flanking fields. This results in 3σ sensitivity limits of ∼26.6 and ∼26.2 AB magnitudes for the central field in the IRAC 3.6 and 4.5 μm bands, respectively. To illustrate the survey strategy and characteristics we introduce the sample, present the details of the data reduction and demonstrate that these data are sufficient for in-depth studies of z ≳ 7 sources (using a z = 9.5 galaxy behind MACS J1149.5+2223 as an example). For the first cluster of the survey (the Bullet Cluster) we have released all high-level data mosaics and IRAC empirical point-spread function models. In the future we plan to release these data products for the entire survey.

  19. Near-infrared-emitting phthalocyanines. A combined experimental and density functional theory study of the structural, optical, and photophysical properties of Pd(II) and Pt(II) α-butoxyphthalocyanines.

    PubMed

    Soldatova, Alexandra V; Kim, Junhwan; Rizzoli, Corrado; Kenney, Malcolm E; Rodgers, Michael A J; Rosa, Angela; Ricciardi, Giampaolo

    2011-02-07

    The structural, optical, and photophysical properties of 1,4,8,11,15,18,22,25-octabutoxyphthalocyaninato-palladium(II), PdPc(OBu)(8), and the newly synthesized platinum analogue PtPc(OBu)(8) are investigated combining X-ray crystallography, static and transient absorption spectroscopy, and relativistic zeroth-order regular approximation (ZORA) Density Functional Theory (DFT)/Time Dependent DFT (TDDFT) calculations where spin-orbit coupling (SOC) effects are explicitly considered. The results are compared to those previously reported for NiPc(OBu)(8) (J. Phys. Chem. A 2005, 109, 2078) in an effort to highlight the effect of the central metal on the structural and photophysical properties of the group 10 transition metal octabutoxyphthalocyanines. Different from the nickel analogue, PdPc(OBu)(8) and PtPc(OBu)(8) show a modest and irregular saddling distortion of the macrocycle, but share with the first member of the group similar UV-vis spectra, with the deep red and intense Q-band absorption experiencing a blue shift down the group, as observed in virtually all tetrapyrrolic complexes of this triad. The blue shift of the Q-band along the MPc(OBu)(8) (M = Ni, Pd, Pt) series is interpreted on the basis of the metal-induced electronic structure changes. Besides the intense deep red absorption, the title complexes exhibit a distinct near-infrared (NIR) absorption due to a transition to the double-group 1E (π,π*) state, which is dominated by the lowest single-group (3)E (π,π*) state. Unlike NiPc(OBu)(8), which is nonluminescent, PdPc(OBu)(8) and PtPc(OBu)(8) show both deep red fluorescence emission and NIR phosphorescence emission. Transient absorption experiments and relativistic spin-orbit TDDFT calculations consistently indicate that fluorescence and phosphorescence emissions occur from the S(1)(π,π*) and T(1)(π,π*) states, respectively, the latter being directly populated from the former, and the triplet state decays directly to the S(0) surface (the triplet

  20. First results from the faint object camera - High-resolution observations of the central object R136 in the 30 Doradus nebula

    NASA Technical Reports Server (NTRS)

    Weigelt, G.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.; Crane, P.; Deharveng, J. M.; Disney, M. J.; Jakobsen, P.; Kamperman, T. M.

    1991-01-01

    R136 is the luminous central object of the giant H II region 30 Doradus in the LMC. The first high-resolution observations of R136 with the Faint Object Camera on board the Hubble Space Telescope are reported. The physical nature of the brightest component R136a has been a matter of some controversy over the last few years. The UV images obtained show that R136a is a very compact star cluster consisting of more than eight stars within 0.7 arcsec diameter. From these high-resolution images a mass upper limit can be derived for the most luminous stars observed in R136.

  1. Symbiotic Stars in X-rays. II. Faint Sources Detected with XMM-Newton and Chandra

    NASA Technical Reports Server (NTRS)

    Nunez, N. E.; Luna, G. J. M.; Pillitteri, I.; Mukai, K.

    2014-01-01

    We report the detection from four symbiotic stars that were not known to be X-ray sources. These four object show a ß-type X-ray spectrum, that is, their spectra can be modeled with an absorbed optically thin thermal emission with temperatures of a few million degrees. Photometric series obtained with the Optical Monitor on board XMM-Newton from V2416 Sgr and NSV 25735 support the proposed scenario where the X-ray emission is produced in a shock-heated region inside the symbiotic nebulae.

  2. The ACS LCID Project. II. Faint Variable Stars in the Isolated Dwarf Irregular Galaxy IC 1613

    NASA Astrophysics Data System (ADS)

    Bernard, Edouard J.; Monelli, Matteo; Gallart, Carme; Aparicio, Antonio; Cassisi, Santi; Drozdovsky, Igor; Hidalgo, Sebastian L.; Skillman, Evan D.; Stetson, Peter B.

    2010-04-01

    We present the results of a new search for variable stars in the Local Group (LG) isolated dwarf galaxy IC 1613, based on 24 orbits of F475W and F814W photometry from the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope. We detected 259 candidate variables in this field, of which only 13 (all of them bright Cepheids) were previously known. Out of the confirmed variables, we found 90 RR Lyrae stars, 49 classical Cepheids (including 36 new discoveries), and 38 eclipsing binary stars for which we could determine a period. The RR Lyrae include 61 fundamental (RRab) and 24 first-overtone (FO, RRc) pulsators, and five pulsating in both modes simultaneously (RRd). As for the majority of LG dwarfs, the mean periods of the RRab and RRc (0.611 and 0.334 days, respectively) as well as the fraction of overtone pulsators (f c = 0.28) place this galaxy in the intermediate regime between the Oosterhoff types. From their position on the period-luminosity diagram and light-curve morphology, we can unambiguously classify 25 and 14 Cepheids as fundamental and FO mode pulsators, respectively. Another two are clearly second-overtone Cepheids, the first ones to be discovered beyond the Magellanic Clouds. Among the remaining candidate variables, five were classified as δ-Scuti and five as long-period variables. Most of the others are located on the main sequence, the majority of them likely eclipsing binary systems, although some present variations similar to pulsating stars. We estimate the distance to IC 1613 using various methods based on the photometric and pulsational properties of the Cepheids and RR Lyrae stars. The values we find are in very good agreement with each other and with previous estimates based on independent methods. When corrected to a common reddening of E(B - V) = 0.025 and true Large Magellanic Cloud (LMC) distance modulus of (m-M)LMC,0 = 18.515 ± 0.085, we find that all the distance determinations from the literature converge to a common value of (m-M)0 = 24.400 ± 0.014 (statistical) or 760 kpc. The parallel WFPC2 field, which lies within three core radii, was also searched for variable stars. We discovered nine RR Lyrae stars (four RRab, four RRc, and one RRd) and two Cepheids, even though the lower signal-to-noise ratio of the observations did not allow us to measure their periods as accurately as for the variables in the ACS field of view. We provide their coordinates and approximate properties for completeness. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program 10505.

  3. THE ACS LCID PROJECT. II. FAINT VARIABLE STARS IN THE ISOLATED DWARF IRREGULAR GALAXY IC 1613

    SciTech Connect

    Bernard, Edouard J.; Monelli, Matteo; Gallart, Carme; Aparicio, Antonio; Drozdovsky, Igor; Hidalgo, Sebastian L.; Cassisi, Santi; Skillman, Evan D.; Stetson, Peter B. E-mail: monelli@iac.e E-mail: antapaj@iac.e E-mail: slhidalgo@iac.e E-mail: skillman@astro.umn.ed

    2010-04-01

    We present the results of a new search for variable stars in the Local Group (LG) isolated dwarf galaxy IC 1613, based on 24 orbits of F475W and F814W photometry from the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope. We detected 259 candidate variables in this field, of which only 13 (all of them bright Cepheids) were previously known. Out of the confirmed variables, we found 90 RR Lyrae stars, 49 classical Cepheids (including 36 new discoveries), and 38 eclipsing binary stars for which we could determine a period. The RR Lyrae include 61 fundamental (RRab) and 24 first-overtone (FO, RRc) pulsators, and five pulsating in both modes simultaneously (RRd). As for the majority of LG dwarfs, the mean periods of the RRab and RRc (0.611 and 0.334 days, respectively) as well as the fraction of overtone pulsators (f{sub c} = 0.28) place this galaxy in the intermediate regime between the Oosterhoff types. From their position on the period-luminosity diagram and light-curve morphology, we can unambiguously classify 25 and 14 Cepheids as fundamental and FO mode pulsators, respectively. Another two are clearly second-overtone Cepheids, the first ones to be discovered beyond the Magellanic Clouds. Among the remaining candidate variables, five were classified as delta-Scuti and five as long-period variables. Most of the others are located on the main sequence, the majority of them likely eclipsing binary systems, although some present variations similar to pulsating stars. We estimate the distance to IC 1613 using various methods based on the photometric and pulsational properties of the Cepheids and RR Lyrae stars. The values we find are in very good agreement with each other and with previous estimates based on independent methods. When corrected to a common reddening of E(B - V) = 0.025 and true Large Magellanic Cloud (LMC) distance modulus of (m-M){sub LMC,0} = 18.515 +- 0.085, we find that all the distance determinations from the literature converge to a common value of (m-M){sub 0} = 24.400 +- 0.014 (statistical) or 760 kpc. The parallel WFPC2 field, which lies within three core radii, was also searched for variable stars. We discovered nine RR Lyrae stars (four RRab, four RRc, and one RRd) and two Cepheids, even though the lower signal-to-noise ratio of the observations did not allow us to measure their periods as accurately as for the variables in the ACS field of view. We provide their coordinates and approximate properties for completeness.

  4. Faint electric dynamic forces in atmosphere is a possible precursor for a Seismic events phenomena

    NASA Astrophysics Data System (ADS)

    Grigoropoulos, K. N.; Nastos, P. T.; Tselentis, G.; Saragas, E.; Ifantis, A.

    2009-04-01

    The objective of this paper is to monitor the propagation of faint electric forces (D.C. potentials) in Athens' atmosphere before an earthquake. Many authors refer to radio emissions (ELF,HF,VLF,UHF ) before an event. Several other researches have been done with ICE (Instrument Champ Electrique), measurement of quasi-continuous electric fields and electric components of waves, from DC up to 3.5 MHz, or IMSC (Measuring the magnetic components of waves), for measuring magnetic field from a few Hz up to 18 kHz. More studies, within the last twenty years are correlated also with monitoring underground electromagnetic fields from different countries, but few are dealing with D.C.field. The concept is that, the aerosols are injected into the lower atmosphere due to intensifying soil gas content during the increase of seismic activity. At our station in Athens, a continuous monitoring has been conducted by three D.C.detectors which follow the ionosphere variations of the electric field daily, for the years 2007-2008. Multiple antennas have been posted and tested up to the height of thirty meters above the ground. The faint electro potentials received, had been continuously registered by two electrometers. A cross over study of aerosols simulation has been simultaneously done with photo detectors. For this purpose an array of four photo diodes, posted in infrared and visible band in function, and was connected to electro meters too. Several approaches have been taken in past years by researchers attempting to correlate changes in geophysical parameters with earthquake phenomena. In particular, many works examine possible connections of Geoelectric Field (Long and Sort Term Geoelectric Potential) variations to seismic activity and their possible use as precursors of seismic events. Long Term Geoelectric Potential (LTGP) acquisition data consists of potential difference measured between pairs of electrodes placed in the ground at specific location and distance. The electric

  5. THE AROMATIC FEATURES IN VERY FAINT DWARF GALAXIES

    SciTech Connect

    Wu Ronin; Hogg, David W.; Moustakas, John

    2011-04-01

    We present optical and mid-infrared photometry of a statistically complete sample of 29 dwarf galaxies (M{sub r} > - 15 mag) selected from the Sloan Digital Sky Survey (SDSS) spectroscopic sample and observed in the mid-infrared with Spitzer IRAC. This sample contains nearby (redshift {approx}<0.005) galaxies 3 mag fainter than previously studied samples. We compare our sample with other star-forming galaxies that have been observed with both IRAC and SDSS. We examine the relationship of the infrared color, [3.6]-[7.8], sensitive to polycyclic aromatic hydrocarbon (PAH) abundance and also hot dust and stellar continuum, with star formation rates (SFRs), oxygen abundances, and radiation hardness, all estimated by optical emission lines. Consistent with studies of more luminous dwarfs, we find that these dwarf galaxies show much redder [3.6]-[7.8] color than luminous galaxies with similar specific SFRs. Unlike luminous galaxies, we find that these dwarf galaxies show no significant dependence at all of the [3.6]-[7.8] color on SFR, oxygen abundance, or radiation hardness, despite the fact that the sample spans a significant range in all of these quantities. When the dwarfs in our sample are compared with more luminous dwarfs, we find that the [3.6]-[7.8] color, potentially tracing the PAH emission, depends on oxygen abundance and radiation hardness. However, these two parameters are correlated with one another as well; we break this degeneracy by looking at the PAH-oxygen abundance relation at a fixed radiation hardness and the PAH-hardness relation at a fixed oxygen abundance. This test shows that the [3.6]-[7.8] color in dwarf galaxies appears to depend more directly on oxygen abundance based on the data currently available.

  6. Searching for Faint Exozodiacal Disks: Keck Results and LBTI Status

    NASA Astrophysics Data System (ADS)

    Defrère, D.; Hinz, P.; Mennesson, B.; Millan-Gabet, R.; Skemer, A.; Bailey, V.; Rodigas, T. J.

    2014-01-01

    The possible presence of dust in the habitable zone around nearby main-sequence stars is considered as a major hurdle toward the direct imaging of Earth-like extrasolar planets with future dedicated space-based telescopes (e.g., Roberge et al. 2012). In this context, NASA has funded two ground-based mid-infrared nulling interferometers to combine the large apertures available at the Keck Observatory and the Large Binocular Telescope (LBT). In this poster, we present the preliminary results of the extended survey carried out with the Keck Interferometer Nuller (KIN) between 2008 and 2011 and describe the forthcoming LBTI survey.

  7. TESTING MASS LOSS IN LARGE MAGELLANIC CLOUD CEPHEIDS USING INFRARED AND OPTICAL OBSERVATIONS. II. PREDICTIONS AND TESTS OF THE OGLE-III FUNDAMENTAL-MODE CEPHEIDS

    SciTech Connect

    Neilson, Hilding R.; Ngeow, Chow-Choong; Kanbur, Shashi M.; Lester, John B.

    2010-06-20

    In this paper, we test the hypothesis that Cepheids have infrared excesses due to mass loss. We fit a model using the mass-loss rate and the stellar radius as free parameters to optical observations from the OGLE-III survey and infrared observations from the Two Micron All Sky Survey and SAGE data sets. The sample of Cepheids has predicted minimum mass-loss rates ranging from 0 to 10{sup -8} M{sub sun} yr{sup -1}, where the rates depend on the chosen dust properties. We use the predicted radii to compute the period-radius relation for LMC Cepheids and to estimate the uncertainty caused by the presence of infrared excess for determining angular diameters with the infrared surface brightness technique. Finally, we calculate the linear and nonlinear period-luminosity (P-L) relations for the LMC Cepheids at VIJHK + IRAC wavelengths and find that the P-L relations are consistent with being nonlinear at infrared wavelengths contrary to previous results.

  8. Infrared spectra of Pt(II) creatinine complexes. Normal coordinate analysis of creatinine and Pt(creat) 2(NO 2) 2

    NASA Astrophysics Data System (ADS)

    Trendafilova, N.; Kurbakova, A. P.; Efimenko, I. A.; Mitewa, M.; Bontchev, P. R.

    Infrared spectra of creatinine (H 3CNC(NH)NHCOCH 2) (creat), cis-Pt(creat) 2(NO 2) 2 and Pt(creat) 4(CIO 4) 2 have been recorded in the range 50-4000 cm -1. The fundamental vibrations for the creatinine molecule were assigned by normal coordinate analysis in the generalized valence force field approximation. The spectrum of cis-Pt(creat) 2(NO 2) 2 was interpreted by comparison with the creatinine vibrational modes. Additionally the Pt(creat) 4(ClO 4) 2 infrared spectrum has been involved to help the assignment.

  9. Fundamental Physics with the Hubble Frontier Fields: Constraining Dark Matter Models with the Abundance of Extremely Faint and Distant Galaxies

    NASA Astrophysics Data System (ADS)

    Menci, N.; Merle, A.; Totzauer, M.; Schneider, A.; Grazian, A.; Castellano, M.; Sanchez, N. G.

    2017-02-01

    We show that the measured abundance of ultra-faint lensed galaxies at z≈ 6 in the Hubble Frontier Fields (HFF) provides stringent constraints on the parameter space of (i) dark matter models based on keV sterile neutrinos; (ii) “fuzzy” wavelike dark matter models, based on Bose–Einstein condensates of ultra-light particles. For the case of sterile neutrinos, we consider two production mechanisms: resonant production through mixing with active neutrinos and the decay of scalar particles. For the former model, we derive constraints for the combination of sterile neutrino mass {m}ν and mixing parameter {\\sin }2(2θ ) which provide the tightest lower bounds on the mixing angle (and hence on the lepton asymmetry) derived so far by methods independent of baryonic physics. For the latter we compute the allowed combinations of the scalar mass, its coupling to the Higgs field, and the Yukawa coupling of scalar to sterile neutrinos. We compare our results to independent existing astrophysical bounds on sterile neutrinos in the same mass range. For the case of “fuzzy” dark matter, we show that the observed number density ≈ 1/{{Mpc}}3 of high-redshift galaxies in the HFF sets a lower limit {m}\\psi ≥slant 8\\cdot {10}-22 eV (at the 3-σ confidence level) on the particle mass, a result that strongly disfavors wavelike bosonic dark matter as a viable model for structure formation. We discuss the impact on our results of uncertainties due to systematics in the selection of highly magnified, faint galaxies at high redshift.

  10. Estimating sizes of faint, distant galaxies in the submillimetre regime

    NASA Astrophysics Data System (ADS)

    Lindroos, L.; Knudsen, K. K.; Fan, L.; Conway, J.; Coppin, K.; Decarli, R.; Drouart, G.; Hodge, J. A.; Karim, A.; Simpson, J. M.; Wardlow, J.

    2016-10-01

    We measure the sizes of redshift ˜2 star-forming galaxies by stacking data from the Atacama Large Millimeter/submillimeter Array (ALMA). We use a uv-stacking algorithm in combination with model fitting in the uv-domain and show that this allows for robust measures of the sizes of marginally resolved sources. The analysis is primarily based on the 344 GHz ALMA continuum observations centred on 88 submillimetre galaxies in the LABOCA ECDFS Submillimeter Survey (ALESS). We study several samples of galaxies at z ≈ 2 with M* ≈ 5 × 1010 M⊙, selected using near-infrared photometry (distant red galaxies, extremely red objects, sBzK-galaxies, and galaxies selected on photometric redshift). We find that the typical sizes of these galaxies are ˜0.6 arcsec which corresponds to ˜5 kpc at z = 2, this agrees well with the median sizes measured in the near-infrared z band (˜0.6 arcsec). We find errors on our size estimates of ˜0.1-0.2 arcsec, which agree well with the expected errors for model fitting at the given signal-to-noise ratio. With the uv-coverage of our observations (18-160 m), the size and flux density measurements are sensitive to scales out to 2 arcsec. We compare this to a simulated ALMA Cycle 3 data set with intermediate length baseline coverage, and we find that, using only these baselines, the measured stacked flux density would be an order of magnitude fainter. This highlights the importance of short baselines to recover the full flux density of high-redshift galaxies.

  11. The faint limit of the Hubble Space Telescope faint object spectrograph and rejection of the cosmic-ray background

    NASA Technical Reports Server (NTRS)

    Tytler, David; Davis, Christopher

    1995-01-01

    The faintest object which can be observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) is set by the detector cosmic-ray background and not by object flux. We use data from Beaver and Lyons to show that 48% of the background counts are from cosmic rays which each generate a near instantaneous burst of two or more counts. Setting the FOS threshold parameter REJLIM = 1, which rejects all frames with more than one count increases the ratio of signal-to-dark counts (S/D) by a factor of 1.94, regardless of the frame time or the object signal, because half of the dark counts which arrive in single counts (from either cosmic-ray bursts or thermal dark current photoemission) are rejected at the same rate as the object signal. But the signal-to-noise ratio (SNR proportional to S/square root of S + D) increases by at most a factor of 1.35, and for realistic parameters and taking into account dead time, we expect a gain in SNR of only 1.18. If a diode has failed and now emits noise, no data at all will be recorded. The chance of this occurring is approximately = 10% , and for this reason we do not recommend the use of REJLIM. The two-point correlation function of dark counts per pixel has strong peaks every four pixels, caused by the action of quarter-stepping on the counts from large bursts. The counts from such bursts spread over at least 80-100 diodes, and we show that such bursts can be rejected during data reduction if the data are recorded in RAPID mode with individual exposures of about 35 seconds. The SNR of the spectrum can also be improved by weighting each exposure by its SNR (a function ofthe mean dark count rate at that time), since dark varies by a factor of 2 around an orbit. These two procedures together increase the SNR by a factor of 1.1.3 (a 28% gain in exposure time) in regions of a spectrum where the object is much fainter than the background. We find that the Ly-alpha and O I sky emission lines give at most 4 (counts

  12. Searching for Faint cataclysmic Variables: Seeking the truth about their Space Density

    NASA Astrophysics Data System (ADS)

    Howell, S. B.; Clowes, R.

    1996-12-01

    The current view of cataclysmic variables is based on theory and observation attempting to reach agreement. However recent work in both these areas has conclusively shown that the present observational sample of CVs is severely limited to intrinsically bright systems, while theory predicts that most should be intrinsically faint. We have begun a program designed to discover faint CVs, ones belonging to the predicted majority population. Using H-alpha and broadband R plates from the UK Schmidt digitized with SuperCOSMOS, we have begun sample selection of candidates to a faint limit of near 20th magnitude. The first spectroscopic results obtained using the ARGUS multi-fiber spectrograph at CTIO will be presented.

  13. Determination of astrometry and photometry of faint companions in the presence of residual speckle noise

    NASA Astrophysics Data System (ADS)

    Burke, Daniel; Devaney, Nicholas; Gladysz, Szymon

    In this paper we examine approaches to faint companion detection and estimation in multi-spectral images. We will employ the Hotelling observer which is the optimal linear algorithm for signal detection. We have shown how to use this observer to estimate faint object position and brightness in the presence of residual speckle which usually limit astrometric and photometric techniques. These speckles can be reduced by differential imaging techniques such as Angular Differential Imaging and Spectral Differential Imaging. Here we present results based on simulations of adaptive optics corrected images from an ELT which contain quasi-static speckle noise. The simulation includes Angular Differential Imaging to reduce the residual speckle and subsequent multi-wavelenght processing. We examine the feasibility of this approach on simulated ELT observations of faint companions.

  14. The VVDS-VLA deep field. II. Optical and near infrared identifications of VLA S1.4 GHz > 80 μ Jy sources in the VIMOS VLT deep survey VVDS-02h field

    NASA Astrophysics Data System (ADS)

    Ciliegi, P.; Zamorani, G.; Bondi, M.; Pozzetti, L.; Bolzonella, M.; Gregorini, L.; Garilli, B.; Iovino, A.; McCracken, H. J.; Mellier, Y.; Radovich, M.; de Ruiter, H. R.; Parma, P.; Bottini, D.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Picat, J. P.; Scaramella, R.; Scodeggio, M.; Tresse, L.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnaboldi, M.; Arnouts, S.; Bardelli, S.; Cappi, A.; Charlot, S.; Contini, T.; Foucaud, S.; Franzetti, P.; Guzzo, L.; Ilbert, O.; Marano, B.; Marinoni, C.; Mathez, G.; Mazure, A.; Meneux, B.; Merighi, R.; Merluzzi, P.; Paltani, S.; Pollo, A.; Zucca, E.; Bongiorno, A.; Busarello, G.; Gavignaud, I.; Pellò, R.; Ripepi, V.; Rizzo, D.

    2005-10-01

    In this paper we present the optical and near-infrared identifications of the 1054 radio sources detected in the 20 cm deep radio survey down to a 5σ flux limit of ~80 μJy obtained with the VLA in the VIMOS VLT Deep Survey VVDS-02h deep field. Using U,B,V,R,I and K data, with limiting magnitudes of UAB˜25.4, BAB˜26.5, VAB˜26.2, RAB˜25.9 IAB˜25.0, JAB˜24.2, KAB˜23.9 (50% completeness) we identified 718 radio sources (~74% of the whole sample). The photometric redshift analysis shows that, in each magnitude bin, the radio sample has a higher median photometric redshift than the whole optical sample, while the median (V-I)AB color of the radio sources is redder than the median color of the whole optical sample. These results suggest that radio detection is preferentially selecting galaxies with higher intrinsic optical luminosity. From the analysis of the optical properties of the radio sources as function of the radio flux, we found that while about 35% of the radio sources are optically unidentified in the higher radio flux bin (S> 1.0 mJy), the percentage of unidentified sources decreases to about 25% in the faintest bins (S< 0.5 mJy). The median IAB magnitude for the total sample of radio sources, i.e. including also the unidentified ones, is brighter in the faintest radio bins than in the bin with higher radio flux. This suggests that most of the faintest radio sources are likely to be associated to relatively lower radio luminosity objects at relatively modest redshift, rather than radio-powerful, AGN type objects at high redshift. Using a classification in early-type and late-type galaxies based on the (B-I)AB color and the photometric redshift, we found that the majority of the radio sources below ~0.15 mJy are indeed late-type star forming galaxies. Finally, the radio sources without optical counterpart in our deep imaging have a median radio flux of 0.15 mJy, equal to that of identified sources. Given the very faint optical limits, these

  15. Cirrus Cloud Properties Derived from High Spectral Resolution Infrared Spectrometry during FIRE II. Part I: The High Resolution Interferometer Sounder (HIS) Systems.

    NASA Astrophysics Data System (ADS)

    Smith, W. L.; Revercomb, H. E.; Knuteson, R. O.; Best, F. A.; Dedecker, R.; Howell, H. B.; Woolf, H. M.

    1995-12-01

    The characteristics of the ER-2 aircraft and ground-based High Resolution Interferometer Sounder (HIS) instruments deployed during FIRE II are described. A few example spectra are given to illustrate the HIS cloud and molecular atmosphere remote sensing capabilities.

  16. Digital image profilers for detecting faint sources which have bright companions, phase 2

    NASA Technical Reports Server (NTRS)

    Morris, Elena; Flint, Graham

    1991-01-01

    A breadboard image profiling system developed for the first phase of this project demonstrated the potential for detecting extremely faint optical sources in the presence of light companions. Experimental data derived from laboratory testing of the device supports the theory that image profilers of this type may approach the theoretical limit imposed by photon statistics. The objective of Phase 2 of this program is the development of a ground-based multichannel image profiling system capable of detecting faint stellar objects slightly displaced from brighter stars. We have finalized the multichannel image profiling system and attempted three field tests.

  17. Influence of pH and counteranion on the structure of tropolonato-lead(II) complexes: structural and infrared characterization of formed lead compounds.

    PubMed

    Lyczko, Krzysztof; Starosta, Wojciech; Persson, Ingmar

    2007-05-28

    Reactions of tropolone with lead(II) trifluoromethanesulfonate, perchlorate, and nitrate in water/methanol mixtures at pH below 1.0 lead to the formation of three different polymeric lead(II) complexes, [Pb(trop)(CF3SO3)(H2O)]n (1), [Pb3(trop)4(ClO4)2]n (2), and [Pb2(trop)2(NO3)2(CH3OH)]n (3), respectively. On the other hand, if the reactions are performed at pH above 2.0, the dimeric compound [Pb(trop)2]2 (4) is obtained independently of the lead(II) salt used, as long as lead(II) does not form any strong complexes with the counterion. The crystal structures of these compounds have been determined by single-crystal X-ray diffraction. The structure of solid tetrakis(tropolonato)lead(IV), Pb(trop)4 (5), has been studied by means of the EXAFS technique because it was not possible to obtain sufficiently large single crystals. In the polymeric structures, the counterions are coordinated to the lead(II) ions and act as bridges. The tropolonato ligand behaves as a chelating agent and a tri- or tetraconnective bridge. The total coordination number of the lead(II) ion is five in compound 4, seven in 1 and 3, and eight in 2, and the lead(IV) ion in 5 is eight-coordinated. The 6s2 lone electron pair on the lead(II) ion seems to be stereochemically active in all lead(II) complexes studied. All compounds have been characterized by IR spectroscopy as well.

  18. Three intervening galaxy absorbers towards GRB 060418: faint and dusty?

    NASA Astrophysics Data System (ADS)

    Ellison, Sara L.; Vreeswijk, Paul; Ledoux, Cédric; Willis, Jon P.; Jaunsen, Andreas; Wijers, Ralph A. M. J.; Smette, Alain; Fynbo, Johan P. U.; Møller, Palle; Hjorth, Jens; Kaufer, Andreas

    2006-10-01

    We present an analysis of three strong, intervening Mg II absorption systems (zabs = 0.603, 0.656, 1.107) towards the optical afterglow of gamma-ray burst (GRB) 060418. From high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES) spectra we measure metal column densities and find that the highest redshift absorber exhibits a large amount of dust depletion compared with damped Lyman absorbers (DLAs) seen in quasi-stellar object (QSO) spectra. The intervening zabs = 1.107 absorber is also unusual in exhibiting a clear 2175-Å bump, the first time this feature has been definitively detected in a GRB spectrum. The GRB afterglow spectrum is best fitted with a two-component extinction curve: a Small Magellanic Cloud (SMC) extinction law at z = 1.49 (the redshift of the host) with E(B - V) = 0.07 +/- 0.01 and a Galactic extinction curve at z ~ 1.1 with E(B - V) = 0.08 +/- 0.01. We also present a moderately deep New Technology Telescope (NTT) R-band image of the GRB 060418 field and spectroscopy of four galaxies within 1 arcmin. None of these objects has a redshift that matches any of the intervening absorbers, and we conclude that the galaxies responsible for the two intervening MgII absorbers at z ~ 0.6 have luminosities .

  19. A dwarf galaxy near the sight line to PKS 0454+0356 - A fading 'faint blue galaxy'?

    NASA Technical Reports Server (NTRS)

    Steidel, Charles C.; Dickinson, Mark; Bowen, David V.

    1993-01-01

    We report the discovery of a dwarf galaxy (MB = -17.2 for H0 = 50 km/s per Mpc) at z = 0.072 which is only 4 arcsec (3.7/h(100) kpc) in projection from the line of sight to the bright quasar PKS 0454+0356 (z(em) = 1.345). The dwarf has very blue optical and optical/IR colors and exhibits line emission indicative of ongoing or recent star formation. However, there is no detection of Ca II 3934 A, 3969 A absorption at z(abs) = 0.072 to equivalent width limits (3 sigma) of about 40 mA, which would suggest an H I column density along the line of sight of less than 5 x 10 exp 19/sq cm, if the Ca II/H I ratio is similar to sight lines in the Galaxy. Based on the absence of Ca II absorption and the unusually weak line emission given the very blue color of the dwarf, we speculate that it may be close to exhausting its supply of gas. As its star formation rate declines, the galaxy's blue magnitude should fade substantially, eventually reaching a quiescent state in accord with its K luminosity of about 0.005 L*. Future observations of the sight line to PKS 0454+0356 using HST in search of Mg II resonance lines, or a search for 21 cm absorption against the quasar radio continuum, could place even more stringent limits on the extent of the gas associated with an intrinsically faint, star-forming dwarf.

  20. PICASSO: an end-to-end image simulation tool for space and airborne imaging systems II. Extension to the thermal infrared: equations and methods

    NASA Astrophysics Data System (ADS)

    Cota, Stephen A.; Lomheim, Terrence S.; Florio, Christopher J.; Harbold, Jeffrey M.; Muto, B. Michael; Schoolar, Richard B.; Wintz, Daniel T.; Keller, Robert A.

    2011-10-01

    In a previous paper in this series, we described how The Aerospace Corporation's Parameterized Image Chain Analysis & Simulation SOftware (PICASSO) tool may be used to model space and airborne imaging systems operating in the visible to near-infrared (VISNIR). PICASSO is a systems-level tool, representative of a class of such tools used throughout the remote sensing community. It is capable of modeling systems over a wide range of fidelity, anywhere from conceptual design level (where it can serve as an integral part of the systems engineering process) to as-built hardware (where it can serve as part of the verification process). In the present paper, we extend the discussion of PICASSO to the modeling of Thermal Infrared (TIR) remote sensing systems, presenting the equations and methods necessary to modeling in that regime.

  1. FAINT LUMINESCENT RING OVER SATURN’S POLAR HEXAGON

    SciTech Connect

    Adriani, Alberto; D’Aversa, Emiliano; Oliva, Fabrizio; Filacchione, Gianrico; Moriconi, Maria Luisa

    2015-07-20

    Springtime insolation is presently advancing across Saturn's north polar region. Early solar radiation scattered through the gaseous giant's atmosphere gives a unique opportunity to sound the atmospheric structure at its upper troposphere/lower stratosphere at high latitudes. Here, we report the detection of a tenuous bright structure in Saturn's northern polar cap corresponding to the hexagon equatorward boundary, observed by Cassini Visual and Infrared Mapping Spectrometer on 2013 June. The structure is spectrally characterized by an anomalously enhanced intensity in the 3610–3730 nm wavelength range and near 2500 nm, pertaining to relatively low opacity windows between strong methane absorption bands. Our first results suggest that a strong forward scattering by tropospheric clouds, higher in respect to the surrounding cloud deck, can be responsible for the enhanced intensity of the feature. This can be consistent with the atmospheric dynamics associated with the jet stream embedded in the polar hexagon. Further investigations at higher spectral resolution are needed to better assess the vertical distribution and microphysics of the clouds in this interesting region.

  2. THE HIGH A{sub V} Quasar Survey: Reddened Quasi-Stellar Objects selected from optical/near-infrared photometry. II

    SciTech Connect

    Krogager, J.-K.; Fynbo, J. P. U.; Vestergaard, M.; Geier, S.; Venemans, B. P.; Ledoux, C.; Møller, P.; Noterdaeme, P.; Kangas, T.; Pursimo, T.; Smirnova, O.; Saturni, F. G.

    2015-03-15

    Quasi-stellar objects (QSOs) whose spectral energy distributions (SEDs) are reddened by dust either in their host galaxies or in intervening absorber galaxies are to a large degree missed by optical color selection criteria like the ones used by the Sloan Digital Sky Survey (SDSS). To overcome this bias against red QSOs, we employ a combined optical and near-infrared (near-IR) color selection. In this paper, we present a spectroscopic follow-up campaign of a sample of red candidate QSOs which were selected from the SDSS and the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and SDSS/UKIDSS photometry are supplemented by mid-infrared photometry from the Wide-field Infrared Survey Explorer. In our sample of 159 candidates, 154 (97%) are confirmed to be QSOs. We use a statistical algorithm to identify sightlines with plausible intervening absorption systems and identify nine such cases assuming dust in the absorber similar to Large Magellanic Cloud sightlines. We find absorption systems toward 30 QSOs, 2 of which are consistent with the best-fit absorber redshift from the statistical modeling. Furthermore, we observe a broad range in SED properties of the QSOs as probed by the rest-frame 2 μm flux. We find QSOs with a strong excess as well as QSOs with a large deficit at rest-frame 2 μm relative to a QSO template. Potential solutions to these discrepancies are discussed. Overall, our study demonstrates the high efficiency of the optical/near-IR selection of red QSOs.

  3. A very faint core-collapse supernova in M85.

    PubMed

    Pastorello, A; Della Valle, M; Smartt, S J; Zampieri, L; Benetti, S; Cappellaro, E; Mazzali, P A; Patat, F; Spiro, S; Turatto, M; Valenti, S

    2007-10-18

    An anomalous transient in the early Hubble-type (S0) galaxy Messier 85 (M85) in the Virgo cluster was discovered by Kulkarni et al. on 7 January 2006 that had very low luminosity (peak absolute R-band magnitude M(R) of about -12) that was constant over more than 80 days, red colour and narrow spectral lines, which seem inconsistent with those observed in any known class of transient events. Kulkarni et al. suggest an exotic stellar merger as the possible origin. An alternative explanation is that the transient in M85 was a type II-plateau supernova of extremely low luminosity, exploding in a lenticular galaxy with residual star-forming activity. This intriguing transient might be the faintest supernova that has ever been discovered.

  4. Black-to-Transmissive Electrochromism with Visible-to-Near-Infrared Switching of a Co(II)-Based Metallo-Supramolecular Polymer for Smart Window and Digital Signage Applications.

    PubMed

    Hsu, Chih-Yu; Zhang, Jian; Sato, Takashi; Moriyama, Satoshi; Higuchi, Masayoshi

    2015-08-26

    Black-to-transmissive electrochromism has been obtained with a Co(II)-based metallo-supramolecular polymer (polyCo). Thin films of polyCo, based on bisterpyridine ligand assembled with Co(II) metal ion, were constructed by spray casting the polymer onto ITO glass. With such simple fabricating means to form good-quality films, polyCo films show stable switching at the central metal ion of the Co(II)/Co(I) redox reaction when immersed in aqueous solution. With an increase in the pH of the aqueous electrolyte solution from neutral, the film exhibits a color response due to the interaction between the d-orbital electron and hydroxide ions affecting the d-d* transition. As a result, a nearly transparent-to-black electrochromic performance can be achieved with a transmittance difference at 550 nm of 74.3% (81.9-7.6%) in pH 13 solution. The light absorption of the film can be tuned over light regions from visible to near-infrared with a large attenuation.

  5. THE [O III] NEBULA OF THE MERGER REMNANT NGC 7252: A LIKELY FAINT IONIZATION ECHO

    SciTech Connect

    Schweizer, Francois; Kelson, Daniel D.; Villanueva, Edward V.; Seitzer, Patrick; Walth, Gregory L.

    2013-08-20

    We present images and spectra of a {approx}10 kpc-sized emission-line nebulosity discovered in the prototypical merger remnant NGC 7252 and dubbed the ''[O III] nebula'' because of its dominant [O III] {lambda}5007 line. This nebula seems to yield the first sign of episodic active galactic nucleus (AGN) activity still occurring in the remnant, {approx}220 Myr after the coalescence of two gas-rich galaxies. Its location and kinematics suggest it belongs to a stream of tidal-tail gas falling back into the remnant. Its integrated [O III] {lambda}5007 luminosity is 1.4 Multiplication-Sign 10{sup 40} erg s{sup -1}, and its spectrum features some high-excitation lines, including He II {lambda}4686. In diagnostic line-ratio diagrams, the nebula lies in the domain of Seyfert galaxies, suggesting that it is photoionized by a source with a power-law spectrum. Yet, a search for AGN activity in NGC 7252 from X-rays to radio wavelengths yields no detection, with the most stringent upper limit set by X-ray observations. The upper luminosity limit of L{sub 2-10{sub keV,0}}<5 Multiplication-Sign 10{sup 39} erg s{sup -1} estimated for the nucleus is {approx}10{sup 3} times lower than the minimum ionizing luminosity of {approx}> 5 Multiplication-Sign 10{sup 42} erg s{sup -1} necessary to excite the nebula. This large discrepancy suggests that the nebula is a faint ionization echo excited by a mildly active nucleus that has declined by {approx}3 orders of magnitude over the past 20,000-200,000 yr. In many ways this nebula resembles the prototypical ''Hanny's Voorwerp'' near IC 2497, but its size is 3 Multiplication-Sign smaller and its [O III] luminosity {approx}100 Multiplication-Sign lower. We propose that it be classified as an extended emission-line region (EELR). The [O III] nebula is then the lowest-luminosity ionization echo and EELR discovered so far, indicative of recent, probably sputtering AGN activity of Seyfert-like intensity in NGC 7252.

  6. Near infra-red emission from a mer-Ru(II) complex: consequences of strong σ-donation from a neutral, flexible ligand with dual binding modes.

    PubMed

    Pal, Amlan K; Zaccheroni, Nelsi; Campagna, Sebastiano; Hanan, Garry S

    2014-07-04

    A rare example of dual coordination modes by a novel tridentate ligand gives rise to unique fac-and mer-Ru((II/III)) complexes. The mer-Ru(II)-complex displays the farthest red-shift of a triplet metal-to-ligand charge transfer ((3)MLCT) emission with a tridentate ligand for a mononuclear complex. This observation is a consequence of large bite angle and strong σ-donation by the ligand, the combined effect of which helps to separate the energy of the (3)MLCT and (3)MC states.

  7. View of southeast side, faint "141" sign, Cranes P76 and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of southeast side, faint "141" sign, Cranes P-76 and P-71 are behind, view facing northwest - U.S. Naval Base, Pearl Harbor, Dry Dock No. 1, Latrine, Sixth Street, adjacent to Dry Dock No. 1, Pearl City, Honolulu County, HI

  8. Study on the faint star extraction technology with MEMS gyro aided APS star tracker

    NASA Astrophysics Data System (ADS)

    Xing, Fei; Zhao, Borui; Sun, Ting; Xu, Wei; You, Zheng

    2013-08-01

    Star tracker is the most accurate attitude sensor for satellite. Generally speaking, the higher the accuracy, the fainter the star can be sensed by the star tracker. How to extract the faint star from a star image is becoming a critical technology in dynamic condition for star tracker, especially using the APS (Active Pixels Sensor) detector. A novel APS star tracker with MEMS Gyroscope aided system was proposed in this paper that could extremely improve the detection effect and capability for the faint stars. During the exposure time of star tracker, the trajectory of star projection on the detector maybe occupy more than ten pixels due to the satellite rotation. In this situation, the signal-to-noise ratio will decline sharply, and the traditional star extraction method for faint star will take no effect. As a result, the accuracy of star tracker would decline sharply, even more, couldn't work. Using the MEMS Gyroscope, the track of star projection can be predicated and measured, on the basis of which the deconvolution algorithm could be taken to recover the faint star signal. The accuracy of the star projection centroid could be improved obviously, and the dynamic performance of the star tracker would be improved by a magnitude. Meanwhile, the MEMS gyroscope has not less volume, mass and power consumption, which make it more suitable for the application of APS star tracker.

  9. Faints, fits, and fatalities from emotion in Shakespeare's characters: survey of the canon

    PubMed Central

    2006-01-01

    Objectives To determine how often Shakespeare's characters faint, fit, or die from extreme emotion; to assess Shakespeare's uniqueness in this regard; and to examine the plausibility of these dramatised events. Design Line by line search through modern editions of these late 16th and early 17th century works for accounts of characters fainting, fitting, or dying while under strong emotion and for no other apparent reason. Data sources All 39 canonical plays by Shakespeare and his three long narrative poems; 18 similar works by seven of Shakespeare's best known contemporaries. Results 10 deaths from strong emotion are recorded by Shakespeare (three occur on stage); all are due to grief, typically at the loss of a loved one. All but two of the deaths are in the playwright's late works. Some deaths are sudden. Another 29 emotion induced deaths are mentioned as possible, but the likelihood of some can be challenged. Transient loss of consciousness is staged or reported in 18 cases (sounding like epilepsy in two) and near fainting in a further 13. Extreme joy is sometimes depicted as a factor in these events. Emotional death and fainting also occur occasionally in works by Shakespeare's contemporaries. Conclusions These dramatic phenomena are part of the early modern belief system but are also plausible by modern understanding of physiology and disease. They teach us not to underestimate the power of the emotions to disturb bodily functions. PMID:17185734

  10. On the Dearth of Ultra-faint Extremely Metal-poor Galaxies

    NASA Astrophysics Data System (ADS)

    Sánchez Almeida, J.; Filho, M. E.; Dalla Vecchia, C.; Skillman, E. D.

    2017-02-01

    Local extremely metal-poor galaxies (XMPs) are of particular astrophysical interest since they allow us to look into physical processes characteristic of the early universe, from the assembly of galaxy disks to the formation of stars in conditions of low metallicity. Given the luminosity–metallicity relationship, all galaxies fainter than Mr ≃ ‑13 are expected to be XMPs. Therefore, XMPs should be common in galaxy surveys. However, they are not common, because several observational biases hamper their detection. This work compares the number of faint XMPs in the SDSS-DR7 spectroscopic survey with the expected number, given the known biases and the observed galaxy luminosity function (LF). The faint end of the LF is poorly constrained observationally, but it determines the expected number of XMPs. Surprisingly, the number of observed faint XMPs (∼10) is overpredicted by our calculation, unless the upturn in the faint end of the LF is not present in the model. The lack of an upturn can be naturally understood if most XMPs are central galaxies in their low-mass dark matter halos, which are highly depleted in baryons due to interaction with the cosmic ultraviolet background and to other physical processes. Our result also suggests that the upturn toward low luminosity of the observed galaxy LF is due to satellite galaxies.

  11. Photoelectric Photometry of Faint M-Type Stars in the Direction of the South Galactic Pole

    NASA Astrophysics Data System (ADS)

    Pesch, P.

    1982-04-01

    Photoelectric V (Johnson-Morgan UBV system) and (V I) (Kron-Mayall PVI system) photometry is presented for 54 faint M-type stars from Pesch and Sanduleak's catalog of probable dwarf stars of type M3 and later in the direction of the south galactic pole. The observations were made in November 1978 with the 1.5-m CTIO reflector.

  12. First results from the Faint Object Camera - Images of the gravitational lens system G2237 + 0305

    NASA Technical Reports Server (NTRS)

    Crane, P.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.

    1991-01-01

    Images of the gravitational lens system G2237 + 0305 have been obtained with the Faint Object Camera on board the Hubble Space Telescope. A preliminary analysis of these images is reported here and includes measurements of the relative positions and magnitudes of the lensed images of the QSO, and of the lensing galaxy. No evidence is found for a fifth lensed image.

  13. A VIRUS-P Survey of Galaxy Clusters to Find Faint Lyα-emitting Galaxies

    NASA Astrophysics Data System (ADS)

    McLinden, Emily; Finkelstein, S. L.; Siana, B. D.; Alavi, A.

    2014-01-01

    The VIRUS-P instrument on the 2.7m telescope at the McDonald Observatory was originally built as a prototype of the larger VIRUS instrument that will be used for HETDEX. We demonstrate that this multi-fiber, optical integral field unit spectrograph can be efficiently used to detect faint Lyα-emitting galaxies (LAEs) at intermediate redshift (z = 2-3) with the aid of gravitational lensing from galaxy clusters. The bulk z=2-3 LAEs to date have been discovered with narrowband imaging campaigns, which are highly efficient only at selecting L > L_star galaxies and only over a narrow redshift slice. By making use of gravitational lensing, however, we are able to observe intrinsically very faint galaxies that only appear to have brightnesses ≥ L_star. Gravitationally lensed faint LAEs, such as our sample from VIRUS-P, allow us to go fainter than existing narrowband surveys and therefore allow for better constraints at the faint end of the Lyα luminosity function at these intermediate redshifts.

  14. Chemical evolution of classical and ultra-faint dwarf spheroidal galaxies

    NASA Astrophysics Data System (ADS)

    Vincenzo, F.; Matteucci, F.; Vattakunnel, S.; Lanfranchi, G. A.

    2014-07-01

    We present updated chemical evolution models of two dwarf spheroidal galaxies (Sculptor and Carina) and the first detailed chemical evolution models of two ultra-faint dwarfs (Hercules and Boötes I). Our results suggest that the dwarf spheroidals evolve with a low efficiency of star formation, confirming previous results, and the ultra-faint dwarfs with an even lower one. Under these assumptions, we can reproduce the stellar metallicity distribution function, the [α/Fe] versus [Fe/H] abundance patterns and the total stellar and gas masses observed at the present time in these objects. In particular, for the ultra-faint dwarfs we assume a strong initial burst of star formation, with the mass of the system being already in place at early times. On the other hand, for the classical dwarf spheroidals the agreement with the data is found by assuming the star formation histories suggested by the colour-magnitude diagrams and a longer time-scale of formation via gas infall. We find that all these galaxies should experience galactic winds, starting in all cases before 1 Gyr from the beginning of their evolution. From comparison with Galaxy data, we conclude that it is unlikely that the ultra-faint dwarfs have been the building blocks of the whole Galactic halo, although more data are necessary before drawing firm conclusions.

  15. VizieR Online Data Catalog: 72 faint CV candidates in CRTS (Breedt+, 2014)

    NASA Astrophysics Data System (ADS)

    Breedt, E.; Gansicke, B. T.; Drake, A. J.; Rodriguez-Gil, P.; Parsons, S. G.; Marsh, T. R.; Szkody, P.; Schreiber, M. R.; Djorgovski, S. G.

    2016-04-01

    We obtained identification spectra of a total of 72 faint CV candidates identified by the CRTS, using the Gran Telescopio Canarias (GTC; La Palma, Spain) and the Gemini telescopes (North: Mauna Kea, Hawaii and South: Cerro Pachon, Chile). The observations were carried out in service mode during 2010, 2011 and 2013. (5 data files).

  16. Infrared Atmospheric Emission. I.

    DTIC Science & Technology

    1982-03-01

    contract. They are (i) "The 5g Levels of Atomic Nitrogen" AO)YA ii Edward S. Chang and Hajime Sakai J. Phys. B 14, L391 (1981) (ii) "Infrared Emission...At. Idol. Phys. 14 (1981) L391 -L395. printed in Great Bjritain LETTER TO THE EDITOR INC 5g levels of atomic nitrogent Edward S Chang and Hajime Sakai...81/120391 +05$01.30 C) 1981 The Institute of Physics L391 The U.S. Qovermnt is authoried to repoduce and sem tns report. Parmb@a- or ur Uther

  17. THE FAINT END OF THE LUMINOSITY FUNCTION AND LOW SURFACE BRIGHTNESS GALAXIES

    SciTech Connect

    Geller, Margaret J.; Kurtz, Michael J.; Fabricant, Daniel G.; Diaferio, Antonaldo; Dell'Antonio, Ian P. E-mail: mkurtz@cfa.harvard.edu E-mail: adiaferio@cfa.harvard.edu

    2012-04-15

    Smithsonian Hectospec Lensing Survey (SHELS) is a dense redshift survey covering a 4 deg{sup 2} region to a limiting R = 20.6. In the construction of the galaxy catalog and in the acquisition of spectroscopic targets, we paid careful attention to the survey completeness for lower surface brightness dwarf galaxies. Thus, although the survey covers a small area, it is a robust basis for computation of the slope of the faint end of the galaxy luminosity function to a limiting M{sub R} = -13.3 + 5log h. We calculate the faint-end slope in the R band for the subset of SHELS galaxies with redshifts in the range 0.02 {<=}z < 0.1, SHELS{sub 0.1}. This sample contains 532 galaxies with R < 20.6 and with a median surface brightness within the half-light radius of SB{sub 50,R} = 21.82 mag arcsec{sup -2}. We used this sample to make one of the few direct measurements of the dependence of the faint end of the galaxy luminosity function on surface brightness. For the sample as a whole the faint-end slope, {alpha} = -1.31 {+-} 0.04, is consistent with both the Blanton et al. analysis of the Sloan Digital Sky Survey and the Liu et al. analysis of the COSMOS field. This consistency is impressive given the very different approaches of these three surveys. A magnitude-limited sample of 135 galaxies with optical spectroscopic redshifts with mean half-light surface brightness, SB{sub 50,R} {>=} 22.5 mag arcsec{sup -2} is unique to SHELS{sub 0.1}. The faint-end slope is {alpha}{sub 22.5} = -1.52 {+-} 0.16. SHELS{sub 0.1} shows that lower surface brightness objects dominate the faint-end slope of the luminosity function in the field, underscoring the importance of surface brightness limits in evaluating measurements of the faint-end slope and its evolution.

  18. NEAR-INFRARED H{sub 2} AND CONTINUUM SURVEY OF EXTENDED GREEN OBJECTS. II. COMPLETE CENSUS FOR THE NORTHERN GALACTIC PLANE

    SciTech Connect

    Lee, Hsu-Tai; Karr, Jennifer; Su, Yu-Nung; Liu, Sheng-Yuan; Takami, Michihiro; Liao, Wei-Ting; Froebrich, Dirk; Ioannidis, Georgios; Lee, Yong-Hyun; Duan, Hao-Yuan

    2013-10-01

    We discuss 94 Extended Green Objects (EGOs) in the northern Galactic plane cataloged by Cyganowski et al., based on near-infrared narrow H{sub 2} (2.122 μm) and continuum observations from the United Kingdom Infrared Telescope. This data set is three times larger than the one in our previous study and is unbiased by preselection. As discussed in the previous paper, the morphologies of the 4.5 μm emission generally resemble those of the near-infrared continuum, but are different from those of the H{sub 2} emission. Of our sample, only 28% of EGOs with H{sub 2} emission show similar morphologies between 4.5 μm and H{sub 2} emission. These results suggest that the 4.5 μm emission mainly comes from scattered continuum from the embedded young stellar objects, and partially from H{sub 2} emission. About half of EGOs are associated with H{sub 2} outflows, if the H{sub 2} outflow incompleteness is considered. The H{sub 2} outflow detection rate for EGOs with K-band detections (61%) is significantly higher than for those without K-band detections (36%). This difference may be due to the fact that both H{sub 2} and K-band emissions are associated with outflows, i.e., H{sub 2} emission and K-band continuum are associated with shocks and outflow cavities, respectively. We also compared the correlation between the H{sub 2} outflows and Class I 44 GHz methanol masers from the literature. The methanol masers can be located upstream or downstream of the H{sub 2} outflows and some bright H{sub 2} spots or outflows are not associated with methanol masers, suggesting that methanol masers and H{sub 2} emission trace different excitation conditions.

  19. Near-Infrared Photoluminescence Enhancement in Ge/CdS and Ge/ZnS Core/Shell Nanocrystals: Utilizing IV/II-VI Semiconductor Epitaxy

    SciTech Connect

    Guo, Yijun; Rowland, Clare E; Schaller, Richard D; Vela, Javier

    2014-08-26

    Ge nanocrystals have a large Bohr radius and a small, size-tunable band gap that may engender direct character via strain or doping. Colloidal Ge nanocrystals are particularly interesting in the development of near-infrared materials for applications in bioimaging, telecommunications and energy conversion. Epitaxial growth of a passivating shell is a common strategy employed in the synthesis of highly luminescent II–VI, III–V and IV–VI semiconductor quantum dots. Here, we use relatively unexplored IV/II–VI epitaxy as a way to enhance the photoluminescence and improve the optical stability of colloidal Ge nanocrystals. Selected on the basis of their relatively small lattice mismatch compared with crystalline Ge, we explore the growth of epitaxial CdS and ZnS shells using the successive ion layer adsorption and reaction method. Powder X-ray diffraction and electron microscopy techniques, including energy dispersive X-ray spectroscopy and selected area electron diffraction, clearly show the controllable growth of as many as 20 epitaxial monolayers of CdS atop Ge cores. In contrast, Ge etching and/or replacement by ZnS result in relatively small Ge/ZnS nanocrystals. The presence of an epitaxial II–VI shell greatly enhances the near-infrared photoluminescence and improves the photoluminescence stability of Ge. Ge/II–VI nanocrystals are reproducibly 1–3 orders of magnitude brighter than the brightest Ge cores. Ge/4.9CdS core/shells show the highest photoluminescence quantum yield and longest radiative recombination lifetime. Thiol ligand exchange easily results in near-infrared active, water-soluble Ge/II–VI nanocrystals. We expect this synthetic IV/II–VI epitaxial approach will lead to further studies into the optoelectronic behavior and practical applications of Si and Ge-based nanomaterials.

  20. Analysis of torsional spectra of molecules with two internal C3v rotors. II - Far infrared and low frequency Raman spectra of dimethylether isotopes

    NASA Technical Reports Server (NTRS)

    Groner, P.; Durig, J. R.

    1977-01-01

    The torsional far infrared and Raman spectra of gaseous CH3OCH3, CD3OCH3, and CD3OCD3 are presented. They are analyzed using a computer program which is based on the results of an extensive investigation of the isometric groups and of the symmetry groups of the rotation-internal rotation Hamiltonians of a series of semirigid two-top models. Four or more Fourier coefficients of the potential functions in two variables could be determined for each isotope. Strong evidence was found for Fermi-resonance-type interactions with the COC bending mode.

  1. Optical Characterization of Antimony-Based, Types-I and -II, Multiple Quantum-Well Semiconductor Structures for Mid-Infrared Laser Applications

    DTIC Science & Technology

    2003-03-01

    material. The type-I sample is represented by a hollow triangle and the type-II materials are represented by filled in symbols. The dashed lines are......Polarizing Beam Splitter λ/2 Vacuum Chamber/ Cryostat Off-Axis Parabolic Mirrors (Au Coated) Neutral Density Filter Wheel Retroreflector Delay Stage

  2. Satellite Infrared (SIRE) Sensor Data Processing Perspective and Definition. Volume II. Appendix A. Survey of Available IR Data Processing Options for SIRE.

    DTIC Science & Technology

    1978-12-31

    International Imaging System’s (12S) System 101, CDC’s Cyber- Ikon System, the Bendix Multispectral Data Analysis System, General Electric’s DIPS...Vision I Cyber- Ikon ESL IDIMS II Number installed 4 installed 40 installed New product 9 installed Processor DCC PDP-11/35 DEC LSI-l Cyber 18/20 HP

  3. Comparative Variable Temperature Studies of Polyamide II with a Benchtop Fourier Transform and a Miniature Handheld Near-Infrared Spectrometer Using 2D-COS and PCMW-2D Analysis.

    PubMed

    Unger, Miriam; Pfeifer, Frank; Siesler, Heinz W

    2016-07-01

    The main objective of this communication is to compare the performance of a miniaturized handheld near-infrared (NIR) spectrometer with a benchtop Fourier transform near-infrared (FT-NIR) spectrometer. Generally, NIR spectroscopy is an extremely powerful analytical tool to study hydrogen-bonding changes of amide functionalities in solid and liquid materials and therefore variable temperature NIR measurements of polyamide II (PAII) have been selected as a case study. The information content of the measurement data has been further enhanced by exploiting the potential of two-dimensional correlation spectroscopy (2D-COS) and the perturbation correlation moving window two-dimensional (PCMW2D) evaluation technique. The data provide valuable insights not only into the changes of the hydrogen-bonding structure and the recrystallization of the hydrocarbon segments of the investigated PAII but also in their sequential order. Furthermore, it has been demonstrated that the 2D-COS and PCMW2D results derived from the spectra measured with the miniaturized NIR instrument are equivalent to the information extracted from the data obtained with the high-performance FT-NIR instrument.

  4. High performance bias-selectable three-color Short-wave/Mid-wave/Long-wave Infrared Photodetectors based on Type-II InAs/GaSb/AlSb superlattices

    PubMed Central

    Hoang, Anh Minh; Dehzangi, Arash; Adhikary, Sourav; Razeghi, Manijeh

    2016-01-01

    We propose a new approach in device architecture to realize bias-selectable three-color shortwave-midwave-longwave infrared photodetectors based on InAs/GaSb/AlSb type-II superlattices. The effect of conduction band off-set and different doping levels between two absorption layers are employed to control the turn-on voltage for individual channels. The optimization of these parameters leads to a successful separation of operation regimes; we demonstrate experimentally three-color photodiodes without using additional terminal contacts. As the applied bias voltage varies, the photodiodes exhibit sequentially the behavior of three different colors, corresponding to the bandgap of three absorbers. Well defined cut-offs and high quantum efficiency in each channel are achieved. Such all-in-one devices also provide the versatility of working as single or dual-band photodetectors at high operating temperature. With this design, by retaining the simplicity in device fabrication, this demonstration opens the prospect for three-color infrared imaging. PMID:27051979

  5. Vibrational spectroscopy of water in hydrated lipid multi-bilayers. II. Two-dimensional infrared and peak shift observables within different theoretical approximations.

    PubMed

    Gruenbaum, Scott M; Pieniazek, Piotr A; Skinner, J L

    2011-10-28

    In a previous report, we calculated the infrared absorption spectrum and both the isotropic and anisotropic pump-probe signals for the OD stretch of isotopically dilute water in dilauroylphosphatidylcholine (DLPC) multi-bilayers as a function of the lipid hydration level. These results were then compared to recent experimental measurements and are in generally good agreement. In this paper, we will further investigate the structure and dynamics of hydration water using molecular dynamics simulations and calculations of the two-dimensional infrared and vibrational echo peak shift observables for hydration water in DLPC membranes. These observables have not yet been measured experimentally, but future comparisons may provide insight into spectral diffusion processes and hydration water heterogeneity. We find that at low hydration levels the motion of water molecules inside the lipid membrane is significantly arrested, resulting in very slow spectral diffusion. At higher hydration levels, spectral diffusion is more rapid, but still slower than in bulk water. We also investigate the effects of several common approximations on the calculation of spectroscopic observables by computing these observables within multiple levels of theory. The impact of these approximations on the resulting spectra affects our interpretation of these measurements and reveals that, for example, the cumulant approximation, which may be valid for certain systems, is not a good approximation for a highly heterogeneous environment such as hydration water in lipid multi-bilayers.

  6. SPATIALLY RESOLVED [Fe II] 1.64 {mu}m EMISSION IN NGC 5135: CLUES FOR UNDERSTANDING THE ORIGIN OF THE HARD X-RAYS IN LUMINOUS INFRARED GALAXIES

    SciTech Connect

    Colina, L.; Pereira-Santaella, M.; Alonso-Herrero, A.; Arribas, S.; Bedregal, A. G.

    2012-04-20

    Spatially resolved near-IR and X-ray imaging of the central region of the luminous infrared galaxy (LIRG) NGC 5135 is presented. The kinematical signatures of strong outflows are detected in the [Fe II] 1.64 {mu}m emission line in a compact region at 0.9 kpc from the nucleus. The derived mechanical energy release is consistent with a supernova rate of 0.05-0.1 yr{sup -1}. The apex of the outflowing gas spatially coincides with the strongest [Fe II] emission peak and with the dominant component of the extranuclear hard X-ray emission. All these features provide evidence for a plausible direct physical link between supernova-driven outflows and the hard X-ray emitting gas in an LIRG. This result is consistent with model predictions of starbursts concentrated in small volumes and with high thermalization efficiencies. A single high-mass X-ray binary (HMXB) as the major source of the hard X-ray emission, although not favored, cannot be ruled out. Outside the active galactic nucleus, the hard X-ray emission in NGC 5135 appears to be dominated by the hot interstellar medium produced by supernova explosions in a compact star-forming region, and not by the emission due to HMXBs. If this scenario is common to (ultra)luminous infrared galaxies, the hard X-rays would only trace the most compact ({<=}100 pc) regions with high supernova and star formation densities, therefore a lower limit to their integrated star formation. The star formation rate derived in NGC 5135 based on its hard X-ray luminosity is a factor of two and four lower than the values obtained from the 24 {mu}m and soft X-ray luminosities, respectively.

  7. On the origin of [Ne II] emission in young stars: mid-infrared and optical observations with the Very Large Telescope

    NASA Astrophysics Data System (ADS)

    Baldovin-Saavedra, C.; Audard, M.; Carmona, A.; Güdel, M.; Briggs, K.; Rebull, L. M.; Skinner, S. L.; Ercolano, B.

    2012-07-01

    Context. The [Ne II] line 12.81 μm was proposed to be a good tracer of gas in the environments of proto-planetary disks; its origin is explained by different mechanisms: jets in outflows, photo-evaporative disk winds driven by stellar X-rays/EUV or by the X-ray irradiated proto-planetary disk atmosphere. Previous Spitzer studies gave hints toward the neon emitting mechanism by exploring correlations between the line luminosity and properties of the star-disk system. These studies concluded that the origin of the emission is likely related to accretion and outflows, with some influence from X-rays. Aims: We provide direct constraints on the origin of the [Ne II] emission using high-spatial and spectral resolution observations that allow us to study the kinematics of the emitting gas. In addition we compare the [Ne II] line with optical forbidden lines. Methods: We obtained high-resolution ground-based observations with VISIR-VLT for 15 stars and UVES-VLT for three of them. The stars were chosen for having bright neon emission lines detected with Spitzer/IRS. The velocity shifts and profiles are used to disentangle the different emitting mechanisms producing the [Ne II] line. A comparison between results from this study and previous high-resolution studies is also presented. Results: The [Ne II] line was detected in seven stars, among them the first confirmed detection of [Ne II] in a Herbig Be star, V892 Tau. In four cases, the large blueshifted lines indicate an origin in a jet. In two stars, the small shifts and asymmetric profiles indicate an origin in a photo-evaporative wind. CoKu Tau 1, seen close to edge-on, shows a spatially unresolved line centered at the stellar rest velocity, although cross-dispersion centroids move within 10 AU from one side of the star to the other as a function of wavelength. The line profile is symmetric with wings extending up to ~±80 km s-1. The origin of the [Ne II] line is unclear and could either be due to the bipolar jet or to

  8. The UDF05 Follow-up of the HUDF: I. The Faint-End Slope of the Lyman-Break Galaxy Population at zeta approx. 5

    NASA Technical Reports Server (NTRS)

    Oesch, P. A.; Stiavelli, M.; Carollo, C. M.; Bergeron, L. E.; Koekemoer, A.; Lucas, R. A.; Pavlovsky, C. M.; Trenti, M.; Lilly, S. J.; Beckwith, S. V. W.; Dahlen, T.; Ferguson, H. C.; Gardner, J. P.; Lacey, C.; Mobasher, B.; Panagia, N.; Rix, H.-W.

    2007-01-01

    We present the UDF05 project, a HST Large Program of deep ACS (F606W, F775W, F850LP, and NICMOS (Fll0W, Fl60W) imaging of three fields, two of which coincide with the NICP1-4 NICMOS parallel observations of the Hubble Ultra Deep Field (HUDF). In this first paper we use the ACS data for the NICP12 field, as well as the original HUDF ACS data, to measure the UV Luminosity Function (LF) of z approximately 5 Lyman Break Galaxies (LBGs) down to very faint levels. Specifically, based on a V - i, i - z selection criterion, we identify a sample of 101 and 133 candidate z approximately 5 galaxies down to z(sub 850) = 28.5 and 29.25 magnitudes in the NICP12 field and in the HUDF, respectively. Using an extensive set of Monte Carlo simulations we derive corrections for observational biases and selection effects, and construct the rest-frame 1400 Angstroms LBG LF over the range M(sub 1400) = [-22.2, -17.1], i.e. down to approximately 0.04 L(sub *) at z = 5. We show that: (i) Different assumptions for the SED distribution of the LBG population, dust properties and intergalactic absorption result in a 25% variation in the number density of LBGs at z = 5 (ii) Under consistent assumptions for dust properties and intergalactic absorption, the HUDF is about 30% under-dense in z = 5 LBGs relative to the NICP12 field, a variation which is well explained by cosmic variance; (iii) The faint-end slope of the LF is independent of the specific assumptions for the input physical parameters, and has a value of alpha approximately -1.6, similar to the faint-end slope of the LF that has been measured for LBGs at z = 3 and z = 6. Our study therefore supports no variation in the faint-end of the LBG LF over the whole redshift range z = 3 to z = 6. The comparison with theoretical predictions suggests that (a,) the majority of the stars in the z = 5 LBG population are produced with a Top-Heavy IMF in merger-driven starbursts, and that (b) possibly, either the fraction of stellar mass produced in

  9. THE EVOLUTION OF THE REST-FRAME V-BAND LUMINOSITY FUNCTION FROM z = 4: A CONSTANT FAINT-END SLOPE OVER THE LAST 12 Gyr OF COSMIC HISTORY

    SciTech Connect

    Marchesini, Danilo; Stefanon, Mauro; Whitaker, Katherine E.

    2012-04-01

    We present the rest-frame V-band luminosity function (LF) of galaxies at 0.4 {<=} z < 4.0, measured from a near-infrared selected sample constructed from the NMBS, the FIRES, the FIREWORKS, and the ultra-deep NICMOS and WFC3 observations in the HDFN, HUDF, and GOODS-CDFS, all having high-quality optical-to-mid-infrared data. This unique sample combines data from surveys with a large range of depths and areas in a self-consistent way, allowing us to (1) minimize the uncertainties due to cosmic variance; and (2) simultaneously constrain the bright and faint ends with unprecedented accuracy over the targeted redshift range, probing the LF down to 0.1L* at z {approx} 3.9. We find that (1) the faint end is fairly flat and with a constant slope from z = 4, with {alpha} = -1.27 {+-} 0.05; (2) the characteristic magnitude has dimmed by 1.3 mag from z {approx} 3.7 to z = 0.1; (3) the characteristic density has increased by a factor of {approx}8 from z {approx} 3.7 to z = 0.1, with 50% of this increase from z {approx} 4 to z {approx} 1.8; and (4) the luminosity density peaks at z Almost-Equal-To 1-1.5, increasing by a factor of {approx}4 from z = 4.0 to z Almost-Equal-To 1-1.5, and subsequently decreasing by a factor of {approx}1.5 by z = 0.1. We find no evidence for a steepening of the faint-end slope with redshift out to z = 4, in contrast with previous observational claims and theoretical predictions. The constant faint-end slope suggests that the efficiency of stellar feedback may evolve with redshift. Alternative interpretations are discussed, such as different masses of the halos hosting faint galaxies at low and high redshifts and/or environmental effects.

  10. A Hero’s Dark Horse: Discovery of an Ultra-faint Milky Way Satellite in Pegasus

    NASA Astrophysics Data System (ADS)

    Kim, Dongwon; Jerjen, Helmut; Mackey, Dougal; Da Costa, Gary S.; Milone, Antonino P.

    2015-05-01

    We report the discovery of an ultra-faint Milky Way satellite galaxy in the constellation of Pegasus. The concentration of stars was detected by applying our overdensity detection algorithm to the SDSS-DR 10 and confirmed with deeper photometry from the Dark Energy Camera at the 4 m Blanco telescope. Fitting model isochrones indicates that this object, Pegasus III, features an old and metal-poor stellar population ([Fe/H] ˜ -2.1) at a heliocentric distance of 205 ± 20 kpc. The new stellar system has an estimated half-light radius of {{r}h}=78-24+30 pc and a total luminosity of {{M}V}˜ -4.1+/- 0.5 that places it into the domain of dwarf galaxies on the size-luminosity plane. Pegasus III is spatially close to the MW satellite Pisces II. It is possible that the two might be physically associated, similar to the Leo IV and Leo V pair. Pegasus III is also well aligned with the Vast Polar Structure, which suggests a possible physical association.

  11. THE SUBARU HIGH-z QUASAR SURVEY: DISCOVERY OF FAINT z ∼ 6 QUASARS

    SciTech Connect

    Kashikawa, Nobunari; Furusawa, Hisanori; Niino, Yuu; Ishizaki, Yoshifumi; Onoue, Masafusa; Toshikawa, Jun; Ishikawa, Shogo; Willott, Chris J.; Im, Myungshin; Shimasaku, Kazuhiro; Ouchi, Masami; Hibon, Pascale

    2015-01-01

    We present the discovery of one or two extremely faint z ∼ 6 quasars in 6.5 deg{sup 2} utilizing a unique capability of the wide-field imaging of the Subaru/Suprime-Cam. The quasar selection was made in (i'-z{sub B} ) and (z{sub B} -z{sub R} ) colors, where z{sub B} and z{sub R} are bandpasses with central wavelengths of 8842 Å and 9841 Å, respectively. The color selection can effectively isolate quasars at z ∼ 6 from M/L/T dwarfs without the J-band photometry down to z{sub R} < 24.0, which is 3.5 mag deeper than the Sloan Digital Sky Survey (SDSS). We have selected 17 promising quasar candidates. The follow-up spectroscopy for seven targets identified one apparent quasar at z = 6.156 with M {sub 1450} = –23.10. We also identified one possible quasar at z = 6.041 with a faint continuum of M {sub 1450} = –22.58 and a narrow Lyα emission with HWHM =427 km s{sup –1}, which cannot be distinguished from Lyman α emitters. We derive the quasar luminosity function at z ∼ 6 by combining our faint quasar sample with the bright quasar samples by SDSS and CFHQS. Including our data points invokes a higher number density in the faintest bin of the quasar luminosity function than the previous estimate employed. This suggests a steeper faint-end slope than lower z, though it is yet uncertain based on a small number of spectroscopically identified faint quasars, and several quasar candidates still remain to be diagnosed. The steepening of the quasar luminosity function at the faint end does increase the expected emission rate of the ionizing photon; however, it only changes by a factor of approximately two to six. This was found to still be insufficient for the required photon budget of reionization at z ∼ 6.

  12. MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THE WIDE-FIELD INFRARED SURVEY EXPLORER. II. PROPERTIES OF WISE-SELECTED ACTIVE GALACTIC NUCLEI IN THE NDWFS BOOeTES FIELD

    SciTech Connect

    Assef, R. J.; Stern, D.; Eisenhardt, P. R. M.; Tsai, C.-W.; Kochanek, C. S.; Blain, A. W.; Brodwin, M.; Brown, M. J. I.; Donoso, E.; Jarrett, T. H.; Yan, L.; Jannuzi, B. T.; Stanford, S. A.; Wu, J.

    2013-07-20

    Stern et al. presented a study of Wide-field Infrared Survey Explorer (WISE) selection of active galactic nuclei (AGNs) in the 2 deg{sup 2} COSMOS field, finding that a simple criterion W1-W2 {>=} 0.8 provides a highly reliable and complete AGN sample for W2 < 15.05, where the W1 and W2 passbands are centered at 3.4 {mu}m and 4.6 {mu}m, respectively. Here we extend this study using the larger 9 deg{sup 2} NOAO Deep Wide-Field Survey Booetes field which also has considerably deeper WISE observations than the COSMOS field, and find that this simple color cut significantly loses reliability at fainter fluxes. We define a modified selection criterion combining the W1-W2 color and the W2 magnitude to provide highly reliable or highly complete AGN samples for fainter WISE sources. In particular, we define a color-magnitude cut that finds 130 {+-} 4 deg{sup -2} AGN candidates for W2 < 17.11 with 90% reliability. Using the extensive UV through mid-IR broadband photometry available in this field, we study the spectral energy distributions of WISE AGN candidates. We find that, as expected, the WISE AGN selection can identify highly obscured AGNs, but that it is biased toward objects where the AGN dominates the bolometric luminosity output. We study the distribution of reddening in the AGN sample and discuss a formalism to account for sample incompleteness based on the step-wise maximum-likelihood method of Efstathiou et al. The resulting dust obscuration distributions depend strongly on AGN luminosity, consistent with the trend expected for a receding torus. At L{sub AGN} {approx} 3 Multiplication-Sign 10{sup 44} erg s{sup -1}, 29% {+-} 7% of AGNs are observed as Type 1, while at {approx}4 Multiplication-Sign 10{sup 45} erg s{sup -1} the fraction is 64% {+-} 13%. The distribution of obscuration values suggests that dust in the torus is present as both a diffuse medium and in optically thick clouds.

  13. HERSCHEL/PACS SURVEY OF PROTOPLANETARY DISKS IN TAURUS/AURIGA—OBSERVATIONS OF [O I] AND [C II], AND FAR-INFRARED CONTINUUM

    SciTech Connect

    Howard, Christian D.; Sandell, Göran; Vacca, William D.; Duchêne, Gaspard; Mathews, Geoffrey; Augereau, Jean-Charles; Ménard, Francois; Pinte, Christophe; Podio, Linda; Thi, Wing-Fai; Dent, William R. F.; Eiroa, Carlos; Meeus, Gwendolyn; Grady, Carol; Roberge, Aki; Kamp, Inga; Vicente, Silvia; Williams, Jonathan P.

    2013-10-10

    The Herschel Space Observatory was used to observe ∼120 pre-main-sequence stars in Taurus as part of the GASPS Open Time Key project. Photodetector Array Camera and Spectrometer was used to measure the continuum as well as several gas tracers such as [O I] 63 μm, [O I] 145 μm, [C II] 158 μm, OH, H{sub 2}O, and CO. The strongest line seen is [O I] at 63 μm. We find a clear correlation between the strength of the [O I] 63 μm line and the 63 μm continuum for disk sources. In outflow sources, the line emission can be up to 20 times stronger than in disk sources, suggesting that the line emission is dominated by the outflow. The tight correlation seen for disk sources suggests that the emission arises from the inner disk (<50 AU) and lower surface layers of the disk where the gas and dust are coupled. The [O I] 63 μm is fainter in transitional stars than in normal Class II disks. Simple spectral energy distribution models indicate that the dust responsible for the continuum emission is colder in these disks, leading to weaker line emission. [C II] 158 μm emission is only detected in strong outflow sources. The observed line ratios of [O I] 63 μm to [O I] 145 μm are in the regime where we are insensitive to the gas-to-dust ratio, neither can we discriminate between shock or photodissociation region emission. We detect no Class III object in [O I] 63 μm and only three in continuum, at least one of which is a candidate debris disk.

  14. Herschel - PACS Survey Of Protoplanetary Disks In Taurus - Auriga Observations Of [O I] And [C Ii], And Far-Infrared Continuum

    NASA Technical Reports Server (NTRS)

    Howard, Christian; Sandell, Goeran; Vacca, William D.; Duchene, Gaspard; Matthews, Geoffrey; Augereau, Jean-Charles; Barbado, David; Dent, William R. F.; Eiroa, Carlos; Grady, Carol; Kamp, Inga; Meeus, Gwendolyn; Menard, Francois; Pinte, Christophe; Podio, Linda; Riviere-Marichalar, Pablo; Roberge, Aki; Thi,, Wing-Fai; Vicente, Silvia; Williams, Jonathan P.

    2013-01-01

    The Herschel Space Observatory was used to observe approx. 120 pre-main-sequence stars in Taurus as part of the GASPS Open Time Key project. Photodetector Array Camera and Spectrometer was used to measure the continuum as well as several gas tracers such as [O I] 63 micron, [O I] 145 micron, [C II] 158, micron OH, H2O, and CO. The strongest line seen is [O I] at 63 micron. We find a clear correlation between the strength of the [O I] 63 micron line and the 63 micron continuum for disk sources. In outflow sources, the line emission can be up to 20 times stronger than in disk sources, suggesting that the line emission is dominated by the outflow. The tight correlation seen for disk sources suggests that the emission arises from the inner disk (<50 AU) and lower surface layers of the disk where the gas and dust are coupled. The [O I] 63 micron is fainter in transitional stars than in normal Class II disks. Simple spectral energy distribution models indicate that the dust responsible for the continuum emission is colder in these disks, leading to weaker line emission. [C II] 158 micron emission is only detected in strong outflow sources. The observed line ratios of [O I] 63 micron to [O I] 145 micron are in the regime where we are insensitive to the gas-to-dust ratio, neither can we discriminate between shock or photodissociation region emission. We detect no Class III object in [O I] 63 micron and only three in continuum, at least one of which is a candidate debris disk.

  15. Why Infrared?

    ERIC Educational Resources Information Center

    Harris, J. R.

    1973-01-01

    Discusses applications of techniques developed for the remote sensing of infrared radiation. In addition to military applications, remote sensing has become important in collecting environmental data and detecting ecological problems. (JR)

  16. Surface Forcing of the Infrared Cooling Profile over the Tibetan Plateau. Part II: Cooling-Rate Variation over Large-Scale Plateau Domain during Summer Monsoon Transition.

    NASA Astrophysics Data System (ADS)

    Shi, Lei; Smith, Eric A.

    1992-05-01

    During the summer east Asian monsoon transition period in 1979, a meteorological field experiment entitled the Qinghai-Xizang Plateau Meteorological Experiment (QXPMEX-79) was conducted over the entire Tibetan Plateau. Data collected on and around the plateau during this period, in conjunction with a medium spectral-resolution infrared radiative transfer model, are used to gain an understanding of how elevation and surface biophysical factors, which are highly variable over the large-scale plateau domain, regulate the spatial distribution of clear-sky infrared cooling during the transition phase of the summer monsoon.The spatial distribution of longwave cooling over the plateau is significantly influenced by variations in biophysical composition, topography, and elevation, the surface thermal diurnal cycle, and various climatological factors. An important factor is soil moisture. Bulk clear-sky longwave cooling rates are larger in the southeast sector of the plateau than in the north. This is because rainfall is greatest in the southeast, whereas the north is highly desertified and relative longwave radiative heating by the surface is greatest. Another important phenomenon is that the locale of a large-scale east-west-aligned spatial gradient in radiative cooling propagates northward with time. During the premonsoon period (May-June), the location of the strong spatial gradient is found in the southeastern margin of the plateau. Due to changes in surface and atmospheric conditions after the summer monsoon commences, the high gradient sector is shifted to the central Qinghai region. Furthermore, an overall decrease in longwave cooling takes place in the lower atmosphere immediately prior to the arrival of the active monsoon.The magnitude of longwave cooling is significantly affected by skin-temperature boundary conditions at plateau altitudes. If skin-temperature discontinuities across the surface-atmosphere interface are neglected, bulk cooling rates will be in

  17. CRIRES-POP: a library of high resolution spectra in the near-infrared. II. Data reduction and the spectrum of the K giant 10 Leonis

    NASA Astrophysics Data System (ADS)

    Nicholls, C. P.; Lebzelter, T.; Smette, A.; Wolff, B.; Hartman, H.; Käufl, H.-U.; Przybilla, N.; Ramsay, S.; Uttenthaler, S.; Wahlgren, G. M.; Bagnulo, S.; Hussain, G. A. J.; Nieva, M.-F.; Seemann, U.; Seifahrt, A.

    2017-02-01

    Context. High resolution stellar spectral atlases are valuable resources to astronomy. They are rare in the 1-5 μm region for historical reasons, but once available, high resolution atlases in this part of the spectrum will aid the study of a wide range of astrophysical phenomena. Aims: The aim of the CRIRES-POP project is to produce a high resolution near-infrared spectral library of stars across the H-R diagram. The aim of this paper is to present the fully reduced spectrum of the K giant 10 Leo that will form the basis of the first atlas within the CRIRES-POP library, to provide a full description of the data reduction processes involved, and to provide an update on the CRIRES-POP project. Methods: All CRIRES-POP targets were observed with almost 200 different observational settings of CRIRES on the ESO Very Large Telescope, resulting in a basically complete coverage of its spectral range as accessible from the ground. We reduced the spectra of 10 Leo with the CRIRES pipeline, corrected the wavelength solution and removed telluric absorption with Molecfit, then resampled the spectra to a common wavelength scale, shifted them to rest wavelengths, flux normalised, and median combined them into one final data product. Results: We present the fully reduced, high resolution, near-infrared spectrum of 10 Leo. This is also the first complete spectrum from the CRIRES instrument. The spectrum is available online. Conclusions: The first CRIRES-POP spectrum has exceeded our quality expectations and will form the centre of a state-of-the-art stellar atlas. This first CRIRES-POP atlas will soon be available, and further atlases will follow. All CRIRES-POP data products will be freely and publicly available online. The spectrum is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/598/A79

  18. Strongly lensed gravitational waves from intrinsically faint double compact binaries—prediction for the Einstein Telescope

    SciTech Connect

    Ding, Xuheng; Biesiada, Marek; Zhu, Zong-Hong E-mail: marek.biesiada@us.edu.pl

    2015-12-01

    With a fantastic sensitivity improving significantly over the advanced GW detectors, Einstein Telescope (ET) will be able to observe hundreds of thousand inspiralling double compact objects per year. By virtue of gravitational lensing effect, intrinsically unobservable faint sources can be observed by ET due to the magnification by intervening galaxies. We explore the possibility of observing such faint sources amplified by strong gravitational lensing. Following our previous work, we use the merger rates of DCO (NS-NS,BH-NS,BH-BH systems) as calculated by Dominik et al.(2013). It turns out that tens to hundreds of such (lensed) extra events will be registered by ET. This will strongly broaden the ET's distance reach for signals from such coalescences to the redshift range z = 2 − 8. However, with respect to the full inspiral event catalog this magnification bias is at the level of 0.001 and should not affect much cosmological inferences.

  19. Hubble Space Telescope Faint Object Camera calculated point-spread functions.

    PubMed

    Lyon, R G; Dorband, J E; Hollis, J M

    1997-03-10

    A set of observed noisy Hubble Space Telescope Faint Object Camera point-spread functions is used to recover the combined Hubble and Faint Object Camera wave-front error. The low-spatial-frequency wave-front error is parameterized in terms of a set of 32 annular Zernike polynomials. The midlevel and higher spatial frequencies are parameterized in terms of set of 891 polar-Fourier polynomials. The parameterized wave-front error is used to generate accurate calculated point-spread functions, both pre- and post-COSTAR (corrective optics space telescope axial replacement), suitable for image restoration at arbitrary wavelengths. We describe the phase-retrieval-based recovery process and the phase parameterization. Resultant calculated precorrection and postcorrection point-spread functions are shown along with an estimate of both pre- and post-COSTAR spherical aberration.

  20. The Ultra-Faint Dwarfs: Fossils From the Epoch of Reionization?

    NASA Astrophysics Data System (ADS)

    Simon, Josh

    2013-02-01

    We propose to obtain larger samples of spectroscopic metallicity measurements in six ultra-faint dwarf galaxies in order to discern any cosmologically-driven synchronization of their formation histories. Combined with our deep HST photometry of the same galaxies, these data will enable us to measure the age of each galaxy to ~200 Myr. Hierarchical galaxy formation models predict that the ultra-faint dwarfs formed their stars before reionization. We will test whether suppression of star formation in low-mass halos by reionization could be responsible for the missing satellite problem. We will also place improved constraints on the dark matter content of UFDs and search for the most metal-poor stars ever found beyond the Milky Way.

  1. A comparison of photon counting and current measuring techniques in spectrophotometry of faint sources.

    PubMed

    Tull, R G

    1968-10-01

    The component of dark noise produced by Cerenkov pulses in photomultipliers due to cosmic ray mu mesons is discussed. It is shown by integration of pulse height spectra that this source of noise can be the limiting factor in de measuring spectrophotometry of faint astronomical sources. Direct current methods of photometry are compared with photon counting, and the advantage of photon counting is demonstrated under various operating conditions.

  2. Faint Radio Sources in the NOAO Bootes Field. VLBA Imaging And Optical Identifications

    SciTech Connect

    Wrobel, J.M.; Taylor, Greg B.; Rector, T.A.; Myers, S.T.; Fassnacht, C.D.; /UC, Davis

    2005-06-13

    As a step toward investigating the parsec-scale properties of faint extragalactic radio sources, the Very Long Baseline Array (VLBA) was used at 5.0 GHz to obtain phase-referenced images of 76 sources in the NOAO Booetes field. These 76 sources were selected from the FIRST catalog to have peak flux densities above 10 mJy at 5'' resolution and deconvolved major diameters of less than 3'' at 1.4 GHz. Fifty-five of these faint radio sources were identified with accretion-powered radio galaxies and quasars brighter than 25.5 mag in the optical I band. On VLA scales at 1.4 GHz, a measure of the compactness of the faint sources (the ratio of the peak flux density from FIRST to the integrated flux density from the NVSS catalog) spans the full range of possibilities arising from source-resolution effects. Thirty of the faint radio sources, or 39{sub -7}{sup +9}%, were detected with the VLBA at 5.0 GHz with peak flux densities above 6 {sigma} {approx} 2 mJy at 2 mas resolution. The VLBA detections occur through the full range of compactness ratios. The stronger VLBA detections can themselves serve as phase-reference calibrators, boding well for opening up much of the radio sky to VLBA imaging. For the adopted cosmology, the VLBA resolution corresponds to 17 pc or finer. Most VLBA detections are unresolved or slightly resolved but one is diffuse and five show either double or core-jet structures; the properties of these latter six are discussed in detail. Eight VLBA detections are unidentified and fainter than 25.5 mag in the optical I band; their properties are highlighted because they likely mark optically-obscured active nuclei at high redshift.

  3. On the faint-end of the high-z galaxy luminosity function

    NASA Astrophysics Data System (ADS)

    Yue, Bin; Ferrara, Andrea; Xu, Yidong

    2016-12-01

    Recent measurements of the luminosity function (LF) of galaxies in the Epoch of Reionization (EoR, z ≳ 6) indicate a very steep increase of the number density of low-mass galaxies populating the LF faint-end. However, as star formation in low-mass haloes can be easily depressed or even quenched by ionizing radiation, a turnover is expected at some faint UV magnitudes. Using a physically motivated analytical model, we quantify reionization feedback effects on the LF faint-end shape. We find that if reionization feedback is neglected, the power-law Schechter parametrization characterizing the LF faint-end remains valid up to absolute UV magnitude ˜-9. If instead radiative feedback is strong enough that quenches star formation in haloes with circular velocity smaller than 50 km s-1, the LF starts to drop at absolute UV magnitude ˜-15, i.e. slightly below the detection limits of current (unlensed) surveys at z ˜ 5. The LFs may rise again at higher absolute UV magnitude, where, as a result of interplay between reionization process and galaxy formation, most of the galaxy light is from relic stars formed before the EoR. We suggest that the galaxy number counts data, particularly in lensed fields, can put strong constraints on reionization feedback. In models with stronger reionization feedback, stars in galaxies with absolute UV magnitude higher than ˜-13 and smaller than ˜-8 are typically older. Hence, the stellar age-UV magnitude relation can be used as an alternative feedback probe.

  4. Eight ultra-faint galaxy candidates discovered in year two of the Dark Energy Survey

    SciTech Connect

    Drlica-Wagner, A.

    2015-11-04

    We report the discovery of eight new ultra-faint dwarf galaxy candidates in the second year of optical imaging data from the Dark Energy Survey (DES). Six of these candidates are detected at high confidence, while two lower-confidence candidates are identified in regions of non-uniform survey coverage. The new stellar systems are found by three independent automated search techniques and are identified as overdensities of stars, consistent with the isochrone and luminosity function of an old and metal-poor simple stellar population. The new systems are faint (MV > -4.7 ) and span a range of physical sizes (17 pc < r1/2 < 181pc) and heliocentric distances (25 kpc < D < 214 kpc). All of the new systems have central surface brightnesses consistent with known ultra-faint dwarf galaxies (μ 27.5 mag arcsec -2). Roughly half of the DES candidates are more distant, less luminous, and/or have lower surface brightnesses than previously known Milky Way satellite galaxies. Most of the candidates are found in the southern part of the DES footprint close to the Magellanic Clouds. We find that the DES data alone exclude (p < 10-3) a spatially isotropic distribution of Milky Way satellites and that the observed distribution can be well, though not uniquely, described by an association between several of the DES satellites and the Magellanic system. Furthermore, our model predicts that the full sky may hold ~100 ultra-faint galaxies with physical properties comparable to the DES satellites and that 20%–30% of these would be spatially associated with the Magellanic Clouds.

  5. Blind Search of Faint Moving Objects in 3D Data Sets

    DTIC Science & Technology

    2013-09-01

    Blind Search of Faint Moving Objects in 3D Data Sets Phan Dao*, Peter Crabtree and Patrick McNicholl AFRL/RVBYC Tamar Payne Applied...using a simulated object signature superimposed on measured background, and show that the limiting magnitude can be improved by up to 6 visual...magnitudes. A quasi blind search algorithm that identifies the streak of photons, assuming no prior knowledge of orbital information, will be discussed

  6. Astrometric Observations of the Faint Outer Satellites of Jupiter During the 1994 and 1995 Oppositions

    NASA Astrophysics Data System (ADS)

    Whipple, Arthur L.; Shelus, Peter J.; Whited, Randy W.; Cochran, Anita L.; MacQueen, Phillip J.; Benedict, George F.

    1996-07-01

    We present astrometric positions for the faint outer satellites of Jupiter VI-XIII during the 1994 and 1995 oppositions. These positions have been obtained from measurements of photographic plates taken with the 2.1 m Otto Struve reflector and from wide field CCD frames taken with the 0.76 m reflector. Both telescopes are located at McDonald Observatory. The new CCD-based instrumentation and astrometric reduction system is described.

  7. Astrometric observations of the faint satellites of Jupiter and minor planets, 1974-1977

    NASA Technical Reports Server (NTRS)

    Benedict, G. R.; Shelus, P. J.; Mulholland, J. D.

    1978-01-01

    Precise positions of the faint satellites VI-XII of Jupiter during the 1974 opposition, and for Jupiter XIII during the 1976-1977 and 1977-1978 oppositions, have been obtained from plates taken with the 2.1-m Otto Struve reflector of the McDonald Observatory by the use of a new quasi-automatic plate measurement and reduction procedure on a PDS microdensitometer. Observations of selected asteroids, including two of 1977 UB (Chiron) are given also.

  8. Eight ultra-faint galaxy candidates discovered in year two of the Dark Energy Survey

    DOE PAGES

    Drlica-Wagner, A.

    2015-11-04

    We report the discovery of eight new ultra-faint dwarf galaxy candidates in the second year of optical imaging data from the Dark Energy Survey (DES). Six of these candidates are detected at high confidence, while two lower-confidence candidates are identified in regions of non-uniform survey coverage. The new stellar systems are found by three independent automated search techniques and are identified as overdensities of stars, consistent with the isochrone and luminosity function of an old and metal-poor simple stellar population. The new systems are faint (MV > -4.7 ) and span a range of physical sizes (17 pc < r1/2more » < 181pc) and heliocentric distances (25 kpc < D⊙ < 214 kpc). All of the new systems have central surface brightnesses consistent with known ultra-faint dwarf galaxies (μ 27.5 mag arcsec -2). Roughly half of the DES candidates are more distant, less luminous, and/or have lower surface brightnesses than previously known Milky Way satellite galaxies. Most of the candidates are found in the southern part of the DES footprint close to the Magellanic Clouds. We find that the DES data alone exclude (p < 10-3) a spatially isotropic distribution of Milky Way satellites and that the observed distribution can be well, though not uniquely, described by an association between several of the DES satellites and the Magellanic system. Furthermore, our model predicts that the full sky may hold ~100 ultra-faint galaxies with physical properties comparable to the DES satellites and that 20%–30% of these would be spatially associated with the Magellanic Clouds.« less

  9. Isotope effects in liquid water by infrared spectroscopy. II. Factor analysis of the temperature effect on H2O and D2O

    NASA Astrophysics Data System (ADS)

    Larouche, Pascal; Max, Jean-Joseph; Chapados, Camille

    2008-08-01

    Some 500 infrared (IR) spectra of light and heavy waters were obtained between 29 and 93 °C in order to identify the species present in liquid water. Factor analysis of these gives two species for each type of water with their IR spectra and abundance curves. Using an orthogonalization procedure, we obtained the temperature factor limits of -22 and +118 °C (+/-5 °C) that we coined cold and hot factors, respectively. Within experimental error, these limits are the same for light and heavy waters. The spectra of the orthogonalized factors presented show a decrease of the OH (OD) stretch band integrated intensities of almost 36% from the cold to the hot factors. No ``free'' OH (OD) group is present or formed in the temperature ramp. This indicates that all water molecules in the bulk are made of an oxygen atom surrounded with four hydrogen atoms, two covalently bonded, and two hydrogen bonded. This is consistent with the previous study of mixtures of H2O and D2O [part I: J.-J. Max and C. Chapados, J. Chem. Phys. 116, 4626 (2002)]. To maintain the ordinary liquid within the limits of 0 and 100 °C at atmospheric pressure, a fraction of the cold and hot factors are necessary. With the spectra of the cold and hot factors and the abundance curves, one can generate the spectrum at any temperature between -22 and +118 °C of light and heavy liquid waters.

  10. Calibration of HST wide field camera for quantitative analysis of faint galaxy images

    NASA Technical Reports Server (NTRS)

    Ratnatunga, Kavan U.; Griffiths, Richard E.; Casertano, Stefano; Neuschaefer, Lyman W.; Wyckoff, Eric W.

    1994-01-01

    We present the methods adopted to optimize the calibration of images obtained with the Hubble Space Telescope (HST) Wide Field Camera (WFC) (1991-1993). Our main goal is to improve quantitative measurement of faint images, with special emphasis on the faint (I approximately 20-24 mag) stars and galaxies observed as a part of the Medium-Deep Survey. Several modifications to the standard calibration procedures have been introduced, including improved bias and dark images, and a new supersky flatfield obtained by combining a large number of relatively object-free Medium-Deep Survey exposures of random fields. The supersky flat has a pixel-to-pixel rms error of about 2.0% in F555W and of 2.4% in F785LP; large-scale variations are smaller than 1% rms. Overall, our modifications improve the quality of faint images with respect to the standard calibration by about a factor of five in photometric accuracy and about 0.3 mag in sensitivity, corresponding to about a factor of two in observing time. The relevant calibration images have been made available to the scientific community.

  11. The morphology of faint galaxies in Medium Deep Survey images using WFPC2

    NASA Technical Reports Server (NTRS)

    Griffiths, R. E.; Casertano, S.; Ratnatunga, K. U.; Neuschaefer, L. W.; Ellis, R. S.; Gilmore, G. F.; Glazebrook, K.; Santiago, B.; Huchra, J. P.; Windhorst, R. A.

    1994-01-01

    First results from Hubble Space Telescope (HST) Medium Deep Survey images taken with Wide Field/Planetary Camera-2 (WFPC2) demonstrate that galaxy classifications can be reliably performed to magnitudes I814 approximately less than 22.0 in the F815W band. Published spectroscopic surveys to this depth indicate a mean redshift of bar-z approximately 0.5. We have classified over 200 galaxies in nine WFPC2 fields according to a basic morphological scheme. The majority of these faint galaxies appear to be similar to regular Hubble-sequence examples observed at low redshift. To the precision of our classification scheme, the relative proportion of spheroidal and disk systems of normal appearance is as expected from nearby samples, indicating that the bulk of the local galaxy population was in place at half the Hubble time. However, the most intriguing result is the relatively high proportion (approximately 40%) of objects which are in some way anomalous, and which may be of relevance in understanding the origin of the familiar excess population of faint galaxies established by others. These diverse objects include apparently interacting pairs whose multiple structure is only revealed with HST's angular resolution, galaxies with superluminous star-forming regions, diffuse low surface brightness galaxies of various forms, and compact galaxies. These anomalous galaxies contribute a substantial fraction of the excess counts at our limiting magnitude, and may provide insights into the 'faint blue galaxy' problem.

  12. Detection of faint BLR components in the starburst/Seyfert galaxy NGC 6221 and measure of the central BH mass

    NASA Astrophysics Data System (ADS)

    La Franca, Fabio; Onori, Francesca; Ricci, Federica; Bianchi, Stefano; Marconi, Alessandro; Sani, Eleonora; Vignali, Cristian

    2016-04-01

    In the last decade, using single epoch virial based techniques in the optical band, it has been possible to measure the central black hole mass on large type 1 Active Galactive Nuclei (AGN) samples. However these measurements use the width of the broad line region as a proxy of the virial velocities and are therefore difficult to be carried out on those obscured (type 2) or low luminosity AGN where the nuclear component does not dominate in the optical. Here we present the optical and near infrared spectrum of the starburst/Seyfert galaxy NGC 6221, observed with X-shooter/VLT. Previous observations of NGC 6221 in the X-ray band shows an absorbed (N_H=8.5 +/- 0.4 x 10^21 cm^-2) spectrum typical of a type 2 AGN with luminosity log(L_14-195/ erg s^-1) = 42.05, while in the optical band its spectrum is typical of a reddened (A_V=3) starburst. Our deep X-shooter/VLT observations have allowed us to detect faint broad emission in the H_alpha, HeI and Pa_beta lines (FWHM=1400-2300 km s^-1) confirming previous studies indicating that NGC 6221 is a reddened starbust galaxy which hosts an AGN. We use the measure of the broad components to provide a first estimate of its central black hole mass (M_BH = 10^6.6+/-0.3 Msol, lambda_Edd=0.01-0.03), obtained using recently calibrated virial relations suitable for moderately obscured (N_H<10^24 cm^-2) AGN.

  13. Synthesis, Infra-red, CP/MAS-NMR characterization, structural study and electrical properties of the bis(4-amino-2-chloropyridinium) tetrachlorozincate (II) monohydrate

    NASA Astrophysics Data System (ADS)

    Karâa, Najla; Hamdi, Besma; Ben Salah, Abdelhamid; Zouari, Ridha

    2013-10-01

    Single crystals of the new ionic salt bis(4-amino-2-chloropyridinium) tetrachlorozincate (II) monohydrate, (C5H6N2Cl)2 ZnCl4ṡH2O, were grown by slow evaporation from aqueous solution at room temperature. The compound was characterized by IR, thermal analysis (TGA-DSC), single crystal X-ray diffraction, CP/MAS-NMR and impedance spectroscopy. The structure (4-amino-2-chloropyridinium)2 ZnCl4·H2O, [(CAP)2ZnCl4·H2O], consists of isolated H2O, isolated [ZnCl4]2- tetrahedral anions and 4-amino-2-chloropyridinium [C5H6N2Cl] + cations, CAP, which are connected together via N-H⋯Cl, N-H⋯O ((N: pyridinium) and (N: amine)), O-H⋯Cl and C-H⋯Cl hydrogen bonds. Cation-cation, offset-face-to-face interactions (π-π stacking) between identical antiparallel CAP (aromatic-aromatic), in which they may be effective in the stabilization of the crystal structure. Solid state CP/MAS-NMR spectra showed five isotropic resonances, 13C, confirming the solid state structure determined by X-ray diffraction. Impedance spectroscopy study, reported for a single crystal, revealed that the conduction in the material was due to a hopping process. This work aims to reveal the thermal properties of a new zinc (II) based organic-inorganic hybrid and the conductivity properties that these compounds exhibit.

  14. A study of ultraviolet absorption lines through the complete Galactic halo by the analysis of HST faint object spectrograph spectra of active Galactic nuclei, 1

    NASA Technical Reports Server (NTRS)

    Burks, Geoffrey S.; Bartko, Frank; Shull, J. Michael; Stocke, John T.; Sachs, Elise R.; Burbidge, E. Margaret; Cohen, Ross D.; Junkkarinen, Vesa T.; Harms, Richard J.; Massa, Derck

    1994-01-01

    The ultraviolet (1150 - 2850 A) spectra of a number of active galactic nuclei (AGNs) observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) have been used to study the properties of the Galactic halo. The objects that served as probes are 3C 273, PKS 0454-220, Pg 1211+143, CSO 251, Ton 951, and PG 1351+640. The equivalent widths of certain interstellar ions have been measured, with special attention paid to the C IV/C II and Si IV/Si II ratios. These ratios have been intercompared, and the highest values are found in the direction of 3C 273, where C IV/C II = 1.2 and Si IV/Si II greater than 1. These high ratios may be due to a nearby supernova remnant, rather than to ionized gas higher up in the Galactic halo. Our data give some support to the notion that QSO metal-line systems may arise from intervening galaxies which contain high supernova rates, galactic fountains, and turbulent mixing layers.

  15. The Dynamic Infrared Sky

    NASA Astrophysics Data System (ADS)

    Kasliwal, Mansi M.; SPIRITS (Spitzer InfraRed Intensive Transients Survey) Team

    2017-01-01

    The dynamic infrared sky is hitherto largely unexplored. I will present the SPitzer InfraRed Intensive Transients Survey (SPIRITS) --- a systematic search of 194 nearby galaxies within 30 Mpc, on timescales ranging between a week to a year, to a depth of 20 mag with Spitzer's IRAC camera. SPIRITS has already uncovered over 95 explosive transients and over 1200 strong variables. Of these, 37 infrared transients are especially interesting as they have no optical counterparts whatsoever even with deep limits from Keck and HST. Interpretation of these new discoveries may include (i) the birth of massive binaries that drive shocks in their molecular cloud, (ii) stellar mergers with dusty winds, (iii) 8--10 solar mass stars experiencing e-capture induced collapse in their cores, (iv) enshrouded supernovae, or (v) formation of stellar mass black holes. SPIRITS reveals that the infrared sky is not just as dynamic as the optical sky; it also provides access to unique, elusive signatures in stellar astrophysics.

  16. Spectroscopic studies of thiatri-, penta- and heptamethine cyanine dyes II. Infrared and resonance Raman spectra of thiatri-, penta- and heptamethine cyanine dyes

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yasuhiko; Katayama, Norihisa; Ozaki, Yukihiro; Yasui, Shigeo; Iriyama, Keiji

    1992-11-01

    Infrared (IR) and resonance Raman (RR) spectra of thiatri-, penta- and heptamethine cyanine dyes in the solid state and in solution have been measured. Most of the intense bands observed in the 1600-1100 cm -1 region of the RR spectra may be assigned to totally symmetric stretching modes of the central conjugated system of the cyanines, while most of the strong IR bands in the 1600-1300 cm -1 region are probably due to antisymmetric stretching modes. The intense RR bands do not have their counterparts in the IR spectra and vice versa. A pseudo-mutual exclusion rule seems to be operative for the cyanine vibrational spectra in the 1600-1300 cm -1 region, indicating that the central conjugated systems of the cyanines have nearly symmetrical structure, i.e. the extended all-trans forms of the methine chains and the bond orders of 1.5 of the CC and CN bonds in both the solution and solid states. The IR spectra of 3-ethyl-2-[3-(3-ethyl-2-benzothiazolinylidene)-1-propenyl]benzothiazolium iodide (NK-76) and 3-ethyl-2-[7-(3-ethyl-2-benzothiazolinylidene)-1,3,5-heptatrienyl]benzothiazolium iodide (NK-126) change little between the solid and solution states while those of 3-octadecyl-2-[3-(3-octadecyl-2-benzothiazolinylidene)-1-propenyl]benzothiazolium iodide (NK-2560) and 3-octadecyl-2-[7-(3-octadecyl-2-benzothiazolinylidene)-1,3,5-heptatrienyl]benzothiazolium perchlorate (NK-2861) alter significantly between the two states in the frequencies of bands due to the stretching modes of their central conjugated systems. The results suggest that the electronic states of the central conjugated systems of NK-2560 and NK-2861 undergo appreciable changes on going from the solid to the solution states.

  17. Herschel far-infrared photometry of the Swift Burst Alert Telescope active galactic nuclei sample of the local universe - II. SPIRE observations

    NASA Astrophysics Data System (ADS)

    Shimizu, T. Taro; Meléndez, Marcio; Mushotzky, Richard F.; Koss, Michael J.; Barger, Amy J.; Cowie, Lennox L.

    2016-03-01

    We present far-infrared (FIR) and submillimetre photometry from the Herschel Space Observatory's Spectral and Photometric Imaging Receiver (SPIRE) for 313 nearby (z < 0.05) active galactic nuclei (AGN). We selected AGN from the 58 month Swift Burst Alert Telescope (BAT) catalogue, the result of an all-sky survey in the 14-195 keV energy band, allowing for a reduction in AGN selection effects due to obscuration and host galaxy contamination. We find 46 per cent (143/313) of our sample is detected at all three wavebands and combined with our Photoconductor Array Camera and Spectrometer (PACS) observations represents the most complete FIR spectral energy distributions of local, moderate-luminosity AGN. We find no correlation among the 250, 350, and 500 μm luminosities with 14-195 keV luminosity, indicating the bulk of the FIR emission is not related to the AGN. However, Seyfert 1s do show a very weak correlation with X-ray luminosity compared to Seyfert 2s and we discuss possible explanations. We compare the SPIRE colours (F250/F350 and F350/F500) to a sample of normal star-forming galaxies, finding the two samples are statistically similar, especially after matching in stellar mass. But a colour-colour plot reveals a fraction of the Herschel-BAT AGN are displaced from the normal star-forming galaxies due to excess 500 μm emission (E500). Our analysis shows E500 is strongly correlated with the 14-195 keV luminosity and 3.4/4.6 μm flux ratio, evidence the excess is related to the AGN. We speculate these sources are experiencing millimetre excess emission originating in the corona of the accretion disc.

  18. Near-infrared spectroscopy of planetary nebulae: How strong is the H2 emission?

    NASA Technical Reports Server (NTRS)

    Dinerstein, H. L.; Carr, J.; Harvey, P. M.; Lester, D. F.

    1986-01-01

    In an effort to understand the systematics of the H2 emission from planetary nebulae, a program of near-infared spectroscopy using the University of Texas infrared reticon spectrometer was started. This instrument has a 1x32 element InSb photodiode array as a detector. All of the observations reported were made on the McDonald Observatory 2.7 m telescope, with spectra resolving power lambda/delta lambda = 600. The spectral coverage allows the measurement strengths of Brackett gamma He I 2.113 microns, HE II 2.189 microns and the v = 1=0 S(1) line of H2 at 2.122 microns. One of the most important advantages of this instrument is that we are able to resolve H2 from the adjacent He I line. Most previous observations of planetaries have been made at spectral resolving powers of about 100, which blend these lines. The contribution of the He I line has generally been dismissed as being unimportant, but we show that this may not be valid. Our higher resolving power also improves the line-to-continuum contrast; in some cases, the continuum is the limiting factor in detecting faint lines.

  19. Solutions to the faint young Sun paradox simulated by a general circulation model

    NASA Astrophysics Data System (ADS)

    Wolf, Eric Theodore

    The faint young Sun paradox has dominated our thinking regarding early climate. Geological evidence abounds for warm, possibly hot, seawater temperatures and the proliferation of early life during the Archean period of Earth's history (3.8-2.5 Ga). However the standard solar model indicates that the Sun was only 75 to 82 percent as bright as today, implying an apparent contradiction between warm surface temperatures and weak solar irradiance. Geological evidence also places constraints on the amount of atmospheric carbon dioxide present early in Earth's history. Over the past four decades there has been much debate amongst geological, planetary, and climate science communities regarding how to properly resolve the issue of the faint young Sun. Up until very recently, 1-dimensional radiative convective models were the standard tool for deep paleoclimate modeling studies. These studies have notably lacked the ability to treat clouds, surface ice, and meridional energy transport. However, advancements in computing technology now allow us to tackle the faint young Sun paradox using a three-dimensional climate model. Here we use a modified version of the Community Atmosphere Model version 3 from the National Center for Atmospheric Research to study early climate. We find that resolving the faint young Sun paradox becomes less problematic when viewing a full representation of the climate system. Modest amounts of carbon dioxide and methane can provide adequate warming for the Archean within given constraints. Cooler climates with large ice caps but temperate tropical regions can be supported with even less carbon dioxide. The incorporation of systematic climate system differences expected during the Archean, such as fewer cloud condensation nuclei, reduced land albedos, and increased atmospheric nitrogen, can provide additional non-greenhouse means of warming the early Earth. A warm Archean no longer appears at odds with a faint young Sun. Here, we will also discuss the

  20. Flap monitoring using infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Keller, Alex; Wright, Leigh P.; Elmandjra, Mohamed; Mao, Jian-min

    2006-02-01

    We report results of clinical trials on flap monitoring in 65 plastic surgeries. Hemoglobin oxygen saturation of flap tissue (StO II) was monitored non-invasively by using ODISsey TM tissue oximeter, an infrared spectroscopic device. StO II measurements were conducted both intra-operatively and post-operatively. From the intra-operative measurements, we observed that StO II values dropped when the main blood vessels supplying the flap were clamped in surgery, and that StO II jumped after anastomosis to a value close to its pre-operative value. From post-operative monitoring measurements for the 65 flap cases, each lasted two days or so, we found that the StO II values approach to a level close to the baseline if the surgery was successful, and that the StO II value dropped to a value below 30% if there is a perfusion compromise, such as vascular thrombosis.

  1. Deep imaging of the field of the z = 4.9 quasar PC 1247+3406, and faint galaxy counts in the K band with the Keck telescope

    NASA Technical Reports Server (NTRS)

    Soifer, B. T.; Matthews, K.; Djorgovski, S.; Larkin, J.; Graham, J. R.; Harrison, W.; Jernigan, G.; Lin, S.; Nelson, J.; Neugebauer, G.

    1994-01-01

    We present deep images in the K(sub s) band of the field of the quasar PC 1247+3406 at z = 4.897, obtained using the near-infrared camera on the W. M. Keck telescope. A number of faint sources have been detected, some of which appear to be quite red. Their nature and redshifts remain uncertain at this time. These data are combined with deep Keck infrared images of five additional fields and present galaxy counts reaching down to K(sub s) = 22 mag, comparable to the deepest K-band surveys to date. The data presented here are in good agreement with the Hawaii Deep Survey and represent the first independent verification of those results. The slope of the log N-log S relation derived from these data agrees well with the Hawaii Deep Survey, while the counts are slightly higher, especially at the faintest levels probed here. This may be due to a presence of groups or clusters around the target objects at high redshifts.

  2. Syncope (Fainting)

    MedlinePlus

    ... medication. This content was last reviewed September 2016. Arrhythmia • Home • About Arrhythmia • Why Arrhythmia Matters • Understand Your ... the Terms and Conditions and Privacy Policy Printable Arrhythmia Information Sheets What is Arrhythmia? What is Atrial ...

  3. Far-infrared to millimeter astrophysical dust emission. II. Comparison of the two-level systems (TLS) model with astronomical data

    NASA Astrophysics Data System (ADS)

    Paradis, D.; Bernard, J.-P.; Mény, C.; Gromov, V.

    2011-10-01

    Aims: In a previous paper we proposed a new model for the emission by amorphous astronomical dust grains, based on solid-state physics. The model uses a description of the disordered charge distribution (DCD) combined with the presence of two-level systems (TLS) defects in the amorphous solid composing the grains. The goal of this paper is to compare this new model to astronomical observations of different Galactic environments in the far-infrared/submillimeter, in order to derive a set of canonical model parameters to be used as a Galactic reference to be compared to in future Galactic and extragalactic studies. Methods: We compare the TLS model with existing astronomical data. We consider the average emission spectrum at high latitudes in our Galaxy as measured with FIRAS and WMAP, as well as the emission from Galactic compact sources observed with the Archeops balloon experiment, for which an inverse relationship between the dust temperature and the emissivity spectral index has been shown. Results: We show that, unlike models previously proposed that often invoke two dust components at different temperatures, the TLS model successfully reproduces both the shape of the Galactic spectral energy distribution and its evolution with temperature as observed in the Archeops data. The best TLS model parameters indicate a charge coherence length of ≃13 nm and other model parameters in broad agreement with expectations from laboratory studies of dust analogs. We conclude that the millimeter excess emission, which is often attributed to the presence of very cold dust in the diffuse ISM, is very likely caused solely by TLS emission in disordered amorphous dust grains. We discuss the implications of the new model, in terms of mass determinations from millimeter continuum observations and the expected variations in the emissivity spectral index with wavelength and dust temperature. The implications for analyzing the Herschel and Planck satellite data are discussed. Table 5

  4. New insights to the photometric structure of Blue Compact Dwarf Galaxies from deep near-infrared studies. II. The sample of northern BCDs

    NASA Astrophysics Data System (ADS)

    Noeske, K. G.; Papaderos, P.; Cairós, L. M.; Fricke, K. J.

    2005-01-01

    This paper is part of a series of publications which present a systematic study of Blue Compact Dwarf (BCD) Galaxies in the near infrared (NIR). Compared to the visible light, NIR data allow a better separation of the starburst emission from the light distribution of the old stellar low-surface brightness (LSB) host galaxy. We analyze deep NIR broad band images of a sample of 11 BCDs, observed with the Calar Alto 3.6 m telescope. This work enlarges the samples presented in preceding papers of this study (Noeske et al. \\cite{Noeske2003}, A&A, 410, 481; Cairós et al. \\cite{c03a}, ApJ, 593, 312) by BCDs of the most common morphological type, displaying a regular elliptical LSB host galaxy. The data presented here allow the detection and quantitative study of the extended stellar LSB host galaxy in all sample BCDs. The NIR surface brightness profiles (SBPs) of the LSB host galaxies agree at large galactocentric radii with those from optical studies, showing also an exponential intensity decrease and compatible scale lengths. Similar to Noeske et al. (\\cite{Noeske2003}), we find centrally flattening exponential (type V) SBPs of the host galaxy for several BCDs. Such SBPs remain mostly undetected in optical bands, due to the comparatively stronger starburst emission at these wavelengths. We apply a modified exponential distribution to decompose and quantitatively analyze SBPs of LSB hosts with a type V intensity distribution. We present the results of the surface photometry and the decomposition of SBPs, and discuss individual objects with respect to morphological details of their star-forming regions. Table 2 is also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http:/ /cdsweb.u-strasbg.fr/ cgi-bin/ qcat?J/A+A/429/115 Figures 2 to 11 are only available in electronic form at http://www.edpsciences.org German-Spanish Astronomical Center, Calar Alto, operated by the Max-Planck-Institute for Astronomy, Heidelberg

  5. Infrared study of the vibrational behavior of CrO 42- guest ions matrix-isolated in metal (II) sulfates (Me=Ca, Sr, Ba, Pb)

    NASA Astrophysics Data System (ADS)

    Stoilova, D.; Georgiev, M.; Marinova, D.

    2005-03-01

    Infrared spectra of matrix-isolated CrO 42- guest ions in host sulfate matrices - CaSO 4·2H 2O, SrSO 4, BaSO 4 and PbSO 4 are reported and discussed with respect to the Cr-O stretching and O-Cr-O bending modes. An adequate measure for the CrO 42- guest ion distortion is the site group splitting Δ νas and Δ νmax (the difference between the highest and the lowest wavenumbered components of the stretching and bending modes). When the smaller SO 42- ions are replaced by the larger CrO 42- ions the mean frequencies of the asymmetric stretching and bending modes ( ν and ν) as well as the frequencies of ν1 of the CrO 42- guest ions are shifted to higher wavenumbers as compared to those in the respective neat chromates due to the larger repulsion potential at the host lattice sites (smaller values of the unit-cell volumes of the neat sulfates than those of the neat chromates). The CrO 42- guest ions exhibit three bands corresponding to the ν3 modes as deduced from the site group analysis ( C2 site symmetry in CaSO 4·2H 2O and Cs site symmetry in SrSO 4, BaSO 4 and PbSO 4). However, the bending modes ν4 and ν2 of the CrO 42- guest ions in SrSO 4, BaSO 4 and PbSO 4 show an effectively higher local symmetry than the 'rigorous' crystallographic one (two bands for ν4 and one band for ν2 instead of a triplet and a doublet expected, respectively). Such different apparent site symmetries observed in various spectral regions may be attributed to the different influence of energetic and geometrical distortions of the polyatomic entities at particular site on various modes.

  6. MOVPE growth of (GaIn)As/Ga(AsSb)/(GaIn)As type-II heterostructures on GaAs substrate for near infrared laser applications

    NASA Astrophysics Data System (ADS)

    Fuchs, C.; Beyer, A.; Volz, K.; Stolz, W.

    2017-04-01

    The growth of high quality (GaIn)As/Ga(AsSb)/(GaIn)As ;W;-quantum well heterostructures is discussed with respect to their application in 1300 nm laser devices. The structures are grown using metal organic vapor phase epitaxy and characterized using high-resolution X-ray diffraction, scanning transmission electron microscopy and photoluminescence measurements. The agreement between experimental high-resolution X-ray diffraction patterns and full dynamical simulations is verified for these structurally challenging heterostructures. Scanning transmission electron microscopy is used to demonstrate that the structure consists of well-defined quantum wells and forms the basis for future improvements of the optoelectronic quality of this materials system. By altering the group-V gas phase ratio, it is possible to cover a large spectral range between 1200 nm and 1470 nm using a growth temperature of 550 °C and a V/III ratio of 7.5. A comparison of a sample with a photoluminescence emission wavelength at 1360 nm with single quantum well material reference samples proves the type-II character of the emission. A further optimization of these structures for application in 1300 nm lasers by applying different V/III ratios yields a stable behavior of the photoluminescence intensity using a growth temperature of 550 °C.

  7. Infrared Thermometer

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Diatek Corporation, San Diego, CA and the Jet Propulsion Lab developed the Diatek Model 7000 aural thermometer which weighs only eight ounces, and measures temperature in less than two seconds using infrared astronomy technology to measure the amount of infrared energy emitted by the eardrum (the same way temperature of stars and planets is measured). This method avoids contact with mucous membranes, virtually eliminating the possibility of cross infection, and permits temperature measurement of newborn, critically ill, or incapacitated patients. Diatek Corporation was purchased by Welch Allyn Inc. The Diatek Model 7000 is now marketed as SureTemp.

  8. Infrared astronomy

    NASA Technical Reports Server (NTRS)

    Gillett, Frederick; Houck, James; Bally, John; Becklin, Eric; Brown, Robert Hamilton; Draine, Bruce; Frogel, Jay; Gatley, Ian; Gehrz, Robert; Hildebrand, Roger

    1991-01-01

    The decade of 1990's presents an opportunity to address fundamental astrophysical issues through observations at IR wavelengths made possible by technological and scientific advances during the last decade. The major elements of recommended program are: the Space Infrared Telescope Facility (SIRTF), the Stratospheric Observatory For Infrared Astronomy (SOFIA) and the IR Optimized 8-m Telescope (IRO), a detector and instrumentation program, the SubMilliMeter Mission (SMMM), the 2 Microns All Sky Survey (2MASS), a sound infrastructure, and technology development programs. Also presented are: perspective, science opportunities, technical overview, project recommendations, future directions, and infrastructure.

  9. Construction of Identical [2 + 2] Schiff-Base Macrocyclic Ligands by Ln(III) and Zn(II) Template Ions Including Efficient Yb(III) Near-Infrared Sensitizers.

    PubMed

    Zhang, Kun; Zhang, Lei; Zhang, Song; Hu, Yong; Zheng, Youxuan; Huang, Wei

    2015-06-01

    Identical 34-membered [2 + 2] pendent-armed Schiff-base macrocyclic ligands (H4La and H4Lb) can be constructed via the condensation reactions between rigid o-phenylenediamine and extended dialdehydes (H2hpdd/H2pdd) in the presence of either Ln(III) or Zn(II) template with remarkable distinction on the ion radii and charge. X-ray single-crystal diffraction analyses reveal the formation of mononuclear Ln(III) complexes (1-4 and 7) and dinuclear Zn(II) complexes (5 and 6). It is noted that Ln(III) macrocyclic complexes have eight-coordinate sandwich-like mononuclear structures fully surrounded by flexible and large-sized macrocyclic ligands. Photophysical studies have demonstrated that both H4La and H4Lb can serve as effective sensitizers for the Yb(III) ion (2 and 7) exhibiting near-infrared emission at 974 nm with high quantum yields in solution (C2H5OH and CH3OH, ∼1%). Moreover, the quantum yields of two Yb(III) complexes 2 and 7 could be increased ∼15% in CH3OH under weak alkaline condition (pH = 8-9), while no significant changes are observed in C2H5OH by contrast. We think the unique sandwich-like macrocyclic structures of Yb(III) complexes 2 and 7 play important roles in simultaneously guaranteeing the effective match of the energy levels of Yb(III) centers as well as shielding from the solvent molecules and counterions.

  10. Characterization of the low-temperature triplet state of chlorophyll in photosystem II core complexes: Application of phosphorescence measurements and Fourier transform infrared spectroscopy.

    PubMed

    Zabelin, Alexey A; Neverov, Konstantin V; Krasnovsky, Alexander A; Shkuropatova, Valentina A; Shuvalov, Vladimir A; Shkuropatov, Anatoly Ya

    2016-06-01

    Phosphorescence measurements at 77 K and light-induced FTIR difference spectroscopy at 95 K were applied to study of the triplet state of chlorophyll a ((3)Chl) in photosystem II (PSII) core complexes isolated from spinach. Using both methods, (3)Chl was observed in the core preparations with doubly reduced primary quinone acceptor QA. The spectral parameters of Chl phosphorescence resemble those in the isolated PSII reaction centers (RCs). The main spectral maximum and the lifetime of the phosphorescence corresponded to 955±1 nm and of 1.65±0.05 ms respectively; in the excitation spectrum, the absorption maxima of all core complex pigments (Chl, pheophytin a (Pheo), and β-carotene) were observed. The differential signal at 1667(-)/1628(+)cm(-1) reflecting a downshift of the stretching frequency of the 13(1)-keto C=O group of Chl was found to dominate in the triplet-minus-singlet FTIR difference spectrum of core complexes. Based on FTIR results and literature data, it is proposed that (3)Chl is mostly localized on the accessory chlorophyll that is in triplet equilibrium with P680. Analysis of the data suggests that the Chl triplet state responsible for the phosphorescence and the FTIR difference spectrum is mainly generated due to charge recombination in the reaction center radical pair P680(+)PheoD1(-), and the energy and temporal parameters of this triplet state as well as the molecular environment and interactions of the triplet-bearing Chl molecule are similar in the PSII core complexes and isolated PSII RCs.

  11. THE MOLECULAR GAS IN LUMINOUS INFRARED GALAXIES. II. EXTREME PHYSICAL CONDITIONS AND THEIR EFFECTS ON THE X{sub co} FACTOR

    SciTech Connect

    Papadopoulos, Padelis P.; Van der Werf, Paul; Xilouris, E.; Isaak, Kate G.; Gao, Yu E-mail: pvdwerf@strw.leidenuniv.nl E-mail: kisaak@rssd.esa.int

    2012-05-20

    In this work, we conclude the analysis of our CO line survey of luminous infrared galaxies (LIRGs: L{sub IR} {approx}> 10{sup 11} L{sub Sun }) in the local universe (Paper I) by focusing on the influence of their average interstellar medium (ISM) properties on the total molecular gas mass estimates via the so-called X{sub co} = M(H{sub 2})/L{sub co,1-0} factor. One-phase radiative transfer models of the global CO spectral line energy distributions (SLEDs) yield an X{sub co} distribution with (X{sub co}) {approx} (0.6 {+-} 0.2) M{sub Sun} (K km s{sup -1} pc{sup 2}){sup -1} over a significant range of average gas densities, temperatures, and dynamic states. The latter emerges as the most important parameter in determining X{sub co}, with unbound states yielding low values and self-gravitating states yielding the highest ones. Nevertheless, in many (U)LIRGs where available higher-J CO lines (J = 3-2, 4-3, and/or J = 6-5) or HCN line data from the literature allow a separate assessment of the gas mass at high densities ({>=}10{sup 4} cm{sup -3}) rather than a simple one-phase analysis, we find that near-Galactic X{sub co} {approx} (3-6) M{sub Sun} (K km s{sup -1} pc{sup 2}){sup -1} values become possible. We further show that in the highly turbulent molecular gas in ULIRGs, a high-density component will be common and can be massive enough for its high X{sub co} to dominate the average value for the entire galaxy. Using solely low-J CO lines to constrain X{sub co} in such environments (as has been the practice up until now) may have thus resulted in systematic underestimates of molecular gas mass in ULIRGs, as such lines are dominated by a warm, diffuse, and unbound gas phase with low X{sub co} but very little mass. Only well-sampled high-J CO SLEDs (J = 3-2 and higher) and/or multi-J observations of heavy rotor molecules (e.g., HCN) can circumvent such a bias, and the latter type of observations may have actually provided early evidence of it in local ULIRGs. The only

  12. Luminosity function of [OII] emission-line galaxies in the MassiveBlack-II simulation

    DOE PAGES

    Park, KwangHo; Khandai, Nishikanta; Matteo, Tiziana Di; ...

    2015-09-18

    We examine the luminosity function (LF) of [OII] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at 0.06 ≤ z ≤ 3.0 using the [OII] emission line luminosity L([OII]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [OII] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([OII]) = 1043.0 erg s–1 while the low redshifts (z ≤ 0.3) show an excessmore » in the prediction of bright [OII] galaxies, but still displaying a good match with observations below L([OII]) = 1041.6 erg s–1. Based on the validity in reproducing the properties of [OII] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [OII] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from –3 to –2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)–1 at z ≤ 2 while the faint end evolves as ~3(z + 1)–1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [OIII] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. As a result, we show that the auto-correlation function of [OII] and [OIII] emitting galaxies shows a rapid evolution from z = 2 to 1.« less

  13. Powder X-ray diffraction, infrared and (13)C NMR spectroscopic studies of the homologous series of some solid-state zinc(II) and sodium(I) n-alkanoates.

    PubMed

    Nelson, Peter N; Taylor, Richard A

    2015-03-05

    A comparative study of the room temperature molecular packing and lattice structures for the homologous series of zinc(II) and sodium(I) n-alkanoates adduced from Fourier transform infrared and solid-state (13)C NMR spectroscopic data in conjunction with X-ray powder diffraction measurements is carried out. For zinc carboxylates, metal-carboxyl bonding is via asymmetric bridging bidentate coordination whilst for the sodium adducts, coordination is via asymmetric chelating bidentate bonding. All compounds are packed in a monoclinic crystal system. Furthermore, the fully extended all-trans hydrocarbon chains are arranged as lamellar bilayers. For zinc compounds, there is bilayer overlap, for long chain adducts (nc>8) but not for sodium compounds where methyl groups from opposing layers in the lamellar are only closely packed. Additionally, the hydrocarbon chains are extended along the a-axis of the unit cell for zinc compounds whilst for sodium carboxylates they are extended along the c-axis. These packing differences are responsible for different levels of Van der Waals effects in the lattices of these two series of compounds, hence, observed odd-even alternation is different. The significant difference in lattice packing observed for these two series of compounds is proposed to be due to the difference in metal-carboxyl coordination mode, arising from the different electronic structure of the central metal ions.

  14. Submonolayer Uniformity of Type II InAs/GaInSb W-shaped Quantum Wells Probed by Full-Wafer Photoluminescence Mapping in the Mid-infrared Spectral Range.

    PubMed

    Dyksik, Mateusz; Motyka, Marcin; Sęk, Grzegorz; Misiewicz, Jan; Dallner, Matthias; Weih, Robert; Kamp, Martin; Höfling, Sven

    2015-12-01

    The spatial uniformity of GaSb- and InAs substrate-based structures containing type II quantum wells was probed by means of large-scale photoluminescence (PL) mapping realized utilizing a Fourier transform infrared spectrometer. The active region was designed and grown in a form of a W-shaped structure with InAs and GaInSb layers for confinement of electrons and holes, respectively. The PL spectra were recorded over the entire 2-in. wafers, and the parameters extracted from each spectrum, such as PL peak energy position, its linewidth and integrated intensity, were collected in a form of two-dimensional spatial maps. Throughout the analysis of these maps, the wafers' homogeneity and precision of the growth procedure were investigated. A very small variation of PL peak energy over the wafer indicates InAs quantum well width fluctuation of only a fraction of a monolayer and hence extraordinary thickness accuracy, a conclusion further supported by high uniformity of both the emission intensity and PL linewidth.

  15. Bias-selectable dual-band mid-/long-wavelength infrared photodetectors based on InAs/InAs{sub 1−x}Sb{sub x} type-II superlattices

    SciTech Connect

    Haddadi, A.; Chevallier, R.; Chen, G.; Hoang, A. M.; Razeghi, M.

    2015-01-05

    A high performance bias-selectable mid-/long-wavelength infrared photodetector based on InAs/InAs{sub 1−x}Sb{sub x} type-II superlattices on GaSb substrate has been demonstrated. The mid- and long-wavelength channels' 50% cut-off wavelengths were ∼5.1 and ∼9.5 μm at 77 K. The mid-wavelength channel exhibited a quantum efficiency of 45% at 100 mV bias voltage under front-side illumination and without any anti-reflection coating. With a dark current density of 1 × 10{sup −7} A/cm{sup 2} under 100 mV applied bias, the mid-wavelength channel exhibited a specific detectivity of 8.2 × 10{sup 12 }cm·√(Hz)/W at 77 K. The long-wavelength channel exhibited a quantum efficiency of 40%, a dark current density of 5.7 × 10{sup −4} A/cm{sup 2} under −150 mV applied bias at 77 K, providing a specific detectivity value of 1.64 × 10{sup 11 }cm·√(Hz)/W.

  16. Infrared Thermometers

    ERIC Educational Resources Information Center

    Schaefers, John

    2006-01-01

    An infrared (IR) thermometer lab offers the opportunity to give science students a chance to measure surface temperatures, utilizing off-the-shelf technology. Potential areas of study include astronomy (exoplanets), electromagnetic spectrum, chemistry, evaporation rates, anatomy, crystal formation, and water or liquids. This article presents one…

  17. Infrared telescope

    NASA Technical Reports Server (NTRS)

    Karr, G. R.; Hendricks, J. B.

    1985-01-01

    The development of the Infrared Telescope for Spacelab 2 is discussed. The design, development, and testing required to interface a stationary superfluid helium dewar with a scanning cryostate capable of operating in the zero-g environment in the space shuttle bay is described.

  18. Fluctuations In The Cosmic Infrared Background Using the Cosmic Infrared Background ExpeRiment (CIBER).

    NASA Astrophysics Data System (ADS)

    Smidt, Joseph; Arai, T.; Battle, J.; Bock, J. J.; Cooray, A.; Frazer, C.; Hristov, V.; Keating, B.; Kim, M.; Lee, D.; Mason, P.; Matsumoto, T.; Mitchell-Wynne, K.; Nam, U.; Renbarger, T.; Smith, A.; Sullivan, I.; Tsumura, K.; Wada, T.; Zemcov, M.

    2012-01-01

    The clustering properties of faint unresolved sources may be probed by examining the anisotropies they create in the Cosmic Infrared Background (CIB). Using information from fluctuations in the CIB at different wavelengths allows us to disentangle how clustering relates to redshift. In this talk, preliminary measurements of clustering using data from the Cosmic Infrared Background ExpeRiment (CIBER), a rocket-borne experiment designed to detect the signatures of unresolved infrared galaxies during reionization, will be discussed. The CIBER payload contains four instruments including two wide field imagers designed to measure fluctuations in the near IR cosmic infrared background (CIB) at 1.0 and 1.6 microns on scales between 0.2 and 100 arcmin in both bands, where the clustering of high-redshift sources is expected to peak. CIBER observations may be combined with Akari/NEP and Spitzer/NDWFS near-infrared surveys to check systematic errors and to fully characterize the electromagnetic spectrum of CIB fluctuations.

  19. TIME-DEPENDENT INFRARED STUDIES.

    DTIC Science & Technology

    INFRARED RESEARCH, TIME , INFRARED PHENOMENA, INFRARED RADIATION, INFRARED SPECTROSCOPY, HIGH ALTITUDE, SOLAR ATMOSPHERE, TRANSMISSIONS(MECHANICAL), VIBRATION, QUANTUM THEORY, CALIBRATION, INFRARED SCANNING.

  20. The VVDS type-1 AGN sample: the faint end of the luminosity function

    NASA Astrophysics Data System (ADS)

    Bongiorno, A.; Zamorani, G.; Gavignaud, I.; Marano, B.; Paltani, S.; Mathez, G.; Møller, P.; Picat, J. P.; Cirasuolo, M.; Lamareille, F.; Bottini, D.; Garilli, B.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Scaramella, R.; Scodeggio, M.; Tresse, L.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnouts, S.; Bardelli, S.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Guzzo, L.; Ilbert, O.; Iovino, A.; McCracken, H. J.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Zucca, E.; Hatziminaoglou, E.; Polletta, M.; Bondi, M.; Brinchmann, J.; Cucciati, O.; de la Torre, S.; Gregorini, L.; Mellier, Y.; Merluzzi, P.; Temporin, S.; Vergani, D.; Walcher, C. J.

    2007-09-01

    In a previous paper (Gavignaud et al. 2006, A&A, 457, 79), we presented the type-1 Active Galactic Nuclei (AGN) sample obtained from the first epoch data of the VIMOS-VLT Deep Survey (VVDS). The sample consists of 130 faint, broad-line AGN with redshift up to z=5 and 17.5faint AGN. In this paper we present the measurement of the Optical Luminosity Function up to z=3.6 derived from this sample, we compare our results with previous results from brighter samples both at low and at high redshift and finally, through the estimate of the bolometric luminosity function, we compare them also with the results from X-ray and mid-IR selected samples. Our data, more than one magnitude fainter than previous optical surveys, allow us to constrain the faint part of the luminosity function up to high redshift. A comparison of our data with the 2dF sample at low redshift (1 < z < 2.1) shows that the VVDS data can not be well fitted with the PLE models derived by previous samples. Qualitatively, this appears to be due to the fact that our data suggest the presence of an excess of faint objects at low redshift (1.0faint VVDS sample with the large sample of bright AGN extracted from the SDSS DR3 (Richards et al. 2006b, AJ, 131, 2766) and testing a number of different evolutionary models, we find that the model which better represents the combined luminosity functions, over a wide range of redshift and luminosity, is a luminosity dependent density evolution (LDDE) model, similar to those derived from the major X-surveys. Such a parameterization allows the redshift of the AGN space density peak to change as a function of luminosity and explains the excess of faint AGN that we find at 1.0 < z < 1.5. On the basis of this model we find, for the

  1. Galaxy populations in the Antlia cluster - III. Properties of faint early-type galaxies

    NASA Astrophysics Data System (ADS)

    Smith Castelli, Analía. V.; Cellone, Sergio A.; Faifer, Favio R.; Bassino, Lilia P.; Richtler, Tom; Romero, Gisela A.; Calderón, Juan Pablo; Caso, Juan Pablo

    2012-01-01

    We present a new analysis of the early-type galaxy population in the central region of the Antlia cluster, focusing on the faint systems such as dwarf ellipticals (dEs) and dwarf spheroidals (dSphs). The colour-magnitude relation (CMR) and the relation between luminosity and mean effective surface brightness for galaxies in the central region of Antlia have been previously studied in Paper I of the present series. Now we confirm 22 early-type galaxies as Antlia members, using Gemini-GMOS and Magellan-MIKE spectra. Among them, 15 are dEs from the FS90 Antlia Group catalogue, two belong to the rare type of compact ellipticals (cEs) and five are new faint dwarfs that had never been catalogued before. In addition, we present 16 newly identified low-surface-brightness galaxy candidates, almost half of them displaying morphologies consistent with being Antlia's counterparts of Local Group dSphs, which extend the faint luminosity limit of our study down to MB=-10.1(BT= 22.6) mag. With these new data, we built an improved CMR in the Washington photometric system, i.e. integrated T1 magnitudes versus (C-T1) colours, which extends ˜4 mag faintwards the limit of spectroscopically confirmed Antlia members. When only confirmed early-type members are considered, this relation extends over 10 mag in luminosity with no apparent change in slope or increase in colour dispersion towards its faint end. The intrinsic colour scatter of the relation is compared with those reported for other clusters of galaxies; we argue that it is likely that the large scatter of the CMR, usually reported at faint magnitudes, is mostly due to photometric errors along with an improper membership/morphological classification. The distinct behaviour of the luminosity versus mean effective surface brightness relation at the bright and faint ends is analysed, while it is confirmed that dE galaxies on the same relation present a very similar effective radius, regardless of their colour. The projected spatial

  2. Finding faint H I structure in and around galaxies: Scraping the barrel

    NASA Astrophysics Data System (ADS)

    Punzo, D.; van der Hulst, J. M.; Roerdink, J. B. T. M.

    2016-10-01

    Soon to be operational H I survey instruments such as APERTIF and ASKAP will produce large datasets. These surveys will provide information about the H I in and around hundreds of galaxies with a typical signal-to-noise ratio of ∼10 in the inner regions and ∼1 in the outer regions. In addition, such surveys will make it possible to probe faint H I structures, typically located in the vicinity of galaxies, such as extra-planar-gas, tails and filaments. These structures are crucial for understanding galaxy evolution, particularly when they are studied in relation to the local environment. Our aim is to find optimized kernels for the discovery of faint and morphologically complex H I structures. Therefore, using H I data from a variety of galaxies, we explore state-of-the-art filtering algorithms. We show that the intensity-driven gradient filter, due to its adaptive characteristics, is the optimal choice. In fact, this filter requires only minimal tuning of the input parameters to enhance the signal-to-noise ratio of faint components. In addition, it does not degrade the resolution of the high signal-to-noise component of a source. The filtering process must be fast and be embedded in an interactive visualization tool in order to support fast inspection of a large number of sources. To achieve such interactive exploration, we implemented a multi-core CPU (OpenMP) and a GPU (OpenGL) version of this filter in a 3D visualization environment (SlicerAstro).

  3. Faint progenitors of luminous z ∼ 6 quasars: Why do not we see them?

    NASA Astrophysics Data System (ADS)

    Pezzulli, Edwige; Valiante, Rosa; Orofino, Maria C.; Schneider, Raffaella; Gallerani, Simona; Sbarrato, Tullia

    2017-04-01

    Observational searches for faint active nuclei at z > 6 have been extremely elusive, with a few candidates whose high-z nature is still to be confirmed. Interpreting this lack of detections is crucial to improve our understanding of high-z supermassive black holes (SMBHs) formation and growth. In this work, we present a model for the emission of accreting black holes (BHs) in the X-ray band, taking into account super-Eddington accretion, which can be very common in gas-rich systems at high-z. We compute the spectral energy distribution for a sample of active galaxies simulated in a cosmological context, which represent the progenitors of a z ∼ 6 SMBH with MBH ∼ 109 M⊙. We find an average Compton-thick fraction of ∼45 per cent and large typical column densities (NH ≳ 1023 cm2). However, faint progenitors are still luminous enough to be detected in the X-ray band of current surveys. Even accounting for a maximum obscuration effect, the number of detectable BHs is reduced at most by a factor of 2. In our simulated sample, observations of faint quasars are mainly limited by their very low active fraction (fact ∼ 1 per cent), which is the result of short, supercritical growth episodes. We suggest that to detect high-z SMBHs progenitors, large area surveys with shallower sensitivities, such as COSMOS Legacy and XMM-LSS+XXL, are to be preferred with respect to deep surveys probing smaller fields, such as Chandra Deep Field South.

  4. DISCOVERY OF A NEW FAINT DWARF GALAXY ASSOCIATED WITH NGC 253

    SciTech Connect

    Sand, D. J.; Crnojević, D.; Strader, J.; Toloba, E.; Guhathakurta, P.; Caldwell, N.; McLeod, B.; Seth, A. C.

    2014-09-20

    We report the discovery of a new faint dwarf galaxy, which we dub Scl-MM-Dw1, at a projected distance of ∼65 kpc from the spiral galaxy NGC 253. The discovery results from the Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), a program with the Magellan/Megacam imager to study faint substructure in resolved stellar light around massive galaxies outside of the Local Group. We measure a tip of the red giant branch distance to Scl-MM-Dw1 of D = 3.9 ± 0.5 Mpc, consistent with that of NGC 253, making their association likely. The new dwarf's stellar population is complex, with an old, metal-poor red giant branch (≳10 Gyr, [Fe/H] ∼ –2), and an asymptotic giant branch with an age of ∼500 Myr. Scl-MM-Dw1 has a half-light radius of r{sub h} = 340 ± 50 pc and an absolute magnitude of M{sub V}  = –10.3 ± 0.6 mag, comparable to the Milky Way's satellites at the same luminosity. Once complete, our imaging survey of NGC 253 and other nearby massive galaxies will provide a census of faint substructure in halos beyond the Local Group, both to put our own environment into context and to confront models of hierarchical structure formation.

  5. THE FAINT END OF THE CLUSTER-GALAXY LUMINOSITY FUNCTION AT HIGH REDSHIFT

    SciTech Connect

    Mancone, Conor L.; Baker, Troy; Gonzalez, Anthony H.; Ashby, Matthew L. N.; Snyder, Greg; Stanford, Spencer A.; Brodwin, Mark; Eisenhardt, Peter R. M.; Stern, Daniel; Wright, Edward L.

    2012-12-20

    We measure the faint-end slope of the galaxy luminosity function (LF) for cluster galaxies at 1 < z < 1.5 using Spitzer IRAC data. We investigate whether this slope, {alpha}, differs from that of the field LF at these redshifts, and with the cluster LF at low redshifts. The latter is of particular interest as low-luminosity galaxies are expected to undergo significant evolution. We use seven high-redshift spectroscopically confirmed galaxy clusters drawn from the IRAC Shallow Cluster Survey to measure the cluster-galaxy LF down to depths of M* + 3 (3.6 {mu}m) and M* + 2.5 (4.5 {mu}m). The summed LF at our median cluster redshift (z = 1.35) is well fit by a Schechter distribution with {alpha}{sub 3.6{mu}m} = -0.97 {+-} 0.14 and {alpha}{sub 4.5{mu}m} = -0.91 {+-} 0.28, consistent with a flat faint-end slope and is in agreement with measurements of the field LF in similar bands at these redshifts. A comparison to {alpha} in low-redshift clusters finds no statistically significant evidence of evolution. Combined with past studies which show that M* is passively evolving out to z {approx} 1.3, this means that the shape of the cluster LF is largely in place by z {approx} 1.3. This suggests that the processes that govern the buildup of the mass of low-mass cluster galaxies have no net effect on the faint-end slope of the cluster LF at z {approx}< 1.3.

  6. The early faint sun paradox: Organic shielding of ultraviolet-labile greenhouse gases

    SciTech Connect

    Sagan, C.; Chyba, C.

    1997-05-23

    Atmospheric mixing ratios of {approximately}10{sup -5 {+-}1} for ammonia on the early Earth would have been sufficient, through the resulting greenhouse warming, to counteract the temperature effects of the faint early sun. One argument against such model atmospheres has been the short time scale for ammonia photodissociation by solar ultraviolet light. Here it is shown that ultraviolet absorption by steady-state amounts of high-altitude organic solids produced from methane photolysis may have shielded ammonia sufficiently that ammonia resupply rates were able to maintain surface temperatures above freezing. 78 refs., 2 figs., 1 tab.

  7. Faint-meteor survey with a large-format CMOS sensor

    NASA Astrophysics Data System (ADS)

    Watanabe, J.; Enomoto, T.; Terai, T.; Kasuga, T.; Miyazaki, S.; Oota, K.; Muraoka, F.; Onishi, T.; Yamasaki, T.; Mito, H.; Aoki, T.; Soyano, T.; Tarusawa, K.; Matsunaga, N.; Sako, S.; Kobayashi, N.; Doi, M.

    2014-07-01

    For observing faint meteors, we need a large telescope or similar optics, which always give a restriction of the field of view. It is a kind of trade-off between the high sensitivity by using larger telescope and narrower field of view. Reconciling this contradiction, we need a large-format imaging detector together with fast readout for meteor observations. A high-sensitivity CMOS sensor of the large format was developed by Canon Inc. in 2010[1]. Its size is 202 mm×205 mm which makes it the largest one-chip CMOS sensor in the world, and approximately 40 times the size of Canon's largest commercial CMOS sensor as shown in the figure. The number of pixel is 1280×1248. Because the increased size of the new CMOS sensor allows more light to be gathered, it enables shooting in low-light environments. The sensor makes image capture possible in one-hundredth the amount of light required by a 35 mm full-frame CMOS sensor, facilitating the shooting of 60 frame-per-second video with a mere 0.3 lux of illumination. We tried to use this large-format CMOS sensor attached to the prime focus of the 1.05-m (F3.1) Schmidt telescope at the Kiso Observatory, University of Tokyo, for surveying faint meteors. The field of view is 3.3 by 3.3 degrees. Test observations including operation check of the system were carried out in January 2011, September 2011,and December 2012. Images were obtained at a time resolution of 60 frames per second. In this system, the limiting magnitude is estimated to be about 11-12. Because of the limitation of the data storage, full-power observations (14-bit data per 1/60 second) were performed for about one or two hours each night. During the first period, we can count a sporadic meteor every 5 seconds. This is about one order higher detection rate of the faint meteors compared with the previous work[2]. Assuming the height of faint meteors at 100 km, the derived flux of the sporadic meteors is about 5 × 10^{-4} km^{-2} sec^{-1}. The last run was

  8. Alignment statistics of clusters with their brightest members at bright and faint isophotes

    SciTech Connect

    Struble, M.F.

    1987-06-01

    For a sample of 21 first-ranked cluster galaxies with published isophotal photometry and position angles of these isophotes, it is found that the major axes of both the bright and faint isophotal contours tend to be aligned within about 30 deg of the major axis of the parent cluster. This supports the hypothesis that first-ranked galaxies are formed already aligned with their parent clusters rather than the hypothesis that only outer envelopes which accreted after formation are aligned with the cluster. 21 references.

  9. Digital image profilers for detecting faint sources which have bright companions

    NASA Technical Reports Server (NTRS)

    Morris, Elena; Flint, Graham; Slavey, Robert

    1992-01-01

    For this program, an image profiling system was developed which offers the potential for detecting extremely faint optical sources that are located in close proximity to bright companions. The approach employed is novel in three respects. First, it does not require an optical system wherein extraordinary measures must be taken to minimize diffraction and scatter. Second, it does not require detectors possessing either extreme uniformity in sensitivity or extreme temporal stability. Finally, the system can readily be calibrated, or nulled, in space by testing against an unresolved singular stellar source.

  10. Application of digital image processing techniques to faint solar flare phenomena

    NASA Technical Reports Server (NTRS)

    Glackin, D. L.; Martin, S. F.

    1980-01-01

    Digital image processing of eight solar flare events was performed using the Video Information Communication and Retrieval language in order to study moving emission fronts, flare halos, and Moreton waves. The techniques used include contrast enhancement, isointensity contouring, the differencing of images, spatial filtering, and geometrical registration. The spatial extent and temporal behavior of the faint phenomena is examined along with the relation of the three types of phenomena to one another. The image processing techniques make possible the detailed study of the history of the phenomena and provide clues to their physical nature.

  11. First results from the Faint Object Camera - Observations of PKS 0521 - 36

    NASA Technical Reports Server (NTRS)

    Macchetto, F.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.

    1991-01-01

    The Faint Object Camera on the Hubble Space Telescope was used to observe the radio galaxy PKS 0521 - 36 which hosts a prominent radio jet. Images of the jet show spatial structure comparable to VLA data and significantly better than optical ground-based observations. The jet structure is resolved at FOC resolution. In addition to the radio knot, well resolved by the FOC, an extension of the jet toward the nucleus is apparent. The rest of the jet does not show much clumpiness, implying that the synchrotron electrons must be accelerated all along the jet to account for the extent in the optical region.

  12. The early faint sun paradox: organic shielding of ultraviolet-labile greenhouse gases

    NASA Technical Reports Server (NTRS)

    Sagan, C.; Chyba, C.

    1997-01-01

    Atmospheric mixing ratios of approximately 10(-5 +/- 1) for ammonia on the early Earth would have been sufficient, through the resulting greenhouse warming, to counteract the temperature effects of the faint early sun. One argument against such model atmospheres has been the short time scale for ammonia photodissociation by solar ultraviolet light. Here it is shown that ultraviolet absorption by steady-state amounts of high-altitude organic solids produced from methane photolysis may have shielded ammonia sufficiently that ammonia resupply rates were able to maintain surface temperatures above freezing.

  13. Far-infrared spectroscopy of galaxies

    NASA Technical Reports Server (NTRS)

    Stacey, G. J.

    1989-01-01

    Far infrared (FIR) spectral line emission from galaxies is discussed with respect to past, present and near future observations. A review of the importance of the FIR lines as probes of the interstellar medium is presented. The various fine structure emission lines detected from the archetypal starburst galaxy M82, and the (C II) line radiation which is now observed toward a large variety of external galaxies are discussed. The improvements allowed by the advent of the Stratospheric Observatory For Infrared Astronomy (SOFIA), the Infrared Space Observatory (ISO) and the Space Infrared Telescope Facility (SIRTF) are underlined.

  14. Infrared floodlight

    DOEpatents

    Levin, Robert E.; English, George J.

    1986-08-05

    An infrared floodlight assembly designed particularly for security purposes and including a heat-conducting housing, a lens secured to the housing to provide a closure therefor, and a floodlight located within (and surrounded by) the housing. The floodlight combines the use of a tungsten halogen light source and dichroic hot and cold mirrors for directing substantially only infrared radiation toward the assembly's forward lens. Visible radiation is absorbed by the housing's interior wall(s) and, optionally, by a filter located between the floodlight and lens. An optional means may be used within the floodlight to reflect all forward radiation back toward the paraboloidal hot mirror or, alternatively, to reflect only visible radiation in this direction. The dichroic hot and cold mirrors preferably each comprise a glass substrate having multiple layers of titanium dioxide and silicon dioxide thereon.

  15. Far-infrared radiation acutely increases nitric oxide production by increasing Ca{sup 2+} mobilization and Ca{sup 2+}/calmodulin-dependent protein kinase II-mediated phosphorylation of endothelial nitric oxide synthase at serine 1179

    SciTech Connect

    Park, Jung-Hyun; Lee, Sangmi; Cho, Du-Hyong; Park, Young Mi; Kang, Duk-Hee; Jo, Inho

    2013-07-12

    Highlights: •Far-infrared (FIR) radiation increases eNOS-Ser{sup 1179} phosphorylation and NO production in BAEC. •CaMKII and PKA mediate FIR-stimulated increases in eNOS-Ser{sup 1179} phosphorylation. •FIR increases intracellular Ca{sup 2+} levels. •Thermo-sensitive TRPV Ca{sup 2+} channels are unlikely to be involved in the FIR-mediated eNOS-Ser{sup 1179} phosphorylation pathway. -- Abstract: Repeated thermal therapy manifested by far-infrared (FIR) radiation improves vascular function in both patients and mouse model with coronary heart disease, but its underlying mechanism is not fully understood. Using FIR as a thermal therapy agent, we investigate the molecular mechanism of its effect on endothelial nitric oxide synthase (eNOS) activity and NO production. FIR increased the phosphorylation of eNOS at serine 1179 (eNOS-Ser{sup 1179}) in a time-dependent manner (up to 40 min of FIR radiation) in bovine aortic endothelial cells (BAEC) without alterations in eNOS expression. This increase was accompanied by increases in NO production and intracellular Ca{sup 2+} levels. Treatment with KN-93, a selective inhibitor of Ca{sup 2+}/calmodulin-dependent protein kinase II (CaMKII) and H-89, a protein kinase A inhibitor, inhibited FIR radiation-stimulated eNOS-Ser{sup 1179} phosphorylation. FIR radiation itself also increased the temperature of culture medium. As transient receptors potential vanilloid (TRPV) ion channels are known to be temperature-sensitive calcium channels, we explore whether TRPV channels mediate these observed effects. Reverse transcription-PCR assay revealed two TRPV isoforms in BAEC, TRPV2 and TRPV4. Although ruthenium red, a pan-TRPV inhibitor, completely reversed the observed effect of FIR radiation, a partial attenuation (∼20%) was found in cells treated with Tranilast, TRPV2 inhibitor. However, ectopic expression of siRNA of TRPV2 showed no significant alteration in FIR radiation-stimulated eNOS-Ser{sup 1179} phosphorylation. This

  16. Infrared Arrays

    NASA Astrophysics Data System (ADS)

    McLean, I.; Murdin, P.

    2000-11-01

    Infrared arrays are small electronic imaging devices subdivided into a grid or `array' of picture elements, or pixels, each of which is made of a material sensitive to photons (ELECTROMAGNETIC RADIATION) with wavelengths much longer than normal visible light. Typical dimensions of currently available devices are about 27-36 mm square, and formats now range from 2048×2048 pixels for the near-infra...

  17. Infrared backscattering

    NASA Technical Reports Server (NTRS)

    Bohren, Craig F.; Nevitt, Timothy J.; Singham, Shermila Brito

    1989-01-01

    All particles in the atmosphere are not spherical. Moreover, the scattering properties of randomly oriented nonspherical particles are not equivalent to those of spherical particles no matter how the term equivalent is defined. This is especially true for scattering in the backward direction and at the infrared wavelengths at which some atmospheric particles have strong absorption bands. Thus calculations based on Mie theory of infrared backscattering by dry or insoluble atmospheric particles are suspect. To support this assertion, it was noted that peaks in laboratory-measured infrared backscattering spectra show appreciable shifts compared with those calculated using Mie theory. One example is ammonium sulfate. Some success was had in modeling backscattering spectra of ammonium sulfate particles using a simple statistical theory called the continuous distribution of ellipsoids (CDE) theory. In this theory, the scattering properties of an ensemble are calculated. Recently a modified version of this theory was applied to measured spectra of scattering by kaolin particles. The particles were platelike, so the probability distribution of ellipsoidal shapes was chosen to reflect this. As with ammonium sulfate, the wavelength of measured peak backscattering is shifted longward of that predicted by Mie theory.

  18. Infrared retina

    DOEpatents

    Krishna, Sanjay [Albuquerque, NM; Hayat, Majeed M [Albuquerque, NM; Tyo, J Scott [Tucson, AZ; Jang, Woo-Yong [Albuquerque, NM

    2011-12-06

    Exemplary embodiments provide an infrared (IR) retinal system and method for making and using the IR retinal system. The IR retinal system can include adaptive sensor elements, whose properties including, e.g., spectral response, signal-to-noise ratio, polarization, or amplitude can be tailored at pixel level by changing the applied bias voltage across the detector. "Color" imagery can be obtained from the IR retinal system by using a single focal plane array. The IR sensor elements can be spectrally, spatially and temporally adaptive using quantum-confined transitions in nanoscale quantum dots. The IR sensor elements can be used as building blocks of an infrared retina, similar to cones of human retina, and can be designed to work in the long-wave infrared portion of the electromagnetic spectrum ranging from about 8 .mu.m to about 12 .mu.m as well as the mid-wave portion ranging from about 3 .mu.m to about 5 .mu.m.

  19. THE SPITZER SURVEY OF INTERSTELLAR CLOUDS IN THE GOULD BELT. II. THE CEPHEUS FLARE OBSERVED WITH IRAC AND MIPS

    SciTech Connect

    Kirk, Jason M.; Ward-Thompson, Derek; Di Francesco, James E-mail: derek.ward-thompson@astro.cf.ac.uk

    2009-11-01

    We present Spitzer Infrared Array Camera (IRAC; {approx}2 deg{sup 2}) and Multiband Imaging Photometer for Spitzer (MIPS; {approx}8 deg{sup 2}) observations of the Cepheus Flare, which is associated with the Gould Belt, at an approximate distance of {approx}300 pc. Around 6500 sources are detected in all four IRAC bands, of which {approx}900 have MIPS 24 {mu}m detections. We identify 133 young stellar object (YSO) candidates using color-magnitude diagram techniques, and a large number of the YSO candidates are associated with the NGC 7023 reflection nebula. Cross-identifications were made with the Guide Star Catalog II and the IRAS Faint Source Catalog, and spectral energy distributions (SEDs) were constructed. SED modeling was conducted to estimate the degree of infrared excess. It was found that a large majority of disks were optically thick accreting disks, suggesting that there has been little disk evolution in these sources. Nearest-neighbor clustering analysis identified four small protostellar groups (L1228, L1228N, L1251A, and L1251B) with 5-15 members each and the larger NGC 7023 association with 32 YSO members. The star-formation efficiency for cores with clusters of protostars and for those without clusters was found to be {approx}8% and {approx}1%, respectively. The cores L1155, L1241, and L1247 are confirmed to be starless down to our luminosity limit of L {sub bol} = 0.06 L {sub sun}.

  20. Analysis of a Close Pair of Faint Sources Near a Massive Young Star

    NASA Astrophysics Data System (ADS)

    Kamon, Saki; Kraus, Adam L.; Rizzuto, Aaron C.; Ireland, Michael; Carpenter, John M.

    2017-01-01

    Directly imaged exoplanets are rare but important, because they provide a rare glimpse at how planet interiors and atmospheres evolve over time via direct measurement of planetary luminosities and spectra. The details of individual planetary system architectures directly inform our understanding of planet formation and evolution. We present our findings from a high-resolution imaging survey of a nearby star-forming region that indicate the presence of a close pair of faint sources near a massive, A-type young star. From multiple epochs of AO imaging obtained with NIRC2, we test for association of each faint source with the host star via measurement of common proper motion. We also assess whether the sources are two planetary mass objects, or a more massive object obscured by an edge on disk. In the case of two planetary mass objects, we estimate the component masses from their luminosities and colors.We conclude by discussing possible future observations to further determine the nature of this complicated system.

  1. The First Science Flight of the Faint Intergalactic medium Redshifted Emission Balloon (FIREBALL)

    NASA Astrophysics Data System (ADS)

    Martin, Christopher; Milliard, Bruno; Schiminovich, David; Tuttle, Sarah; Matuszewski, Matt; Rahman, Shahin; Evrard, Jean; Frank, Stephan; Deharveng, Jean-Michel; Peroux, Celine

    We have completed the second flight of the path-finding experiment, the Faint Intergalactic medium Redshifted Emission Balloon (FIREBALL), designed to discover and map faint emis-sion from the Intergalactic Medium (IGM). The second flight was fully successful, proving a fully functional fine pointing gondola with arcsec level capability, a 1 meter diameter (fixed) parabola primary telescope with planar sidereostat for pointing, a complete closed loop guide camera and control software, and a fiber fed UV integral field spectrograph feeding a spare GALEX Near UV detector. Three scientific targets were observed, and analysis of the data shows that the instrument performed as expected. The flux measurements obtained will be compared to models for IGM emission. We discuss future modifications to the payload that will achieve a 10-to 30-fold increase in sensitivity over science flight 1. We also discuss other instrument configurations that can utilize the 1-meter UV telescope and arcsecond pointing platform, and their corresponding science objectives. FIREBALL is a collaboration of NASA, Caltech, Columbia University, CNES, and Laboratorie Astrophysique Marseille, and is sup-ported by NASA, CNES, and CNRS.

  2. Star/galaxy separation at faint magnitudes: Application to a simulated Dark Energy Survey

    SciTech Connect

    Soumagnac, M.T.; et al.

    2013-06-21

    We address the problem of separating stars from galaxies in future large photometric surveys. We focus our analysis on simulations of the Dark Energy Survey (DES). In the first part of the paper, we derive the science requirements on star/galaxy separation, for measurement of the cosmological parameters with the Gravitational Weak Lensing and Large Scale Structure probes. These requirements are dictated by the need to control both the statistical and systematic errors on the cosmological parameters, and by Point Spread Function calibration. We formulate the requirements in terms of the completeness and purity provided by a given star/galaxy classifier. In order to achieve these requirements at faint magnitudes, we propose a new method for star/galaxy separation in the second part of the paper. We first use Principal Component Analysis to outline the correlations between the objects parameters and extract from it the most relevant information. We then use the reduced set of parameters as input to an Artificial Neural Network. This multi-parameter approach improves upon purely morphometric classifiers (such as the classifier implemented in SExtractor), especially at faint magnitudes: it increases the purity by up to 20% for stars and by up to 12% for galaxies, at i-magnitude fainter than 23.

  3. Faint blue counts from formation of dwarf galaxies at z approximately equals 1

    NASA Technical Reports Server (NTRS)

    Babul, Arif; Rees, Martin J.

    1993-01-01

    The nature of faint blue objects (FBO's) has been a source of much speculation since their detection in deep CCD images of the sky. Their high surface density argues against them being progenitors of present-day bright galaxies and since they are only weakly clustered on small scales, they cannot be entities that merged together to form present-day galaxies. Babul & Rees (1992) have suggested that the observed faint blue counts may be due to dwarf elliptical galaxies undergoing their initial starburst at z is approximately equal to 1. In generic hierarchical clustering scenarios, however, dwarf galaxy halos (M is approximately 10(exp 9) solar mass) are expected to form at an earlier epoch; for example, typical 10(exp 9) solar mass halos will virialize at z is approximately equal to 2.3 if the power-spectrum for the density fluctuations is that of the standard b = 2 cold dark matter (CDM) model. Under 'ordinary conditions' the gas would rapidly cool, collect in the cores, and undergo star-formation. Conditions at high redshifts are far from 'ordinary'. The intense UV background will prevent the gas in the dwarf halos from cooling, the halos being released from their suspended state only when the UV flux has diminished sufficiently.

  4. Revealing a comet-like shape of the faint periphery of the nearby galaxy M 32

    NASA Astrophysics Data System (ADS)

    Georgiev, Ts. B.

    2016-02-01

    We performed BVRI photometry of the galaxy M 32 building images and isophote maps in magnitudes and in color indexes. While searching for the faint thick disk of M 32 we apply median filtering with aperture of 7.3 arcmin to detach the residual image of M 32 and its periphery above the surrounding magnitude or color background. The residual images in all photometric systems show that the periphery of M 32 possesses a comet-like shape with a tail oriented to SSE, in a direction opposite to the direction of M 110. The images calibrated in color indexes (b - v) and (b - v)+(r - i) show that the tail is redder than the local median background. The residual images in color indexes show that the red tail broadens and curves in direction towards S and SW. Simultaneously, the brightest part of M 32 occurs bounded from NW-NE-SE sides by a sickle-like formation with a significantly lower red color index. Generally, we do not find a faint thick disk of M 32. However, the comet-like shape on the periphery of M 32, especially as a formation with an increased red color index, provokes involuntarily the impression that the satellite M 32 overtakes the Andromeda galaxy. The redshifts show that the intimacy velocity of M 32 and Andromeda galaxy is about 100 km/s.

  5. Discovery of a New Photometric Sub-class of Faint and Fast Classical Novae

    NASA Astrophysics Data System (ADS)

    Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Ofek, E. O.; Quimby, R.; Rau, A.

    2011-07-01

    We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60 inch telescope during a search for "Fast Transients In Nearest Galaxies" (P60-FasTING). Designed as a fast cadence (1 day) and deep (g < 21 mag) survey, P60-FasTING was particularly sensitive to short-lived and faint optical transients. The P60-FasTING nova sample includes 10 novae in M 31, 6 in M 81, 3 in M 82, 1 in NGC 2403, and 1 in NGC 891. This significantly expands the known sample of extragalactic novae beyond the Local Group, including the first discoveries in a starburst environment. Surprisingly, our photometry shows that this sample is quite inconsistent with the canonical maximum-magnitude-rate-of-decline (MMRD) relation for classical novae. Furthermore, the spectra of the P60-FasTING sample are indistinguishable from classical novae. We suggest that we have uncovered a sub-class of faint and fast classical novae in a new phase space in luminosity-timescale of optical transients. Thus, novae span two orders of magnitude in both luminosity and time. Perhaps the MMRD, which is characterized only by the white dwarf mass, was an oversimplification. Nova physics appears to be characterized by a relatively rich four-dimensional parameter space in white dwarf mass, temperature, composition, and accretion rate.

  6. The Origin of the Heaviest Metals in Most Ultra-faint Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Roederer, Ian U.

    2017-01-01

    The heaviest metals found in stars in most ultra-faint dwarf (UFD) galaxies in the Milky Way halo are generally underabundant by an order of magnitude or more when compared with stars in the halo field. Among the heavy elements produced by n-capture reactions, only Sr and Ba can be detected in red giant stars in most UFD galaxies. This limited chemical information is unable to identify the nucleosynthesis process(es) responsible for producing the heavy elements in UFD galaxies. Similar [Sr/Ba] and [Ba/Fe] ratios are found in three bright halo field stars, BD‑18°5550, CS 22185–007, and CS 22891–200. Previous studies of high-quality spectra of these stars report detections of additional n-capture elements, including Eu. The [Eu/Ba] ratios in these stars span +0.41 to +0.86. These ratios and others among elements in the rare Earth domain indicate an r-process origin. These stars have some of the lowest levels of r-process enhancement known, with [Eu/H] spanning ‑3.95 to ‑3.32, and they may be considered nearby proxies for faint stars in UFD galaxies. Direct confirmation, however, must await future observations of additional heavy elements in stars in the UFD galaxies themselves.

  7. Biomediated Precipitation of Calcium Carbonate and Sulfur in a Faintly Acidic Hot Spring

    NASA Astrophysics Data System (ADS)

    Jiang, L.; Peng, X.; Qiao, H.

    2014-12-01

    A faintly acidic hot spring named "female Tower" (T=73.5 ℃, pH=6.64 ) is located in the Jifei Geothermal Field,Yunnan province, Southwest China. The precipitates in the hot spring are composed of large amounts of calcite and sulfur, as reveals by XRD analysis. Scanning electron microscopy (SEM) analysis show the microbial mats are formed of various coccoid, rod and filamentous microbes. Transmission electron microscopy (TEM) analysis show that intracellular sulfur granules are commonly associated with these microbes. Energy dispersive X-ray spectrometer (EDS) analysis shows that the surface of microbes are mainly composed of Ca, C, O and S. A culture-independent molecular phylogenetic analysis demonstrates the majority of bacteria in the spring are sulfur-oxidizing bacteria. In the spring water, H2S concentration was up to 60 ppm, while SO42- concentration was only about 10 ppm. We suggest that H2S might be utilized by sulfur-oxidizing bacteria in this hot spring water, leading to the formation of sulfur granules intracellularly and extracellularly. In the meantime, this reaction increases the pH in ambient environments, which fosters the precipitation of calcium carbonate precipitation in the microbial mats. This study suggests that the sulfur-oxidizing bacteria could play an important role in calcium carbonate precipitation in faintly acidic hot spring environments.

  8. THE DISCOVERY OF AN ULTRA-FAINT STAR CLUSTER IN THE CONSTELLATION OF URSA MINOR

    SciTech Connect

    Munoz, R. R.; Geha, M.; Vargas, L. C.; Cote, P.; Stetson, P.; Santana, F. A.; Simon, J. D.; Djorgovski, S. G.

    2012-07-01

    We report the discovery of a new ultra-faint globular cluster in the constellation of Ursa Minor, based on stellar photometry from the MegaCam imager at the Canada-France-Hawaii Telescope. We find that this cluster, Munoz 1, is located at a distance of 45 {+-} 5 kpc and at a projected distance of only 45' from the center of the Ursa Minor dwarf spheroidal galaxy. Using a maximum-likelihood technique we measure a half-light radius of 0.'5, or equivalently 7 pc, and an ellipticity consistent with being zero. We estimate its absolute magnitude to be M{sub V} -0.4 {+-} 0.9, which corresponds to L{sub V} = 120{sup +160}{sub -65} L{sub Sun} and we measure a heliocentric radial velocity of -137 {+-} 4 km s{sup -1} based on Keck/DEIMOS spectroscopy. This new satellite is separate from Ursa Minor by {approx}30 kpc and 110 km s{sup -1} suggesting the cluster is not obviously associated with the dSph, despite the very close angular separation. Based on its photometric properties and structural parameters we conclude that Munoz 1 is a new ultra-faint stellar cluster. Along with Segue 3 this is one of the faintest stellar clusters known to date.

  9. The Intensity Distribution of Faint Gamma-Ray Bursts Detected with BATSE

    NASA Technical Reports Server (NTRS)

    Kommers, Jefferson; Lewin, Walter H.; Kouveliotou, Chryssa; vanParadijs, Jan; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.

    1998-01-01

    We have recently completed a search of 6 years of archival Burst and Transient Source Experiment (BATSE) data for gamma-ray bursts (GRBS) that were too faint to activate the real-time burst detection system running onboard the spacecraft. These "non-triggered" bursts can be combined with the "triggered" bursts detected onboard to produce a GRB intensity distribution that reaches peak fluxes a factor of approximately 2 lower than could be studied previously. The value of the (V/V(max)) statistic (in Euclidean space) for the bursts we detect is 0.177 +/- 0.006. This surprisingly low value is obtained because we detected very few bursts on the 4.096 s and 8.192 s time scales (where most bursts have their highest signal-to-noise ratio) that were not already detected on the 1.024 s time scale. If allowance is made for a power-law distribution of intrinsic peak luminosities, the extended peak flux distribution is consistent with models in which the redshift distribution of the gamma-ray burst rate approximately traces the star formation history of the Universe. We argue that this class of models is preferred over those in which the burst rate is independent of redshift. These results lend support to the conclusions of previous studies predicting that relatively few faint bursts are waiting to be found below the BATSE onboard detection threshold.

  10. Star/galaxy separation at faint magnitudes: application to a simulated Dark Energy Survey

    SciTech Connect

    Soumagnac, M. T.; Abdalla, F. B.; Lahav, O.; Kirk, D.; Sevilla, I.; Bertin, E.; Rowe, B. T. P.; Annis, J.; Busha, M. T.; Da Costa, L. N.; Frieman, J. A.; Gaztanaga, E.; Jarvis, M.; Lin, H.; Percival, W. J.; Santiago, B. X.; Sabiu, C. G.; Wechsler, R. H.; Wolz, L.; Yanny, B.

    2015-04-14

    We address the problem of separating stars from galaxies in future large photometric surveys. We focus our analysis on simulations of the Dark Energy Survey (DES). In the first part of the paper, we derive the science requirements on star/galaxy separation, for measurement of the cosmological parameters with the gravitational weak lensing and large-scale structure probes. These requirements are dictated by the need to control both the statistical and systematic errors on the cosmological parameters, and by point spread function calibration. We formulate the requirements in terms of the completeness and purity provided by a given star/galaxy classifier. In order to achieve these requirements at faint magnitudes, we propose a new method for star/galaxy separation in the second part of the paper. We first use principal component analysis to outline the correlations between the objects parameters and extract from it the most relevant information. We then use the reduced set of parameters as input to an Artificial Neural Network. This multiparameter approach improves upon purely morphometric classifiers (such as the classifier implemented in SExtractor), especially at faint magnitudes: it increases the purity by up to 20 per cent for stars and by up to 12 per cent for galaxies, at i-magnitude fainter than 23.

  11. Observations of faint comets at McDonald Observatory: 1978-1980

    NASA Technical Reports Server (NTRS)

    Barker, E. S.; Cochran, A. L.; Rybski, P. M.

    1981-01-01

    Modern observational techniques, developed for spectroscopy and photometry of faint galaxies and quasars, successfully applied to faint comets on the 2.7 m telescope. The periodic comets Van Biesbrock, Ashbrook-Jackson, Schwassmann-Wachmann 1, Tempel 2, Encke, Forbes, Brooks 2, Stephan-Oterma and the new comets Bradfield (19791), Bowell (1980b), Chernis-Petrauskas (1980k) were observed. The comets ranged in magnitude from 10th to 20th magnitude. For comets fainter than 19th magnitude, reflectance spectra at 100A resolution and area photometry were obtained. On comets of 17th or 18th magnitude, spectrometric scans (6A resolution) of the nucleus or inner coma region. On those comets which are brighter than 16th magnitude spatial spectrophotometric (6A resolution) studies of the inner and extended comae were done. An extensive spatial study of the comae of P/Encke and P/Stephen-Oterma, correlated with heliocentric distance is taking place. The observing process used is described and examples of the results obtained to date are discussed.

  12. Searching for Faint Companions to Nearby Stars with the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Schroeder, Daniel J.; Golimowski, David A.

    1996-01-01

    A search for faint companions (FC's) to selected stars within 5 pc of the Sun using the Hubble Space Telescope's Planetary Camera (PC) has been initiated. To assess the PC's ability to detect FCs, we have constructed both model and laboratory-simulated images and compared them to actual PC images. We find that the PC's point-spread function (PSF) is 3-4 times brighter over the angular range 2-5 sec than the PSF expected for a perfect optical system. Azimuthal variations of the PC's PSF are 10-20 times larger than expected for a perfect PSF. These variations suggest that light is scattered nonuniformly from the surface of the detector. Because the anomalies in the PC's PSF cannot be precisely simulated, subtracting a reference PSF from the PC image is problematic. We have developed a computer algorithm that identifies local brightness anomalies within the PSF as potential FCs. We find that this search algorithm will successfully locate FCs anywhere within the circumstellar field provided that the average pixel signal from the FC is at least 10 sigma above the local background. This detection limit suggests that a comprehensive search for extrasolar Jovian planets with the PC is impractical. However, the PC is useful for detecting other types of substellar objects. With a stellar signal of 10(exp 9) e(-), for example, we may detect brown dwarfs as faint as M(sub I) = 16.7 separated by 1 sec from alpha Cen A.

  13. Near Infrared Astronomical Observing During the Daytime

    NASA Astrophysics Data System (ADS)

    Tinn Chee Jim, Kevin; Pier, Edward Alan; Cognion, Rita L.

    2015-08-01

    Ground-based, near-infrared astronomy has been mostly restriced to nighttime observing with occasional, bright solar system objects observed during the daytime. But for astronomical phenomena that are time-varying on timescales of less than a day, it would be advantageous to be able to gather data during the day and night. We explore some of the limitations of observing in the J, H, and K bands during the daytime. Atmospheric radiative transfer simulations show that K is the optimal common astronomical filter for daytime observations on Mauna Kea, but the J and H filters can also be used. Observations from Mauna Kea show that it is possible to observe objects at least as faint as K=15.5 during the early afternoon, with photometric accuracies only slightly worse than those obtained at night.

  14. Infrared Interferometry and Circumstellar Dust

    NASA Astrophysics Data System (ADS)

    Coudé du Foresto, Vincent

    2009-08-01

    Exozodiacal dust plays an important role for the feasibility and dimensioning of future space missions dedicated to the spectroscopic analysis of the atmosphere of Earth-like planets. Thus, a survey of dust clouds around potential targets is called for in order to reduce the need for such observations using space-based missions and not waste time on sources where exo-Earths cannot be detected. Aladdin is an infrared (L band) nulling interferometer optimized for this objective. Although relatively modest in size (two 1-meter class telescopes on a maximum baseline of 32 meters), it takes advantage of the favorable atmospheric conditions of the Antarctic plateau to achieve a sensitivity better than what can be obtained with a pair of 8-meter-class telescopes at a more temperate site. Beyond its main mission, the science potential of Aladdin extends to the study of all kinds of faint circumstellar material (dust and/or molecules) around young, old or main-sequence stars.

  15. Portrait of a Dark Horse: a Photometric and Spectroscopic Study of the Ultra-faint Milky Way Satellite Pegasus III

    NASA Astrophysics Data System (ADS)

    Kim, Dongwon; Jerjen, Helmut; Geha, Marla; Chiti, Anirudh; Milone, Antonino P.; Da Costa, Gary; Mackey, Dougal; Frebel, Anna; Conn, Blair

    2016-12-01

    Pegasus III (Peg III) is one of the few known ultra-faint stellar systems in the outer halo of the Milky Way. We present the results from a follow-up campaign with Magellan/IMACS and Keck/DEIMOS. Deep stellar photometry down to {r}0≈ 25 mag at 50% completeness level has allowed accurate measurements of its photometric and structural properties. The color-magnitude diagram of Peg III confirms that the stellar system is well described by an old (≳12 Gyr) and metal-poor ([Fe/H] ≲ -2.0 dex) stellar population at a heliocentric distance of 215 ± 12 kpc. The revised half-light radius {r}h=53+/- 14 pc, ellipticity ɛ ={0.38}-0.38+0.22, and total luminosity {M}V=-3.4+/- 0.4 are in good agreement with the values quoted in our previous paper. We further report on the spectroscopic identification of seven, possibly eight, member stars of Peg III. The Ca ii triplet lines of the brightest member stars indicate that Peg III contains stars with metallicity as low as [Fe/H] = -2.55 ± 0.15 dex. Peg III has a systemic velocity of -222.9 ± 2.6 km s-1 and a velocity dispersion of {5.4}-2.5+3.0 km s-1. The inferred dynamical mass within the half-light radius is {1.4}-1.1+3.0× {10}6{M}⊙ and the mass-to-light ratio M/{L}V={1470}-1240+5660 {M}⊙ /{L}⊙ , providing further evidence that Peg III is a dwarf galaxy satellite. We find that Peg III and another distant dwarf satellite Pisces II lie relatively close to each other ({{Δ }}{d}{spatial}=43+/- 19 kpc) and share similar radial velocities in the Galactic standard-of-rest frame ({{Δ }}{v}{GSR}=12.3+/- 3.7 km s-1). This suggests that they may share a common origin. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  16. High-performance short-wavelength infrared photodetectors based on type-II InAs/InAs{sub 1-x}Sb{sub x}/AlAs{sub 1−x}Sb{sub x} superlattices

    SciTech Connect

    Haddadi, A.; Suo, X. V.; Adhikary, S.; Dianat, P.; Chevallier, R.; Hoang, A. M.; Razeghi, M.

    2015-10-05

    A high-performance short-wavelength infrared n-i-p photodiode based on InAs/InAs{sub 1−x}Sb{sub x}/AlAs{sub 1−x}Sb{sub x} type-II superlattices on GaSb substrate has been demonstrated. The device is designed to have a 50% cut-off wavelength of ∼1.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.47 A/W at 1.6 μm, corresponding to a quantum efficiency of 37% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 285 Ω cm{sup 2} and a dark current density of 9.6 × 10{sup −5} A/cm{sup 2} under −50 mV applied bias at 300 K, the photodiode exhibited a specific detectivity of 6.45 × 10{sup 10 }cm Hz{sup 1/2}/W. At 200 K, the photodiode exhibited a dark current density of 1.3 × 10{sup −8} A/cm{sup 2} and a quantum efficiency of 36%, resulting in a detectivity of 5.66 × 10{sup 12 }cm Hz{sup 1/2}/W.

  17. Far-infrared radiation acutely increases nitric oxide production by increasing Ca(2+) mobilization and Ca(2+)/calmodulin-dependent protein kinase II-mediated phosphorylation of endothelial nitric oxide synthase at serine 1179.

    PubMed

    Park, Jung-Hyun; Lee, Sangmi; Cho, Du-Hyong; Park, Young Mi; Kang, Duk-Hee; Jo, Inho

    2013-07-12

    Repeated thermal therapy manifested by far-infrared (FIR) radiation improves vascular function in both patients and mouse model with coronary heart disease, but its underlying mechanism is not fully understood. Using FIR as a thermal therapy agent, we investigate the molecular mechanism of its effect on endothelial nitric oxide synthase (eNOS) activity and NO production. FIR increased the phosphorylation of eNOS at serine 1179 (eNOS-Ser(1179)) in a time-dependent manner (up to 40min of FIR radiation) in bovine aortic endothelial cells (BAEC) without alterations in eNOS expression. This increase was accompanied by increases in NO production and intracellular Ca(2+) levels. Treatment with KN-93, a selective inhibitor of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and H-89, a protein kinase A inhibitor, inhibited FIR radiation-stimulated eNOS-Ser(1179) phosphorylation. FIR radiation itself also increased the temperature of culture medium. As transient receptors potential vanilloid (TRPV) ion channels are known to be temperature-sensitive calcium channels, we explore whether TRPV channels mediate these observed effects. Reverse transcription-PCR assay revealed two TRPV isoforms in BAEC, TRPV2 and TRPV4. Although ruthenium red, a pan-TRPV inhibitor, completely reversed the observed effect of FIR radiation, a partial attenuation (∼20%) was found in cells treated with Tranilast, TRPV2 inhibitor. However, ectopic expression of siRNA of TRPV2 showed no significant alteration in FIR radiation-stimulated eNOS-Ser(1179) phosphorylation. This study suggests that FIR radiation increases NO production via increasing CaMKII-mediated eNOS-Ser(1179) phosphorylation but TRPV channels may not be involved in this pathway. Our results may provide the molecular mechanism by which FIR radiation improves endothelial function.

  18. Improving the Ability of Image Sensors to Detect Faint Stars and Moving Objects Using Image Deconvolution Techniques

    PubMed Central

    Fors, Octavi; Núñez, Jorge; Otazu, Xavier; Prades, Albert; Cardinal, Robert D.

    2010-01-01

    In this paper we show how the techniques of image deconvolution can increase the ability of image sensors as, for example, CCD imagers, to detect faint stars or faint orbital objects (small satellites and space debris). In the case of faint stars, we show that this benefit is equivalent to double the quantum efficiency of the used image sensor or to increase the effective telescope aperture by more than 30% without decreasing the astrometric precision or introducing artificial bias. In the case of orbital objects, the deconvolution technique can double the signal-to-noise ratio of the image, which helps to discover and control dangerous objects as space debris or lost satellites. The benefits obtained using CCD detectors can be extrapolated to any kind of image sensors. PMID:22294896

  19. Faint meteor observation by large-format CMOS sensor with 1.05-m Kiso schmidt telescope

    NASA Astrophysics Data System (ADS)

    Watanabe, J.; Kasuga, T.; Terai, T.; Miyazaki, S.; Ohta, K.; Murooka, F.; Ohnishi, T.; Yamasaki, T.; Mito, H.; Aoki, T.; Soyano, T.; Tarusawa, K.; Matsunaga, N.; Sako, S.; Kobayashi, N.; Doi, M.; Enomoto, T.

    2014-07-01

    We tried to use a new high-sensitivity CMOS sensor of the world's largest size as a one-chip 20cmx 20cm square attached to the prime focus of the 1.05 m (F3.1) Schmidt telescope at the Kiso Observatory, University of Tokyo, for faint meteor observation. The resulting field of view was 3.3 by 3.3 degrees, with a limiting magnitude of about 12 in our preliminary analysis. Assuming the height of faint meteors at 100 km, the derived flux of sporadic meteors is about 5x10^{-4} km^{-2}s^{-1}. Although the analysis is still on going, it is clear that this CMOS sensor is useful and effective for observing faint meteors.

  20. Improving the ability of image sensors to detect faint stars and moving objects using image deconvolution techniques.

    PubMed

    Fors, Octavi; Núñez, Jorge; Otazu, Xavier; Prades, Albert; Cardinal, Robert D

    2010-01-01

    In this paper we show how the techniques of image deconvolution can increase the ability of image sensors as, for example, CCD imagers, to detect faint stars or faint orbital objects (small satellites and space debris). In the case of faint stars, we show that this benefit is equivalent to double the quantum efficiency of the used image sensor or to increase the effective telescope aperture by more than 30% without decreasing the astrometric precision or introducing artificial bias. In the case of orbital objects, the deconvolution technique can double the signal-to-noise ratio of the image, which helps to discover and control dangerous objects as space debris or lost satellites. The benefits obtained using CCD detectors can be extrapolated to any kind of image sensors.

  1. Cosmic Infrared Background Fluctuations and Zodiacal Light

    NASA Technical Reports Server (NTRS)

    Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

    2017-01-01

    We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

  2. Far infrared supplement: Catalog of infrared observations

    NASA Technical Reports Server (NTRS)

    Gezari, D. Y.; Schmitz, M.; Mead, J. M.

    1984-01-01

    The Far Infrared Supplement: catalog of infrared observations summarizes all infrared astronomical observations at far infrared wavelengths published in the scientific literature between 1965 and 1982. The Supplement list contains 25% of the observations in the full catalog of infrared observations (C10), and essentially eliminates most visible stars from the listings. The Supplement is more compact than the main Catalog (it does not contain the bibliography and position index of the C10), and is intended for easy reference during astronomical observations.

  3. Dust and Molecular Gas from the Optically Faint Quasars at z 6

    NASA Astrophysics Data System (ADS)

    Wang, Ran; Carilli, C.; Neri, R.; Riechers, D.; Wagg, J.; Walter, F.; Bertoldi, F.; Omont, A.; Cox, P.; Menten, K.; Fan, X.; Strauss, M.

    2011-01-01

    We present millimeter observations of the twelve z 6 quasars discovered from the SDSS southern survey. These objects are typically one or two magnitudes fainter in the optical (i.e., 20.6 faint quasars at z 6 reveal strong FIR emission from 40 to 60 K warm dust and highly excited molecular gas in the quasar host galaxies. The molecular gas masses of the two CO detections are all about 10^10 Msun, which are comparable to that of the CO-detected optically bright quasars at z 6. Their FIR-to-CO luminosity ratios are also consistent with that of the previous CO-detected quasars at z 2 to 6 and the dusty starbusrt systems, e.g., the submillimeter galaxies. However, their FIR-to-UV luminosity ratios are higher than that of the millimeter-detected optically bright quasars at z 6. This confirms the shallow nonlinear FIR-to-AGN luminosity relationship found with other AGN-starburst systems at local and high-z universe. All these results suggest massive star formation coeval with rapid black hole accretion in the host galaxies of the millimeter-detected optically faint quasars at z 6. Further high-resolution imaging of the Molecular CO emission (e.g., with ALMA) will be important to measure the dynamical masses of the spheroidal hosts and understand the black hole-bulge relationship of the optically faint quasars at the earliest epoch.

  4. THE FAINT-END SLOPE OF THE REDSHIFT 5.7 Ly{alpha} LUMINOSITY FUNCTION

    SciTech Connect

    Henry, Alaina L.; Martin, Crystal L.; Dressler, Alan; McCarthy, Patrick; Sawicki, Marcin

    2012-01-10

    Using new Keck DEIMOS spectroscopy, we examine the origin of the steep number counts of ultra-faint emission-line galaxies recently reported by Dressler et al. We confirm six Ly{alpha} emitters (LAEs), three of which have significant asymmetric line profiles with prominent wings extending 300-400 km s{sup -1} redward of the peak emission. With these six LAEs, we revise our previous estimate of the number of faint LAEs in the Dressler et al. survey. Combining these data with the density of bright LAEs in the Cosmic Evolution Survey and Subaru Deep Field provides the best constraints to date on the redshift 5.7 LAE luminosity function (LF). Schechter function parameters, {phi}* = 4.5 Multiplication-Sign 10{sup -4} Mpc{sup -3}, L* = 9.1 Multiplication-Sign 10{sup 42} erg s{sup -1}, and {alpha} = -1.70, are estimated using a maximum likelihood technique with a model for slit-losses. To place this result in the context of the UV-selected galaxy population, we investigate how various parameterizations of the Ly{alpha} equivalent width distribution, along with the measured UV-continuum LF, affect shape and normalization of the Ly{alpha} LF. The nominal model, which uses z {approx} 6 equivalent widths from the literature, falls short of the observed space density of LAEs at the bright end, possibly indicating a need for higher equivalent widths. This parameterization of the equivalent width distribution implies that as many as 50% of our faintest LAEs should have M{sub UV} > -18.0, rendering them undetectable in even the deepest Hubble Space Telescope surveys at this redshift. Hence, ultra-deep emission-line surveys find some of the faintest galaxies ever observed at the end of the reionization epoch. Such faint galaxies likely enrich the intergalactic medium with metals and maintain its ionized state in the post-reionization era. Observations of these objects provide a glimpse of the building blocks of present-day galaxies at an early time.

  5. The Faint-End Slopes of Galaxy Luminosity Functions in the COSMOS Field

    NASA Astrophysics Data System (ADS)

    Liu, Charles T.; Capak, Peter; Mobasher, Bahram; Paglione, Timothy A. D.; Rich, R. Michael; Scoville, Nicholas Z.; Tribiano, Shana M.; Tyson, Neil D.

    2008-01-01

    We examine the faint-end slope of the rest-frame V-band luminosity function (LF), with respect to galaxy spectral type, of field galaxies with redshift z < 0.5, using a sample of 80,820 galaxies with photometric redshifts in the 2 deg2 Cosmic Evolution Survey (COSMOS) field. For all galaxy spectral types combined, the LF slope ranges from -1.24 to -1.12, from the lowest redshift bin to the highest. In the lowest redshift bin (0.02 < z < 0.1), where the magnitude limit is MVlesssim - 13, the slope ranges from α ~ - 1.1 for galaxies with early-type spectral energy distributions (SEDs) to α ~ - 1.9 for galaxies with low-extinction starburst SEDs. In each galaxy SED category (early-type, Sbc, Scd+Irr, and starburst), the faint-end slopes grow shallower with increasing redshift; in the highest redshift bin (0.4 < z < 0.5), α ~ - 0.5 and -1.3 for early types and starbursts, respectively. The steepness of α at lower redshifts could be qualitatively explained by LF evolution, or by large numbers of faint dwarf galaxies, perhaps of low surface brightness, that are not detected at higher redshifts. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555; also based on data collected at Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and the National Optical Astronomy Observatory, which are operated by AURA, Inc., under cooperative agreement with the National Science Foundation; at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; at the European Southern Observatory under Large Program 175.A-0839, Chile; at the Canada-France-Hawaii Telescope with MegaPrime/MegaCam, operated as a joint project by the CFHT

  6. Infrared Heaters

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The heating units shown in the accompanying photos are Panelbloc infrared heaters, energy savers which burn little fuel in relation to their effective heat output. Produced by Bettcher Manufacturing Corporation, Cleveland, Ohio, Panelblocs are applicable to industrial or other facilities which have ceilings more than 12 feet high, such as those pictured: at left the Bare Hills Tennis Club, Baltimore, Maryland and at right, CVA Lincoln- Mercury, Gaithersburg, Maryland. The heaters are mounted high above the floor and they radiate infrared energy downward. Panelblocs do not waste energy by warming the surrounding air. Instead, they beam invisible heat rays directly to objects which absorb the radiation- people, floors, machinery and other plant equipment. All these objects in turn re-radiate the energy to the air. A key element in the Panelbloc design is a coating applied to the aluminized steel outer surface of the heater. This coating must be corrosion resistant at high temperatures and it must have high "emissivity"-the ability of a surface to emit radiant energy. The Bettcher company formerly used a porcelain coating, but it caused a production problem. Bettcher did not have the capability to apply the material in its own plant, so the heaters had to be shipped out of state for porcelainizing, which entailed extra cost. Bettcher sought a coating which could meet the specifications yet be applied in its own facilities. The company asked The Knowledge Availability Systems Center, Pittsburgh, Pennsylvania, a NASA Industrial Applications Center (IAC), for a search of NASA's files

  7. Spectra of faint sources in crowded fields with FRODOSpec on the Liverpool Robotic Telescope

    NASA Astrophysics Data System (ADS)

    Shalyapin, V. N.; Goicoechea, L. J.

    We check the performance of the FRODOSpec integral-field spectrograph for observations of faint sources in crowded fields. Although the standard processing pipeline L2 yields too noisy fibre spectra, we present a new processing software (L2LENS) that gives rise to accurate spectra for the two images of the gravitationally lensed quasar Q0957+561. Among other things, this L2LENS reduction tool accounts for the presence of cosmic-ray events, scattered-light backgrounds, blended sources, and chromatic source displacements due to differential atmospheric refraction. Our non-standard reduction of Q0957+561 data shows the ability of FRODOSpec to provide useful information on a wide variety of targets, and thus, the big potential of integral-field spectrographs on current and future robotic telescopes.

  8. Cosmic reionization on computers: The faint end of the galaxy luminosity function

    DOE PAGES

    Gnedin, Nickolay Y.

    2016-07-01

    Using numerical cosmological simulations completed under the “Cosmic Reionization On Computers” project, I explore theoretical predictions for the faint end of the galaxy UV luminosity functions atmore » $$z\\gtrsim 6$$. A commonly used Schechter function approximation with the magnitude cut at $${M}_{{\\rm{cut}}}\\sim -13$$ provides a reasonable fit to the actual luminosity function of simulated galaxies. When the Schechter functional form is forced on the luminosity functions from the simulations, the magnitude cut $${M}_{{\\rm{cut}}}$$ is found to vary between -12 and -14 with a mild redshift dependence. Here, an analytical model of reionization from Madau et al., as used by Robertson et al., provides a good description of the simulated results, which can be improved even further by adding two physically motivated modifications to the original Madau et al. equation.« less

  9. Cosmic reionization on computers: The faint end of the galaxy luminosity function

    SciTech Connect

    Gnedin, Nickolay Y.

    2016-07-01

    Using numerical cosmological simulations completed under the “Cosmic Reionization On Computers” project, I explore theoretical predictions for the faint end of the galaxy UV luminosity functions at $z\\gtrsim 6$. A commonly used Schechter function approximation with the magnitude cut at ${M}_{{\\rm{cut}}}\\sim -13$ provides a reasonable fit to the actual luminosity function of simulated galaxies. When the Schechter functional form is forced on the luminosity functions from the simulations, the magnitude cut ${M}_{{\\rm{cut}}}$ is found to vary between -12 and -14 with a mild redshift dependence. Here, an analytical model of reionization from Madau et al., as used by Robertson et al., provides a good description of the simulated results, which can be improved even further by adding two physically motivated modifications to the original Madau et al. equation.

  10. Hubble Space Telescope: Faint object camera instrument handbook. Version 2.0

    NASA Technical Reports Server (NTRS)

    Paresce, Francesco (Editor)

    1990-01-01

    The Faint Object Camera (FOC) is a long focal ratio, photon counting device designed to take high resolution two dimensional images of areas of the sky up to 44 by 44 arcseconds squared in size, with pixel dimensions as small as 0.0007 by 0.0007 arcseconds squared in the 1150 to 6500 A wavelength range. The basic aim of the handbook is to make relevant information about the FOC available to a wide range of astronomers, many of whom may wish to apply for HST observing time. The FOC, as presently configured, is briefly described, and some basic performance parameters are summarized. Also included are detailed performance parameters and instructions on how to derive approximate FOC exposure times for the proposed targets.

  11. Hubble Space Telescope faint object camera instrument handbook (Post-COSTAR), version 5.0

    NASA Technical Reports Server (NTRS)

    Nota, A. (Editor); Jedrzejewski, R. (Editor); Greenfield, P. (Editor); Hack, W. (Editor)

    1994-01-01

    The faint object camera (FOC) is a long-focal-ratio, photon-counting device capable of taking high-resolution two-dimensional images of the sky up to 14 by 14 arc seconds squared in size with pixel dimensions as small as 0.014 by 0.014 arc seconds squared in the 1150 to 6500 A wavelength range. Its performance approaches that of an ideal imaging system at low light levels. The FOC is the only instrument on board the Hubble Space Telescope (HST) to fully use the spatial resolution capabilities of the optical telescope assembly (OTA) and is one of the European Space Agency's contributions to the HST program.

  12. Long-Term Continuous Double Station Observation of Faint Meteor Showers

    PubMed Central

    Vítek, Stanislav; Páta, Petr; Koten, Pavel; Fliegel, Karel

    2016-01-01

    Meteor detection and analysis is an essential topic in the field of astronomy. In this paper, a high-sensitivity and high-time-resolution imaging device for the detection of faint meteoric events is presented. The instrument is based on a fast CCD camera and an image intensifier. Two such instruments form a double-station observation network. The MAIA (Meteor Automatic Imager and Analyzer) system has been in continuous operation since 2013 and has successfully captured hundreds of meteors belonging to different meteor showers, as well as sporadic meteors. A data processing pipeline for the efficient processing and evaluation of the massive amount of video sequences is also introduced in this paper. PMID:27649179

  13. Cosmic Reionization on Computers: The Faint End of the Galaxy Luminosity Function

    NASA Astrophysics Data System (ADS)

    Gnedin, Nickolay Y.

    2016-07-01

    Using numerical cosmological simulations completed under the “Cosmic Reionization On Computers” project, I explore theoretical predictions for the faint end of the galaxy UV luminosity functions at z≳ 6. A commonly used Schechter function approximation with the magnitude cut at {M}{{cut}}˜ -13 provides a reasonable fit to the actual luminosity function of simulated galaxies. When the Schechter functional form is forced on the luminosity functions from the simulations, the magnitude cut {M}{{cut}} is found to vary between -12 and -14 with a mild redshift dependence. An analytical model of reionization from Madau et al., as used by Robertson et al., provides a good description of the simulated results, which can be improved even further by adding two physically motivated modifications to the original Madau et al. equation.

  14. Long-Term Continuous Double Station Observation of Faint Meteor Showers.

    PubMed

    Vítek, Stanislav; Páta, Petr; Koten, Pavel; Fliegel, Karel

    2016-09-14

    Meteor detection and analysis is an essential topic in the field of astronomy. In this paper, a high-sensitivity and high-time-resolution imaging device for the detection of faint meteoric events is presented. The instrument is based on a fast CCD camera and an image intensifier. Two such instruments form a double-station observation network. The MAIA (Meteor Automatic Imager and Analyzer) system has been in continuous operation since 2013 and has successfully captured hundreds of meteors belonging to different meteor showers, as well as sporadic meteors. A data processing pipeline for the efficient processing and evaluation of the massive amount of video sequences is also introduced in this paper.

  15. Faint quasi-stellar-object candidates in selected areas 28 and 68 identified from multicolor photometry

    SciTech Connect

    Shields, J.C.; Koo, D.C.; Kron, R.C.; California Univ., Berkeley; Lick Observatory, Santa Cruz, CA; Yerkes Observatory, Williams Bay, WI )

    1989-04-01

    Forty-five QSO candidates over a total area of 0.53 square degree in two fields at high Galactic latitudes have been identified. These candidates reached B of about 21.5 for field Lynx.3 in SA 28 and B of about 22 for field SA68.2, and were selected from a subset of objects in catalogs generated from multicolor photometry (UBV) of deep Kitt Peak 4-m plates with limits of B of about 24. This subset consists of all objects which appeared stellar-like in size but which did not have the UBV colors of common Galactic stars. Besides several probable high-redshift QSOs, this study yields faint QSO counts consistent with those from other surveys, and thus provides further support to models that include mainly the luminosity evolution of QSOs. 29 refs.

  16. Two New Ultra-Faint Star Clusters in the Milky Way Halo

    NASA Astrophysics Data System (ADS)

    Kim, Dongwon

    2016-08-01

    Kim 1 & 2 are two new star clusters discovered in the Stromlo Missing Satellite Survey. Kim 1, located at a heliocentric distance of 19.8 +/- 0.9 kpc, features an extremely low total luminosity (M V = 0.3 +/- 0.5 mag) and low star concentration. Together with the large ellipticity (ɛ = 0.42 +/- 0.10) and irregular isophotes, these properties suggest that Kim 1 is an intermediate mass star cluster being stripped by the Galactic tidal field. Kim 2 is a rare ultra-faint outer halo globular cluster located at a heliocentric distance of 104.7 +/- 4.1 kpc. The cluster exhibits evidence of significant mass loss such as extra-tidal stars and mass-segregation. Kim 2 is likely to follow an orbit confined to the peripheral region of the Galactic halo, and/or to have formed in a dwarf galaxy that was later accreted into the Galactic halo.

  17. Discovery of a Type Ia Supernova in a Faint Dwarf Galaxy

    NASA Astrophysics Data System (ADS)

    Williams, R.; Hsiao, E. Y.; Mahabal, A.; Djorgovski, S. G.; Drake, A. J.; Graham, M. J.; Graham, M. L.; Pritchet, C. J.; Parker, A.; Sadavoy, S.; Balam, D.; Catelan, M.; Beshore, E. C.; Larson, S. M.; Boattini, A.; Christensen, E.

    2008-11-01

    We have discovered a supernova in observations from CSS, Palomar 60 and the Plaskett Telescope starting from 22 Nov UT. The discovery has the following parameters:

    CSS081122:094326+251021 2008-11-22 UT 10:18:11 RA 09:43:26.22 Dec 25:10:21.9 Mag 16.4 Type SN Iaz=0.027
    CSS081122:094326+251021 is associated with a very faint anonymous galaxy seen in SDSS DR7 images (mags: u= 23.2, g=22.7, r=22.8, i=22.7, z=23.6).

  18. Starburst and AGN Indicators in Optically Faint X-ray Sources in the Cosmic Evolution Survey

    NASA Astrophysics Data System (ADS)

    Robins, Derek; Elvis, M.; Civano, F.

    2011-01-01

    A sample of 55 faint, X-ray selected objects were chosen for analysis from the COSMOS survey with high quality Keck DEIMOS data. The average redshift of the sample was 1.36, consistent with the average redshift of type 1 AGN in COSMOS of 1.4. Emission lines, NeV - an indicator of AGN luminosity - and OII - an indicator of star formation rate, were measured for a subset of 34 objects. Line properties for these objects were measured. The combination of the two lines is evidence for significant star formation in these obscured AGN. Differences between OII and NeV redshifts were measured carefully. Significant differences between OII and NeV redshifts were found in 10-14 objects, implying OII outflows. The results are consistent with current models of galaxy evolution that invoke an interplay between AGN activity and star formation.

  19. A redshift limit for the faint blue galaxy population from deep U band imaging

    SciTech Connect

    Guhathakurta, P.; Tyson, J.A.; Majewski, S.R. AT T Bell Laboratories, Murray Hill, NJ Yerkes Observatory, Williams Bay, WI )

    1990-07-01

    A definitive upper limit for the redshift of the population of faint blue galaxies found in deep imaging surveys is obtained. The U-B(j), and particularly the B(j)-R, colors of these objects show a blueing trend toward fainter magnitudes. A typical galaxy at R = 26 has colors that are only slightly redder than a flat spectrum. For any reasonable Lyman limit break, this constrains 93 percent or more of the galaxies to under z about 3, beyond which the break gets redshifted through the U band. The galaxies appear to be undergoing relatively recent evolution with rest frame spectra that are approximately flat down to the Lyman limit. 23 refs.

  20. The Faint Young Sun Paradox in the Context of Modern Cosmology

    NASA Astrophysics Data System (ADS)

    Dumin, Yu. V.

    2015-09-01

    The Faint Young Sun Paradox comes from the fact that solar luminosity (2-4)x10^9 years ago was insufficient to support the Earth's temperature necessary for the efficient development of geological and biological evolution (particularly, for the existence of considerable volumes of liquid water). It remains unclear by now if the so-called greenhouse effect on the Earth can resolve this problem. An interesting alternative explanation was put forward recently by M.Krizek (New Astron. 2012, 17, 1), who suggested that planetary orbits expand with time due to the local Hubble effect, caused by the uniformly-distributed Dark Energy. Then, under a reasonable value of the local Hubble constant, it is easy to explain why the Earth was receiving an approximately constant amount of solar irradiation for a long period in the past and will continue to do so for a quite long time in future.