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1

Are the infrared-faint radio sources pulsars?  

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

2

Morphology and astrometry of Infrared-Faint Radio Sources  

NASA Astrophysics Data System (ADS)

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.

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

2008-10-01

3

Fainting  

MedlinePLUS

... a medicine you're taking. Alcohol, cocaine and marijuana can also cause fainting. More serious causes of fainting include seizures and problems with the heart or with the blood vessels leading to the brain. Who is at risk for fainting? People who ...

4

VLBI observations of Infrared-Faint Radio Sources  

NASA Astrophysics Data System (ADS)

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.

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

2006-10-01

5

Meridian observations of faint objects with a CCD micrometer.  

NASA Astrophysics Data System (ADS)

The authors have constructed an experiment model of new CCD micrometer for the Tokyo Photoelectric Meridian Circle (PMC). The experiment model consists of a single field CCD image sensor TH7883 (Thomson-CSF) cooled by liquid nitrogen to around 200K, a clock-drive board, 16 bit ADC (Analog-to-Digital Converter), and an EWS to control the system. The so-called drift scanning method is the basic electrical architecture for detecting and accumulating the incoming photons from celestial objects. This architecture, if realized with a CCD chip of Q.E. higher than 30%, enables to achieve direct astrometric observations of faint objects up to 15th mag, e.g., some bright QSOs, faint galactic stars, and faint minor planets. The performance of the experiment model of the authors' CCD micrometer is under study through the observations of real stars by using the Gotier meridian circle at Mitaka, Tokyo.

Yoshizawa, M.; Suzuki, S.; Kuwabara, T.; Ishizaki, H.

6

The Faint Object Camera (Phase a). Volume 2: Detector Design.  

National Technical Information Service (NTIS)

Detector options were considered for the faint object camera of the NASA 2.4 m space telescope. Performance figures were recalculated for the most promising systems identified during previous studies. The systems are the following: I4-P four-stage magneti...

A. Boksenberg C. I. Coleman D. Weighton P. J. Bowen R. Nettleship

1976-01-01

7

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

NASA Astrophysics Data System (ADS)

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 ?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 >~ 1) active galactic nuclei.

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

2010-02-01

8

The radio properties of infrared-faint radio sources  

NASA Astrophysics Data System (ADS)

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 ?m when using sensitive Spitzer observations with ?Jy 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 ?m 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.

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

2011-02-01

9

A faint object spectrograph for the William Herschel Telescope  

Microsoft Academic Search

The design and performance of the faint object spectrograph on the 4.2-m William Herschel Telescope (La Palma) are discussed. The collimatorless design provides high efficiency and a large spectral range. The dispersion is shown to be 8.7 A\\/pixel in first order and 4.3 A\\/pixel in second order, with a resolution of 1.5 pixels FWHM. The total efficiency is found to

J. R. Allington-Smith; J. M. Breare; B. E. Carrasco; R. S. Ellis; I. R. Parry; J. Webster; D. W. Gellatly; F. J. Gribbin; M. Ingle; P. R. Jorden; C. M. Lowne; J. R. Powell; D. J. Thorne; C. Taylor; I. G. van Breda; N. R. Waltham; S. P. Worswick; C. G. Wynne

1989-01-01

10

A faint object spectrograph for the William Herschel Telescope  

Microsoft Academic Search

The design and performance of the FOS-2 faint-object spectrograph for the Herschel Telescope at the Observatorio del Roque de los Muchachos are described and illustrated with diagrams and drawings. The FOS-2 has an image scale of 223 microns\\/arcsec at the slit and features a cryostat-cooled 385 x 578-pixel CCD detector with 22-micron-sq pixels, operating with resolution 1.5 pixels and dispersion

J. R. Allington-Smith; J. M. Breare; R. S. Ellis; I. R. Parry; J. Webster

1990-01-01

11

Faint Star Counts in the Near-Infrared  

NASA Astrophysics Data System (ADS)

We discuss near-infrared star counts at the Galactic pole with a view to guiding the Next Generation Space Telescope and ground-based near-infrared cameras. Star counts from deep K-band images from the Canada-France-Hawaii Telescope are presented and compared with results from the 2MASS survey and some galaxy models. With appropriate corrections for detector artifacts and galaxies, the data agree with the models down to K~18 but indicate a larger population of fainter red stars. There is also a significant population of compact galaxies that extend to the observational faint limit of K=20.5. Recent galaxy models agree well down to K~19 but diverge at fainter magnitudes.

Hutchings, J. B.; Stetson, P. B.; Robin, A.; Webb, T.

2002-07-01

12

Infrared Faint Radio Sources in the Extended Chandra Deep Field South  

NASA Astrophysics Data System (ADS)

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).

Huynh, Minh T.

2009-01-01

13

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

NASA Astrophysics Data System (ADS)

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.

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

2009-04-01

14

Infrared and Optical Study of Faint IRAS-FSC Sources  

NASA Astrophysics Data System (ADS)

Extragalactic sources from the IRAS Faint Source Catalog (FSC) which have the optically faintest magnitudes (E>18) were selected by spatial coincidence with a source in the FIRST radio survey, and 28 of these sources have been observed with the Infrared Spectrograph on Spitzer (IRS). The sources luminosities encompass the range from local ULIRGs to the most luminous sources discovered by Spitzer at z~2. Detectable PAH features are found in 15 of the sources (54%), and measurable silicate absorption are present in 19 sources (68%); both PAH emission and silicate absorption are present in 11 sources. PAH luminosities are used to determine the SB fraction of bolometric luminosity, and model predictions for a dusty torus are used to determine the AGN fraction of luminosity in all sources based on ?L? (5.5 mum). The ratio of infrared to radio flux, defined as q=log[fnu(25mum)]/[fnu(1.4Ghz)], does not distinguish between AGN and SB for these sources.

Sargsyan, Lusine A.; Mickaelian, Areg M.; Weedman, Daniel W.; Houck, James R.

2010-11-01

15

NOTE: Red, Gray, and Blue: Near Infrared Spectrophotometry of Faint Moons of Uranus and Neptune  

Microsoft Academic Search

Using the CoCo Cold Coronagraph at NASA's Infrared Telescope Facility on Mauna Kea, we observed the uranian satellites Miranda, Puck, Portia, and Rosalind and the neptunian satellite Proteus in the near infrared (JHK) to determine the albedos of those faint satellites. In V-J, all of Puck, Portia, Rosalind, and Proteus are very blue, similar to the colors of many icy

David E. Trilling; Robert H. Brown

2000-01-01

16

Red, Gray, and Blue: Near Infrared Spectrophotometry of Faint Moons of Uranus and Neptune  

Microsoft Academic Search

Using the CoCo Cold Coronagraph at NASA's Infrared Telescope Facility on Mauna Kea, we observed the uranian satellites Miranda, Puck, Portia, and Rosalind and the neptunian satellite Proteus in the near infrared (JHK) to determine the albedos of those faint satellites. In V-J, all of Puck, Portia, Rosalind, and Proteus are very blue, similar to the colors of many icy

David E. Trilling; Robert H. Brown

2000-01-01

17

The first VLBI image of an infrared-faint radio source  

NASA Astrophysics Data System (ADS)

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.

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

2008-11-01

18

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

NASA Astrophysics Data System (ADS)

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.

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

2010-04-01

19

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

NASA Astrophysics Data System (ADS)

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.

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

2009-04-01

20

MID-INFRARED SPECTROSCOPY OF OPTICALLY FAINT EXTRAGALACTIC 70 {mu}M SOURCES  

SciTech Connect

We present mid-infrared (mid-IR) spectra of 16 optically faint sources with 70 {mu}m fluxes in the range 19 mJy objects show prominent polycyclic aromatic hydrocarbon (PAH) emission features; four of 16 show weak PAHs and strong silicate absorption, and two objects have no discernable spectral features. Compared to samples with f {sub {nu}}(24 {mu}m) > 10 mJy, the 70 {mu}m sample has steeper IR continua and higher luminosities. The PAH-dominated sources are among the brightest starbursts seen at any redshift, and reside in a redshift range where other selection methods turn up relatively few sources. The absorbed sources are at higher redshifts and have higher luminosities than the PAH-dominated sources, and may show weaker luminosity evolution. We conclude that a 70 {mu}m selection extending to {approx}20 mJy, in combination with selections at mid-IR and far-IR wavelengths, is necessary to obtain a complete picture of the evolution of IR-luminous galaxies over 0 < z < 2.

Farrah, D. [Astronomy Center, University of Sussex, Falmer, Brighton BN1 9RH (United Kingdom); Weedman, D.; Houck, J. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Lonsdale, C. J. [ALMA Science Center, National Radio Astronomy Observatory, Edgemont Rd., Charlottesville, VA 22904 (United States); Polletta, M. [INAF-ISAF Milano, via E. Bassini, Milan 20133 (Italy); Rowan-Robinson, M. [Astrophysics Group, Imperial College, London SW7 2BW (United Kingdom); Smith, H. E. [Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla, CA 92093 (United States)

2009-05-10

21

FAR-INFRARED AND MOLECULAR CO EMISSION FROM THE HOST GALAXIES OF FAINT QUASARS AT z {approx} 6  

SciTech Connect

We present new millimeter and radio observations of nine z {approx} 6 quasars discovered in deep optical and near-infrared surveys. We observed the 250 GHz continuum in eight of the nine objects and detected three of them. New 1.4 GHz radio continuum data have been obtained for four sources, and one has been detected. We searched for molecular CO (6-5) line emission in the three 250 GHz detections and detected two of them. Combined with previous millimeter and radio observations, we study the far-infrared (FIR) and radio emission and quasar-host galaxy evolution with a sample of 18 z {approx} 6 quasars that are faint at UV and optical wavelengths (rest-frame 1450 A magnitudes of m{sub 1450} {>=} 20.2). The average FIR-to-active galactic nucleus (AGN) UV luminosity ratio of this faint quasar sample is about two times higher than that of the bright quasars at z {approx} 6 (m{sub 1450} < 20.2). A fit to the average FIR and AGN bolometric luminosities of both the UV/optically faint and bright z {approx} 6 quasars, and the average luminosities of samples of submillimeter/millimeter-observed quasars at z {approx} 2-5, yields a relationship of L{sub FIR} {approx} L{sub bol}{sup 0.62}. Five of the 18 faint z {approx} 6 quasars have been detected at 250 GHz. These 250 GHz detections, as well as most of the millimeter-detected optically bright z {approx} 6 quasars, follow a shallower trend of L{sub FIR} {approx} L{sub bol}{sup 0.45} defined by the starburst-AGN systems in local and high-z universe. The millimeter continuum detections in the five objects and molecular CO detections in three of them reveal a few x 10{sup 8} M{sub sun} of FIR-emitting warm dust and 10{sup 10} M{sub sun} of molecular gas in the quasar host galaxies. All these results argue for massive star formation in the quasar host galaxies, with estimated star formation rates of a few hundred M{sub sun} yr{sup -1}. Additionally, the higher FIR-to-AGN luminosity ratio found in these 250 GHz detected faint quasars also suggests a higher ratio between star formation rate and supermassive black hole accretion rate than the UV/optically most luminous quasars at z {approx} 6.

Wang Ran; Wagg, Jeff; Carilli, Chris L. [National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801 (United States); Neri, Roberto [Institute de Radioastronomie Millimetrique, St. Martin d'Heres F-38406 (France); Walter, Fabian [Max-Planck-Institute for Astronomy, Koenigsstuhl 17, 69117 Heidelberg (Germany); Omont, Alain [Institut d'Astrophysique de Paris, CNRS and Universite Pierre et Marie Curie, Paris (France); Riechers, Dominik A. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Bertoldi, Frank [Argelander-Institut fuer Astronomie, University of Bonn, Auf dem Huegel 71, 53121 Bonn (Germany); Menten, Karl M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 71, 53121 Bonn (Germany); Cox, Pierre [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19 (Chile); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Fan Xiaohui; Jiang Linhua [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

2011-10-15

22

Science in crowded fields with Hubble Space Telescope Faint Object Spectrograph plus COSTAR  

Microsoft Academic Search

We describe plans for several science programs in crowded fields using the faint object spectrograph (FOS) which rely critically on the enhanced angular resolution provided by the COSTAR corrective optics. Based on ground-based calibration of the COSTAR and on-orbit performance of the FOS, the anticipated performance of the COSTAR+\\/FOS should allow many important scientific studies to be completed which have

Richard J. Harms; Holland C. Ford; George F. Hartig; Frank Bartko

1994-01-01

23

H{alpha} DOTS: A CATALOG OF FAINT EMISSION-LINE OBJECTS DISCOVERED IN NARROWBAND IMAGES  

SciTech Connect

During a wide-field narrowband H{alpha} imaging survey, we noted the presence of numerous isolated emission-line point sources in the data. These objects could represent ultra-low-luminosity galaxies at low-redshift (detection via H{alpha}), isolated extragalactic H II regions associated with the galaxy targeted by the original observation, or background galaxies or QSOs where strong emission lines (most often [O III] {lambda}5007) redshift into our narrowband filter. We have carried out a systematic search for these 'H{alpha} dots' in over 200 15 Multiplication-Sign 15 arcmin fields. To date we have cataloged 61 candidate emission-line sources in roughly 11.7 deg{sup 2}. The sample has a median R magnitude of 19.5, and detects objects as faint as R = 22.6. Follow-up spectroscopy reveals that {approx}85% of the candidates are bona fide emission-line objects, with roughly 60% of the real sources being lower-redshift objects (detection via H{alpha}) and 40% being higher-redshift objects detected via [O III] emission or some other emission line. Here we present the results of our initial survey and follow-up spectroscopy. We use our sample to study the properties (including star-formation rates and metal abundances) of low-luminosity star-forming galaxies in the nearby universe and of low-metallicity star-forming galaxies at z Almost-Equal-To 0.33.

Kellar, Jessica A.; Wegner, Gary [Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755 (United States); Salzer, John J.; Williams, Anna [Department of Astronomy, Indiana University, 727 East Third Street, Bloomington, IN 47405 (United States); Gronwall, Caryl, E-mail: jessica.a.kellar@dartmouth.edu, E-mail: gaw@northstar.dartmouth.edu, E-mail: slaz@astro.indiana.edu, E-mail: caryl@astro.psu.edu, E-mail: williams@astro.wisc.edu [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)

2012-06-15

24

Sensitive imaging polarimetry of the faint infrared reflection nebula in B5 IRS1  

NASA Astrophysics Data System (ADS)

The paper presents sensitive polarimetric images at J, H, and K of the faint reflection nebulosity in the low-mass young stellar object B5 IRS1. Multiepoch photometry, compared with existing data, shows that the near-IR luminosity of B5 IRS1 has varied significantly between 1983 and 1990, declining steadily in near-IR brightness while maintaining virtually constant near-IR colors. This may suggest an increase of neutral extinction by grains which are growing in a circumstellar disk, which is speculated to have later accreted into planetesimals. The nebula is composed of light scattered in a thin, limb-brightened dust shell partly surrounding the blueshifted lobe of the molecular outflow from IRS1. An estimate of the density in the scattering dust shell indicates rough pressure equilibrium between the shell and the molecular flow, and a sound-crossing time in the shell close to the dynamical age of the flow.

Moore, T. J. T.; Emerson, J. P.

1992-11-01

25

Observations of SN1988A with the Faint Object Spectrograph on the 4.2 M William Herschel telescope  

Microsoft Academic Search

Two spectra of the supernova SN1988A in M58 (NGC 4579) are presented over the wavelength range 4000-9700 A, as recorded by the Faint Object Spectrograph on the 4.2 m William Herschel Telescope at the Observatorio del Roque de los Muchachos. It is concluded that SN1988A was a type II supernova.

G. Pearce; B. E. Patchett; J. R. Allington-Smith

1990-01-01

26

Observations of SN1988A with the faint object spectrograph on the 4.2 m William Herschel Telescope  

Microsoft Academic Search

We present two spectra of the supernova SN1988A in M58 (NGC4579) over the wavelength range 4000–9700 Å, as recorded by the Faint Object Spectrograph on the 4.2 m William Herschel Telescope at the Observatorio del Roque de los Muchachos. We conclude that SN1988A was a type II supernova.

G. Pearce; B. E. Patchett; J. R. Allington-Smith

1990-01-01

27

Formation of UV Continua and Faint Lines in Herbig-Haro Objects  

NASA Astrophysics Data System (ADS)

We propose to obtain one two-shift exposure (14-15 hour) of each of the Herbig-Haro (H-H) objects H-H1 and H-H2. This will be done jointly with Drs. Reinhard Mundt and Josef Solf of the Max-Planck-Institut for Astronomie, who are submitting the corresponding proposal to E.S.A. It is the primary purpose of this study to determine the energy distribution in the unexpectedly strong continuum of H-H objects with higher accuracy and reliability than was possible from the relatively short (and underexposed) observations available now. The results will be used for a critical test of the hypothesis that the continuum is collisionally enhanced two-photon radiation of hydrogen. Especially, the investigation of the wavelength interval 1216A <~ x <~ 1410A, in which the theory predicts a very steep drop of the intensity towards shorter wavelengths will be very useful in this respect. The possibility that other (emission or absorption) mechanisms contribute to the shape of the continuum will also be investigated. We plan to determine the possible contribution of the Orion reflection nebulosity (ORN) to the observed H-H spectrum by also studying the spectrum in the parts of the aperture not covered by the H-H object. The H-H spectrum will be corrected for this ORN contribution. We shall also identify and measure fainter emission lines so that the elimination of the faint emission line contribution from the apparent continuum can be done as accurately as possible. As a byproduct, this study will give us useful information about the physical conditions in H-H objects by adding to the available information on their emission lines. We hope that this will help us to contribute to the further clarification of the apparent contradiction between the ionization determined from optical lines and that indicated by the ultraviolet lines.

Bohm, Karl-Heinz

28

First results from the faint object camera - High-resolution observations of the central object R136 in the 30 Doradus nebula  

Microsoft Academic Search

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

G. Weigelt; R. Albrecht; C. Barbieri; J. C. Blades; A. Boksenberg; P. Crane; J. M. Deharveng; M. J. Disney; P. Jakobsen; T. M. Kamperman; I. R. King; F. Macchetto; C. D. Mackay; F. Paresce; D. Baxter; P. Greenfield; R. Jedrzejewski; A. Nota; W. B. Sparks

1991-01-01

29

Athermalization of a fast infrared telescope objective  

NASA Astrophysics Data System (ADS)

In high performance optical systems, a frequent requirement is 'athermalization' or the stabilization of optical performance with environmental temperature. This is particularly relevant in the case of refracting infrared systems for which the variations of refractive index as a function of temperature are relatively large. In this paper, as an example of an athermalization problem, the approach adopted for the stabilization of an infrared multi- magnification 'zoom' telescope objective is reviewed and the mechanism devised for introducing the necessary adjustments is described. Finally, the variation in performance of an actual athermalized system, following heat soak over a temperature range of 130 degrees Celsius, is discussed. The telescope, which was designed for use in the 8.0 micrometer to 13.0 micrometer waveband, provides a set of four fixed magnifications ranging from X3.5 to X20. It employs germanium and zinc selenide as refracting materials.

Simmons, Richard C.

1995-10-01

30

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

NASA Astrophysics Data System (ADS)

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 5? sensitivities as low as 1 ?Jy. 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.

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

2011-07-01

31

Observations of Close Pairs of Faint Blue Objects: Towards Mirage or Reality  

Microsoft Academic Search

The authors present the results of a preliminary observational run of the FRV sample (Fringant et al., 1983) of close pairs of UVX objects at high galactic latitude. The extragalactic physical pairs are ?30% and most of them do appear as \\

H. Reboul; A. M. Fringant; C. Vanderriest

1986-01-01

32

Observations of Close Pairs of Faint Blue Objects: Towards Mirage or Reality  

NASA Astrophysics Data System (ADS)

The authors present the results of a preliminary observational run of the FRV sample (Fringant et al., 1983) of close pairs of UVX objects at high galactic latitude. The extragalactic physical pairs are ?30% and most of them do appear as "interactivating" AGNs. The method seems equally adapted to find new gravitational mirages as well as really double QSOs.

Reboul, H.; Fringant, A. M.; Vanderriest, C.

33

Observations of the supernova SN1987L with the new Faint Object Spectrograph on the 4.2 m William Herschel Telescope  

Microsoft Academic Search

We present the spectrum of the supernova SN1987L in NGC 2336 over the wavelength range 4000–9700 Å as recorded in one 500 s exposure on 20–21 October, 1987. This spectrum was taken using the new Faint Object Spectrograph on the 4.2 m William Herschel Telescope (WHT) at the Observatorio del Roque de los Muchachos.

Gillian Pearce; Bruce Patchett; Jeremy Allington-Smith; Ian Parry

1988-01-01

34

Syncope (Fainting)  

MedlinePLUS

... What is syncope? Syncope is temporary loss of consciousness and posture, described as "fainting" or "passing out." ... circulation to the brain and causing loss of consciousness. Typical NMS occurs while standing and is often ...

35

Hubble Space Telescope Faint Object Spectrograph Optical and Ultraviolet Spectroscopy of the Bow Shock HH 47A  

NASA Astrophysics Data System (ADS)

We present new spectra obtained with the Faint Object Spectrograph aboard the Hubble Space Telescope of the HH 47A bow shock and Mach disk that cover the entire spectral range between lambdalambda2220 and 6810. In addition to emission lines seen previously from HH objects, we uncover over a dozen weak Fe IItransitions in the ultraviolet. The flux ratios between these permitted lines can only be understood if transitions to the ground state are resonantly scattered within HH 47A. The expected column density of Fe II within HH 47A suffices to scatter these lines, although the scattering optical depths imply that the Fe II line broadening must exceed that expected from thermal motions. Excitation of ultraviolet Fe II occurs locally within HH 47A, probably from collisions within the hot postshock gas and not from UV pumping from some nearby O stars. The data show no evidence for significant depletion of Fe within HH 47A. The emission line's fluxes and ratios indicate that jet material currently enters the Mach disk with a density of ~350 cm^-3 and a velocity of ~40 km s^-1. The mass-loss rate of the exciting star, as measured by the mass flux through the Mach disk, is 1.6x10^-8 M_solar yr^-1. This mass-loss rate is considerably lower than that closer to the star where the jet is brighter, probably because the density along the jet is highly nonuniform. A single-shock velocity does not match the bow shock spectrum well. We propose that secondary shocks reheat the gas within the cooling zone of the HH 47A bow shock. Compression from the first shock will cause these secondary shocks to be strongly magnetized, and the secondary shocks should emit strongly in low-excitation lines such as Mg II, C II], and [S II]. The weak blue continua seen at optical wavelengths in spectra of the Mach disk and bow shock extend into the ultraviolet and have spectral energy distributions and total fluxes consistent with those expected from two-photon emission.

Hartigan, Patrick; Morse, Jon A.; Tumlinson, Jason; Raymond, John; Heathcote, Steve

1999-02-01

36

Spaced based infrared detection and characterization of near earth objects  

Microsoft Academic Search

An infrared space-based survey system would be an invaluable adjunct to the ground based visible searches for the discovery of Near Earth Objects (NEOs). It would significantly increase the discovery rate of NEOs and would have unique capabilities to probe their physical character. An infrared NEO survey compensates for the bias of visible searches to preferentially discover high albedo objects

Stephan D. Price; Michael P. Egan

2001-01-01

37

THE OPTICAL SPECTRA OF SPITZER 24 mum GALAXIES IN THE COSMIC EVOLUTION SURVEY FIELD. II. FAINT INFRARED SOURCES IN THE zCOSMOS-BRIGHT 10k CATALOG  

SciTech Connect

We have used the zCOSMOS-bright 10k sample to identify 3244 Spitzer/MIPS 24 mum-selected galaxies with 0.06 mJy < S{sub 24{sub m}}u{sub m} approx< 0.50 mJy and I{sub AB} < 22.5, over 1.5 deg{sup 2} of the COSMOS field, and studied different spectral properties, depending on redshift. At 0.2 < z < 0.3, we found that different reddening laws of common use in the literature explain the dust extinction properties of approx80% of our infrared (IR) sources, within the error bars. For up to 16% of objects, instead, the Halpha lambda6563/Hbeta lambda4861 ratios are too high for their IR/UV attenuations, which is probably a consequence of inhomogeneous dust distributions. In only a few of our galaxies at 0.2 < z < 0.3, the IR emission could be mainly produced by dust heated by old rather than young stars. Besides, the line ratios of approx22% of our galaxies suggest that they might be star-formation/nuclear-activity composite systems. At 0.5 < z < 0.7, we estimated galaxy metallicities for 301 galaxies: at least 12% of them are securely below the upper-branch mass-metallicity trend, which is consistent with the local relation. Finally, we performed a combined analysis of the H{sub d}elta equivalent width versus D{sub n} (4000) diagram for 1722 faint and bright 24 mum galaxies at 0.6 < z < 1.0, spanning two decades in mid-IR luminosity. We found that, while secondary bursts of star formation are necessary to explain the position of the most luminous IR galaxies in that diagram, quiescent, exponentially declining star formation histories can well reproduce the spectral properties of approx40% of the less luminous sources. Our results suggest a transition in the possible modes of star formation at total IR luminosities L{sub TIR} approx (3 +- 2) x 10{sup 11} L{sub sun}.

Caputi, K. I.; Lilly, S. J.; Maier, C.; Carollo, C. M. [Institute of Astronomy, Swiss Federal Institute of Technology (ETH), Wolfgang-Pauli-Strasse 27, CH-8093 Zuerich (Switzerland); Aussel, H.; Floc'h, E. Le [CEA/DSM-CNRS, Universite Paris Diderot, DAPNIA/SAp, Orme des Merisiers, 91191 Gif-sur-Yvette (France); Sanders, D. [Institute for Astronomy, University of Hawaii, Honololu, HI (United States); Frayer, D. [Spitzer Science Center, California Institute of Technology, Pasadena, CA (United States); Contini, T. [Laboratoire d'Astrophysique de Toulouse-Tarbes, Universite de Toulouse, 14 avenue Edouard Belin, Toulouse (France); Kneib, J.-P.; Le Fevre, O. [Laboratoire d'Astrophysique de Marseille, 38 rue Frederic Joliot-Curie, Marseille (France); Mainieri, V. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching (Germany); Renzini, A. [Dipartimento di Astronomia, Universita di Padova, Padova (Italy); Scodeggio, M. [INAF-IASF Milano, via E. Bassini 15, 20133 Milan (Italy); Scoville, N. [California Institute of Technology, Pasadena, CA (United States); Zamorani, G.; Bardelli, S.; Bolzonella, M.; Coppa, G. [INAF Osservatorio Astronomico di Bologna, Bologna (Italy); Bongiorno, A., E-mail: kic@roe.ac.u [Max Planck Institut fuer Extraterrestrische Physik, Garching (Germany)

2009-12-20

38

Infrared system for monitoring movement of objects  

SciTech Connect

A system is described for monitoring moving objects, such as the flight of honeybees and other insects, using a pulsed laser light source. This system has a self-powered micro-miniaturized transmitting unit powered, in the preferred embodiment, with an array of solar cells. This transmitting unit is attached to the object to be monitored. These solar cells provide current to a storage energy capacitor to produce, for example, five volts for the operation of the transmitter. In the simplest embodiment, the voltage on the capacitor operates a pulse generator to provide a pulsed energizing signal to one or more very small laser diodes. The pulsed light is then received at a receiving base station using substantially standard means which converts the light to an electrical signal for processing in a microprocessor to create the information as to the movement of the object. In the case of a unit for monitoring honeybees and other insects, the transmitting unit weighs less than 50 mg, and has a size no larger than 1[times]3[times]5 millimeters. Also, the preferred embodiment provides for the coding of the light to uniquely identify the particular transmitting unit that is being monitored. A wake-up' circuit is provided in the preferred embodiment whereby there is no transmission until the voltage on the capacitor has exceeded a pre-set threshold. Various other uses of the motion-detection system are described. 4 figures.

Valentine, K.H.; Falter, D.D.; Falter, K.G.

1991-04-30

39

Infrared system for monitoring movement of objects  

DOEpatents

A system is described for monitoring moving objects, such as the flight of honeybees and other insects, using a pulsed laser light source. This system has a self-powered micro-miniaturized transmitting unit powered, in the preferred embodiment, with an array of solar cells. This transmitting unit is attached to the object to be monitored. These solar cells provide current to a storage energy capacitor to produce, for example, five volts for the operation of the transmitter. In the simplest embodiment, the voltage on the capacitor operates a pulse generator to provide a pulsed energizing signal to one or more very small laser diodes. The pulsed light is then received at a receiving base station using substantially standard means which converts the light to an electrical signal for processing in a microprocessor to create the information as to the movement of the object. In the case of a unit for monitoring honeybees and other insects, the transmitting unit weighs less than 50 mg, and has a size no larger than 1[times]3[times]5 millimeters. Also, the preferred embodiment provides for the coding of the light to uniquely identify the particular transmitting unit that is being monitored. A wake-up' circuit is provided in the preferred embodiment whereby there is no transmission until the voltage on the capacitor has exceeded a pre-set threshold. Various other uses of the motion-detection system are described. 4 figures.

Valentine, K.H.; Falter, D.D.; Falter, K.G.

1991-04-30

40

MID-INFRARED SPECTRAL VARIABILITY ATLAS OF YOUNG STELLAR OBJECTS  

SciTech Connect

Optical and near-infrared variability is a well-known property of young stellar objects. However, a growing number of recent studies claim that a considerable fraction of them also exhibit mid-infrared flux changes. With the aim of studying and interpreting variability on a decadal timescale, here we present a mid-infrared spectral atlas containing observations of 68 low- and intermediate-mass young stellar objects. The atlas consists of 2.5-11.6 {mu}m low-resolution spectra obtained with the ISOPHOT-S instrument on board the Infrared Space Observatory (ISO) between 1996 and 1998, as well as 5.2-14.5 {mu}m low-resolution spectra obtained with the Infrared Spectrograph instrument on board the Spitzer Space Telescope between 2004 and 2007. The observations were retrieved from the ISO and Spitzer archives and were post-processed interactively by our own routines. For those 47 objects where multi-epoch spectra were available, we analyze mid-infrared spectral variability on annual and/or decadal timescales. We identify 37 variable candidate sources. Many stars show wavelength-independent flux changes, possibly due to variable accretion rates. In several systems, all exhibiting 10 {mu}m silicate emission, the variability of the 6-8 {mu}m continuum, and the silicate feature exhibit different amplitudes. A possible explanation is variable shadowing of the silicate-emitting region by an inner disk structure of changing height or extra silicate emission from dust clouds in the disk atmosphere. Our results suggest that mid-infrared variability, in particular, the wavelength-dependent changes, is more ubiquitous than was known before. Interpreting this variability is a new possibility for exploring the structure of the disk and its dynamical processes.

Kospal, A. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden (Netherlands); Abraham, P.; Kun, M.; Moor, A. [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, P.O. Box 67, 1525 Budapest (Hungary); Acosta-Pulido, J. A. [Instituto de Astrofisica de Canarias, Via Lactea s/n, 38200 La Laguna, Tenerife (Spain); Dullemond, C. P. [Institut fuer Theoretische Astrophysik, Zentrum fuer Astronomie der Universitaet Heidelberg, Albert-Ueberle-Str. 2, 69120 Heidelberg (Germany); Henning, Th.; Leinert, Ch. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany); Turner, N. J., E-mail: akospal@rssd.esa.int [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2012-08-01

41

GTC/OSIRIS SPECTROSCOPIC IDENTIFICATION OF A FAINT L SUBDWARF IN THE UKIRT INFRARED DEEP SKY SURVEY  

SciTech Connect

We present the discovery of an L subdwarf in 234 deg{sup 2} common to the UK InfraRed Telescope (UKIRT) Infrared Deep Sky Survey Large Area Survey Data Release 2 and the Sloan Digital Sky Survey Data Release 3. This is the fifth L subdwarf announced to date, the first one identified in the UKIRT Infrared Deep Sky Survey, and the faintest known. The blue optical and near-infrared colors of ULAS J135058.86+081506.8 and its overall spectra energy distribution are similar to the known mid-L subdwarfs. Low-resolution optical (700-1000 nm) spectroscopy with the Optical System for Imaging and low Resolution Integrated Spectroscopy spectrograph on the 10.4 m Gran Telescopio de Canarias reveals that ULAS J135058.86+081506.8 exhibits a strong K I pressure-broadened line at 770 nm and a red slope longward of 800 nm, features characteristics of L-type dwarfs. From direct comparison with the four known L subdwarfs, we estimate its spectral type to be sdL4-sdL6 and derive a distance in the interval 94-170 pc. We provide a rough estimate of the space density for mid-L subdwarfs of 1.5 x 10{sup -4} pc{sup -3}.

Lodieu, N. [Instituto de AstrofIsica de Canarias, C/VIa Lactea s/n, E-38205 La Laguna, Tenerife (Spain); Osorio, M. R. Zapatero; MartIn, E. L.; Solano, E.; Aberasturi, M. [Centro de AstrobiologIa (CSIC/INTA), 28850 Torrejon de Ardoz, Madrid (Spain)], E-mail: nlodieu@iac.es

2010-01-10

42

NEAR-INFRARED SPECTRA OF CENTAURS AND KUIPER BELT OBJECTS  

Microsoft Academic Search

We present here an extensive survey of near-infrared (NIR) spectra of Kuiper belt objects (KBOs) and Centaurs taken with the Keck I Telescope. We find that most spectra in our sample are well characterized by a combination of water ice and a featureless continuum. A comparative analysis reveals that the NIR spectral properties have little correlation to the visible colors

K. M. Barkume; M. E. Brown; E. L. Schaller

2008-01-01

43

The Faint Sky Variability Survey - Who's Faint and Variable?  

Microsoft Academic Search

The Faint Sky Variability Survey is a large (23 sq. deg.), deep field (V=17-24 mags), optical (BVI), photometric (0.005-0.1 mags), and proper motion (30''\\/yr) survey using the Wide-Field Camera at the Isaac Newton Telescope on La Palma. Time-sampled observations span 10's of minutes to years and provide a unique database for studies of faint population classes (e.g. Kuiper Belt objects,

M. E. Huber; S. B. Howell; M. E. Everett; P. J. Groot

2002-01-01

44

Born-big TNOs and the shallow size distribution of faint objects in the Edgeworth-Kuiper belt  

NASA Astrophysics Data System (ADS)

ALICANDEP (Asteroid-LIke Collisional ANd Dynamical Evolution Package) is a collisional evolution code [1] including a) statistical elimination of objects by dynamical effects within the frame of a disc that migrates and is excited dynamically, and b) the dynamical migration of objects within the disc itself, as described by the Nice model [2]. The model meets the Nice model requirements and matches available current observables (the existence of Pluto and the rest of dwarf planets in the region; the number of objects larger than 100 km in different dynamical populations and the corresponding size distributions, as found by the Canadian France Ecliptic Plane Survey, CFEPS [3,4])

Campo Bagatin, A.; Benavidez, P. G.

2011-10-01

45

Infrared Spectroscopy of Intermediate-mass Young Stellar Objects  

NASA Astrophysics Data System (ADS)

In this paper, we present Spitzer Infrared Spectrograph spectroscopy for 14 intermediate-mass young stellar objects (YSOs). We use Spitzer spectroscopy to investigate the physical properties of these sources and their environments. Our sample can be divided into two types of objects: young isolated, embedded objects with spectra that are dominated by ice and silicate absorption bands, and more evolved objects that are dominated by extended emission from polycyclic aromatic hydrocarbons (PAHs) and pure H2 rotational lines. We are able to constrain the illuminating FUV fields by classifying the PAH bands below 9 ?m. For most of the sources we are able to detect several atomic fine structure lines. In particular, the [Ne II] line appearing in two regions could originate from unresolved photodissociation regions or J-shocks. We relate the identified spectral features to observations obtained from NIR through submillimeter imaging. The spatial extent of several H2 and PAH bands is matched with morphologies identified in previous Infrared Array Camera observations. This also allows us to distinguish between the different H2 excitation mechanisms. In addition, we calculate the optical extinction from the silicate bands and use this to constrain the spectral energy distribution fit, allowing us to estimate the masses of these YSOs.

Pitann, Jan; Hennemann, Martin; Birkmann, Stephan; Bouwman, Jeroen; Krause, Oliver; Henning, Thomas

2011-12-01

46

A fuzzy automated object classification by infrared laser camera  

NASA Astrophysics Data System (ADS)

Home security in night is very important, and the system that watches a person's movements is useful in the security. This paper describes a classification system of adult, child and the other object from distance distribution measured by an infrared laser camera. This camera radiates near infrared waves and receives reflected ones. Then, it converts the time of flight into distance distribution. Our method consists of 4 steps. First, we do background subtraction and noise rejection in the distance distribution. Second, we do fuzzy clustering in the distance distribution, and form several clusters. Third, we extract features such as the height, thickness, aspect ratio, area ratio of the cluster. Then, we make fuzzy if-then rules from knowledge of adult, child and the other object so as to classify the cluster to one of adult, child and the other object. Here, we made the fuzzy membership function with respect to each features. Finally, we classify the clusters to one with the highest fuzzy degree among adult, child and the other object. In our experiment, we set up the camera in room and tested three cases. The method successfully classified them in real time processing.

Kanazawa, Seigo; Taniguchi, Kazuhiko; Asari, Kazunari; Kuramoto, Kei; Kobashi, Syoji; Hata, Yutaka

2011-05-01

47

SearchCal: a Virtual Observatory tool for searching calibrators in optical long-baseline interferometry. II. The faint-object case  

NASA Astrophysics Data System (ADS)

Context. In long-baseline interferometry, images or astrophysical parameters are obtained from the raw fringe contrast after a careful calibration process. We have already developed the software (SearchCal) to select suitable bright calibration stars (V ? 10; K ? 5.0) for obtaining the ultimate precision of current interferometric instruments like the VLTI. With the expected gain in sensitivity of AMBER and PRIMA on the VLTI, the need for fainter calibrators should now be adressed. Aims: We present a new version of SearchCal dedicated to the creation of an evolving catalog of stars suitable as calibrators with K magnitude >5 around the scientific target. Methods: Star catalogs available at the CDS are searched via web requests and provide the useful astrometric and photometric informations for selecting calibrators. The missing photometries are computed with an accuracy of about 0.1 mag. The stellar angular diameter is estimated with a precision of about 10% through newly determined surface-brightness versus color-index relations based on the I, J, H and K magnitudes. For each star the squared visibility is computed taking into account the central wavelength and the maximum baseline of the predicted observations. Results: The version of SearchCal for faint objects that allows to find calibrators for interferometric observations up to K ~ 15 is available as a web service at the address: http://www.jmmc.fr/searchcal

Bonneau, D.; Delfosse, X.; Mourard, D.; Lafrasse, S.; Mella, G.; Cetre, S.; Clausse, J.-M.; Zins, G.

2011-11-01

48

A Complete Multiwavelength Characterization of Faint Chandra X-Ray Sources Seen in the Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey  

NASA Astrophysics Data System (ADS)

We exploit deep combined observations with Spitzer and Chandra of the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) in the ELAIS N1 region to investigate the nature of the faint X-ray and IR sources in common, to identify active galactic nucleus (AGN)/starburst diagnostics, and to study the sources of the X-ray and IR cosmic backgrounds (XRB and CIRB). In the 17'×17' area of the Chandra ACIS-I image there are approximately 3400 SWIRE near-IR sources with 4 ? detections in at least two Infrared Array Camera (IRAC) bands and 988 sources detected at 24 ?m with the Multiband Imaging Photometer (MIPS) brighter than S24~=0.1 mJy. Of these, 102 IRAC and 59 MIPS sources have Chandra counterparts, out of a total of 122 X-ray sources present in the area with S0.5-8keV>10-15 ergs cm-2 s-1. We have constructed spectral energy distributions (SEDs) for each source using data from the four IRAC wavebands, Chandra fluxes in the hard (2-8 keV) and soft (0.5-2 keV) X-rays, and optical follow-up data in the wavebands U, g', r', i', Z, and H. We fit a number of spectral templates to the SEDs at optical and IR wavelengths to determine photometric redshifts and spectral categories and also make use of diagnostics based on the X-ray luminosities, hardness ratios, X-ray to IR spectral slopes, and optical morphologies. Although we have spectroscopic redshifts for only a minority of the Chandra sources (10 type 1 QSOs or Seyfert sources and three galaxies), the available SEDs constrain the redshifts for most of the sample sources, which turn out to be typically at 0.5

Franceschini, Alberto; Manners, James; Polletta, Maria del Carmen; Lonsdale, Carol; Gonzalez-Solares, Eduardo; Surace, Jason; Shupe, Dave; Fang, Fan; Xu, C. Kevin; Farrah, Duncan; Berta, Stefano; Rodighiero, Giulia; Perez-Fournon, Ismael; Hatziminaoglou, Evanthia; Smith, Harding E.; Siana, Brian; Rowan-Robinson, Michael; Nandra, Kirpal; Babbedge, Tom; Vaccari, Mattia; Oliver, Seb; Wilkes, Belinda; Owen, Frazer; Padgett, Deborah; Frayer, Dave; Jarrett, Tom; Masci, Frank; Stacey, Gordon; Almaini, Omar; McMahon, Richard; Johnson, Olivia; Lawrence, Andrew; Willott, Chris

2005-05-01

49

Diffraction Limited Images of Faint Field Galaxies  

Microsoft Academic Search

We have used the Keck Adaptive Optics System to observe six galaxies at resolutions close to 50 milliarcseconds in the near infrared (1.6 microns). These are the highest resolution images ever achieved on faint galaxies at these wavelengths and are sharper than Hubble Space Telescope optical images. We are able to determine accurate bulge and disk sizes and general morphologies

J. E. Larkin; T. M. Glassman; P. Wizinowich; O. Lai

1999-01-01

50

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 ...

51

Fainting in animals.  

PubMed

Fainting (syncope) is unconsciousness due to insufficient cerebral circulation in the context of a temporary failure of the systemic circulation. This paper firstly aims to discuss fainting in animals, and secondly to discuss animal physiology to broaden the understanding of human fainting. Of the three major syncope types (cardiac, orthostatic and reflex syncope), only cardiac syncope occurs in animals as in man, through arrhythmia or output failure. Man's orthostatic fainting tendency has been blamed on his upright posture. A comparison with animals shows that giraffes, tree climbing snakes, and animals that quickly raise and lower their heads face more serious gravitational circulatory challenges than man, but do not appear to faint. Merely carrying the brain above the heart does not explain a fainting tendency, as the human heart-to-brain height is smaller than that of many mammals with similar blood pressure. Two evolutionary novelties may be to blame: the proportion of cardiac output going upwards to the brain is much larger than in apes, and man's large legs suggest that the volume lost to venous pooling is also larger. Emotional factors play a role in many reflex syncope events. Tonic immobility ('feigning death','playing possum') is not a good model, as it concerns immobility as a survival strategy of an attentive brain, rather than unconsciousness due to circulatory breakdown. Whether orienting and defense responses form a valid model remains to be proven. Emotional fainting may be uniquely human; how mental processes can shut down the circulation and thereby the brain needs serious study, as it may hold the key to syncope prevention. PMID:12955549

van Dijk, J Gert

2003-08-01

52

Effect of micro-motion dynamics on the infrared radiation of space objects  

Microsoft Academic Search

In addition to the centroid translation along the trajectory, space objects undergo micro-motion dynamics, such as coning and spinning motions. The micro-motion dynamics of an object might induce fluctuant on infrared signature received by a space-based sensor. In this paper, we develop an infrared signature simulation model for space objects. Formulae of aspect transform matrices for coning and spinning motions

Fubing Li; Xiaojian Xu

2008-01-01

53

Numerical study of the thermal infrared characteristics for orbital objects  

Microsoft Academic Search

When a space object in spin stabilization, three-axis stabilization or roll-motion is running on orbit, heat transfer such as radiation and conduction takes place, which makes the temperature field on the object in an unsteady state. Besides, the methods of stabilization on orbit also affect the temperature distribution as well as projected area to a spaceborne sensor, thus influence IR

Fubing Li; Xiaojian Xu

2010-01-01

54

Simultaneous Optical and Infrared Observations of Bl-Lacertae Objects  

NASA Astrophysics Data System (ADS)

The energy distribution of bright BL Lac objects is being monitored simultaneously in the IR to visible range. Results derived from spectrophotometric ( 4000 to 7400 Å ) and photometric ( J,H,K and L ) observations of 16 objects, obtained in 1987 - 1988, are reported. Repeated measurements at different intensity levels were obtained for three program objects, PKS 0048-09, PKS 0422+00, and PKS 0537-44, thus allowing a preliminary discussion of the dynamical behavior of the IR to visible energy distribution.

Tanzi, E. G.; Falomo, R.; Bouchet, P.; Bersanelli, M.; Maraachi, L.; Treves, A.

55

Optically faint radio sources: reborn AGN?  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

56

Near-infrared spectra of 12 Near-Earth Objects  

NASA Astrophysics Data System (ADS)

We present a number of spectra of Near-Earth Objects taken in the period 1998-2003 with two different instruments (CGS4 and UIST) on the UKIRT telescope. Since observations with CGS4 require multiple spectral fragments to be observed sequentially and then spliced together we assess the reliability of this technique using comparisons between multiple observations of the same object, between observations of the same object with both instruments and with independent spectra of common objects. We conclude that while problems in the spectral splicing can occur, they are usually intuitively obvious and that overall our dataset is sound. The objects for which we present new spectral data are: 1627 Ivar, 4179 Toutatis, 5381 Sekhmet, (5587) 1990 SB, 6489 Golevka, (11405) 1999 CV 3, (14402) 1991 DB, 25143 Itokawa, (25330) 1999 KV 4, (52760) 1998 ML 14, (66391) 1999 KW 4, and (101955) 1999 RQ 36. Our results, together with albedo data from the literature, suggest carbonaceous compositions for 25330 and 101955. The available data for 14402 suggest it may belong to the relatively rare M class. Our analysis suggests an S or Sq classification for 52760 and a V classification for 5381 Sekhmet. For all remaining objects the UKIRT data are consistent with published spectral classifications. We find that only 3 of the 12 objects are not S/Q/V-class, which is roughly consistent with the results of Binzel et al. [Binzel, R.P., Rivkin, A.S., Stuart, J.S., Harris, A.W., Bus, S.J., Burbine, T.H., 2004. Icarus 170, 259-294]. Four spectra of Toutatis taken over a range of solar phase angles between 0.7°-81° and at intervals of several weeks are indistinguishable within the uncertainties and therefore do not reveal any evidence for phase reddening or surface variegation.

Davies, John K.; Harris, Alan W.; Rivkin, Andrew S.; Wolters, Stephen D.; Green, Simon F.; McBride, Neil; Mann, Rita K.; Kerr, Tom H.

2007-01-01

57

Infrared Spectra of Comet-Asteroid Transition Object 944 Hidalgo  

Microsoft Academic Search

Asteroid 944 Hidalgo is suspected of being an extinct comet. Understanding the origin of this enigmatic object is relevant to several areas of planetary astronomy, and the study of its surface composition may be diagnostic of its origin. Silicates have been detected in active comets, and on Jupiter Trojans. Our team investigated Hidalgo in the 8-30 micron range to determine

K. Hargrove; H. Campins; M. Kelley; Y. Fernandez; J. Ziffer; J. Licandro; J. Emery; D. Cruikshank; C. Hergenrother; N. Pinilla-Alonso; D. Clautice

2008-01-01

58

Detecting the highest redshift (z > 8) quasi-stellar objects in a wide, near-infrared slitless spectroscopic survey  

NASA Astrophysics Data System (ADS)

We investigate the prospects of extending observations of high-redshift quasi-stellar objects (QSOs) from the current z˜ 7 to z > 8 by means of a very wide-area near-infrared slitless spectroscopic survey, considering as an example the planned survey with the European Space Agency's Euclid telescope (scheduled for a 2019 launch). For any QSOs at z > 8.06, the strong Lyman ? line will enter the wavelength range of the Euclid Near-Infrared Spectometer and Imaging Photometer (NISP). We perform a detailed simulation of near infrared spectrometer and imaging photometer (Euclid) NISP slitless spectroscopy (with the parameters of the wide survey) in an artificial field containing QSO spectra at all redshifts up to z= 12 and to a faint limit H= 22.5. QSO spectra are represented with a template based on a Sloan Digital Sky Survey composite spectrum, with the added effects of absorption from neutral hydrogen in the intergalactic medium. The spectra extracted from the simulation are analysed with an automated redshift finder, and a detection rate estimated as a function of H magnitude and redshift (defined as the proportion of spectra with both correct redshift measurements and classifications). We show that, as expected, spectroscopic identification of QSOs would reach deeper limits for the redshift ranges where either ? (0.67 < z < 2.05) or Lyman ? (z > 8.06) is visible. Furthermore, if photometrically selected z > 8 spectra can be re-examined and refitted to minimize the effects of spectral contamination, the QSO detection rate in the Lyman ? window will be increased by an estimated ˜60 per cent and will then be better here than at any other redshift, with an effective limit H? 21.5. With an extrapolated rate of QSO evolution, we predict that the Euclid wide (15 000 ?) spectroscopic survey will identify and measure spectroscopic redshifts for a total of 20-35 QSOs at z > 8.06 (reduced slightly to 19-33 if we apply a small correction for missed weak-lined QSOs). However, for a model with a faster rate of evolution, this prediction goes down to four or five. In any event, the survey will give important constraints on the evolution of QSO at z > 8 and therefore the formation of the first supermassive black holes. The z > 8.06 detections would be very luminous objects (with MB=-26 to -28) and many would also be detectable by the proposed Wide Field X-ray Telescope.

Roche, Nathan; Franzetti, Paolo; Garilli, Bianca; Zamorani, Giovanni; Cimatti, Andrea; Rossetti, Emanuel

2012-02-01

59

Infrared detection, recognition and identification of handheld objects  

NASA Astrophysics Data System (ADS)

A main criterion for comparison and selection of thermal imagers for military applications is their nominal range performance. This nominal range performance is calculated for a defined task and standardized target and environmental conditions. The only standardization available to date is STANAG 4347. The target defined there is based on a main battle tank in front view. Because of modified military requirements, this target is no longer up-to-date. Today, different topics of interest are of interest, especially differentiation between friend and foe and identification of humans. There is no direct way to differentiate between friend and foe in asymmetric scenarios, but one clue can be that someone is carrying a weapon. This clue can be transformed in the observer tasks detection: a person is carrying or is not carrying an object, recognition: the object is a long / medium / short range weapon or civil equipment and identification: the object can be named (e. g. AK-47, M-4, G36, RPG7, Axe, Shovel etc.). These tasks can be assessed experimentally and from the results of such an assessment, a standard target for handheld objects may be derived. For a first assessment, a human carrying 13 different handheld objects in front of his chest was recorded at four different ranges with an IR-dual-band camera. From the recorded data, a perception experiment was prepared. It was conducted with 17 observers in a 13-alternative forced choice, unlimited observation time arrangement. The results of the test together with Minimum Temperature Difference Perceived measurements of the camera and temperature difference and critical dimension derived from the recorded imagery allowed defining a first standard target according to the above tasks. This standard target consist of 2.5 / 3.5 / 5 DRI line pairs on target, 0.24 m critical size and 1 K temperature difference. The values are preliminary and have to be refined in the future. Necessary are different aspect angles, different carriage and movement.

Adomeit, Uwe

2012-10-01

60

Infrared photometry of the young stellar objects V346 Normae and RE 13  

Microsoft Academic Search

We have examined the infrared properties of Re 13 and V346 Nor which excite Herbig-Haro objects 56 and 57 respectively. We provide the first detection of Re 13 in the infrared. In the IRAS Point Source Catlaog Re 13 and V346 Nor are confused into a single source IRAS 16289-4449. We have applied maximum entropy based deconvolution techniques to demonstrate

T. Prusti; Tj. R. Bontekoe; J. E. Chiar; D. J. M. Kester; D. C. B. Whittet

1993-01-01

61

Performance of HAWAII2 FPA for Subaru Multi-Object Near-Infrared Camera and Spectrograph  

Microsoft Academic Search

MOIRCS (Multi-Object Infrared Camera and Spectrograph) is a new Cassegrain instrument for Subaru Telescope, which is designed for multi-slit spectroscopy and wide-field imaging in the near-infrared. The notable feature is the capability of multi-slit spectroscopy in K band with cooled slit masks. Twenty-three slit masks kept in a carousel at 150 K are interchangeable during observations. To cover a wide

Takashi Ichikawa; Yuka Katsuno; Ryuji Suzuki; Chihiro Tokoku; Tetsuo Nishimura

2004-01-01

62

Research and analysis small infrared object detection track algorithm and its image processing technology  

Microsoft Academic Search

In order to realize infrared small object track detection, the paper analyses the principle of the target tracking detection, the technology combining Mean Shift track algorithm and image processing is proposed. According to the principle, every tache of detection system is analyzed, and then the optic detection model is set up. The detection model of dynamic object is set up.

Liping Lu; Junxue Geng; Tianren Zhao

2011-01-01

63

The Lack of Torus Emission from BL Lacertae Objects: An Infrared View of Unification with WISE  

NASA Astrophysics Data System (ADS)

We use data from the Wide-Field Infrared Survey Explorer (WISE) to perform a statistical study on the mid-infrared (IR) properties of a large number (~102) of BL Lac objects—low-luminosity active galactic nuclei (AGNs) with a jet beamed toward the Earth. As expected, many BL Lac objects are so highly beamed that their jet synchrotron emission dominates their IR spectral energy distributions. In other BL Lac objects, however, the jet is not strong enough to completely dilute the rest of the AGN emission. We do not see observational signatures of the dusty torus from these weakly beamed BL Lac objects. The lack of observable torus emission is consistent with suggestions that BL Lac objects are fed by radiatively inefficient accretion disks. Implications for the "nature versus nurture" debate for FR I and FR II radio galaxies are briefly discussed. Our study supports the notion that, beyond orientation, accretion rate plays an important role in AGN unification.

Plotkin, Richard M.; Anderson, Scott F.; Brandt, W. N.; Markoff, Sera; Shemmer, Ohad; Wu, Jianfeng

2012-02-01

64

Research and development of infrared object detection system based on FPGA  

NASA Astrophysics Data System (ADS)

Infrared object detection is an important technique of digital image processing. It is widely used in automatic navigation, intelligent video surveillance systems, traffic detection, medical image processing etc. Infrared object detection system requires large storage and high speed processing technology. The current development trend is the system which can be achieved by hardware in real-time with fewer operations and higher performance. As a main large-scale programmable specific integrated circuit, field programmable gate array (FPGA) can meet all the requirements of high speed image processing, with the characteristics of simple algorithm realization, easy programming, good portability and inheritability. So it could get better result by using FPGA to infrared object detection system. According to the requirements, the infrared object detection system is designed on FPGA. By analyzing some of the main algorithms of object detection, two new object detection algorithms called integral compare algorithm (ICA) and gradual approach centroid algorithm (GACA) are presented. The system design applying FPGA in hardware can implement high speed processing technology, which brings the advantage of both performance and flexibility. ICA is a new type of denoising algorithm with advantage of lower computation complexity and less execution time. What is more important is that this algorithm can be implemented in FPGA expediently. Base on image preprocessing of ICA, GACA brings high positioning precision with advantage of insensitivity to the initial value and fewer times of convergence iteration. The experiments indicate that the infrared object detection system can implement high speed infrared object detecting in real-time, with high antijamming ability and high precision. The progress of Verilog-HDL and its architecture are introduced in this paper. Considering the engineering application, this paper gives the particular design idea and the flow of this method's realization in FPGA device. And we also discuss the problems on how to describe the hardware system in Verilog-HDL. Based on the hardware architecture of infrared object detection system, the component units of the system are discussed in detail, such as image data acquisition unit, data pre-processing unit and logical control unit etc. The design of the FPGA function and its implementation are carried on Verilog-HDL with TOP-DOWN method. The ending is the prospect of the project.

Zhao, Jianhui; He, Jianwei; Wang, Pengpeng; Li, Fan

2009-07-01

65

Status of the KMOS multi-object near-infrared integral field spectrograph  

NASA Astrophysics Data System (ADS)

KMOS is a multi-object near-infrared integral field spectrograph being built by a consortium of UK and German institutes. We report on the final integration and test phases of KMOS, and its performance verification, prior to commissioning on the ESO VLT later this year.

Sharples, Ray; Bender, Ralf; Agudo Berbel, Alex; Bennett, Richard; Bezawada, Naidu; Cirasuolo, Michele; Clark, Paul; Davidson, George; Davies, Richard; Davies, Roger; Dubbeldam, Marc; Fairley, Alasdair; Finger, Gert; Genzel, Reinhard; Haefner, Reinhold; Hess, Achim; Lewis, Ian; Montgomery, David; Murray, John; Muschielok, Bernard; Förster-Schreiber, Natascha; Pirard, Jeff; Ramsay, Suzanne; Rees, Phil; Richter, Josef; Robertson, David; Robson, Ian; Rolt, Stephen; Saglia, Roberto; Schlichter, Jörg; Tecza, Mathias; Todd, Stephen; Wegner, Michael; Wiezorrek, Erich

2012-09-01

66

Infrared space studies of Solar-System objects: The post-ISO era  

Microsoft Academic Search

The ISO mission is expected to allow significant progress in the study of Solar-System objects, especially concerning planetary and cometary atmospheres. Beyond ISO, future Solar-System studies using infrared space missions will require an extension of the spectral coverage toward longer wavelengths and increased spatial capabilities for imaging spectroscopy.

Therese Encrenaz

1992-01-01

67

MOSFIRE: a multi-object near-infrared spectrograph and imager for the Keck Observatory  

Microsoft Academic Search

MOSFIRE, the multi-object spectrometer for infra-red exploration, is a near-IR (0.97-2.45 micron) spectrograph and imager for the Cassegrain focus of the Keck I telescope. The optical design provides imaging and multi-object spectroscopy over a field of view (FOV) of 6.14' x 6.14' with a resolving power of R~3,270 for a slit width of 0.7 arc seconds (2.9 pixels along dispersion).

Ian S. McLean; Charles C. Steidel; Keith Matthews; Harland Epps; Sean M. Adkins

2008-01-01

68

OBJECT X: THE BRIGHTEST MID-INFRARED POINT SOURCE IN M33  

SciTech Connect

We discuss the nature of the brightest mid-IR point source (which we dub Object X) in the nearby galaxy M33. Although multi-wavelength data on this object have existed in the literature for some time, it had not previously been recognized as the most luminous mid-IR object in M33 because it is entirely unremarkable in both optical and near-IR light. In the Local Group Galaxies Survey, Object X is a faint red source visible in VRI and H{alpha} but not U or B. It was easily seen at JHK{sub s} in the Two Micron All Sky Survey. It is the brightest point source in all four Spitzer IRAC bands and is also visible in the MIPS 24 {mu}m band. Its bolometric luminosity is {approx}5 x 10{sup 5} L{sub sun}. The source is optically variable on short timescales (tens of days) and is also slightly variable in the mid-IR, indicating that it is a star. Archival photographic plates (from 1949 and 1991) show no optical source, so the star has been obscured for at least half a century. Its properties are similar to those of the Galactic OH/IR star IRC+10420, which has a complex dusty circumstellar structure resulting from episodic low-velocity mass ejections. We propose that Object X is an M {approx}> 30 M{sub sun} evolved star obscured in its own dust ejected during episodic mass-loss events over at least {approx}half a century. It may emerge from its current ultra-short evolutionary phase as a hotter post-red-supergiant star analogous to M33 Var A. The existence and rarity of such objects can be an important probe of a very brief yet eventful stellar evolutionary phase.

Khan, Rubab; Stanek, K. Z.; Kochanek, C. S. [Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210 (United States); Bonanos, A. Z., E-mail: khan@astronomy.ohio-state.edu, E-mail: kstanek@astronomy.ohio-state.edu, E-mail: ckochanek@astronomy.ohio-state.edu, E-mail: bonanos@astro.noa.gr [Institute of Astronomy and Astrophysics, National Observatory of Athens, I. Metaxa and Vas. Pavlou St., P. Penteli, 15236 Athens (Greece)

2011-05-01

69

Centaurs and Scattered Disk Objects in the Thermal Infrared: Analysis of WISE/NEOWISE Observations  

NASA Astrophysics Data System (ADS)

The Wide-field Infrared Survey Explorer (WISE) observed 52 Centaurs and Scattered Disk Objects in the thermal infrared, including discoveries of 15 previously unknown objects. At this writing, this is the largest published collection of thermal infrared measurements of Centaur and SDOs. We present analyses of these observations to estimate sizes and mean optical albedos derived from photometry of the WISE images taken simultaneously at wavelengths of 3.4, 4.6, 12, and 22 microns. We find mean visual-wavelength geometric albedos of 0.08, +/- 0.04 standard deviations, for the entire data set. Thermal fits yield average beaming parameters of 0.9 +/- 0.2 that are similar for both SDO and Centaur sub-classes, and there appears to be no trend of beaming with heliocentric distance. Raw cumulative size distributions for objects with diameters > 20 km yield size-frequency distribution power law indices ~ -1.7 +/- 0.3. The data also reveal a relation between albedo and color at the 3-sigma level, with those objects with visual-wavelength B-R colors < 1.4 magnitudes having significantly lower albedos than those with B-R colors exceeding 1.4 magnitudes. No significant relation between diameter and albedos is found. We will also discuss the implications of these survey results concerning the related comet and TNO populations.

Bauer, James M.; Grav, T.; Mainzer, A. K.; Masiero, J. R.; Blauvelt, E.; Stevenson, R.; Kramer, E.; Fernandez, Y. R.; Lisse, C. M.; Cutri, R. M.; Weissman, P. R.; Dailey, J. W.; Masci, F. J.; Walker, R.; Waszczak, A.; Nugent, C. R.; Meech, K. J.; Lucas, A.; Pearman, G.; Wilkins, A.; Watkins, J.; Kulkarni, S.; Wright, E. L.; WISE team; PTF team

2013-10-01

70

Results and analyses of faint field galaxy surveys with the Keck Telescope  

NASA Astrophysics Data System (ADS)

A large collaboration at Caltech has been using the Keck and other telescopes to perform UBVRIKL imaging and take spectra of faint galaxies. The spectroscopic samples contain several hundred objects to K=20 mag or R=24 mag and the imaging samples contain thousands of sources to R~ 27. Faint field galaxies are found to be strongly clustered in velocity space; the angular coherence, masses and morphologies in configuration space of these structures are investigated. In cooperation with the University of Hawaii group, the luminosity function of galaxies is computed in the near-infrared; strong evolution is found in the number of low-luminosity galaxies to z~ 1, although the statistical properties of high-luminosity objects are relatively constant. A range of models for the faint galaxy counts are constructed, not on the basis of a priori information about galaxy properties (from, say, cosmogonic theory) but rather by ``inverting'' the data under a range of qualitatively distinct simplifying assumptions. Predictions are made for ongoing or future imaging and spectroscopy surveys which will clearly distinguish the models. The prospects for a ``meta-analysis'' of a large collection of heterogeneous surveys to create consistent galaxy evolution models from z=0 to the highest observed redshifts are discussed.

Hogg, D. W.

1996-12-01

71

Young Stellar Objects in Taurus in the Near- and Mid-Infrared  

NASA Astrophysics Data System (ADS)

We present several near- and mid-infrared images of newly discovered young stellar objects (YSOs) in the Taurus cloud complex. The emission seen at these wavelengths is higher than what is expected from a stellar photosphere; the excess radiation originates in the dusty circumstellar disks surrounding these young stars. In addition to circumstellar disks, YSOs often have nearby companions. Our observations resolve the multiplicity and spectral energy distribution of our sample of YSOs and thus aid in determining their evolutionary stage.

Furlan, E.; Uchida, K. I.; Herter, T. L.; Forrest, W. J.; Watson, D. M.

2004-12-01

72

Visible and Near-Infrared Photometry of the Centaur Objects 1995 GO and 5145 Pholus  

Microsoft Academic Search

We present visible and near-infrared broadband photometry of the Centaur objects 1995 GO and 5145 Pholus. Our data confirm the extremely redV?Jcolor and nearly solarJ?HandH?Kcolors of 5145 Pholus. OurV?Jdata reveal that 1995 GO is as red as the reddest D-type asteroid, 1748 Mauderli, but not nearly as red as 5145 Pholus. We suggest that the red color of 1995 GO

David A. Weintraub; Stephen C. Tegler; W. Romanishin

1997-01-01

73

Observations of Near-Earth Objects by the Japanese infrared Survey mission ASTRO-F  

Microsoft Academic Search

The infrared astronomical satellite ASTRO-F, which has a 70 cm cooled telescope, will be launched in 2003 fiscal year. The main research items of ASTRO-F are formation and evolution of galaxies, star formation, interstellar matter, brown dwarf, and dark matter. In addition to these items, ASTRO-F also observes objects in the solar system, such as asteroids, comets, and interplanetary dust.

M. Yoshikawa; S. Hasegawa; I. Yamamura; M. Ueno

2002-01-01

74

Time-resolved infrared spectrophotometric observations of high area to mass ratio (HAMR) objects in GEO  

NASA Astrophysics Data System (ADS)

Optical surveys have identified a class of high area-to-mass ratio (HAMR) objects in the vicinity of the Geostationary Earth Orbit (GEO) ring [1]. The exact origin and nature of these objects are not well known, although their proximity to the GEO ring poses a hazard to active GEO satellites. Due to their high area-to-mass ratios, solar radiation pressure perturbs their orbits in ways that makes it difficult to predict their orbital trajectories over periods of time exceeding a week. To better understand these objects and their origins, observations that allow us to derive physical characteristics are required in order to improve the non-conservative force modeling for orbit determination and prediction. Information on their temperatures, areas, emissivities, and albedos may be obtained from thermal infrared, mid-wave infrared (MWIR), and visible measurements. Spectral features may help to identify the composition of the material, and thus possible origins for these objects.We have collected observational data on various HAMR objects from the AMOS observatory 3.6 m AEOS telescope. The thermal-IR spectra of these low-earth orbit objects acquired by the Broadband Array Spectrograph System (BASS) span wavelengths 3-13 ?m and constitute a unique data set, providing a means of measuring, as a function of time, object fluxes. These, in turn, allow temperatures and emissivity-area products to be calculated. In some instances we have also collected simultaneous filtered visible photometric data on the observed objects. The multi-wavelength observations of the objects provide possible clues as to the nature of the observed objects.We describe briefly the nature and status of the instrumental programs used to acquire the data, our data of record, our data analysis techniques, and our current results, as well as future plans.

Skinner, Mark A.; Russell, Ray W.; Rudy, Richard J.; Gutierrez, David J.; Kim, Daryl L.; Crawford, Kirk; Gregory, Steve; Kelecy, Tom

2011-12-01

75

Further analysis of infrared spectrophotometric observations of high area to mass ratio (HAMR) objects in GEO  

NASA Astrophysics Data System (ADS)

Optical surveys have identified a class of high area-to-mass ratio (HAMR) objects in the vicinity of the Geostationary Earth Orbit (GEO) ring?. The exact origin and nature of these objects are not well known, although their proximity to the GEO belt poses a hazard to active GEO satellites. The prevalent conjecture is that many of these objects may be thermal materials shed from derelict spacecraft in ‘graveyard’ orbits above the GEO ring. Due to their high area-to-mass ratios and unknown attitude dynamics and material characteristics, solar radiation pressure (SRP) perturbs their orbits in ways that makes it difficult to predict their orbital trajectories over periods of time exceeding a week or less. To better understand and track these objects and infer their origins, we have made observations that allow us to determine physical characteristics that will improve the non-conservative force modeling used for orbit determination (OD) and prediction. Information on their temperatures, areas, emissivities, and albedos may be obtained from thermal infrared and visible measurements. Simultaneous observations in the thermal infrared and visible wavelengths may allow disentangling of projected area, albedo, and object emissivity.Further analysis and modeling of observational data on certain of the HAMR objects collected at the AMOS observatory 3.6 m AEOS telescope are presented. The thermal-IR spectra of these geosynchronous orbit objects acquired by the Broadband Array Spectrograph System (BASS) span wavelengths 3 to 13 ?m and constitute a unique data set, providing a means of measuring object fluxes in the infrared and visible wavelengths. These, in turn, allow temperatures and emissivity-area products to be calculated, and in some cases provide information on rotation rates. We compare our observational results with the outputs of simple models, in terms of visible and infrared flux and orbital characteristics. The resulting temperatures and rotation rates are used in SRP acceleration models to demonstrate improvements in OD and prediction performance relative to models which assume default ambient temperature and static attitude dynamics. Additionally, we have the capability and plans to measure material properties with the same instrument in the lab as used at the telescope to facilitate direct comparisons.

Skinner, Mark A.; Russell, Ray W.; Kelecy, Tom; Gregory, Steve; Rudy, Richard J.; Gutierrez, David J.; Kim, Daryl L.; Crawford, Kirk

2012-11-01

76

First results from VLTI near-infrared interferometry on high-mass young stellar objects  

NASA Astrophysics Data System (ADS)

Due to the recent dramatic technological advances, infrared interferometry can now be applied to new classes of objects, resulting in exciting new science prospects, for instance, in the area of high-mass star formation. Although extensively studied at various wavelengths, the process through which massive stars form is still only poorly understood. For instance, it has been proposed that massive stars might form like low-mass stars by mass accretion through a circumstellar disk/envelope, or otherwise by coalescence in a dense stellar cluster. Therefore, clear observational evidence, such as the detection of disks around high-mass young stellar objects (YSOs), is urgently needed in order to unambiguously identify the formation mode of the most massive stars. After discussing the technological challenges which result from the special properties of these objects, we present first near-infrared interferometric observations, which we obtained on the massive YSO IRAS 13481-6124 using VLTI/AMBER infrared long-baseline interferometry and NTT speckle interferometry. From our extensive data set, we reconstruct a model-independent aperture synthesis image which shows an elongated structure with a size of ~ 13 x 19 AU, consistent with a disk seen under an inclination of - 45°. The measured wavelengthdependent visibilities and closure phases allow us to derive the radial disk temperature gradient and to detect a dust-free region inside of 9.5 AU from the star, revealing qualitative and quantitative similarities with the disks observed in low-mass star formation. In complementary mid-infrared Spitzer and sub-millimeter APEX imaging observations we detect two bow shocks and a molecular outflow, which are oriented perpendicular to the disk plane and indicate the presence of a bipolar outflow emanating from the inner regions of the system.

Kraus, Stefan; Hofmann, Karl-Heinz; Menten, Karl M.; Schertl, Dieter; Weigelt, Gerd; Wyrowski, Friedrich; Meilland, Anthony; Perraut, Karine; Petrov, Romain; Robbe-Dubois, Sylvie; Schilke, Peter; Testi, Leonardo

2010-07-01

77

THE LACK OF TORUS EMISSION FROM BL LACERTAE OBJECTS: AN INFRARED VIEW OF UNIFICATION WITH WISE  

SciTech Connect

We use data from the Wide-Field Infrared Survey Explorer (WISE) to perform a statistical study on the mid-infrared (IR) properties of a large number ({approx}10{sup 2}) of BL Lac objects-low-luminosity active galactic nuclei (AGNs) with a jet beamed toward the Earth. As expected, many BL Lac objects are so highly beamed that their jet synchrotron emission dominates their IR spectral energy distributions. In other BL Lac objects, however, the jet is not strong enough to completely dilute the rest of the AGN emission. We do not see observational signatures of the dusty torus from these weakly beamed BL Lac objects. The lack of observable torus emission is consistent with suggestions that BL Lac objects are fed by radiatively inefficient accretion disks. Implications for the 'nature versus nurture' debate for FR I and FR II radio galaxies are briefly discussed. Our study supports the notion that, beyond orientation, accretion rate plays an important role in AGN unification.

Plotkin, Richard M.; Markoff, Sera [Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands); Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Brandt, W. N.; Wu Jianfeng [Department of Astronomy and Astrophysics, Pennsylvania Sate University, 525 Davey Laboratory, University Park, PA 16802 (United States); Shemmer, Ohad, E-mail: r.m.plotkin@uva.nl [Department of Physics, University of North Texas, Denton, TX 76203 (United States)

2012-02-15

78

Syncope (Fainting) (Beyond the Basics)  

MedlinePLUS

... as fainting, refers to a sudden loss of consciousness, followed by a rapid and complete recovery. If ... symptoms of dizziness or lightheadedness, without loss of consciousness, this is called presyncope. Syncope should not be ...

79

A Near-Infrared Search for Companions around Very Low Luminosity Young Stellar Objects in Taurus  

NASA Astrophysics Data System (ADS)

We have carried out a near-infrared search for companions around 23 very low luminosity young stellar objects (YSOs) in the Taurus molecular cloud. After sophisticated photometry and analysis, five extremely low luminosity YSO (ELL-YSO) candidate companions were identified by both their near-infrared colors and proximity to the primary (separation less than 6"). They show infrared excess, as do ordinary YSOs. Their absolute J-band magnitudes range from 9 to 12 mag. The masses of these companions are estimated from their J-band luminosities, which use recent evolutionary tracks for very low mass objects. It is found that all are young brown dwarf candidates. The Ks-band magnitude difference between the ELL-YSO candidate companions and their primaries ranges from 2 to 6 mag, significantly larger than observed in T Tauri binaries. It is suggested that the companions are formed by the fragmentation of a disk around the primary. The binary frequency is 22^+9_-10% for systems with a period ranging between 10^7-10^8 days. This frequency is consistent with that of T Tauri stars, but it is significantly higher than that of low-mass main-sequence stars.

Itoh, Yoichi; Tamura, Motohide; Nakajima, Tadashi

1999-03-01

80

Mid-infrared interferometry of the massive young stellar object NGC 2264 IRS 1  

NASA Astrophysics Data System (ADS)

Context. The optically invisible infrared-source NGC 2264 IRS 1 lying north of the Cone Nebula is thought to be a massive young stellar object (~10 M?). Although strong infrared excess clearly shows that the central object is surrounded by large amounts of circumstellar material, no information about the spatial distribution of this circumstellar material has been available until now. Aims: We used the ESO Very Large Telescope Interferometer to perform long-baseline interferometric observations of NGC 2264 IRS 1 in the mid-infrared regime. Our observations resolve the circumstellar material around NGC 2264 IRS 1, provide the first direct measurement of the angular size of the mid-infrared emission, and yield direct constraints on the spatial distribution of the dust. Methods: We analyze the spectrally dispersed interferometric data taken with MIDI at two different position angles and baseline lengths. We use different approaches (a geometrical model, a temperature-gradient model, and radiative transfer models) to jointly model the observed interferometric visibilities and the spectral energy distribution. Results: The derived visibility values between ~0.02 and ~0.3 show that the mid-infrared emission is clearly resolved. The characteristic size of the MIR-emission region is ~30-60 AU; this value is typical for other YSOs with similar or somewhat lower luminosities. A comparison of the sizes for the two position angles shows a significant elongation of the dust distribution. Simple spherical envelope models are therefore inconsistent with the data. The radiative transfer modeling of our data suggests that we observe a geometrically thin and optically thick circumstellar disk with a mass of about 0.1 M?. Conclusions: Our modeling indicates that NGC 2264 IRS 1 is surrounded by a flat circumstellar disk that has properties similar to disks typically found around lower-mass young stellar objects. This result supports the assumption that massive young stellar objects form via accretion from circumstellar disks. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, observing programs 076.C-0725(B) and 082.C-899(A).

Grellmann, R.; Ratzka, T.; Kraus, S.; Linz, H.; Preibisch, T.; Weigelt, G.

2011-08-01

81

Near-Infrared Spectroscopy of Warm Spitzer-observed Near-Earth Objects  

NASA Astrophysics Data System (ADS)

We have completed a spectroscopic observing campaign to complement the ExploreNEOs Warm Spitzer program. ExploreNEOs or “The Warm Spitzer NEO Survey: Exploring the history of the inner Solar System and near-Earth space” was allocated 500 hours over two years (2009-2011) to determine diameters and albedos for approximately 600 near-Earth objects using the 3.6 and 4.5 micron IRAC bands. We present the results of the SpeX component of our campaign. In order to increase our sample size we also include all near-infrared observations of ExploreNEOs targets in the MIT-UH-IRTF Joint Campaign for Spectral Reconnaissance. Our complete dataset includes 125 observations of 92 objects from our survey and 213 observations of 154 objects from the MIT survey. The combination of the two surveys includes near-infrared spectroscopy of 187 ExploreNEOs targets. We find no correlation between spectral band parameters and ExploreNEOs albedos and diameters. We identified all potential ordinary chondrites within our sample and determined likely ordinary chondrite types using the equations derived by Dunn et al. 2010. Our resulting proportions of H, L, and LL ordinary chondrites are different than those previously calculated for ordinary chondrite-like near-Earth objects and meteorite falls.

Thomas, Cristina A.; Emery, J. P.; Trilling, D. E.; Delbo, M.; Hora, J. L.; Mueller, M.

2013-10-01

82

Measurements of the Ca II infrared triplet lines of young stellar objects  

NASA Astrophysics Data System (ADS)

Equivalent widths and line widths of Ca II infrared triplet emission lines were measured in the high-resolution optical spectra of 39 young stellar objects. We found that the equivalent widths of the emission lines decrease with stellar evolution. It has often been claimed that strong chromospheric activity is generated by a dynamo process caused by fast rotation of the photosphere. However, we found no clear correlation between the strength of the Ca II lines and the stellar rotation velocity. Instead, we found that the objects with high mass accretion rates had stronger Ca II emission lines. This correlation supports the turbulent chromosphere model or the magnetic accretion theory for classical T Tauri stars. We also noticed that the equivalent widths of Ca II lines in transitional disk objects are one-tenth of those in classical T Tauri stars, even if the masses of the circumstellar disks are comparable.

Moto'oka, Keiko; Itoh, Yoichi

2013-10-01

83

Long-term optical and infrared variability of the BL Lac object PKS 0537 - 441  

NASA Astrophysics Data System (ADS)

The long-term optical and infrared variability of the BL Lac object PKS 0537 - 441 has been studied. The source exhibits strong variability in the optical and infrared bands, and long-term variations of spectral indices have been analysed. The results indicate that there is a complex relationship between the spectral index and the brightness. In the low state, a redder-when-brighter chromatism has been found, in the sense that the spectrum steepens as the brightness increases, whereas in the high state, the source shows an opposite trend. The correlations between different bands have been investigated by means of the discrete correlation function method. The results show that the variations in the various optical and infrared bands are strongly correlated, but with no significant lags. It is, however, expected that there will be time lags of minutes to hours between the bands. Therefore, any attempt to detect the time lag needs a much denser monitoring of the source. Structure function analysis suggests that the source varies with a short-term time-scale of 34-46 d. An intra-day variability with a 24.5-min time-scale has been detected in the optical V band. The optical emission diameter is estimated to be 4.33 × 1014 cm, and the mass of the central black hole is estimated to be 2.3 × 108 M?.

Zhang, Bing-Kai; Wang, Sen; Zhao, Xiao-Yun; Dai, Ben-Zhong; Zha, Min

2013-02-01

84

Design and fabrication of an infrared wide field of view objective utilizing a hybrid refractive/diffractive optical element  

NASA Astrophysics Data System (ADS)

Many infrared (IR) imaging systems have been proposed which utilize hybrid refractive/diffractive optical elements; however, examples of their use in wide field-of-view (WFOV) lens assemblies have been noticeably absent. This paper discusses the design and aspects of the fabrication of a high performance WFOV infrared objective which utilizes a hybrid refractive/diffractive optical element.

Hudyma, Russell M.; Karow, Hank; Giammona, Larry; Meyer, George R.

1993-08-01

85

Infrared Spectroscopy and Young Stellar Objects: Characterizing the Dust and Gas in Circumstellar Disks  

NASA Astrophysics Data System (ADS)

In this dissertation, I describe my work in infrared spectroscopy and in studying the circumstellar disks around young stellar objects. In the first part, I detail an electronic component I designed for the Texas Echelon Cross Echelle Spectrograph (TEXES), which has acted as a visiting instrument on Gemini North and the NASA Infrared Telescope Facility. In order to detect the incoming infrared flux, a bias voltage is applied across the detector to sweep out the photo-excited electrons. If the bias voltage is too weak, the electrons can recombine before being swept out, while a strong bias can create unstable photoconductive gain. The initial design of TEXES required the operator to open the electronics and change the bias voltage by hand. However, the optimal bias is not the same for different instrument modes, which wasted substantial observing time when changing instrument modes. In order to save future observing time, and to fulfill a precondition set by Gemini North for TEXES to act as a visiting instrument, I created an electronic component to change the detector bias from the computer control room. I investigate and characterize the optimal voltages for the Raytheon 2562 SiAs IBC "SIRTF" array for the different instrument modes used by TEXES. In the following sections, I describe our observing campaign using the Spitzer IRS module and three ground-based telescopes to investigate edge-on circumstellar disks and classical infrared companions. Observations of the terrestrial planet forming regions of circumstellar disks are difficult to obtain, but recent detections of molecular absorption originating from these regions have proven valuable for disk models. We were granted time with the Spitzer Space Telescope to observe seven targets classified as young stellar objects, likely with their disks seen edge-on, to search for molecular absorption features. We used ground-based telescopes, including Gemini South, W. M. Keck Observatory, and the European Southern Observatory's Very Large Telescope, to further investigate and characterize our targets. I begin with a comparison of the disks around DG Tau B and VV CrA, showing evidence for extensive grain growth and settling in DG Tau B and characterizing the disk geometry of VV CrA. I discuss findings of Glass I, which proves to be extremely variable and shows high ionization ratios of fine structure emission not previously seen in young stars. Finally, I discuss the disk geometry of DoAr 24E and investigate the source of high extinction toward the infrared companion of this binary system.

Kruger, Andrew James

86

NEAR-INFRARED H{sub 2} AND CONTINUUM SURVEY OF EXTENDED GREEN OBJECTS  

SciTech Connect

The Spitzer GLIMPSE survey has revealed a number of 'Extended Green Objects' (EGOs) that display extended emission at 4.5 {mu}m. These EGOs are potential candidates for high-mass protostellar outflows. We used high-resolution (<1'') H{sub 2} 1-0 S(1) line, K-, and H-band images from the United Kingdom Infrared Telescope to study 34 EGOs to investigate their nature. We found that 12 EGOs exhibit H{sub 2} outflows (two with chains of H{sub 2} knotty structures, five with extended H{sub 2} bipolar structures, three with extended H{sub 2} lobes, and two with pairs of H{sub 2} knots). Of the 12 EGOs with H{sub 2} outflows, three exhibit similar morphologies between the 4.5 {mu}m and H{sub 2} emission. However, the remaining nine EGOs show that the H{sub 2} features are more extended than the continuum features, and the H{sub 2} emission is seldom associated with continuum emission. Furthermore, the morphologies of the near-infrared continuum and 4.5 {mu}m emission are similar to each other for those EGOs with K-band emission, implying that at least part of the IRAC-band continuum emission of EGOs comes from scattered light from the embedded young stellar objects.

Lee, Hsu-Tai; Takami, Michihiro; Duan, Hao-Yuan; Karr, Jennifer; Su, Yu-Nung; Liu, Sheng-Yuan; Yeh, Cosmos C. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Froebrich, Dirk, E-mail: htlee@asiaa.sinica.edu.tw [Centre for Astrophysics and Planetary Science, University of Kent, Canterbury CT2 7NH (United Kingdom)

2012-05-01

87

THE ORIGIN OF THE INFRARED EMISSION IN RADIO GALAXIES. III. ANALYSIS OF 3CRR OBJECTS  

SciTech Connect

We present Spitzer photometric data for a complete sample of 19 low-redshift (z< 0.1) 3CRR radio galaxies as part of our efforts to understand the origin of the prodigious mid- to far-infrared (MFIR) emission from radio-loud active galactic nuclei (AGNs). Our results show a correlation between AGN power (indicated by [O III]{lambda}5007 emission line luminosity) and 24 {mu}m luminosity. This result is consistent with the 24 {mu}m thermal emission originating from warm dust heated directly by AGN illumination. Applying the same correlation test for 70 {mu}m luminosity against [O III] luminosity we find this relation to suffer from increased scatter compared to that of 24 {mu}m. In line with our results for the higher-radio-frequency-selected 2 Jy sample, we are able to show that much of this increased scatter is due to heating by starbursts that boost the far-infrared emission at 70 {mu}m in a minority of objects (17%-35%). Overall this study supports previous work indicating AGN illumination as the dominant heating mechanism for MFIR emitting dust in the majority of low-to-intermediate redshift radio galaxies (0.03 < z < 0.7), with the advantage of strong statistical evidence. However, we find evidence that the low-redshift broad-line objects (z < 0.1) are distinct in terms of their positions on the MFIR versus [O III] correlations.

Dicken, D.; Axon, D.; Robinson, A.; Kharb, P. [Department of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623 (United States); Tadhunter, C. [Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield, S3 7RH (United Kingdom); Morganti, R., E-mail: dxdsps@rit.ed, E-mail: djasps@rit.ed, E-mail: axrsps@rit.ed, E-mail: c.tadhunter@sheffield.ac.u, E-mail: morganti@astron.n [ASTRON, P.O. Box 2, 7990 AA Dwingeloo (Netherlands)

2010-10-20

88

a Faint and Lonely Brown Dwarf in the Solar Vicinity  

NASA Astrophysics Data System (ADS)

Discovery of KELU-1 Promises New Insights into Strange Objects Brown Dwarfs are star-like objects which are too small to become real stars, yet too large to be real planets. Their mass is too small to ignite those nuclear processes which are responsible for the large energies and high temperatures of stars, but it is much larger than that of the planets we know in our solar system. Until now, very few Brown Dwarfs have been securely identified as such. Two are members of double-star systems, and a few more are located deep within the Pleiades star cluster. Now, however, Maria Teresa Ruiz of the Astronomy Department at Universidad de Chile (Santiago de Chile), using telescopes at the ESO La Silla observatory, has just discovered one that is all alone and apparently quite near to us. Contrary to the others which are influenced by other objects in their immediate surroundings, this new Brown Dwarf is unaffected and will thus be a perfect object for further investigations that may finally allow us to better understand these very interesting celestial bodies. It has been suggested that Brown Dwarfs may constitute a substantial part of the unseen dark matter in our Galaxy. This discovery may therefore also have important implications for this highly relevant research area. Searching for nearby faint stars The story of this discovery goes back to 1987 when Maria Teresa Ruiz decided to embark upon a long-term search (known as the Calan-ESO proper-motion survey ) for another type of unusual object, the so-called White Dwarfs , i.e. highly evolved, small and rather faint stars. Although they have masses similar to that of the Sun, such stars are no larger than the Earth and are therefore extremely compact. They are particularly interesting, because they most probably represent the future end point of evolution of our Sun, some billions of years from now. For this project, the Chilean astronomer obtained large-field photographic exposures with the 1-m ESO Schmidt telescope at 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 as a hydrogen line in emission. However, when the colour of this mysterious object was measured

1997-04-01

89

[Cotton identification and extraction using near infrared sensor and object-oriented spectral segmentation technique].  

PubMed

The real-time, effective and reliable method of identifying crop is the foundation of scientific management for crop in the precision agriculture. It is also one of the key techniques for the precision agriculture. However, this expectation cannot be fulfilled by the traditional pixel-based information extraction method with respect to complicated image processing and accurate objective identification. In the present study, visible-near infrared image of cotton was acquired using high-resolution sensor. Object-oriented segmentation technique was performed on the image to produce image objects and spatial/spectral features of cotton. Afterwards, nearest neighbor classifier integrated the spectral, shape and topologic information of image objects to precisely identify cotton according to various features. Finally, 300 random samples and an error matrix were applied to undertake the accuracy assessment of identification. Although errors and confusion exist, this method shows satisfying results with an overall accuracy of 96.33% and a KAPPA coefficient of 0.926 7, which can meet the demand of automatic management and decision-making in precision agriculture. PMID:19798933

Deng, Jin-Song; Shi, Yuan-Yuan; Chen, Li-Su; Wang, Ke; Zhu, Jin-Xia

2009-07-01

90

An objective method for computing advective surface velocities from sequential infrared satellite images  

NASA Astrophysics Data System (ADS)

Using cross correlations between sequential infrared satellite images, an objective technique is developed to compute advective sea surface velocities. Cross correlations are computed in 32 × 32 pixel search (second image) and 22 × 22 template (first image) windows from gradients of sea surface temperature computed from the satellite images. Velocity vectors, computed from sequential images of the British Columbia coastal ocean, generally appear coherent and consistent with the seasonal surface current in the region. During periods of strong wind forcing, as indicated by maps of sea level pressure, the image advective velocities are stronger and more coherent spatially and appear to cross surface temperature gradients; when winds are weaker, the advective velocities correspond better with the infrared temperature patterns, suggesting the increased contribution of the geostrophic current to the surface flow. Velocities determined from coincident, near-surface drogued (5-10 m) buoys, positioned every half hour by internal LORAN-C units in mid-June, show excellent agreement with the image advective velocities. In addition, conductivity, temperature, and depth (CTD) measurements (taken during the buoy tracking) confirm the homogeneity of the upper 10 m, and CTD-derived geostrophic currents are consistent with both buoy and sequential image displacement velocities.

Emery, W. J.; Thomas, A. C.; Collins, M. J.; Crawford, W. R.; Mackas, D. L.

1986-11-01

91

Design and performance of a MEMS-based infrared multi-object spectrometer  

NASA Astrophysics Data System (ADS)

The Infrared Multi-Object Spectrometer (IRMOS) is an innovative near-IR instrument employing an array of MEMS micro mirrors for focal plane target selection. IRMOS is a joint project of the Space Telescope Science Institute, the NASA James Webb Space Telescope, and the Kitt Peak National Observatory and will shortly become available to the community at Kitt Peak. IRMOS uses a Texas Instruments 848x600 element DMD as a micro mirror array to synthesize slits to obtain up to 100 simultaneous spectra. It provides R~300, 1000, and 3000 spectroscopy in the J, H, and K bands plus R~1000 in Z together with imaging in all bands. Designed for the KPNO 4 and 2.1-meter telescopes, IRMOS will provide 3x2 and 6x4 arc minute fields of view on these telescopes. We describe the design and status of IRMOS, summarize its expected performance, and present early test data from system level lab tests.

MacKenty, John W.; Green, Richard F.; Greenhouse, Matthew A.; Ohl, Raymond G.

2004-09-01

92

Multiple protostellar systems. I. A deep near infrared survey of Taurus and Ophiuchus protostellar objects  

NASA Astrophysics Data System (ADS)

We performed a deep infrared imaging survey of 63 embedded young stellar objects (YSOs) located in the Taurus and Ophiuchus clouds to search for companions. The sample includes Class I and flat infrared spectrum protostellar objects. We find 17 companions physically bound to 15 YSOs with angular separations in the range 0.8-10 arcsec (110-1400 AU) and derive a companion star fraction of 23 ± 9% and 29 ± 7% for embedded YSOs in Taurus and Ophiuchus, respectively, about twice as large as that found among G dwarfs in the solar neighborhood. Therefore, binary and multiple protostellar systems are a very frequent outcome of the fragmentation of prestellar cores. In spite of different properties of the clouds and especially of the prestellar cores, the fraction of wide companions, 27 ± 6% for the combined sample, is identical in the two star-forming regions. This suggests that the frequency and properties of wide multiple protostellar systems are not very sensitive to specific initial conditions. Comparing the companion star fraction of the youngest YSOs still surrounded by extended envelopes to that of more evolved YSOs, we find evidence for a possible evolution of the fraction of wide multiple systems, which seems to decrease by a factor of about two on a timescale of ˜105 yr. For the first time it is possible to confront the result of a multiplicity survey of a nearly complete population of embedded YSOs at an age of ˜105 yr to numerical simulations of molecular cloud collapse which, after a few free fall times, reach this evolutionary stage. Somewhat contrary to model predictions, we do not find evidence for a sub-clustering of embedded sources at this stage on a scale of a few 100 AU that could be related to the formation of small-N protostellar clusters. Possible interpretations of this discrepancy are discussed. Based on observations obtained at the Canada-France-Hawaii Telescope and at the European Southern Observatory, La Silla, Chile.

Duchêne, G.; Bouvier, J.; Bontemps, S.; André, P.; Motte, F.

2004-11-01

93

The MOAO system of the IRMOS near-infrared multi-object spectrograph for TMT  

NASA Astrophysics Data System (ADS)

The near-Infrared Multi-Object Spectrograph (IRMOS) for TMT is one of the most powerful astronomical instruments ever envisioned. The combination of the collecting area of TMT, the unique image-sharpening capabilities of the Multi-Object Adaptive Optics (MOAO) system, and the multiplexing advantage of the multi-object integral-field spectra provided by the IRMOS back-end make it capable of addressing some of the leading scientific challenges of the coming decades. Here we present an overview of one potential IRMOS concept and then focus on the MOAO system. In particular we will describe our concept for the laser and natural guide star wavefront sensors, deformable mirrors and the calibration system of MOAO. For each of these design elements, we describe the key trade studies which help define each subsystem. From results of our studies, we assemble a MOAO ensquared energy budget. We find that 50% of the energy is ensquared within the 50 milli-arcsecond spatial pixel of the IRMOS integral field units for a wavelength of 1.65?m. Given the requirements placed on the MOAO system to achieve this performance, large ensquared energies can be achieved with even finer plate scales for wavelengths longer than 1.5?m.

Andersen, David R.; Eikenberry, Stephen S.; Fletcher, Murray; Gardhouse, William; Leckie, Brian; Véran, Jean-Pierre; Gavel, Don; Clare, Richard; Guzman, Rafael; Jolissaint, Laurent; Julian, Roger; Rambold, William

2006-07-01

94

Discovery of three near infrared objects in CCD images of the Galactic Center  

SciTech Connect

At visible wavelengths, the light of the Galactic Center is extinguished by a factor of approx.10/sup 12/ due to the absorbing matter along the 10 kpc path to the Sun. Thus, direct visible observations are not possible. However, at far red wavelengths (lambda>7000A), the extinction declines dramatically, dropping to approx.10/sup 5/ near a wavelength of 0.9..mu..m. Recently, sensitive charge-coupled devices (CCDs) have been developed with high quantum efficiency in the 0.9..mu..m-1.0..mu..m range. On 1981 September 4/5 and 5/6, we used a CCD detector system (the ''MASCOT'') at the Cerro Tololo Inter-American Observatory, to detect 3 extremely red objects in the direction of the Galactic Center which were not previously known. All three objects are <10'' from the location of Sgr A West. If these objects do indeed lie at a distance of 10 kpc, then they are located within the innermost 1 pc of the Galaxy. One of these objects, designated NIR 1, lies within the extended 2.2..mu..m infrared source IRS 16, which is thought to contain the dynamic center of Galaxy. Two interpretations which we consider for these three objects (NIR 1, NIR 2, and NIR 3) are that they are either tightly knit clusters of K5-MO giant stars, or that they are extremely compact H II regions seen in the light of forbidden, doubly-ionized sulfur. Further observational tests of these two hypotheses are suggested.

Ricker, G.R.; Bautz, M.W.; DePoy, D.L.; Meyer, S.S.

1982-05-01

95

An Infrared Multi-Object Spectrograph (IRMS) with adaptive optics for TMT: the science case  

NASA Astrophysics Data System (ADS)

It has been recognized that a Near-Infrared Multi-object Spectrograph (IRMS) as one of the first light instrument on the Thirty Meter Telescope (TMT) would significantly increase the scientific capability of the observatory. The IRMS is planned to be a clone of the MOSFIRE instrument on the Keck telescope. As a result, we use the already available MOSFIRE design and expertise, significantly reducing the total cost and its development time. The IRMS will be a quasi diffraction limited multi-slit spectrograph with moderate resolution (R~4000), fed by Narrow-Field Infrared Adaptive Optics System (NFIRAOS). It images over the 2 arcmin diameter field of view of the NFIRAOS. There are a number of exceedingly important scientific questions, waiting to be addressed by the TMT/IRMS combination. Given its relatively small field of view, it is less affected by the sky background, which is a limiting factor in ground-based observations at near-IR wavelengths. The IRMS is the ideal instrument for studying spectroscopic properties of galaxies at the re-ionization epoch (z > 7), where the Lyman alpha line shifts to the near-ir wavelenghths. It can be used to measure rotation curves of spiral and velocity dispersion of elliptical galaxies at z~2-3 and hence, their spectroscopic mass. It can be used to search for population III stars via their spectroscopic signature and to perform measurement of spectroscopic lines at high redshifts, diagnostic of metallicity. Finally, IRMS allows measurement of the blue shifts in the rest-frame MgII line for high redshift galaxies, used to study the winds, leading to the feedback mechanism, responsible for quenching star formation activity in galaxies.

Mobasher, Bahram; Crampton, David; Simard, Luc

2010-07-01

96

MASSIVE YOUNG STELLAR OBJECTS IN THE GALACTIC CENTER. I. SPECTROSCOPIC IDENTIFICATION FROM SPITZER INFRARED SPECTROGRAPH OBSERVATIONS  

SciTech Connect

We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic center (GC). Our sample of 107 YSO candidates was selected based on Infrared Array Camera (IRAC) colors from the high spatial resolution, high sensitivity Spitzer/IRAC images in the Central Molecular Zone, which spans the central {approx}300 pc region of the Milky Way. We obtained IRS spectra over 5-35 {mu}m using both high- and low-resolution IRS modules. We spectroscopically identify massive YSOs by the presence of a 15.4 {mu}m shoulder on the absorption profile of 15 {mu}m CO{sub 2} ice, suggestive of CO{sub 2} ice mixed with CH{sub 3}OH ice on grains. This 15.4 {mu}m shoulder is clearly observed in 16 sources and possibly observed in an additional 19 sources. We show that nine massive YSOs also reveal molecular gas-phase absorption from CO{sub 2}, C{sub 2}H{sub 2}, and/or HCN, which traces warm and dense gas in YSOs. Our results provide the first spectroscopic census of the massive YSO population in the GC. We fit YSO models to the observed spectral energy distributions and find YSO masses of 8-23 M{sub sun}, which generally agree with the masses derived from observed radio continuum emission. We find that about 50% of photometrically identified YSOs are confirmed with our spectroscopic study. This implies a preliminary star formation rate of {approx}0.07 M{sub sun} yr{sup -1} at the GC.

An, Deokkeun [Department of Science Education, Ewha Womans University, Seoul 120-750 (Korea, Republic of); RamIrez, Solange V.; Boogert, A. C. Adwin [NASA Exoplanet Science Institute, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125 (United States); Sellgren, Kris [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Arendt, Richard G. [CRESST/UMBC/GSFC, Code 665, NASA/Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Robitaille, Thomas P.; Smith, Howard A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Schultheis, Mathias [Observatoire de Besancon, 41bis, avenue de l'Observatoire, 25000 Besancon (France); Cotera, Angela S. [SETI Institute, 515 North Whisman Road, Mountain View, CA 94043 (United States); Stolovy, Susan R., E-mail: deokkeun@ewha.ac.kr [Spitzer Science Center, California Institute of Technology, Mail Code 220-6, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

2011-08-01

97

Infrared Multi-Object Spectrometer Using a MEMS Programmable Slit Device  

NASA Astrophysics Data System (ADS)

IRMOS is a ground-based low to medium resolution infrared multi-object spectrometer with a 170 X 120 arc second field of view and 0.2 arc second spatial sampling. It will provide spectral resolutions of 300, 1000, and 3000 for spectroscopy in the J, H and K bands together with direct imaging. IRMOS' unique element is the Texas Instruments Digital Micro-Mirror Device (DMD), which uses Micro Electrical Mechanical Systems (MEMS) technology to provide a computer controlled aperture mask. The 848 X 600 element DMD consists of individually actuated 17x17 micron square mirrors, which can be placed into either of two states to create spectroscopic slits operating in reflection. Typically, up to 100 slits of various sizes can be formed across the array. The instrument will be operated on the Kitt Peak National Observatory 4 meter and 2.1 meter telescopes. Because of its spectral resolution and multi-object capability, the instrument will be ideally suited to study densely populated compact regions such as Galactic star clusters, star forming regions, the contents of nearby galaxies and clusters of galaxies at medium redshifts.

Winsor, R. S.; MacKenty, J. W.; Stiavelli, M.; Greenhouse, M.; Green, R.

2000-05-01

98

Integration, testing, and performance of the Infrared Multi-Object Spectrometer  

NASA Astrophysics Data System (ADS)

The Infrared Multi-Object Spectrometer (IRMOS) is a principle investigator-class instrument for the Kitt Peak National Observatory 2.1 m and Mayall 3.8 m telescopes. IRMOS is a near-IR (0.8--2.5 micron) spectrometer with low- to mid-resolving power (R = ?/?? = 300-3000). On the 3.8 m telescope, IRMOS produces simultaneous spectra of ~100 objects in its 2.8 ' 2.0 arcmin field of view using a commercial micro electro-mechanical systems (MEMS) digital micro-mirror device (DMD) from Texas Instruments. The multi-mirror array DMD operates as a real-time programmable slit mask. The all-reflective optical design consists of two imaging subsystems. The focal reducer images the focal plane of the telescope onto the DMD field stop, and the spectrograph images the DMD onto a large-format detector. The instrument operates at ~90 K, cooled by a single electro-mechanical cryocooler. The bench and all components are made from aluminum 6061. There are three cryogenic mechanisms. We describe laboratory integration and test of IRMOS before shipment to Kitt Peak National Observatory. We give an overview of the optical alignment technique and integration of optical, mechanical, electrical and cryogenic subsystems. We compare optical test results to model predictions of point spread function size. We discuss some lessons learned and conclude with a prediction for performance on the telescope.

Ohl, Raymond G.; Connelly, Joseph A.; Boyle, Robert F.; Derro, Rebecca J.; Fitzgerald, Danette L.; Greenhouse, Matthew A.; Madison, Timothy J.; Mentzell, John E.; Nord, Brian; Sparr, Leroy M.; Hylan, Jason E.; Ray, Knute; MacKenty, John W.

2004-09-01

99

The faint young Sun problem  

NASA Astrophysics Data System (ADS)

For more than four decades, scientists have been trying to find an answer to one of the most fundamental questions in paleoclimatology, the “faint young Sun problem.” For the early Earth, models of stellar evolution predict a solar energy input to the climate system that is about 25% lower than today. This would result in a completely frozen world over the first 2 billion years in the history of our planet if all other parameters controlling Earth's climate had been the same. Yet there is ample evidence for the presence of liquid surface water and even life in the Archean (3.8 to 2.5 billion years before present), so some effect (or effects) must have been compensating for the faint young Sun. A wide range of possible solutions have been suggested and explored during the last four decades, with most studies focusing on higher concentrations of atmospheric greenhouse gases like carbon dioxide, methane, or ammonia. All of these solutions present considerable difficulties, however, so the faint young Sun problem cannot be regarded as solved. Here I review research on the subject, including the latest suggestions for solutions of the faint young Sun problem and recent geochemical constraints on the composition of Earth's early atmosphere. Furthermore, I will outline the most promising directions for future research. In particular I would argue that both improved geochemical constraints on the state of the Archean climate system and numerical experiments with state-of-the-art climate models are required to finally assess what kept the oceans on the Archean Earth from freezing over completely.

Feulner, Georg

2012-05-01

100

In situ synchrotron far infrared micro-spectroelectrochemistry with a grazing angle objective  

NASA Astrophysics Data System (ADS)

We demonstrate the use of a grazing angle objective attachment to carry out in situ far infrared micro-spectroelectrochemistry at a copper electrode on a nano-scale. A thin-layer spectrochemical cell made out of Teflon was used, fitted with a 20-?m thick Mylar window; the working electrode was 500 ?m in diameter. Measurements were carried out in 0.1 M NaOH solution as a function of applied potential between 1.4 and 0 V vs a Hg/Hg2SO4 reference electrode. Spectra were obtained with excellent signal to noise ratio for the surface oxide film, formed on copper electrochemically with less than 1 nL of active solution volume. The surface film at 0 V was about 130 nm thick and consisted mainly of CuO, with possibly some Cu(OH)2 also present. This interpretation is consistent with previous works and thermodynamic calculations. The technique should be useful in other investigations and the further development of electrochemical surface science.

Hahn, F.; Mathis, Y.-L.; Bonnefont, A.; Maillard, F.; Melendres, C. A.

2008-05-01

101

Remote-sensing visible and infrared method of underground objects using thermal image technique  

NASA Astrophysics Data System (ADS)

The infrared radiometer is widely used to detect invisible internal flaws of industrial structural elements, as one of the remote sensing devices. The thermal image method (TIM) was carried out to analyze the location and dimension of the flaw numerically. The method was applied to detect the obscured and underground structural elements, like piping, vessel, concrete slab and ancient tomb using solar and radiation heaters. Detection characteristics are numerically and empirically estimated using a model test piece. The detection limit and heat transfer mechanism pertaining to the present technique is also discussed quantitatively. It was clarified from a series of experiments and analysis that our proposed method was useful to detect the buried object and carried out the verification of heat transfer analysis. We examined experimentally to detect the buried ancient tombs as the application tests. We verified the existence of the invisible buried tomb by observing the non-uniform temperature distribution, as in the case of the test results using radar and electric resistance methods.

Okamoto, Yoshizo; Liu, Chanliang; Agu, Hirotsugu; Inagaki, Terumi

1997-04-01

102

IRMOS: an infrared multi-object spectrometer using a MEMS micro-mirror array  

NASA Astrophysics Data System (ADS)

The Infrared Multi-Object Spectrometer (IRMOS) is an innovative near-IR instrument approaching completion. IRMOS will provide R~300, 1000, and 3000 spectroscopy in the J, H, and K bands plus R~1000 in Z together with imaging in all bands. Using a Texas Instruments 848x600 element DMD as a micro mirror array to synthesize slits in an imaging spectrometer obtaining up to 100 simultaneous spectra will be possible. Designed for the KPNO 4 and 2.2 meter telescopes, IRMOS will provide 3x2 and 6x4 arc minute fields of view on these telescopes. IRMOS is constructed mainly of 6061 Aluminum using diamond machined optics which has permitted a complex, compact, all reflective optical design. We describe the design and status of IRMOS, summarize its expected performance, and discuss several interesting aspects of its development and the use of TI DMD devices. IRMOS is a joint project of the Space Telescope Science Institute, the NASA Next Generation Space Telescope Project, and the Kitt Peak National Observatory.

MacKenty, John W.; Greenhouse, Matthew A.; Green, Richard F.; Sparr, Leroy; Ohl, Raymond G., IV; Winsor, Robert S.

2003-03-01

103

WIDE-FIELD INFRARED SURVEY EXPLORER OBSERVATIONS OF YOUNG STELLAR OBJECTS IN THE WESTERN CIRCINUS MOLECULAR CLOUD  

SciTech Connect

The Wide-field Infrared Survey Explorer has uncovered a population of young stellar objects (YSOs) in the Western Circinus molecular cloud. Images show the YSOs to be clustered into two main groups that are coincident with dark filamentary structure in the nebulosity. Analysis of photometry shows numerous Class I and II objects. The locations of several of these objects are found to correspond to known dense cores and CO outflows. Class I objects tend to be concentrated in dense aggregates, and Class II objects more evenly distributed throughout the region.

Liu, Wilson M.; Fajardo-Acosta, Sergio [Infrared Processing and Analysis Center, California Institute of Technology, MC 100-22, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Padgett, Deborah L. [Spitzer Science Center, California Institute of Technology, MC 314-6, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Leisawitz, David; Koenig, Xavier P., E-mail: wliu@ipac.caltech.edu [NASA Goddard Space Flight Center, Code 605, Greenbelt, MD 20771 (United States)

2011-05-20

104

MOSFIRE: a multi-object near-infrared spectrograph and imager for the Keck Observatory  

NASA Astrophysics Data System (ADS)

MOSFIRE, the multi-object spectrometer for infra-red exploration, is a near-IR (0.97-2.45 micron) spectrograph and imager for the Cassegrain focus of the Keck I telescope. The optical design provides imaging and multi-object spectroscopy over a field of view (FOV) of 6.14' x 6.14' with a resolving power of R~3,270 for a slit width of 0.7 arc seconds (2.9 pixels along dispersion). The detector is a 2.5 micron cut-off 2K x 2K H2-RG HgCdTe array with a SIDECAR ASIC for detector control. A special feature of MOSFIRE is that its multiplex advantage of up to 46 slits is achieved using a cryogenic Configurable Slit Unit (developed in collaboration with the Swiss Centre for Electronics and Micro Technology) reconfigurable under remote control in <5 minutes without thermal cycling. Slits are formed by moving opposable bars from both sides of the focal plane. An individual slit has a length of ~7.1 arc seconds but bar positions can be aligned to make longer slits. A single diffraction grating in two positions along with order-sorting filters gives essentially full coverage of the K, H, J and Y bands using 3rd, 4th, 5th or 6th order respectively. The grating and a mirror are mounted back-to-back, and when the bars are retracted from the FOV MOSFIRE becomes a wide-field imager. A piezo tip-tilt mirror following the field lens is used to provide flexure compensation at the 0.1 pixel level. Two large CCR heads allow the instrument to reach operating temperature in ~7 days. MOSFIRE is currently in construction.

McLean, Ian S.; Steidel, Charles C.; Matthews, Keith; Epps, Harland; Adkins, Sean M.

2008-08-01

105

MOSFIRE, the multi-object spectrometer for infra-red exploration at the Keck Observatory  

NASA Astrophysics Data System (ADS)

This paper describes the as-built performance of MOSFIRE, the multi-object spectrometer and imager for the Cassegrain focus of the 10-m Keck 1 telescope. MOSFIRE provides near-infrared (0.97 to 2.41 ?m) multi-object spectroscopy over a 6.1' x 6.1' field of view with a resolving power of R~3,500 for a 0.7" (0.508 mm) slit (2.9 pixels in the dispersion direction), or imaging over a field of view of ~6.9' diameter with ~0.18" per pixel sampling. A single diffraction grating can be set at two fixed angles, and order-sorting filters provide spectra that cover the K, H, J or Y bands by selecting 3rd, 4th, 5th or 6th order respectively. A folding flat following the field lens is equipped with piezo transducers to provide tip/tilt control for flexure compensation at the <0.1 pixel level. Instead of fabricated focal plane masks requiring frequent cryo-cycling of the instrument, MOSFIRE is equipped with a cryogenic Configurable Slit Unit (CSU) developed in collaboration with the Swiss Center for Electronics and Microtechnology (CSEM). Under remote control the CSU can form masks containing up to 46 slits with ~0.007-0.014" precision. Reconfiguration time is < 6 minutes. Slits are formed by moving opposable bars from both sides of the focal plane. An individual slit has a length of 7.0" but bar positions can be aligned to make longer slits in increments of 7.5". When masking bars are retracted from the field of view and the grating is changed to a mirror, MOSFIRE becomes a wide-field imager. The detector is a 2K x 2K H2-RG HgCdTe array from Teledyne Imaging Sensors with low dark current and low noise. Results from integration and commissioning are presented.

McLean, Ian S.; Steidel, Charles C.; Epps, Harland W.; Konidaris, Nicholas; Matthews, Keith Y.; Adkins, Sean; Aliado, Theodore; Brims, George; Canfield, John M.; Cromer, John L.; Fucik, Jason; Kulas, Kristin; Mace, Greg; Magnone, Ken; Rodriguez, Hector; Rudie, Gwen; Trainor, Ryan; Wang, Eric; Weber, Bob; Weiss, Jason

2012-09-01

106

Faintness  

MedlinePLUS

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107

Fainting  

MedlinePLUS

... severely dehydrated ) Standing up very suddenly from a lying position Less common but more serious reasons for ... avoid or change them. Get up from a lying or seated position slowly. If having blood drawn ...

108

A Search For Optically Faint GEO Debris  

NASA Astrophysics Data System (ADS)

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.

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

2011-09-01

109

Near-infrared integral field spectroscopy of massive young stellar objects  

NASA Astrophysics Data System (ADS)

We present medium-resolution (R ? 5300) K-band integral field spectroscopy of six massive young stellar objects (MYSOs). The targets are selected from the Red MSX Source (RMS) survey, and we used the ALTAIR adaptive optics assisted Near-Infrared Integral Field Spectrometer (NIFS) mounted on the Gemini North telescope. The data show various spectral line features including Br?, CO, H2 and He I. The Br? line is detected in emission in all objects with vFWHM ˜ 100-200 km s-1. V645 Cyg shows a high-velocity P-Cygni profile between -800 and -300 km s-1. We performed three-dimensional spectroastrometry to diagnose the circumstellar environment in the vicinity of the central stars using the Br? line. We measured the centroids of the velocity components with sub-mas precision. The centroids allow us to discriminate the blueshifted and redshifted components in a roughly east-west direction in both IRAS 18151-1208 and S106 in Br?. This lies almost perpendicular to observed larger scale outflows. We conclude, given the widths of the lines and the orientation of the spectroastrometric signature, that our results trace a disc wind in both IRAS 18151-1208 and S106. The CO ? = 2-0 absorption lines at low J transitions are detected in IRAS 18151-1208 and AFGL 2136. We analysed the velocity structure of the neutral gas discs, which we find to have nearly Keplerian motions. In IRAS 18151-1208, the absorption centroids of the blueshifted and redshifted components are separated in a direction of north-east to south-west, nearly perpendicular to that of the larger scale H2 jet. The position-velocity relations of these objects can be reproduced with central masses of 30 M? for IRAS 18151-1208 and 20 M? for AFGL 2136. We also detect CO ? = 2-0 bandhead emission in IRAS 18151-1208, S106 and V645 Cyg. The results can be fitted reasonably with a Keplerian rotation model, with masses of 15, 20 and 20 M?, respectively. These results for a sample of MYSOs can be explained with disc and outflow models and support the hypothesis of massive star formation via mass accretion through discs as is the case for lower mass counterparts.

Murakawa, K.; Lumsden, S. L.; Oudmaijer, R. D.; Davies, B.; Wheelwright, H. E.; Hoare, M. G.; Ilee, J. D.

2013-09-01

110

Near-infrared integral field spectroscopy of massive young stellar objects  

NASA Astrophysics Data System (ADS)

We present medium-resolution (R ? 5300) K-band integral field spectroscopy of six massive young stellar objects (MYSOs). The targets are selected from the Red MSX Source (RMS) survey, and we used the ALTAIR adaptive optics assisted Near-Infrared Integral Field Spectrometer (NIFS) mounted on the Gemini North telescope. The data show various spectral line features including Br?, CO, H2 and He I. The Br? line is detected in emission in all objects with vFWHM ˜ 100-200 km s-1. V645 Cyg shows a high-velocity P-Cygni profile between -800 and -300 km s-1. We performed three-dimensional spectroastrometry to diagnose the circumstellar environment in the vicinity of the central stars using the Br? line. We measured the centroids of the velocity components with sub-mas precision. The centroids allow us to discriminate the blueshifted and redshifted components in a roughly east-west direction in both IRAS 18151-1208 and S106 in Br?. This lies almost perpendicular to observed larger scale outflows. We conclude, given the widths of the lines and the orientation of the spectroastrometric signature, that our results trace a disc wind in both IRAS 18151-1208 and S106. The CO ? = 2-0 absorption lines at low J transitions are detected in IRAS 18151-1208 and AFGL 2136. We analysed the velocity structure of the neutral gas discs, which we find to have nearly Keplerian motions. In IRAS 18151-1208, the absorption centroids of the blueshifted and redshifted components are separated in a direction of north-east to south-west, nearly perpendicular to that of the larger scale H2 jet. The position-velocity relations of these objects can be reproduced with central masses of 30 M? for IRAS 18151-1208 and 20 M? for AFGL 2136. We also detect CO ? = 2-0 bandhead emission in IRAS 18151-1208, S106 and V645 Cyg. The results can be fitted reasonably with a Keplerian rotation model, with masses of 15, 20 and 20 M?, respectively. These results for a sample of MYSOs can be explained with disc and outflow models and support the hypothesis of massive star formation via mass accretion through discs as is the case for lower mass counterparts.

Murakawa, K.; Lumsden, S. L.; Oudmaijer, R. D.; Davies, B.; Wheelwright, H. E.; Hoare, M. G.; Ilee, J. D.

2013-11-01

111

Near-infrared Spectroscopy of Infrared-excess Stellar Objects in the Young Supernova Remnant G54.1+0.3  

NASA Astrophysics Data System (ADS)

We present the results of broadband near-infrared spectroscopic observations of the recently discovered mysterious stellar objects in the young supernova remnant G54.1+0.3. These objects, which show significant mid-infrared-excess emission, are embedded in a diffuse loop structure of ~1' in radius. Their near-infrared spectra reveal characteristics of late O- or early B-type stars with numerous H and He I absorption lines, and we classify their spectral types to be between O9 and B2 based on an empirical relation derived here between the equivalent widths of the H lines and stellar photospheric temperatures. The spectral types, combined with the results of spectral energy distribution fits, constrain the distance to the objects to be 6.0 ± 0.4 kpc. The photometric spectral types of the objects are consistent with those from the spectroscopic analyses, and the extinction distributions indicate a local enhancement of matter in the western part of the loop. If these objects originate via triggered formation by the progenitor star of G54.1+0.3, then their formations likely began during the later evolutionary stages of the progenitor, although a rather earlier formation may still be possible. If the objects and the progenitor belong to the same cluster of stars, then our results constrain the progenitor mass of G54.1+0.3 to be between 18 and ~35 M ? and suggest that G54.1+0.3 was either a Type IIP supernova or, with a relatively lower possibility, Type Ib/c from a binary system.

Kim, Hyun-Jeong; Koo, Bon-Chul; Moon, Dae-Sik

2013-09-01

112

MOONS: a multi-object optical and near-infrared spectrograph for the VLT  

NASA Astrophysics Data System (ADS)

MOONS is a new conceptual design for a Multi-Object Optical and Near-infrared Spectrograph for the Very Large Telescope (VLT), selected by ESO for a Phase A study. The baseline design consists of ~1000 fibers deployable over a field of view of ~500 square arcmin, the largest patrol field offered by the Nasmyth focus at the VLT. The total wavelength coverage is 0.8?m-1.8?m and two resolution modes: medium resolution and high resolution. In the medium resolution mode (R~4,000-6,000) the entire wavelength range 0.8?m-1.8?m is observed simultaneously, while the high resolution mode covers simultaneously three selected spectral regions: one around the CaII triplet (at R~8,000) to measure radial velocities, and two regions at R~20,000 one in the J-band and one in the H-band, for detailed measurements of chemical abundances. The grasp of the 8.2m Very Large Telescope (VLT) combined with the large multiplex and wavelength coverage of MOONS - extending into the near-IR - will provide the observational power necessary to study galaxy formation and evolution over the entire history of the Universe, from our Milky Way, through the redshift desert and up to the epoch of re-ionization at z<8-9. At the same time, the high spectral resolution mode will allow astronomers to study chemical abundances of stars in our Galaxy, in particular in the highly obscured regions of the Bulge, and provide the necessary follow-up of the Gaia mission. Such characteristics and versatility make MOONS the long-awaited workhorse near-IR MOS for the VLT, which will perfectly complement optical spectroscopy performed by FLAMES and VIMOS.

Cirasuolo, M.; Afonso, J.; Bender, R.; Bonifacio, P.; Evans, C.; Kaper, L.; Oliva, Ernesto; Vanzi, Leonardo; Abreu, Manuel; Atad-Ettedgui, Eli; Babusiaux, Carine; Bauer, Franz E.; Best, Philip; Bezawada, Naidu; Bryson, Ian R.; Cabral, Alexandre; Caputi, Karina; Centrone, Mauro; Chemla, Fanny; Cimatti, Andrea; Cioni, Maria-Rosa; Clementini, Gisella; Coelho, João.; Daddi, Emanuele; Dunlop, James S.; Feltzing, Sofia; Ferguson, Annette; Flores, Hector; Fontana, Adriano; Fynbo, Johan; Garilli, Bianca; Glauser, Adrian M.; Guinouard, Isabelle; Hammer, Jean-François; Hastings, Peter R.; Hess, Hans-Joachim; Ivison, Rob J.; Jagourel, Pascal; Jarvis, Matt; Kauffman, G.; Lawrence, A.; Lee, D.; Li Causi, G.; Lilly, S.; Lorenzetti, D.; Maiolino, R.; Mannucci, F.; McLure, R.; Minniti, D.; Montgomery, D.; Muschielok, B.; Nandra, K.; Navarro, R.; Norberg, P.; Origlia, L.; Padilla, N.; Peacock, J.; Pedicini, F.; Pentericci, L.; Pragt, J.; Puech, M.; Randich, S.; Renzini, A.; Ryde, N.; Rodrigues, M.; Royer, F.; Saglia, R.; Sánchez, A.; Schnetler, H.; Sobral, D.; Speziali, R.; Todd, S.; Tolstoy, E.; Torres, M.; Venema, L.; Vitali, F.; Wegner, M.; Wells, M.; Wild, V.; Wright, G.

2012-09-01

113

Development of an integral field unit for a near-infrared multi-object imaging spectrograph SWIMS  

NASA Astrophysics Data System (ADS)

We are developing an integral field unit (IFU) for a near-infrared multi-object imaging spectrograph SWIMS (Simultaneous-color Wide-field Infrared Multi-object Spectrograph). SWIMS is an instrument for the 6.5m telescope of the University of Tokyo Atacama Observatory (TAO) project on the summit of Co. Chajnantor (altitude of 5,640m) in northern Chile. Most of near infrared integral field spectrographs (IFSs) on 8-10m class telescopes are used with adaptive optics and have fine spatial sampling. Compared with them, SWIMS IFU has higher sensitivity for extended objects because it has coarser spatial sampling optimized for seeing-limit observations. We have investigated the feasible optical design, and found a possible layout whose field of view is about 14 x 10 arcsec2 with 0.4 arcsec slice width. All IFU mirror arrays will be made of aluminum alloy to match the thermal expansion with support structures, as they are placed in a cryogenic environment. They will be fabricated monolithically with high precision machining to reduce alignment process. We have carried out a fabrication test of a spherical surface and confirmed that surface roughness and surface figure error are enough low for near-infrared light. As a next step, fabrication of a prototype mirror array with 3 reflective surfaces is planned. In this paper, we will show our project outline, the IFU optical design and the results of prototyping works.

Ozaki, Shinobu; Kitagawa, Yutaro; Motohara, Kentaro; Konishi, Masahiro; Takahashi, Hidenori; Yoshikawa, Tomohiro; Tateuchi, Ken; Kato, Natsuko

2012-09-01

114

The Las Campanas Infrared Survey - V. Keck spectroscopy of a large sample of extremely red objects  

NASA Astrophysics Data System (ADS)

We present deep Keck spectroscopy, using the Deep Imaging Multi-Object Spectrograph and the Low-Resolution Imaging Spectrometer spectrographs, of a large and representative sample of 67 extremely red objects (EROs) to H= 20.5 in three fields (SSA22, Chandra Deep Field South and NTT Deep Field) drawn from the Las Campanas Infrared Survey (LCIRS). Using the colour cut (I-H) > 3.0 (Vega magnitudes) adopted in earlier papers in this series, we verify the efficiency of this selection for locating and studying distant old sources. Spectroscopic redshifts are determined for 44 sources, of which only two are contaminating low-mass stars. When allowance is made for incompleteness, the spectroscopic redshift distribution closely matches that predicted earlier on the basis of photometric data. Our spectra are of sufficient quality that we can address the important question of the nature and homogeneity of the z > 0.8 ERO population. A dominant old stellar population is inferred for 75 per cent of our spectroscopic sample, a higher fraction than that seen in smaller, less complete samples with broader photometric selection criteria (e.g. R-K). However, only 28 per cent have spectra with no evidence of recent star formation activity, such as would be expected for a strictly passively evolving population. More than ~30 per cent of our absorption-line spectra are of the `E+A' type with prominent Balmer absorption consistent, on average, with mass growth of 5-15 per cent in the past gigayear. We use our spectroscopic redshifts to improve earlier estimates of the spatial clustering of this population as well as to understand the significant field-to-field variation. Our spectroscopy enables us to pinpoint a filamentary structure at z= 1.22 in the Chandra Deep Field South. Overall, our study suggests that the bulk of the ERO population is an established population of clustered massive galaxies undergoing intermittent activity consistent with continued growth over the redshift interval 0.8 < z < 1.6.

Doherty, M.; Bunker, A. J.; Ellis, R. S.; McCarthy, P. J.

2005-08-01

115

Photometry of faint blue stars - IX  

NASA Astrophysics Data System (ADS)

Stromgren uv by photometry is presented for 129 `faint blue' stars taken from various catalogues. The photometry is used to estimate photometric `classifications' for the stars, which indicate a mixture of hot subdwarfs, horizontal-branch stars, metal-weak subdwarfs and so on. Attention is drawn to stars (from this paper and previous papers in the series) which appear to be somewhat reddened. Some are probably binaries, and others might be objects with peculiar colours, such as cataclysmic variables. One star, LB 9963, almost certainly falls into the latter category. Two stars which, from their colours, are Population II A-F stars are variable; one of these, OM 89, is the known RR Lyrae star, VW Dor.

Kilkenny, D.

1995-12-01

116

The population of faint Jupiter family comets near the Earth  

NASA Astrophysics Data System (ADS)

We study the population of faint Jupiter family comets (JFCs) that approach the Earth (perihelion distances q<1.3 AU) by applying a debiasing technique to the observed sample. We found for the debiased cumulative luminosity function (CLF) of absolute total magnitudes H a bimodal distribution in which brighter comets (H?9) follow a linear relation with a steep slope ?=0.65±0.14, while fainter comets follow a much shallower slope ?=0.25±0.06 down to H˜18. The slope can be pushed up to ?=0.35±0.09 if a second break in the H distribution to a much shallower slope is introduced at H˜16. We estimate a population of about 103 faint JFCs with q<1.3 AU and 10faint near-Earth JFCs may be explained either as: (i) the source population (the scattered disk) has an equally very shallow distribution in the considered size range, or (ii) the distribution is flattened by the disintegration of small objects before that they have a chance of being observed. The fact that the slope of the magnitude distribution of the faint active JFCs is very similar to that found for a sample of dormant JFCs candidates suggests that for a surviving (i.e., not disintegrated) object, the probability of becoming dormant versus keeping some activity is roughly size independent.

Fernández, Julio A.; Morbidelli, Alessandro

2006-11-01

117

Detection of buried objects by fusing dual-band infrared images  

SciTech Connect

We have conducted experiments to demonstrate the enhanced detectability of buried land mines using sensor fusion techniques. Multiple sensors, including visible imagery, infrared imagery, and ground penetrating radar (GPR), have been used to acquire data on a number of buried mines and mine surrogates. Because the visible wavelength and GPR data are currently incomplete. This paper focuses on the fusion of two-band infrared images. We use feature-level fusion and supervised learning with the probabilistic neural network (PNN) to evaluate detection performance. The novelty of the work lies in the application of advanced target recognition algorithms, the fusion of dual-band infrared images and evaluation of the techniques using two real data sets.

Clark, G.A.; Sengupta, S.K.; Sherwood, R.J.; Buhl, M.R.; Schaich, P.C.; Kane, R.J.; Barth, M.J.; Fields, D.J.; Carter, M.R.

1993-11-01

118

Faint Young Sun, Radiocarbon dating  

NSDL National Science Digital Library

The first problem in this assignment is the culmination of the unit on energy balance and greenhouse gases. The students have already calculated blackbody temperatures as a function of albedo, sun's luminosity and distance from sun. They have also already calculated the magnitude of the greenhouse effect (optical thickness) of the modern atmosphere. In this first problem, the students apply these same calculations to the Faint Young Sun hypothesis and infer what can account for the geological evidence for liquid water on earth since 4.3 Ga. The second problem follows an introductory lecture on radiometric decay and radiometric dating. The students have seen the decay equation and learned what are decay constants and stable versus radioactive isotopes. In this problem, the students apply these concepts to radiocarbon.

Cook, Mea

119

Objects recognition in visible and infrared images from the road scene  

Microsoft Academic Search

The detection of an obstacle in a traffic scene situation (obstacle which most often means a pedestrian or a vehicle) is a real challenge due to the outdoor environment and the variety of appearance of the obstacle. In this paper some details about our recognition module applied on visible and infrared image databases are presented. Given an image, or a

A. Apatean; A. Rogozan; A. Bensrhair

2008-01-01

120

Observations of near-Earth objects by the Japanese infrared survey mission ASTRO-F  

Microsoft Academic Search

The infrared astronomical satellite ASTRO-F, which has a 67 cm cooled telescope, will be launched in early 2004 and it will carry out all sky survey observation. The obtained data will be used to study various fields of astronomy, such as formation and evolution of galaxies, star formation, interstellar matter, brown dwarf, and dark matter. In addition to these, ASTRO-F

M. Yoshikawa; D. Kuroda; S. Hasegawa; I. Yamamura; M. Ueno

2004-01-01

121

Visible and near-infrared colors of Transneptunian objects and Centaurs from the second ESO large program  

Microsoft Academic Search

Aims: We investigate color properties and define or check taxonomic classifications of objects observed in our survey. Methods: All observations were performed between October 2006 and September 2007 at the European Southern Observatory 8 m Very Large Telescope, UT1 and UT2 at the Paranal Observatory in Chile. For visible photometry, we used the FORS1 instrument, and for near-infrared, ISAAC. Taxonomic

F. E. DeMeo; S. Fornasier; M. A. Barucci; D. Perna; S. Protopapa; A. Alvarez-Candal; A. Delsanti; A. Doressoundiram; F. Merlin; C. de Bergh

2009-01-01

122

Modeling the effects of a faint dust coma on asteroid spectra  

NASA Astrophysics Data System (ADS)

In this work we use a simple model to study the influence of a faint dust coma on asteroid spectra, in an effort to reproduce the unusual spectral behavior seen on the asteroid (5201) Ferraz-Mello and other objects.

Carvano, Jorge Márcio; Lorenz-Martins, Silvia

123

Changes in heart rate variability during fainting.  

PubMed

Studies of heart rate variability in people who faint may yield insights into normal physiologic mechanisms which probably are dynamic. These insights might be gained because fainting appears to be due to a breakdown of these mechanisms. Tilt table testing reliably induces fainting in patients with a history of fainting and can be used to study these mechanisms. During tilt tests ending in fainting heart rate changes markedly, with a loss of high-frequency components on power spectral analysis and a progressive slowing of overall sinus node discharge. These changes appear to be due to changes in efferent vagal nerve traffic. Several possible mechanisms of these changes in heart rate variability are discussed. PMID:12779923

Sheldon, Robert; Riff, Kenneth

1991-10-01

124

High-sensitivity and cost-effective system for infrared imaging of concealed objects in dynamic mode  

NASA Astrophysics Data System (ADS)

Novel, cost-efficient, and highly-sensitive IR imaging systems play an important role in homeland security functions. Technical limitations in the areas of sensitivity, contrast ratio, bandwidth and cost continue to constrain imaging capabilities. We have designed and prototyped a compact computer-piloted high sensitivity infrared imaging system. The device consists of infrared optics, cryostat, low-noise pre-amplifier, Analog-to-Digital hardware, feedback electronics, and unique image processing software. Important advantages of the developed system are: (i) Eight electronic channels are available for simultaneous registration of IR and visible images in multiple spectral ranges, (ii) Capability of real-time analysis such as comparing the "sensed" image with "reference" images from a database, (iii) High accuracy temperature measurement of multiple points on the image by referencing the radiation intensity from the object to a black body model, (iv) Image generation by real-time integration of images from multiple sensors operating from the visible to the terahertz range. The device was tested with a liquid-nitrogen-cooled, single-pixel HgCdTe detector for imaging in 8-12 microns range. The demonstrated examples of infrared imaging of concealed objects in static and dynamic modes include a hammer (metal head and wooden handle), plastic imitator of handguns hidden under clothes, powder in an envelope, and revealing complex wall structures under decorative plaster.

Gordiyenko, E.; Yefremenko, V.; Pearson, J.; Bader, S. D.; Novosad, V.

2005-05-01

125

Study on effect of SNR and fill factor on faint target signature quantitative measurement  

NASA Astrophysics Data System (ADS)

Target signature quantitative measurement is a key problem in target signature studies. There are many factors to affect the measurement precision, especially when the target is faint. This article studies two of the most important factors, infrared imagery SNR and infrared detector fill factor. The former is related to the detector energy acquisition parameters, such as NETD, caliber, integral time, and so on. The latter is related to the detector spatial sampling feature. The conclusion of this article could give reference to infrared target quantitative measurement and infrared detector design.

Liu, Zheng; Mao, Hongxia; Dai, Yinghong

2013-09-01

126

Frontal Lobe Activation during Object Permanence: Data from Near-Infrared Spectroscopy  

Microsoft Academic Search

The ability to create and hold a mental schema of an object is one of the milestones in cognitive development. Developmental scientists have named the behavioral manifestation of this competence object permanence. Convergent evidence indicates that frontal lobe maturation plays a critical role in the display of object permanence, but methodological and ethical constrains have made it difficult to collect

Abigail A. Baird; Jerome Kagan; Thomas Gaudette; Kathryn A. Walz; Natalie Hershlag; David A. Boas

2002-01-01

127

A study of the Chamaeleon I dark cloud and T-association. IV - Infrared objects near Cederblad 110  

NASA Astrophysics Data System (ADS)

IRAS Pointed Observations are used to study the premain sequence (PMS) objects associated with the reflection nebula Cederblad 110 in the Chamaeleon I star forming cloud. Nine PMS stars are identified, and near-infrared observations are presented and combined with IRAS data to investigate their evolutionary status. The nine objects represent various low-mass PMS stages from deeply embedded protostar candidates to naked T Tauri stars approaching the ZAMS, indicating that star formation has been going on for millions of years in the immediate vicinity of Cederblad 110. The two youngest PMS objects, Ced 110 IRS4 and Ced 110 IRS6, are projected on to the densest gas of the Chamaeleon I cloud suggesting an ongoing star formation process in the Cederblad 110 region.

Prusti, T.; Clark, F. O.; Whittet, D. C. B.; Laureijs, R. J.; Zhang, C. Y.

1991-07-01

128

Probing nuclear activity versus star formation at z ˜ 0.8 using near-infrared multi-object spectroscopy  

NASA Astrophysics Data System (ADS)

We present near-infrared (NIR) spectroscopic observations of 28 X-ray and mid-infrared selected sources at a median redshift of z ˜ 0.8 in the Extended Groth Strip (EGS). To date this is the largest compilation of NIR spectra of active galactic nuclei (AGN) at this redshift. The data were obtained using the multi-object spectroscopic mode of the Long-slit Intermediate Resolution Infrared Spectrograph (LIRIS) at the 4.2 m William Herschel Telescope (WHT). These galaxies are representative of a larger sample studied in a previous work, consisting of over a hundred X-ray selected sources with mid-infrared counterparts, which were classified either as AGN dominated or host galaxy dominated, depending on the shape of their spectral energy distributions (SEDs). Here, we present new NIR spectra of 13 and 15 sources of each class, respectively. We detect the H? line at ?1.5? above the continuum for the majority of the galaxies. Using attenuation-corrected H? luminosities and observed Spitzer/MIPS 24 ?m fluxes, and after subtracting an AGN component estimated using an AGN empirical correlation and multifrequency SED fits, we obtain average star formation rates (SFRs) of 7 ± 7 and 20 ± 50 M? yr-1, respectively (median SFRs = 7 and 5 M? yr-1). These values are lower than the SFRs reported in the literature for different samples of non-active star-forming galaxies of similar stellar masses and redshifts (M* ˜ 1011 M? and z ˜ 1). In spite of the small size of the sample studied here, as well as the uncertainty affecting the AGN-corrected SFRs, we speculate with the possibility of AGN quenching the star formation in galaxies at z ˜ 0.8. Alternatively, we might be seeing a delay between the offset of the star formation and AGN activity, as observed in the local Universe.

Ramos Almeida, C.; Rodríguez Espinosa, J. M.; Acosta-Pulido, J. A.; Alonso-Herrero, A.; Pérez García, A. M.; Rodríguez-Eugenio, N.

2013-03-01

129

Improved Observations of Faint Planetary Nebulae in the Magellanic Clouds  

NASA Astrophysics Data System (ADS)

The accuracy of spectrophotometry for Magellanic Cloud planetary nebulae is limited by a number of physical effects and operational difficulties: atmospheric dispersion, wavelength-dependent seeing, pointing and guiding errors, and a background of numerous stars and diffuse emission. We describe procedures to minimize the impact of some of these. We then compare our results for both bright and faint objects with published values. There are a few exceptional cases (e.g., LMC 89), but generally we find that bright planetary nebulae in the Clouds have been observed with high accuracy. On the other hand, observations of the faint sample from Jacoby (1980) suffer seriously from many of these effects. We also compare published ?5007 photometry with new CCD photometry for nine faint planetary nebulae. We find the photographic photometry presented by Jacoby (1980) to be accurate to 0.26 mag. Fluxes for the fainter objects that are derived from spectrophotometry (Boroson & Liebert 1989) are found to be less reliable. In comparison, spectrophotometry using the observational techniques presented in this paper provides reliable absolute fluxes. With these improved observations, we review the correlations presented by Kaler & Jacoby (1990, 1991) between abundance ratios and central star mass. The new results fit our earlier correlation for N/O, strengthen that for He/H, and change little about those for C/O and O/H.

Jacoby, George H.; Kaler, James B.

1993-11-01

130

Observations of faint eclipsing cataclysmic variables  

NASA Astrophysics Data System (ADS)

We present time-resolved photometry of six faint (V>17mag) cataclysmic variables (CVs); one of them is V849 Oph and the others are identified from the Sloan Digital Sky Survey (SDSS J0920+0042, SDSS J1327+6528, SDSS J1227+5139, SDSS J1607.02+3623, SDSS J1457+5148). The optical CCD photometric observations of these objects were performed at the TÜB?TAK National Observatory (Turkey) between February 2006 and March 2009. We aimed to detect short time scale orbital variability arisen from hot-spot modulation, flickering structures which occur from rapid fluctuations of material transferring from red star to white dwarf and orbital period changes for selected short-period (P<4h) CVs at quiescence. Results obtained from eclipse timings and light curves morphology related to white dwarf stars, accretion disks and hot-spots are discussed for each system. Analysis of the short time coverage of data, obtained for SDSS J1227+5139 indicates a cyclical period change arisen from magnetic activity on the secondary star. Photometric period of SDSS J1607+3623 is derived firstly in this study, while for the other five systems light elements are corrected using the previous and new photometric observations. The nature of SDSS J1457+5148 is not precisely revealed that its light curve shows any periodicity that could be related to the orbital period.

Zengin Çamurdan, D.; ?banog?lu, C.; Çamurdan, C. M.

2010-07-01

131

Near-infrared emission-line images of three Herbig-Haro objects  

SciTech Connect

Flux-calibrated imagery in five emission-line and four narrow-band continuum filters are presented for three classical Herbig-Haro (HH) objects, HH 7-11, HH 12, and HH 34. 1.64 micron forbidden Fe II emission is detected in all three objects whose intensity is typically 20 percent. This line should be an excellent tracer of shocked ionized gas in highly obscured regions. Extinction appears to be unimportant in determining the morphology of these HH object systems. No near-IR continuum emission was detected from any of the HH objects, implying that these regions do not contain embedded stars. At positions where the flow terminates against a large obstacle, there are significant offsets between the shocked flow material and the shocked ambient medium. 39 refs.

Stapelfeldt, K.R.; Scoville, N.Z.; Beichman, C.A.; Hester, J. J.; Gautier, T.N., III (Palomar Observatory, Pasadena, CA (USA))

1991-04-01

132

Near Infrared Hydrogen Lines as Diagnostic of Accretion and Winds in Young Stellar Objects  

NASA Astrophysics Data System (ADS)

The magnetospheric accretion model for T Tauri stars provides a possible answer for the long standing problem in low mass star formation of how angular momentum is shed in order to keep the rotational velocities as low as observed despite accreting matter from a quasi-Keplerian accretion disk. Given its importance for a better understanding of T Tauri stars the model should be thoroughly tested observationally. The work presented in this Thesis tests some aspects of the magnetospheric accretion model by using high spectral resolution observations of near infrared hydrogen lines. The presence of winds in T Tauri stars and their possible influence on the line profiles of near infrared hydrogen lines is also investigated. These lines are optically thinner than the more commonly studied Balmer lines and may give better indications of accretion. A sample of 50 T Tauri stars, mostly from the Taurus-Auriga complex, was chosen. Pa? line profiles were obtained for 49 of these stars and Br? profiles for 37 of the stars in the sample. Emission at Pa? was observed for 41 stars and emission at Br? was found for 30 stars. The most conspicuous features in the line profiles is the almost complete absence of blueshifted absorption components and the high frequency of inverse P Cygni profiles (IPC). At Pa?, 34% of the profiles are IPC while at Br? 20% are IPC. The redshifted absorption features indicate infall at velocities of about 200 kms-1, compatible with free fall from a few radii out as expected in a magnetospheric accretion picture. In general, line profiles are broad centrally peaked with slightly blueshifted line peaks. These observations are consistent with the Pa? and Br? lines forming predominantly in infalling material. Radiative transfer calculations of the Pa? and Br? line profiles in a very simplified spherically symmetric situation are discussed and the results compared with the observations. The identification of photospheric lines in the observed spectra allows the computation of the veiling at J for 75% of the observed stars and at K for 70% of the stars. Average values are < rJ > = 0.56 and < rK > = 1.31. In the remaining 25% of the stars at J and 30% of stars at K no photospheric lines were identified, i.e. they were observed to be 'continuum' stars in the observed wavelengths regions. The implications of these results are discussed. Thesis available through http://astro.up.pt/users/dfmf/Thesis/thesis.html

Folha, Daniel F. M.

1998-08-01

133

The MYStIX YSO Catalog: The Dark Art of Finding Young Stellar Objects Via Infrared Excess Emission  

NASA Astrophysics Data System (ADS)

The MYStIX project (Massive Young stellar clusters Study in Infrared and X-rays) is compiling comprehensive catalogs of the stellar membership in ~20 Galactic massive star-forming regions (d = 0.4 to 3.6 kpc). MYStIX is the first project of its kind to study such a large sample of Galactic regions in parallel, employing a homogeneous set of multiwavelength data analysis techniques. Probable stellar members in each target region are identified using X-ray and/or infrared photometry via two pathways: (1) X-ray detections of young/massive stars with coronal activity/strong winds or (2) Infrared (IR) excess selection of young stellar objects (YSOs) with circumstellar disks and/or protostellar envelopes. In this contribution, we present the methodology and initial results of pathway (2), using Spitzer/IRAC, 2MASS, and UKIDSS imaging and photometry. Although IR excess selection of YSOs is well-trodden territory, MYStIX presents unique challenges. The target regions run the gamut from relatively nearby, lower-mass clusters in uncrowded fields located toward the outer Galaxy (e.g. NGC 2264, the Flame Nebula), to massive clusters located at greater distances along complicated, inner Galaxy sightlines (e.g. NGC 6357, M17). We have developed a new procedure combining IR spectral energy distribution fitting with IR color cuts and spatial clustering analysis to separate probable YSO members in each MYStIX target field from the myriad types of contaminating objects that resemble YSOs: extragalactic sources, evolved stars, PAH nebular knots, and even unassociated foreground/background YSOs. Applying this technique consistently across our target regions, we have produced a catalog comprising several thousand YSOs that can serve as the basis for follow-up studies of diverse phenomena related to massive cluster formation, including protostellar outflows, circumstellar disks, and triggered star formation.

Povich, Matthew S.; Kuhn, M.; Getman, K. V.; Feigelson, E.; Broos, P. S.; Townsley, L. K.; Naylor, T.

2013-01-01

134

Near-infrared H2 and Continuum Survey of Extended Green Objects. II. Complete Census for the Northern Galactic Plane  

NASA Astrophysics Data System (ADS)

We discuss 94 Extended Green Objects (EGOs) in the northern Galactic plane cataloged by Cyganowski et al., based on near-infrared narrow H2 (2.122 ?m) 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 ?m emission generally resemble those of the near-infrared continuum, but are different from those of the H2 emission. Of our sample, only 28% of EGOs with H2 emission show similar morphologies between 4.5 ?m and H2 emission. These results suggest that the 4.5 ?m emission mainly comes from scattered continuum from the embedded young stellar objects, and partially from H2 emission. About half of EGOs are associated with H2 outflows, if the H2 outflow incompleteness is considered. The H2 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 H2 and K-band emissions are associated with outflows, i.e., H2 emission and K-band continuum are associated with shocks and outflow cavities, respectively. We also compared the correlation between the H2 outflows and Class I 44 GHz methanol masers from the literature. The methanol masers can be located upstream or downstream of the H2 outflows and some bright H2 spots or outflows are not associated with methanol masers, suggesting that methanol masers and H2 emission trace different excitation conditions.

Lee, Hsu-Tai; Liao, Wei-Ting; Froebrich, Dirk; Karr, Jennifer; Ioannidis, Georgios; Lee, Yong-Hyun; Su, Yu-Nung; Liu, Sheng-Yuan; Duan, Hao-Yuan; Takami, Michihiro

2013-10-01

135

Functional connectivity in the prefrontal cortex measured by near-infrared spectroscopy during ultrarapid object recognition  

PubMed Central

Near-infrared spectroscopy (NIRS) is a developing technology for low-cost noninvasive functional brain imaging. With multichannel optical instruments, it becomes possible to measure not only local changes in hemoglobin concentrations but also temporal correlations of those changes in different brain regions which gives an optical analog of functional connectivity traditionally measured by fMRI. We recorded hemodynamic activity during the Go-NoGo task from 11 right-handed subjects with probes placed bilaterally over prefrontal areas. Subjects were detecting animals as targets in natural scenes pressing a mouse button. Data were low-pass filtered <1 Hz and cardiac?respiration?superficial layers artifacts were removed using Independent Component Analysis. Fisher's transformed correlations of poststimulus responses (30 s) were averaged over groups of channels unilaterally in each hemisphere (intrahemispheric connectivity) and the corresponding channels between hemispheres (interhemispheric connectivity). The hemodynamic response showed task-related activation (an increase?decrease in oxygenated?deoxygenated hemoglobin, respectively) greater in the right versus left hemisphere. Intra- and interhemispheric functional connectivity was also significantly stronger during the task compared to baseline. Functional connectivity between the inferior and the middle frontal regions was significantly stronger in the right hemisphere. Our results demonstrate that optical methods can be used to detect transient changes in functional connectivity during rapid cognitive processes.

Medvedev, Andrei V.; Kainerstorfer, Jana M.; Borisov, Sergey V.; VanMeter, John

2011-01-01

136

Infrared Astronomy  

NSDL National Science Digital Library

NASA's Infrared Processing and Analysis Center (IPAC) provides the Infrared Astronomy Website as one of its outreach programs. Infrared Astronomy, or "the detection and study of the infrared radiation (heat energy) emitted from objects in the Universe," is described and placed in context in the sections Discovery of Infrared, What is Infrared, Infrared Astronomy, Background, and the Infrared Universe. For current information, see the News & Discoveries, Active/ Future Projects, and Activities sections; past and current projects supported by IPAC are featured in the Infrared Gallery. The site targets a broad audience and is geared towards many learning levels.

137

IRMOS: The near-infrared multi-object spectrograph for the TMT  

NASA Astrophysics Data System (ADS)

We present an overview of the near-InfraRed Multi-Object Spectrograph (IRMOS) for the Thirty Meter Telescope, as developed under a Feasibility Study at the University of Florida and Herzberg Institute of Astrophysics. IRMOS incorporates a multi-object adaptive optics correction capability over a 5-arcminute field of regard on TMT. Up to 20 independently-selectable target fields-of-view with ~2-arcsec diameter can be accessed within this field simultaneously. IRMOS provides near-diffraction-limited integral field spectroscopy over the 0.8-2.5 ?m bandpass at R~1,000-20,000 for each target field. We give a brief summary of the Design Reference science cases for IRMOS. We then present an overview of the IRMOS baseline instrument design.

Eikenberry, Stephen; Andersen, David; Guzman, Rafael; Bally, John; Cuevas, Salvador; Fletcher, Murray; Gardhouse, Rusty; Gavel, Don; Gonzalez, Anthony; Gruel, Nicolas; Hamann, Fred; Hamner, Sam; Julian, Roger; Julian, Jeff; Koo, David; Lada, Elizabeth; Leckie, Brian; Lopez, J. Alberto; Pello, Roser; Perez, Jorge; Rambold, William; Roman, Carlos; Sarajedini, Ata; Tan, Jonathan; Venn, Kim; Veran, Jean-Pierre; Ziegert, John

2006-07-01

138

Visible and near-infrared colors of Transneptunian objects and Centaurs from the second ESO large program  

NASA Astrophysics Data System (ADS)

Aims: We investigate color properties and define or check taxonomic classifications of objects observed in our survey. Methods: All observations were performed between October 2006 and September 2007 at the European Southern Observatory 8 m Very Large Telescope, UT1 and UT2 at the Paranal Observatory in Chile. For visible photometry, we used the FORS1 instrument, and for near-infrared, ISAAC. Taxonomic classifications from the Barucci system were assigned using G-mode analysis. Results: We present photometric observations of 23 TNOs and Centaurs, nine of which have never been previously observed. Eighteen of these objects were assigned taxonomic classifications: six BB, four BR, two RR, and six that are given two or more categories due to insufficient data. Three objects that had been previously observed and classified, changed classes most likely due to surface variation: 26375 (1999 DE9), 28978 (Ixion), and 32532 (Thereus). Two objects, 47932 (2000 GN171) and 54598 (Bienor) had absolute magnitude values that were significantly different from previously published results, attributed to extreme lightcurve amplitudes. Based on observations at the European Southern Observatory, Chile under programs 178.C-0867 and 178.C-0036.

DeMeo, F. E.; Fornasier, S.; Barucci, M. A.; Perna, D.; Protopapa, S.; Alvarez-Candal, A.; Delsanti, A.; Doressoundiram, A.; Merlin, F.; de Bergh, C.

2009-01-01

139

Extreme Faint Flux Imaging with an EMCCD  

NASA Astrophysics Data System (ADS)

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.

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

2009-08-01

140

The Faint Young Sun Paradox: a Resolution  

NASA Astrophysics Data System (ADS)

The "faint young sun" paradox, the apparent existence of mild climate conditions (especially liquid water) during a time when the standard model of stellar evolution predicts solar luminosity 20-30% less than at present, has proven difficult to resolve. It is widely recognized that higher concentrations of greenhouse gases offer a reasonable mechanism to eliminate the paradox. Suggestions that higher CO2 concentrations could accomplish the necessary warming require concentrations so high that even the sparse early geologic record should exhibit clear effects. The actual concentrations of CO2 in the early atmosphere remain the subject of considerable debate, but there is skepticism that CO2 levels sufficient to resolve the paradox were maintained throughout the Hadean and Archean. Suggestions that either methane or ammonia, considerably more potent greenhouse gases than CO2, have been met with the objection that their rapid rate of destruction by ultraviolet light, and thus removal from the atmosphere, preclude levels high enough to maintain warm conditions for any considerable length of time. Further suggestions that biologic production of methane may have been a factor in maintaining high methane levels may be reasonable for the later Archean, but would be problematical for the earlier Archean unless the necessary organisms had developed very early in Earth's history, a point still under discussion. However, if the early Earth had a large surface reservoir of reduced carbon compounds, whether in solution, suspension, floating or deposited on the ocean floor, a strictly non-biologic mechanism - hydrothermal processing, could produce both methane and ammonia at rates high enough to counteract photochemical destruction in the atmosphere and thus maintain levels sufficient for global warming during the Hadean and Early Archean.

Shaw, G. H.

2009-05-01

141

FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini  

NASA Astrophysics Data System (ADS)

We report on the design, on-sky performance, and status of the FLAMINGOS-2 instrument - the fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048x2048- pixel HAWAII-2 0.9-2.4 ?m detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6x2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi-Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3x1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On-Instrument WaveFront Sensor subsystems. We also present the on-sky performance measured during acceptance testing in 2009, as well as current status of the project and future plans.

Eikenberry, Stephen; Bandyopadhyay, Reba; Bennett, J. Greg; Bessoff, Aaron; Branch, Matt; Charcos, Miguel; Corley, Richard; Dewitt, Curtis; Eriksen, John-David; Elston, Richard; Frommeyer, Skip; Gonzalez, Anthony; Hanna, Kevin; Herlevich, Michael; Hon, David; Julian, Jeff; Julian, Roger; Lasso, Nestor; Marin-Franch, Antonio; Marti, Jose; Murphey, Charlie; Raines, S. N.; Rambold, William; Rashkind, David; Warner, Craig; Leckie, Brian; Gardhouse, W. R.; Fletcher, Murray; Hardy, Tim; Dunn, Jennifer; Wooff, Robert; Pazder, John

2012-09-01

142

FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini  

NASA Astrophysics Data System (ADS)

We report on the design and status of the FLAMINGOS-2 instrument - a fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048×2048-pixel HAWAII-2 0.9-2.4 ?m detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6×2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi- Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3×1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On- Instrument WaveFront Sensor subsystems. We also present the current status of the project, currently in final testing in mid-2006.

Eikenberry, Stephen; Elston, Richard; Raines, S. Nicholas; Julian, Jeff; Hanna, Kevin; Hon, David; Julian, Roger; Bandyopadhyay, R.; Bennett, J. Greg; Bessoff, Aaron; Branch, Matt; Corley, Richard; Eriksen, John-David; Frommeyer, Skip; Gonzalez, Anthony; Herlevich, Michael; Marin-Franch, Antonio; Marti, Jose; Murphey, Charlie; Rashkin, David; Warner, Craig; Leckie, Brian; Gardhouse, W. Rusty; Fletcher, Murray; Dunn, Jennifer; Wooff, Robert; Hardy, Tim

2006-07-01

143

FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini  

NASA Astrophysics Data System (ADS)

We report on the design and status of the FLAMINGOS-2 instrument - a fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048×2048-pixel HAWAII-2 0.9-2.4 ?m detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6×2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi- Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3×1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On- Instrument WaveFront Sensor subsystems. We also present the current status of the project and future plans, including on-sky delivery planned for late 2008.

Eikenberry, Stephen; Elston, Richard; Raines, S. Nicholas; Julian, Jeff; Hanna, Kevin; Warner, Craig; Julian, Roger; Bandyopadhyay, Reba; Bennett, J. Greg; Bessoff, Aaron; Branch, Matt; Corley, Richard; Dewitt, Curtis; Eriksen, John-David; Frommeyer, Skip; Gonzalez, Anthony; Herlevich, Michael; Hon, David; Marin-Franch, Antonio; Marti, Jose; Murphey, Charlie; Rambold, William; Rashkin, David; Leckie, Brian; Gardhouse, W. Rusty; Fletcher, Murray; Hardy, Tim; Dunn, Jennifer; Wooff, Robert

2008-08-01

144

FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini  

NASA Astrophysics Data System (ADS)

We report on the design and status of the FLAMINGOS-2 instrument - a fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048x2048-pixel HAWAII-2 0.9-2.4 mm detector array. A slit/Dekker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6x2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi-Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3x1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On-Instrument WaveFront Sensor subsystems. We also present the current status of the project, midway through its construction phase in June 2004.

Eikenberry, Stephen S.; Elston, Richard; Raines, S. Nicholas; Julian, Jeff; Corley, Richard J.; Hanna, Kevin; Hon, David; Julian, Roger; Rashkin, David; Leckie, Brian; Gardhouse, W. Rusty; Fletcher, Murray; Dunn, Jennifer; Wooff, Robert

2004-09-01

145

Near-infrared spectra of ISO selected Chamaeleon I young stellar objects  

NASA Astrophysics Data System (ADS)

We present 0.95-2.5 mu m moderate (R ~ 500) resolution spectra of 19 ISOCAM detected sources in the Chamaeleon I dark cloud. Thirteen of these stars are candidate very low mass members of the cloud proposed by Persi et al. (\\cite{per00}) on basis of the mid-IR color excess. The sample also includes a bona-fide young brown dwarf (Cha H? 1), a transition - stellar/sub-stellar - object (Cha H? 2), one previously known T Tauri star (Sz 33) and three ISOCAM sources with no mid-IR excess. The spectra of the mid-IR color excess sources are relatively flat and featureless in this wavelength range. Both atomic and molecular lines (when in absorption) are partially veiled suggesting the presence of continuum emission from circumstellar dust. In addition some of the sources show Paschen and Brackett lines in emission. We apply the 2 mu m water vapor index defined by Wilking et al. (\\cite{wil99}) to estimate spectral types. These stars have spectral types M0-8. We use Persi et al.'s stellar luminosity determinations, in combination with D'Antona & Mazzitelli latest pre-main sequence evolutionary tracks, to estimate masses and ages. The ISOCAM detected mid-IR excess sources have sub-solar masses down to the H-burning limit and a median age of few x106 yr, in good agreement with the higher mass members of this cloud. Based on observations collected at the European Southern Observatory, Chile, (ESO proposal N.65.I-0054).

Gómez, M.; Persi, P.

2002-07-01

146

Structure from fleeting illumination of faint spinning objects in flight  

Microsoft Academic Search

Moves are afoot to illuminate particles in flight with powerful X-ray bursts, to determine the structure of single molecules, viruses and nanoparticles. This would circumvent important limitations of current techniques, including the need to condense molecules into pure crystals. Proposals to reconstruct the molecular structure from diffraction `snapshots' of unknown orientation, however, require ~1,000 times more signal than available from

Russell Fung; Valentin Shneerson; Dilano K. Saldin; Abbas Ourmazd

2009-01-01

147

Verification of Luminosity Classes for Suspected Faint Red Giant Stars  

NASA Astrophysics Data System (ADS)

This project is using CCD images taken through different filters to determine the reliability of luminosity classifications based on objective-prism spectra. Kron-Cousins R and I filters are used in conjunction with an intermediate-band calcium hydride (CaH) filter to create a two-color plot. CaH-r vs. R-I diagrams are used to photometrically distinguish between red giants and dwarfs. The objective-prism plates from which this sample has been derived are currently being scanned to identify a much larger group of faint red stars. Accurate determinations of the luminosity classes for these sample stars would allow a more objective evaluation of the reliability of luminosity classes for stars detected in this larger survey. Photometric data taken at the National Undergraduate Research Observatory (NURO) and the Ball State University Observatory are combined in this study. Data gathered to date shows that the giant classification is much more reliable than the dwarf classification based on objective-prism spectral classification. Data collected to date will be reviewed in the context of the overall sample of faint red giant stars. Some data for this project were obtained at the Lowell Observatory 31 inch telescope, which, under an agreement with Northern Arizona University and the NURO Consortium, is operated 33% of the time as the National Undergraduate Research Observatory. Funding for this project has been provided by the Indiana Space Grant Consortium, the National Science Foundation REU Program and Ball State University.

Matney, J. E.; Robertson, T. H.; Jordan, T. M.; Snyder, L. A.; Welsh, F. V.; Croy, J. R.; Poweska, S. J.; Seaton, R. E.

2003-12-01

148

Hemodynamic mechanisms underlying prolonged post-faint hypotension  

Microsoft Academic Search

Objective  During hypotension induced by tilt-table testing, low presyncopal blood pressure (BP) usually recovers within 1 min after\\u000a tilt back. However, in some patients prolonged post faint hypotension (PPFH) is observed. We assessed the hemodynamics underlying\\u000a PPFH in a retrospective study.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Seven patients (2 females, aged 31–72 years) experiencing PPFH were studied. PPFH was defined as a systolic BP below 85 mmHg\\u000a for at

Wouter Wieling; Josien Rozenberg; Ingeborg K. Go-Schön; John M. Karemaker; Berend E. Westerhof; David L. Jardine

149

Thick gas discs in faint dwarf galaxies  

NASA Astrophysics Data System (ADS)

We determine the intrinsic axial ratio distribution of the gas discs of extremely faint MB < -14.5 dwarf irregular galaxies. We start with the measured (beam corrected) distribution of apparent axial ratios in the HI 21-cm images of dwarf irregular galaxies observed as part of the Faint Irregular Galaxy GMRT Survey (FIGGS). Assuming that the discs can be approximated as oblate spheroids, the intrinsic axial ratio distribution can be obtained from the observed apparent axial ratio distribution. We use a variety of methods to do this, and our final results are based on using Lucy's deconvolution algorithm. This method is constrained to produce physically plausible distributions, and also has the added advantage of allowing for observational errors to be accounted for. While one might a priori expect that gas discs would be thin (because collisions between gas clouds would cause them to quickly settle down to a thin disc), we find that the HI discs of faint dwarf irregulars are quite thick, with mean axial ratio ~ 0.6. While this is substantially larger than the typical value of ~0.2 for the stellar discs of large spiral galaxies, it is consistent with the much larger ratio of velocity dispersion to rotational velocity (?/vc) in dwarf galaxy HI discs as compared to that in spiral galaxies. Our findings have implications for studies of the mass distribution and the Tully-Fisher relation for faint dwarf irregular galaxies, where it is often assumed that the gas is in a thin disc.

Roychowdhury, Sambit; Chengalur, Jayaram N.; Begum, Ayesha; Karachentsev, Igor D.

2010-05-01

150

Faint Radio Sources and Gamma Ray Bursts  

Microsoft Academic Search

We calculate the number density of faint radio sources that are expected in radio source surveys due to the isotropic emission of Gamma Ray Burst sources. The calculation assumes the beamed supernovae model for gamma ray burst sources detected in gamma rays, x-rays, optical and radio wavelengths. Since the radio wavelength emission is expected to be more isotropically radiated, the

G. I. Langston; A. H. Minter; T. M. Freismuth

2002-01-01

151

Near-infrared Photometric Search For Volatile Ices On The Surfaces Of Cold Classical Kuiper Belt Objects  

NASA Astrophysics Data System (ADS)

The surprisingly complex dynamic distribution of small bodies among and beyond the orbits of the planets has changed our understanding of Solar System evolution. Compositional information about the small bodies in the Solar System provides constraints for emerging models of Solar System formation. The cold classical Kuiper Belt population is particularly interesting; according to the Nice model, cold classicals have not migrated much from where they formed, 42 - 45 AU. At these distances, the cold classicals have undergone little thermal evolution and we expect them to be rich with volatile ices of diverse composition (H2O, N2, CH4, light hydrocarbons, e.g. CH3OH). Despite this expectation, Barucci et al. (2011) find no evidence for ices in their sample (3 objects) of cold classical objects. Broad absorption features from most, if not all, volatile ices occur at ? > 2.5 µm. Absorptions are identified using a combination of JHK bands on terrestrial IR telescopes and the 3.6 µm and 4.5 µm channels of the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. Increasing the wavelength range of data with IRAC observations further constrains the composition of materials on KBO surfaces. We report IRAC measurements of reflectances of 45 cold classical KBOs. These longer wavelength albedos are added to ground-based NIR data to extend the KBOs' known spectra to a broader range. Upper limits for the bands at which the objects were not detected provide useful constraints as well. Compositional spectral modeling is used to match the observed photometry from the more completely observed objects with laboratory spectra. We expect volatiles to be uniformly distributed with respect to orbital parameters, such as semi-major axis, inclination, eccentricity, and perihelion, and physical properties, such as absolute magnitude and size. Support for this work was provided by NASA through an award issued by JPL/Caltech.

Wright, Daine M.; Emery, J.; Cruikshank, D.; Dalle Ore, C.; Fernandez, Y.; Stansberry, J.; Brown, M.; Fraser, W.; McGuire, R.; Trilling, D.

2012-10-01

152

Molecular gas in submillimetre-faint, star-forming ultraluminous galaxies at z > 1  

Microsoft Academic Search

We present interferometric CO observations of 12 z˜ 2 submillimetre-faint, star-forming radio galaxies (SFRGs) which are thought to be ultraluminous infrared galaxies (ULIRGs) possibly dominated by warmer dust (Tdust ≳ 40 K) than submillimetre galaxies (SMGs) of similar luminosities. Four other CO-observed SFRGs are included from the literature, and all the observations are taken at the Plateau de Bure Interferometer

C. M. Casey; S. C. Chapman; R. Neri; F. Bertoldi; I. Smail; K. Coppin; T. R. Greve; M. S. Bothwell; R. J. Beswick; A. W. Blain; P. Cox; R. Genzel; T. W. B. Muxlow; A. Omont; A. M. Swinbank

2011-01-01

153

Faint Satellites of Outer Planets  

NASA Astrophysics Data System (ADS)

In astronomy, as in other matters, the charm 01 novelty is one of the important lactors that govern the choice 01 the observations. How many objects saw suddenly many eyes or kinds of detectors looking at them, before linding again, some months or years later, their sidereal quietness! ... However, it is often after a long time of regular observations that they confide a (small) part 01 their secrets. The laint satellites 01 planets don't transgress this fortunately approximative rule. The deliciency in observations during many consecutive years makes the determination 01 their motion very difficult, and it is olten too late to make up lor lost time. We shall try to i1lustrate this lact in the next lines using the observations of the systems of Saturn, Uranus and Neptune we made in April 1981 on the DanishESO 1.5-m reflector.

Veillet, C.

1982-03-01

154

Faint Interacting Galaxies (de Mello+ 1997)  

NASA Astrophysics Data System (ADS)

We have carried out an extensive survey of faint galaxies in order to examine the rise in the merger rate with redshift and to study the statistical relations between close interacting galaxies and the field galaxy population. In paper I (1997ApJS..108...99D), we present the catalog of faint pairs and groups of galaxies of 46 equatorial fields taken with the Cerro Tololo Inter-American Observatory 4 m prime focus. The data set contains 73,988 galaxies, covering a total area of 2.23deg2. We have found 1751 isolated pairs and 30 groups of galaxies within 19 faint pairs and groups of galaxies in order to study galaxy evolution at intermediate redshifts. In paper II (1997ApJS..110..227D) we present the second catalog of faint interacting galaxies of 49 equatorial fields taken with the Cerro Tololo Inter-American Observatory 4 m prime focus camera. The data set contains 11,297 galaxies within 19

de Mello, D. F.; Infante, L.; Menanteau, F.

1997-09-01

155

Imaging faint companions very close to stars  

NASA Astrophysics Data System (ADS)

A vortex coronagraph on our extreme adaptive optics ``well-corrected subaperture'' on the Hale telescope has recently allowed the imaging of the triple-planet HR8799 system with a 1.5 m subaperture. Moreover, a faint, low-mass companion to a second star was imaged only one diffraction beam width away from the primary. These results illustrate the potential of the vortex coronagraph, which can enable exoplanet imaging and characterization with smaller telescopes than previously thought.

Serabyn, Eugene; Mawet, Dimitri; Burruss, Rick

2011-11-01

156

Extreme faint flux imaging with an EMCCD  

Microsoft Academic Search

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 Exp\\\\'erimentale (LAE), Universit\\\\'e de Montr\\\\'eal. This new camera achieves sub-electron read-out noise and very low Clock Induced Charge (CIC) levels,

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

2009-01-01

157

Study of the Chamaeleon I Dark Cloud and T-Association-IV Infrared Objects Near Cederblad 110. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

IRAS Pointed Observations are used to study the pre-main sequence (PMS) objects associated with the reflection nebula Cederblad 110 in the Chamaeleon 1 star forming cloud. Nine PMS stars are identified, and near-infrared observations are presented and com...

T. Prusti F. O. Clark D. C. Whittet R. J. Laureijs C. Y. Zhang

1991-01-01

158

Measurement of the eye’s near infrared wave-front aberration using the objective crossed-cylinder aberroscope technique  

Microsoft Academic Search

We used the crossed-cylinder aberroscope technique to obtain the near infrared (784 nm) wave-front aberration of the human eye. We compared the results with those obtained under the same conditions using red light (633 nm). Other than the greater retinal scattering of the near infrared light, third- and fourth-order wave-front aberrations are similar in both wavelengths. Values of the calculated

Norberto López-Gil; Howard C. Howland

1999-01-01

159

High-sensitivity and cost-effective system for infrared imaging of concealed objects in dynamic mode  

Microsoft Academic Search

Novel, cost-efficient, and highly-sensitive IR imaging systems play an important role in homeland security functions. Technical limitations in the areas of sensitivity, contrast ratio, bandwidth and cost continue to constrain imaging capabilities. We have designed and prototyped a compact computer-piloted high sensitivity infrared imaging system. The device consists of infrared optics, cryostat, low-noise pre-amplifier, Analog-to-Digital hardware, feedback electronics, and unique

E. Gordiyenko; V. Yefremenko; J. Pearson; S. D. Bader; V. Novosad

2005-01-01

160

Mid-Infrared Spectroscopy of Mercury from the Kuiper Airborne Observatory  

NASA Astrophysics Data System (ADS)

We present mid-infrared (5 - 10mic) spectroscopic measurements of the planet Mercury obtained from the Kuiper Airborne Observatory (KAO) using the High Efficiency Infrared Faint Object Grating Spectrograph (HIFOGS). Spectra show features characteristic of plagioclase feldspar that was previously observed near 120 deg mercurian longitude. The spectra also show spectral features that could be interpreted indicative of the presence of pyrrhotite (pyrr). An analysis that fully accounts for the effects of large field of view (FOV), thermal gradients, rough surface and absolute calibration is still underway.

Sprague, A. L.; Witteborn, F. C.; Kozlowski, R. W. H.; Wooden, D. H.

1996-03-01

161

Structural parameters of 11 faint Galactic globular clusters derived with 2MASS  

Microsoft Academic Search

Context: Structural parameters and the total MV magnitude are important properties for the characterisation of individual globular clusters. With the growth in statistics, especially of the intrinsically faint objects, the collective properties of the Galactic globular cluster system will be better defined, leading to a deeper understanding of the Galaxy formation processes. Aims: We determine the structural parameters of 11

C. Bonatto; E. Bica

2008-01-01

162

Identification of Class I Methanol Masers with Objects of Near and Mid-Infrared Bands and the Third Version of the Class I Methanol Maser (MMI) Catalog  

NASA Astrophysics Data System (ADS)

An identification has been conducted of class I methanol masers with 1) short-wave infrared objects EGO (extended green objects) - tracer bipolar outflow of matter in young stellar objects, and 2) isolated pre-protostellar gas-dust cores of the interstellar medium which are observed in absorption in the mid-infrared in the Galactic plane. It is shown that more than 50% of class I methanol masers are identified with bipolar outflows, considering the EGO as bipolar outflows (as compared with the result of 22% in the first version of the MMI catalog that contains no information about EGO). 99 from 139 class I methanol masers (71%) are identified with SDC. Thus, it seems possible that the MMI can be formed in isolated self-gravitating condensations, which are the silhouette of dark clouds - IRDC and SDC.

Bayandina, Olga; Val'tts, Irina; Larionov, Grigorii

2012-07-01

163

IRAS Faint Source Catalog, |b| > 10, Version 2.0 (Moshir+ 1989)  

NASA Astrophysics Data System (ADS)

The Faint Source Survey (FSS) is the definitive Infrared Astronomical Satellite data set for faint point sources. The FSS was produced by point-source filtering the individual detector data streams and then coadding those data streams using a trimmed-average algorithm. The resulting images, or plates, give the best estimate from the IRAS survey data of the point source flux density at every surveyed point of the sky. The Faint Source Catalog (FSC) is a compilation of the sources extracted from the FSS plates that have met reasonable reliability requirements. Averaged over the whole catalog, the FSC is at least 98.5% reliable at 12 and 25 microns, and ~94% at 60 microns. For comparison, the IRAS Point Source Catalog (PSC) is >99.997% reliable, but the sensitivity of the FSC exceeds that of the PSC by about a factor of 2.5. The FSC contains data for 173,044 point sources in unconfused regions with flux densities typically above 0.2 Jy at 12, 25, and 60 microns, and above 1.0 Jy at 100 microns. The FSS plates are somewhat more sensitive but less reliable than the FSC; typically, only sources with SNR>5-6 in the plates are contained in the FSC. Sources with SNR>3 but which do not meet the reliability requirements of the FSC are catalogued in the Faint Source Reject File (FSR, Cat. II/275). The data products, the processing methods used to produce them, results of an analysis of these products, and cautionary notes are given in the Explanatory Supplement to the IRAS Faint Source Survey (see references in fsc.txt). (8 data files).

Moshir, M.; Copan, G.; Conrow, T.; McCallon, H.; Hacking, P.; Gregorich, D.; Rohrbach, G.; Melnyk, M.; Rice, W.; Fullmer, L.

1993-02-01

164

Herschel-ATLAS: the far-infrared properties and star formation rates of broad absorption line quasi-stellar objects  

NASA Astrophysics Data System (ADS)

We have used data from the Herschel Astrophysical Terahertz Large-Area Survey (H-ATLAS) at 250, 350 and 500 ?m to determine the far-infrared (FIR) properties of 50 broad absorption line quasars (BAL QSOs). Our sample contains 49 high-ionization BAL QSOs (HiBALs) and one low-ionization BAL QSO (LoBAL) which are compared against a sample of 329 non-BAL QSOs. These samples are matched over the redshift range 1.5 ? z < 2.3 and in absolute i-band magnitude over the range -28 ? Mi ? -24. Of these, three BAL QSOs (HiBALs) and 27 non-BAL QSOs are detected at the >5 ? level. We calculate star formation rates (SFRs) for our individually detected HiBAL QSOs and the non-detected LoBAL QSO as well as average SFRs for the BAL and non-BAL QSO samples based on stacking the Herschel data. We find no difference between the HiBAL and non-BAL QSO samples in the FIR, even when separated based on differing BAL QSO classifications. Using Mrk 231 as a template, the weighted mean SFR is estimated to be ?240 ± 21 M? yr-1 for the full sample, although this figure should be treated as an upper limit if active galactic nucleus (AGN)-heated dust makes a contribution to the FIR emission. Despite tentative claims in the literature, we do not find a dependence of C IV equivalent width on FIR emission, suggesting that the strength of any outflow in these objects is not linked to their FIR output. These results strongly suggest that BAL QSOs (more specifically HiBALs) can be accommodated within a simple AGN unified scheme in which our line of sight to the nucleus intersects outflowing material. Models in which HiBALs are caught towards the end of a period of enhanced spheroid and black hole growth, during which a wind terminates the star formation activity, are not supported by the observed FIR properties. The Herschel-ATLAS is a project with Herschel, which is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. The H-ATLAS website is http://www/h-atlas.org/.

Cao Orjales, J. M.; Stevens, J. A.; Jarvis, M. J.; Smith, D. J. B.; Hardcastle, M. J.; Auld, R.; Baes, M.; Cava, A.; Clements, D. L.; Cooray, A.; Coppin, K.; Dariush, A.; De Zotti, G.; Dunne, L.; Dye, S.; Eales, S.; Hopwood, R.; Hoyos, C.; Ibar, E.; Ivison, R. J.; Maddox, S.; Page, M. J.; Valiante, E.

2012-12-01

165

Autonomic profile of subjects prone to fainting.  

PubMed

Syncope is the most common form of fainting that may occur at least once during a life-time in up to one-third of the general population. In 50% of patients the cause remains unknown. In an attempt to identify subtle disturbances of the autonomic nervous system, we examined 70 subjects, aged from 14 to 39 years, who suffered from recurrent neurally mediated syncope. We performed a battery of non-invasive tests assessing cardiovagal, sympathetic cholinergic and sympathetic adrenergic function. We compared the results with a group of 30 healthy, non-fainting subjects matched for age and sex. Basal records were similar in both groups. Patients had preserved cardiovagal function. The multivariate cluster analysis allowed us to find a homogeneous group of cases (46%) that simultaneously presented: greater fall in systolic and diastolic blood pressure after standing, increased 15:30 ratio, exaggerated absolute heart rate rise in response to standing and subclinical reduced sudomotor function in the foot. The results suggest the existence of a subclinical autonomic profile, with subtle sympathetic postganglionic impairment, evident in lower limbs. These findings may contribute to proving the existence of different types of neurally mediated syncope, all different in their onset and mechanism but with a common final manifestation: syncopal loss of consciousness. PMID:8926494

Ferrer, T; Pérez-Jiménez, A; Pérez-Sales, P; Alvarez, E; Ramos, M J

1996-01-01

166

Early Hominids / Early Faint Young Sun Paradox  

NSDL National Science Digital Library

This radio broadcast discusses the discovery in a Pleistocene cave site in Atapuerca, Spain of a new species of hominid - one that may be the common ancestor of both modern humans and our extinct cousins, the Neanderthals. The new species, named Homo antecessor, is thought to have lived some 800,000 years ago, yet has a face that looks strikingly similar to modern humans. These new discoveries are changing our understanding of the relationships between members of our primate family. The radio broadcast also discusses a paper by Drs. Carl Sagan and Christopher Chyba presenting a theory to explain the Early Faint Sun Paradox. This paradox arises out of the fact that the Earth once was a cold world - too cold, it is thought, to support life. However, at a time when the sun was still too faint to warm the surface of the Earth above freezing, some 3.5 billion years ago, the oceans teemed with photosynthetic bacteria. The greenhouse effect, driven by ammonia and methane, had been offered as a solution, but a mystery still remained. Without life, it was thought, there would not be enough of these gases to warm the world. But without a warm world, there could be no life. The broadcast is 48 minutes long.

167

Faint HI 21-cm Emission Line Wings at Forbidden Velocities  

NASA Astrophysics Data System (ADS)

We present the results of a search for faint HI 21-cm emission line wings at velocities forbidden by the galactic rotation in large-scale (?,v) diagrams of the galactic plane using the Leiden & Dwingeloo (LD) Survey. These ``forbidden-velocity (FV) wings" protrude from their surroundings over more than 20 km s-1 in limited (< 2 °) spatial regions. They are different from high-velocity clouds, but must be associated with some dynamical processes. We have found 73 FV wings in the region mid b mid ? 13 ° and 0objects. We discuss the statistical properties of FV wings and their origins.

Kang, J.; Koo, B.-C.; Heiles, C.

2004-12-01

168

A LARGE AND FAINT PHOTOMETRIC CATALOG ON THE ECLIPTIC  

SciTech Connect

A photometric catalog, developed for the calibration of the Deep Ecliptic Survey, is presented. The catalog contains 213,272 unique sources that were measured in V and R filters and transformed to the Johnson-Cousins systems using the Landolt standard catalog. All of the sources lie within 6{sup 0} of the ecliptic and cover all longitudes except for the densest stellar regions nearest the galactic center. Seventeen percent of the sources in the catalog are derived from three or more nights of observation. The catalog contains sources as faint as R {approx}19 but the largest fraction fall in the R {approx}15-16 (V {approx}16-17) mag range. All magnitude bins down to R = 19 have a significant fraction of objects with uncertainties {<=}0.1 mag.

Buie, Marc W. [Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302 (United States); Trilling, David E. [Department of Physics and Astronomy, Northern Arizona University, Flagstaff, AZ (United States); Wasserman, Lawrence H. [Lowell Observatory, 1400 W. Mars Hill Rd., Flagstaff, AZ 86001 (United States); Crudo, Richard A., E-mail: buie@boulder.swri.edu, E-mail: david.trilling@nau.edu, E-mail: lhw@lowell.edu, E-mail: rcrudo@gmail.com [George Washington University Law School, George Washington University (United States)

2011-06-01

169

LBT/LUCIFER near-infrared spectroscopy of PV Cephei. An outbursting young stellar object with an asymmetric jet  

NASA Astrophysics Data System (ADS)

Context. Young stellar objects (YSOs) occasionally experience enhanced accretion events, the nature of which is still poorly understood. The discovery of various embedded outbursting YSOs has recently questioned the classical definition of EXors and FUors. Aims: We present a detailed spectroscopic investigation of the young eruptive star PV Cep, to improve our understanding of its nature and characterise its circumstellar environment after its last outburst in 2004. Methods: The analysis of our medium-resolution spectroscopy in the near-infrared (NIR, 0.9-2.35 ?m), collected in 2012 at the Large Binocular Telescope with the IR spectrograph LUCIFER, allows us to infer the main stellar parameters (visual extinction, accretion luminosity, mass accretion and ejection rates), and model the inner disc, jet, and wind. Results: The NIR spectrum displays several strong emission lines associated with accretion/ejection activity and circumstellar environment. Our analysis shows that the brightness of PV Cep is fading, as well as the mass accretion rate (2 × 10-7 M? yr-1 in 2012 vs. ~5 × 10-6 M? yr-1 in 2004), which is more than one order of magnitude lower than in the outburst phase. Among the several emission lines, only the [Fe ii] intensity increased after the outburst. The observed [Fe ii] emission delineates blue- and red-shifted lobes, both with high- and low-velocity components, which trace an asymmetric jet and wind, respectively. The observed emission in the jet has a dynamical age of 7-8 years, indicating that it was produced during the last outburst. The visual extinction decreases moving from the red-shifted (AV(red) = 10.1 ± 0.7 mag) to the blue-shifted lobe (AV(blue) = 6.5 ± 0.4 mag). We measure an average electron temperature of 17 500 K and electron densities of 30 000 cm-3 and 15 000 cm-3 for the blue and the red lobe, respectively. The mass ejection rate in both lobes is ~1.5 × 10-7 M? yr-1, approximately matching the high accretion rate observed during and immediately after the outburst (?out/?acc ~ 0.05-0.1). The observed jet/outflow asymmetries are consistent with an inhomogeneous medium. Our modelling of the CO emission hints at a small-scale gaseous disc ring, extending from ~0.2-0.4 AU to ~3 AU from the source, with an inner temperature of ~3000 K. Our H i lines modelling indicates that most of the observed emission comes from an expanding disc wind at Te = 10 000 K. The line profiles are strongly affected by scattering, disc screening, and outflow self-absorption. Conclusions: According to the classical definition, PV Cep is not an EXor object, because it is more massive and younger than typical EXors. Nevertheless, its spectrum shows the signature of an "EXor-like" outburst, suggesting a common origin. Based on observations collected at LBT. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia.Appendix A is available in electronic form at http://www.aanda.org

Caratti o Garatti, A.; Garcia Lopez, R.; Weigelt, G.; Tambovtseva, L. V.; Grinin, V. P.; Wheelwright, H.; Ilee, J. D.

2013-06-01

170

The VLTI/MIDI survey of massive young stellar objects . Sounding the inner regions around intermediate- and high-mass young stars using mid-infrared interferometry  

NASA Astrophysics Data System (ADS)

Context. Because of inherent difficulties involved in observations and numerical simulations of the formation of massive stars, an understanding of the early evolutionary phases of these objects remains elusive. In particular, observationally probing circumstellar material at distances ?100 AU from the central star is exceedingly difficult, as such objects are rare (and thus, on average, far away) and typically deeply embedded. Long-baseline mid-infrared interferometry provides one way of obtaining the necessary spatial resolution at appropriate wavelengths for studying this class of objects; however, interpreting such observations is often difficult due to sparse spatial-frequency coverage. Aims: We aim to characterize the distribution and composition of circumstellar material around young massive stars and to investigate exactly which physical structures in these objects are probed by long-baseline mid-infrared interferometric observations. Methods: We used the two-telescope interferometric instrument MIDI of the Very Large Telescope Interferometer of the European Southern Observatory to observe a sample of 24 intermediate- and high-mass young stellar objects in the N band (8-13 ?m). We had successful fringe detections for 20 objects and present spectrally-resolved correlated fluxes and visibility levels for projected baselines of up to 128 m. We fit the visibilities with geometric models to derive the sizes of the emitting regions, as well as the orientation and elongation of the circumstellar material. Fourteen objects in the sample show the 10 ?m silicate feature in absorption in the total and correlated flux spectra. For 13 of these objects, we were able to fit the correlated flux spectra with a simple absorption model, allowing us to constrain the composition and absorptive properties of the circumstellar material. Results: Nearly all of the massive young stellar objects observed show significant deviations from spherical symmetry at mid-infrared wavelengths. In general, the mid-infrared emission can trace both disks and outflows, and in many cases it may be difficult to disentangle these components on the basis of interferometric data alone, because of the sparse spatial frequency coverage normally provided by current long-baseline interferometers. For the majority of the objects in this sample, the absorption occurs on spatial scales larger than those probed by MIDI. Finally, the physical extent of the mid-infrared emission around these sources is correlated with the total luminosity, albeit with significant scatter. Conclusions: Circumstellar material is ubiquitous at distances ?100 AU around young massive stars. Long-baseline mid-infrared interferometry provides the resolving power necessary for observing this material directly. However, in particular for deeply-embedded sources, caution must be used when attempting to attribute mid-infrared emission to specific physical structures, such as a circumstellar disk or an outflow. Appendix A is available in electronic form at http://www.aanda.orgBased on observations with the Very Large Telescope Interferometer of the European Southern Observatory.The reduced interferometric data presented here are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A24

Boley, Paul A.; Linz, Hendrik; van Boekel, Roy; Henning, Thomas; Feldt, Markus; Kaper, Lex; Leinert, Christoph; Müller, André; Pascucci, Ilaria; Robberto, Massimo; Stecklum, Bringfried; Waters, L. B. F. M.; Zinnecker, Hans

2013-10-01

171

Measuring the Star Formation Rate of the Universe at z 1 from H-alpha with Multi-Object Near-Infrared Spectroscopy  

Microsoft Academic Search

We have demonstrated the first near-infrared multi-object spectrograph,CIRPASS, on the 4.2-m William Herschel Telescope (WHT) and the 3.9-m Anglo-Australian Telescope. We have conducted an Halpha survey of 38 0.77

Andrew J. Bunker; Michelle Doherty; Rob Sharp; Ian Parry; Gavin Dalton; Ian Lewis

2006-01-01

172

GRAVITY: The AO-Assisted, Two-Object Beam-Combiner Instrument for the VLTI  

NASA Astrophysics Data System (ADS)

We present the proposal for the infrared adaptive optics (AO) assisted, two-object, high-throughput, multiple-beam-combiner GRAVITY for the VLTI. This instrument will be optimized for phase-referenced interferometric imaging and narrow-angle astrometry of faint, red objects. Following the scientific drivers, we analyze the VLTI infrastructure, and subsequently derive the requirements and concept for the optimum instrument. The analysis can be summarized with the need for highest sensitivity, phase referenced imaging and astrometry of two objects in the VLTI beam, and infrared wavefront-sensing. Consequently our proposed instrument allows the observations of faint, red objects with its internal infrared wavefront sensor, pushes the optical throughput by restricting observations to K-band at low and medium spectral resolution, and is fully enclosed in a cryostat for optimum background suppression and stability. Our instrument will thus increase the sensitivity of the VLTI significantly beyond the present capabilities. With its two fibers per telescope beam, GRAVITY will not only allow the simultaneous observations of two objects, but will also push the astrometric accuracy for UTs to 10 ?as, and provide simultaneous astrometry for up to six baselines.

Eisenhauer, F.; Perrin, G.; Rabien, S.; Eckart, A.; Léna, P.; Genzel, R.; Abuter, R.; Paumard, T.; Brandner, W.

173

THE AGN, STAR-FORMING, AND MORPHOLOGICAL PROPERTIES OF LUMINOUS IR-BRIGHT/OPTICALLY-FAINT GALAXIES  

SciTech Connect

We present the active galactic nucleus (AGN), star-forming, and morphological properties of a sample of 13 MIR-luminous (f {sub 24} {approx}> 700 {mu}Jy) IR-bright/optically-faint galaxies (IRBGs, f{sub 24}/f {sub R} {approx}> 1000). While these z {approx} 2 sources were drawn from deep Chandra fields with >200 ks X-ray coverage, only seven are formally detected in the X-ray and four lack X-ray emission at even the 2{sigma} level. Spitzer InfraRed Spectrograph (IRS) spectra, however, confirm that all of the sources are AGN-dominated in the mid-IR, although half have detectable polycyclic aromatic hydrocarbon (PAH) emission responsible for {approx}25% of their mid-infrared flux density. When combined with other samples, this indicates that at least 30%-40% of luminous IRBGs have star formation rates in the ultraluminous infrared galaxy (ULIRG) range ({approx}100-2000 M{sub sun} yr{sup -1}). X-ray hardness ratios and MIR to X-ray luminosity ratios indicate that all members of the sample contain heavily X-ray obscured AGNs, 80% of which are candidates to be Compton thick. Furthermore, the mean X-ray luminosity of the sample, log L{sub 2-10keV}(erg s{sup -1}) {approx}44.6, indicates that these IRBGs are Type 2 QSOs, at least from the X-ray perspective. While those sources most heavily obscured in the X-ray are also those most likely to display strong silicate absorption in the mid-IR, silicate absorption does not always accompany X-ray obscuration. Finally, {approx}70% of the IRBGs are merger candidates, a rate consistent with that of sub-mm galaxies (SMGs), although SMGs appear to be physically larger than IRBGs. These characteristics are consistent with the proposal that these objects represent a later, AGN-dominated, and more relaxed evolutionary stage following soon after the star-formation-dominated one represented by the SMGs.

Donley, J. L. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Rieke, G. H.; Egami, E.; Perez-Gonzalez, P. G. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Alexander, D. M., E-mail: donley@stsci.ed [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)

2010-08-20

174

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) high-resolution near-infrared multi-object fiber spectrograph  

Microsoft Academic Search

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) will use a dedicated 300-fiber, narrow-band (1.5-1.7 micron), high resolution (R~30,000), near-infrared spectrograph to survey approximately 100,000 giant stars across the Milky Way. This survey, conducted as part of the Sloan Digital Sky Survey III (SDSS III), will revolutionize our understanding of kinematical and chemical enrichment histories of all Galactic stellar populations.

John C. Wilson; Fred Hearty; Michael F. Skrutskie; Steven Majewski; Ricardo Schiavon; Daniel Eisenstein; Jim Gunn; Basil Blank; Chuck Henderson; Stephen Smee; Robert Barkhouser; Al Harding; Greg Fitzgerald; Todd Stolberg; Jim Arns; Matt Nelson; Sophia Brunner; Adam Burton; Eric Walker; Charles Lam; Paul Maseman; Jim Barr; French Leger; Larry Carey; Nick MacDonald; Todd Horne; Erick Young; George Rieke; Marcia Rieke; Tom O'Brien; Steve Hope; John Krakula; Jeff Crane; Bo Zhao; Mike Carr; Craig Harrison; Robert Stoll; Mary A. Vernieri; Jon Holtzman; Matt Shetrone; Carlos Allende-Prieto; Jennifer Johnson; Peter Frinchaboy; Gail Zasowski; Dmitry Bizyaev; Bruce Gillespie; David Weinberg

2010-01-01

175

Star Formation Histories From Faint Galaxy Counts  

NASA Astrophysics Data System (ADS)

Multispectral faint galaxy counts, including the deepest Hubble DeepField, are interpreted with the help of our evolution model PEGASE(Fioc and Rocca-Volmerange, 1997). The best fits correspond to galaxyformations at high redshifts, a pure luminosity evolution andclassical luminosity functions. The adopted cosmology is a flatuniverse with the matter density parameter ?M =0.3 and acosmological constant ?? =0.7. A solution with ?M=0.01 (open universe) is also acceptable. But a flat universe with?M =1 is clearly excluded. The star formation histories for galaxytypes are derived from scenarios of evolution. The comparison with resultsalready published in the litterature, arises puzzling problems needinga further analysis of star formation tracers, specifically for bright galaxies.

Rocca-Volmerange, B.; Fioc, M.

1999-07-01

176

Optical Color Selection of Faint AGN in the COSMOS Field  

NASA Astrophysics Data System (ADS)

We outline a strategy to select faint (iAB < 25.5) AGN candidates for spectroscopic targeting in the COSMOS field (Scoville et al. 2007, ApJS, in press). Similar in design to the SDSS QSO selection algorithm outlined by Richards et al. (2002), this selection picks candidates by their nonstellar colors in ubvriz broadband photometry from the Subaru and CFH Telescopes. Although the COSMOS field has been used extensively to survey the galaxy population, QSO optical color selection has not been applied to this faint a level. Since the catalog is complete to magnitude iAB < 25.9, we are testing AGN optical color selection at the Seyfert/QSO boundary all the way out to z 3. While stars are easily identified as the dominant contaminant for bright QSO candidate selection at z < 2, we anticipate a high contamination rate from compact red galaxies, which will lower selection efficiency and make the algorithm more complex. To create our candidate pool, we quantify the behavior of the stellar locus in 4D multicolor space. Objects that stray from the locus significantly are tagged as stellar outliers and potential QSO candidates. With a set of 350 known QSOs (X-ray selected, radio selected, and optically selected from SDSS) and type 1 quasar templates designed by Budavari et al. (2001), we have a “training” data set with which to measure efficiency and completeness as a function of redshift. After initial classification in multicolor space, supplemental morphological selection will be applied to stellar outliers using the Gini coefficient, cross-checked against resolved AGN in the training data set, and a final candidate pool will be determined. Candidates will be observed spectroscopically with the IMACS-spectrograph on the Magellan (Baade) Telescope in Chile. This work was partially supported by NSF's REU program at the Institute for Astronomy, University of Hawaii.

Casey, Caitlin M.; Impey, C. D.

2006-12-01

177

MEASURING SIZES OF ULTRA-FAINT DWARF GALAXIES  

SciTech Connect

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.

Munoz, Ricardo R. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Padmanabhan, Nikhil; Geha, Marla, E-mail: rmunoz@das.uchile.cl [Department of Astronomy, Yale University, New Haven, CT 06520 (United States)

2012-02-01

178

Companions around Faint YSOs in Taurus  

NASA Astrophysics Data System (ADS)

We have carried out a near-infrared search for companions around 23 very low-luminosity YSOs (VLL-YSOs) in the Taurus molecular cloud. Five extremely low-luminosity YSO (ELL-YSO) candidate companions were identified by both their near-infrared colors and proximity to the primary. They show infrared excess as ordinary YSOs. Their absolute J band magnitudes range from 9 to 12 mag, from which the masses of these companions are estimated. It is found that all are young brown dwarf candidates. The binary frequency is consistent with that of T Tauri stars, but significantly higher than that of low-mass main-sequence stars.

Itoh, Yoichi; Tamura, Motohide; Nakajima, Tadashi

179

Faints, fits, and fatalities from emotion in Shakespeare's characters: survey of the canon  

PubMed Central

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.

2006-01-01

180

DISCOVERY AND CHARACTERIZATION OF A FAINT STELLAR COMPANION TO THE A3V STAR zeta VIRGINIS  

SciTech Connect

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.

Hinkley, Sasha; Hillenbrand, Lynne [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Oppenheimer, Ben R.; Brenner, Douglas; Zimmerman, Neil; Sivaramakrishnan, Anand [Astrophysics Department, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Roberts, Lewis C.; Roberts, Jennifer E.; Burruss, Rick; Shao, Michael; Vasisht, Gautam [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109 (United States); Parry, Ian R.; King, David L. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Soummer, Remi [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Simon, Michal [Stony Brook University, NY (United States); Perrin, Marshall D. [UCLA Department of Astronomy, CA (United States); Lloyd, James P. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Bouchez, Antonin; Dekany, Richard [Caltech Optical Observatories, California Institute of Technology, Pasadena, CA 91125 (United States); Beichman, Charles [NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, CA 91125 (United States)

2010-03-20

181

The wide-field Fourier spectroscopic-imaging of the radiation heat from the object itself in the middle infrared region for the health monitoring  

NASA Astrophysics Data System (ADS)

We are aiming at the realization of the wide-field spectroscopic-imaging-sensor that is available for the health monitoring or the plant factory. Conventionally, the body temperature is measured by the thermography as a total intensity of the middle infrared radiation. We are trying to analyze the spectroscopic characteristics of the radiation heat from the human body in detail to measure the blood glucose or the moisture-retaining properties of the human skin. The proposed imaging-type 2-dimensional Fourier spectroscopy can measure the radiation heat from the object itself with the wide field of view and the wide wavelength-band. In this proposed method, we install the phase-shifter on the optical Fourier-transform-plane of the imaging optics to give the arbitrary phase-shift to the half flux of the object beams. Thus, the interferogram can be formed on the imaging plane in each bright point by the phase-shift interference-phenomena between the object beams that are emitted from the each corresponding bright point on the objective surface. In this report, we mention the feasibility results of the wide-field spectroscopic-imaging using the black body for the basic optical evaluation and the house plants for measuring the glucose distribution with the infrared camera(wavelength: 8?m-14?m).

Qi, Wei; Takuma, Takashi; Inui, Asuka; Tsutsumi, Ryosuke; Yuzuriha, Takehiko; Kagiyama, Hiroyasu; Kojima, Daisuke; Nishiyama, Akira; Ishimaru, Ichirou

2012-02-01

182

Optical and Infrared Backgrounds from HST and Beyond  

NASA Astrophysics Data System (ADS)

The sum total of the energy released by the earliest era of star formation should show up today within the diffuse extragalactic background light (EBL), its signature peaking in the near-infrared. There is considerable controversy over estimates of the average EBL per steradian at wavelengths longward of 1µm, over measurements of background fluctuations, and over the interpretation of the measurements. Resolving this controversy is important because the EBL constrains the history of galaxy evolution, and because the near-infrared fluctuations may contain important information about Population III stars and the earliest era of star formation. We compare number counts from recent galaxy surveys, correcting for their differing passbands. With some assumptions about galaxy sizes and surface-brightness profiles, we account for the light missed in standard photometric estimates, integrating the resulting corrected counts to estimate the total EBL due to resolved galaxies. We then present an analysis of background fluctuations in observations of the HUDF, the GOODS field, and the CANDELS fields obtained with WFC3. The fluctuation signal provides a constraint on the slope of galaxy counts fainter than the levels of individual detection. The color dependence of the fluctuations provides a constraint on the redshift distribution of these very faint sources. Fluctuations of the near-infrared EBL due to undetected sources help also constrain the nature of galaxies below current detection levels in other deep fields. The spatial and spectral information of these anisotropies provide valuable information about the EoR, as well as new populations of faint objects at lower redshifts. Via various analysis tools such as power spectra, P(D) fitting, and cross-correlations, best-fit models to faint sources can be obtained.

Dolch, Timothy; Ferguson, H. C.; Chary, R.; Cooray, A. R.; Koekemoer, A. M.; Ravindranath, S.; Sukhbold, T.

2011-05-01

183

LUCI in the sky: performance and lessons learned in the first two years of near-infrared multi-object spectroscopy at the LBT  

NASA Astrophysics Data System (ADS)

LUCI (former LUCIFER) is the full cryogenic near-infrared multi-object spectrograph and imager at the LBT. It presently allows for seeing limited imaging and multi-object spectroscopy at R~2000-4000 in a 4x4arcmin2 FOV from 0.9 to 2.5 micron. We report on the instrument performance and the lessons learned during the first two years on sky from a technical and operational point of view. We present the upcoming detector upgrade to Hawaii-2 RG arrays and the operating modes to utilize the binocular mode, the LBT facility AO system for diffraction limited imaging as well as to use the wide-field AO correction afforded by the multi-laser GLAO System ARGOS in multi-object spectroscopy.

Buschkamp, Peter; Seifert, Walter; Polsterer, Kai; Hofmann, Reiner; Gemperlein, Hans; Lederer, Reinhard; Lehmitz, Michael; Naranjo, Vianak; Ageorges, Nancy; Kurk, Jaron; Eisenhauer, Frank; Rabien, Sebastian; Honsberg, Mathias; Genzel, Reinhard

2012-09-01

184

Infrared Gallery  

NSDL National Science Digital Library

Human eyes cannot see infrared wavelengths, but with the help of false-color imaging, temperature differences become visible and invisible features are suddenly illuminated. This interactive gallery shows images of a variety of objects and geothermal features in both visible and infrared light, and explains why the infrared images show the items as they do. A background essay and list of discussion questions are also provided.

185

An All-Sky Catalog of Faint Extreme Ultraviolet Sources  

NASA Astrophysics Data System (ADS)

We present a list of 534 objects detected jointly in the Extreme Ultraviolet Explorer (EUVE) 100 Angstroms all-sky survey and in the ROSAT X-Ray Telescope 0.25 keV band. The joint selection criterion permits use of a low count rate threshold in each survey. This low threshold is roughly 60% of the threshold used in the previous EUVE all-sky surveys, and 166 of the objects listed here are new EUV sources, appearing in neither the Second EUVE Source Catalog nor the ROSAT Wide Field Camera Second Catalog. The spatial distribution of this all-sky catalog shows three features: an enhanced concentration of objects in Ursa Major, where the Galactic integrated H I column reaches its global minimum; an enhanced concentration in the third quadrant of the Galaxy (lII from 180 deg to 270 deg) including the Canis Major tunnel, where particularly low H I columns are found to distances beyond 200 pc; and a particularly low number of faint objects in the direction of the fourth quadrant of the Galaxy, where nearby intervening H I columns are appreciable. Of particular interest is the composition of the 166 detections not previously reported in any EUV catalog. We offer preliminary identifications for 105 of these sources. By far the most numerous (81) of the identifications are late-type stars (F, G, K, M), while 18 are other stellar types, only five are white dwarfs (WDs), and none are extragalactic. The paucity of WDs and extragalactic objects may be explained by a strong horizon effect wherein interstellar absorption strongly limits the effective new-source search volume and, thereby, selectively favors low-luminosity nearby sources over more luminous but distant objects.

Lampton, M.; Lieu, R.; Schmitt, J. H. M. M.; Bowyer, S.; Voges, W.; Lewis, J.; Wu, X.

1997-02-01

186

Design and development of MOSFIRE: the multi-object spectrometer for infrared exploration at the Keck Observatory  

Microsoft Academic Search

MOSFIRE is a unique multi-object spectrometer and imager for the Cassegrain focus of the 10 m Keck 1 telescope. A refractive optical design provides near-IR (0.97 to 2.45 mum) multi-object spectroscopy over a 6.14' x 6.14' field of view with a resolving power of R~3,270 for a 0.7\\

Ian S. McLean; Charles C. Steidel; Harland Epps; Keith Matthews; Sean Adkins; Nicholas Konidaris; Bob Weber; Ted Aliado; George Brims; John Canfield; John Cromer; Jason Fucik; Kristin Kulas; Greg Mace; Ken Magnone; Hector Rodriguez; Eric Wang; Jason Weiss

2010-01-01

187

Near-Infrared Color Properties of Kuiper Belt Objects and Centaurs: Final Results from the ESO Large Program  

Microsoft Academic Search

We present near-IR JHK broadband photometry for 17 Kuiper Belt objects (KBOs) and Centaurs. The observations were performed within the ESO Large Program on the ``Physical Properties of Kuiper Belt Objects and Centaurs'' from 2001 January to 2002 August. We used the ISAAC instrument at the ESO 8 m Very Large Telescope. We compiled visible-near-IR colors for a total of

Audrey Delsanti; Nuno Peixinho; Hermann Boehnhardt; Antonella Barucci; Frédéric Merlin; Alain Doressoundiram; John K. Davies

2006-01-01

188

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) high-resolution near-infrared multi-object fiber spectrograph  

NASA Astrophysics Data System (ADS)

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) will use a dedicated 300-fiber, narrow-band (1.5-1.7 micron), high resolution (R~30,000), near-infrared spectrograph to survey approximately 100,000 giant stars across the Milky Way. This survey, conducted as part of the Sloan Digital Sky Survey III (SDSS III), will revolutionize our understanding of kinematical and chemical enrichment histories of all Galactic stellar populations. The instrument, currently in fabrication, will be housed in a separate building adjacent to the 2.5 m SDSS telescope and fed light via approximately 45-meter fiber runs from the telescope. The instrument design includes numerous technological challenges and innovations including a gang connector that allows simultaneous connection of all fibers with a single plug to a telescope cartridge that positions the fibers on the sky, numerous places in the fiber train in which focal ratio degradation must be minimized, a large (290 mm x 475 mm elliptically-shaped recorded area) mosaic-VPH, an f/1.4 sixelement refractive camera featuring silicon and fused silica elements with diameters as large as 393 mm, three near-within a custom, LN2-cooled, stainless steel vacuum cryostat with dimensions 1.4 m x 2.3 m x 1.3 m.

Wilson, John C.; Hearty, Fred; Skrutskie, Michael F.; Majewski, Steven; Schiavon, Ricardo; Eisenstein, Daniel; Gunn, Jim; Blank, Basil; Henderson, Chuck; Smee, Stephen; Barkhouser, Robert; Harding, Al; Fitzgerald, Greg; Stolberg, Todd; Arns, Jim; Nelson, Matt; Brunner, Sophia; Burton, Adam; Walker, Eric; Lam, Charles; Maseman, Paul; Barr, Jim; Leger, French; Carey, Larry; MacDonald, Nick; Horne, Todd; Young, Erick; Rieke, George; Rieke, Marcia; O'Brien, Tom; Hope, Steve; Krakula, John; Crane, Jeff; Zhao, Bo; Carr, Mike; Harrison, Craig; Stoll, Robert; Vernieri, Mary A.; Holtzman, Jon; Shetrone, Matt; Allende-Prieto, Carlos; Johnson, Jennifer; Frinchaboy, Peter; Zasowski, Gail; Bizyaev, Dmitry; Gillespie, Bruce; Weinberg, David

2010-07-01

189

HIGH-RESOLUTION MID-INFRARED SPECTROSCOPY OF NGC 7538 IRS 1: PROBING CHEMISTRY IN A MASSIVE YOUNG STELLAR OBJECT  

SciTech Connect

We present high-resolution (R = 75,000-100,000) mid-infrared spectra of the high-mass embedded young star IRS 1 in the NGC 7538 star-forming region. Absorption lines from many rotational states of C{sub 2}H{sub 2}, {sup 13}C{sup 12}CH{sub 2}, CH{sub 3}, CH{sub 4}, NH{sub 3}, HCN, HNCO, and CS are seen. The gas temperature, column density, covering factor, line width, and Doppler shift for each molecule are derived. All molecules were fit with two velocity components between -54 and -63 km s{sup -1}. We find high column densities ({approx}10{sup 16} cm{sup -2}) for all the observed molecules compared to values previously reported and present new results for CH{sub 3} and HNCO. Several physical and chemical models are considered. The favored model involves a nearly edge-on disk around a massive star. Radiation from dust in the inner disk passes through the disk atmosphere, where large molecular column densities can produce the observed absorption line spectrum.

Knez, Claudia; Lacy, John H.; Evans, Neal J. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Van Dishoeck, Ewine F. [Leiden Observatory, P.O. Box 9513, 2300 RA Leiden (Netherlands); Richter, Matthew J. [Department of Physics, University of California, Davis, One Shields Ave., Davis, CA 95616 (United States)], E-mail: claudia@astro.umd.edu

2009-05-01

190

Characterization and testing of FLAMINGOS-2: the Gemini facility near-infrared multi-object spectrometer and wide-field imager  

NASA Astrophysics Data System (ADS)

FLAMINGOS-2 is a near-infrared wide-field imager and fully cryogenic multi-object spectrometer for Gemini Observatory being built by the University of Florida. FLAMINGOS-2 can simultaneously carry 9 custom cryogenic multi-object slit masks exchangeable without thermally cycling the entire instrument. Three selectable grisms provide resolving powers which are ~1300 to ~3000 over the entire spectrograph bandpass of 0.9-2.5 microns. We present and discuss characterization data for FLAMINGOS-2 including imaging throughput, image quality, spectral performance, and noise performance. After a lengthy integration process, we expect that FLAMINGOS-2 will be in the midst of commissioning at Gemini South by the fall of 2008.

Raines, Steven N.; Eikenberry, Stephen S.; Bandyopadhyay, Reba M.; Julian, Jeffrey A.; Hanna, Kevin T.; Warner, Craig D.; Julian, Roger E.; Bennett, J. Greg; DeWitt, Curtis N.; Frommeyer, Skip; Gonzalez, Anthony; Herlevich, Michael D.; Murphey, Charles

2008-08-01

191

A Consideration of Some Correlates of Fainting in Blood Donors.  

National Technical Information Service (NTIS)

In two studies of fainting in Army blood donors: Data gathered on 172 donors showed no significant differences in intelligence or educational level between reactors and nonreactors. Data on 394 donors showed no significant differences between the two grou...

L. J. Misantone

1970-01-01

192

Photometry of a complete sample of faint galaxies  

NASA Astrophysics Data System (ADS)

Techniques are developed for the automatic measurement of the colors and magnitudes of a complete sample of very faint galaxies. The observations consist of photographic surface photometry in two wavebands for approximately 20,000 galaxies in two widely separated, high-latitude fields, each having an area of approximately 1080 sq arcmin. The photometric zero points are derived directly from faint stars in the same fields measured photoelectrically by other observers. The photometry of the galaxy sample is complete to a limit about 10 times fainter than has been systematically investigated before. The sample is characterized by a population of galaxies which becomes bluer with increasing faintness and which increases steeply in number with increasing faintness in the blue waveband.

Kron, R. G.

1980-06-01

193

Faint cataclysmic variables from SDSS (Woudt+, 2012)  

NASA Astrophysics Data System (ADS)

We present high-speed photometric observations of 20 faint cataclysmic variables (CVs) selected from the Sloan Digital Sky Survey (SDSS) and Catalina catalogues. Measurements are given of 15 new directly measured orbital periods, including four eclipsing dwarf novae (SDSS 0904+03, CSS 0826-00, CSS 1404-10 and CSS 1626-12), two new polars (CSS 0810+00 and CSS 1503-22) and two dwarf novae with superhumps in quiescence (CSS 0322+02 and CSS 0826-00). Whilst most of the dwarf novae presented here have periods below 2h, SDSS 0805+07 and SSS 0617-36 have relatively long orbital periods of 5.489 and 3.440h, respectively. The double-humped orbital modulations observed in SSS 0221-26, CSS 0345-01, CSS 1300+11 and CSS 1443-17 are typical of low-mass transfer rate dwarf novae. The white dwarf primary of SDSS 0919+08 is confirmed to have non-radial oscillations, and quasi-periodic oscillations were observed in the short-period dwarf nova CSS 1028-08 during outburst. We further report the detection of a new nova-like variable (SDSS 1519+06). The frequency distribution of orbital periods of CVs in the Catalina Real-time Transient Survey (CRTS) has a high peak near ~80min orbital period, independently confirming that found by Gansicke et al. (2009MNRAS.397.2170G) from SDSS sources. We also observe a marked correlation between the median in the orbital period distribution and the outburst class, in the sense that dwarf novae with a single observed outburst (over the 5-year baseline of the CRTS coverage) occur predominantly at shortest orbital period. (2 data files).

Woudt, P. A.; Warner, B.; de Bude, D.; Macfarlane, S.; Schurch, M. P. E.; Zietsman, E.

2013-01-01

194

Faint solar radio structures from decametric observations  

NASA Astrophysics Data System (ADS)

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.

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

195

Objective qualitative and quantitative assessment of blood flow with near-infrared angiography in microvascular anastomoses in the rat model.  

PubMed

Intraoperative near-infrared indocyanine-green (ICG) angiography enables the visualization of microvascular perfusion and may help in the early detection of complications. The purpose of the present study was to examine whether the effect of microvascular stenoses can be quantitatively assessed by analysis of ICG-angiography in a microvascular model. Graded stenoses and total vessel occlusion of the carotid, aorta, and femoral arteries were created in 25 Wistar rats. Stenoses were graded to reduce arterial flow by 25%, 50%, 75%, and 100% of baseline flow as measured by transit-time flowmeter analyzing the emission signal of the ICG detected and investigated by the mathematical software tool (FLOW 800). ICG angiography was performed to assess vessel perfusion and flow curves were analyzed and correlated with the stenosis rate. A total of 576 investigations were performed. The area under the curve (P < 0.001), first and second maximum (P < 0.001), and the maximum slope to the first maximum (P < 0.001) were found to be of high prognostic value in evaluating the different flow patterns. Differences were displayed in comparisons by the maximum intensity of the ICG-concentrations. The maximum slope to the second maximum was found to be predictive in selected vessel types, and specific changes of the flow curve were found to indicate compromised vascular flow. The FLOW 800 tool applied for ICG angiography has shown to be a quick and reliable method for assessing blood flow in vessels in this study. The dynamic assessment of the ICG signal allows reliable identification of microanastomotic complications with the described parameters. PMID:23436399

Mücke, Thomas; Reeps, Christian; Wolff, Klaus-Dietrich; Mitchell, David A; Fichter, Andreas M; Scholz, Martin

2013-02-25

196

Infrared Astronomy  

NSDL National Science Digital Library

Despite the claims of certain science fiction novels and films, humans cannot see in infrared. As many people know, the primary source of infrared radiation is heat, and the study of infrared astronomy allows scientists to detect radiation emitted from objects throughout the universe. This delightful website (created by NASA and the Infrared Processing and Analysis Center at the California Institute of Technology) provides a wide range of material on this fascinating area of scientific study. Visitors can lean about the discovery of infrared, learn about the technology that is used in such endeavors, and of course, look over dozens of infrared images and video clips. Educators will be glad to learn that there are a number of activities offered here for use in the classroom, including one that will help students learn how to build a photocell detector.

Hermans-Killam, Linda

197

The Meudon Multicolor Survey (2MS) of Centaurs and Trans-Neptunian Objects: From Visible to Infrared Colors  

NASA Astrophysics Data System (ADS)

We present the latest results of the Meudon Multicolor Survey. This survey is aimed at characterizing the color properties and trends of Centaurs and trans-Neptunian objects. We report IJHK photometry of objects obtained with CFHT-IR at the 3.6 m Canada-France-Hawaii Telescope (Hawaii), JHK photometry with INGRID at the 4.2 m William Hershel Telescope (La Palma), and BVRI photometry with OIG at the 3.6 m Telescopio Nazionale Galileo Telescope (La Palma). We present visible—near-IR colors for 38 objects. Either these were acquired simultaneously, or the new near-IR photometry was tied to previously published visible measurements using the I magnitude measured in both sets. This large sample allows an extended characterization of the color properties of these primitive objects over the B (0.4 ?m) to K (2.2 ?m) wavelength range. We performed a detailed statistical analysis of all available IR colors in order to search for significant trends. The most relevant conclusion about visible and near-IR color-color correlations is that, basically, JHK bands alone do not show evidence of correlations, either between them or with BVRIJ bands. Only Centaurs show an anticorrelation between visible colors and H - K. Colors within each dynamical family compare very similarly. Based on observations obtained at (1) the Canada-France-Hawaii Telescope, 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; (2) the Italian Telescopio Nazionale Galileo operated at la Palma, Spain, by the Centro Nazionale Galilei of the INAF (Istituto Nazionale di Astrofisica); and (3) the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

Doressoundiram, A.; Peixinho, N.; Moullet, A.; Fornasier, S.; Barucci, M. A.; Beuzit, J.-L.; Veillet, C.

2007-12-01

198

Bayesian approach to joint super-resolution and trajectory estimation for midcourse closely spaced objects via space-based infrared sensor  

NASA Astrophysics Data System (ADS)

The problem of super-resolution and tracking for midcourse closely spaced objects (CSO) is examined using a space-based infrared sensor. Within a short time window, the midcourse CSO trajectories on the focal plane can be modeled as following a straight line with a constant velocity. Thus, the object's initial state (location and velocity on the focal plane) exclusively corresponds to its trajectory on the focal plane. Thereupon, the objects number, intensities and initial states, as well as the sensor noise variances, are considered random variables, and a Bayesian model is proposed which is utilized to define a posterior distribution on the joint parameter space. To maximize this distribution, reversible jump Markov chain Monte Carlo algorithm is adopted to perform the Bayesian computation. The proposed approach simultaneously used the multiple time-consecutive frame data to estimate model parameters. Compared with the single-frame method, it not only gains the super-resolution capability but also can directly estimate focal plane trajectories without using explicit data association techniques. Results show that the performance (estimation precision of objects number, focal plane locations, intensities and ballistic trajectories for the CSO, together with the computation load) of the proposed approach outperforms the conventional single-frame and multiframe approaches.

Lin, Liangkui; Sheng, Weidong; Xu, Dan

2012-11-01

199

Planetcam: A Visible And Near Infrared Lucky-imaging Camera To Study Planetary Atmospheres And Solar System Objects  

NASA Astrophysics Data System (ADS)

PlanetCam is a two-channel fast-acquisition and low-noise camera designed for a multispectral study of the atmospheres of the planets (Venus, Mars, Jupiter, Saturn, Uranus and Neptune) and the satellite Titan at high temporal and spatial resolutions simultaneously invisible (0.4-1 ?m) and NIR (1-2.5 ?m) channels. This is accomplished by means of a dichroic beam splitter that separates both beams directing them into two different detectors. Each detector has filter wheels corresponding to the characteristic absorption bands of each planetary atmosphere. Images are acquired and processed using the “lucky imaging” technique in which several thousand images of the same object are obtained in a short time interval, coregistered and ordered in terms of image quality to reconstruct a high-resolution ideally diffraction limited image of the object. Those images will be also calibrated in terms of intensity and absolute reflectivity. The camera will be tested at the 50.2 cm telescope of the Aula EspaZio Gela (Bilbao) and then commissioned at the 1.05 m at Pic-duMidi Observatory (Franca) and at the 1.23 m telescope at Calar Alto Observatory in Spain. Among the initially planned research targets are: (1) The vertical structure of the clouds and hazes in the planets and their scales of variability; (2) The meteorology, dynamics and global winds and their scales of variability in the planets. PlanetCam is also expected to perform studies of other Solar System and astrophysical objects. Acknowledgments: This work was supported by the Spanish MICIIN project AYA2009-10701 with FEDER funds, by Grupos Gobierno Vasco IT-464-07 and by Universidad País Vasco UPV/EHU through program UFI11/55.

Sanchez-Lavega, Agustin; Rojas, J.; Hueso, R.; Perez-Hoyos, S.; de Bilbao, L.; Murga, G.; Ariño, J.; Mendikoa, I.

2012-10-01

200

Asteroid observations with the Hubble Space Telescope and the Space Infrared Telescope Facility  

NASA Astrophysics Data System (ADS)

The ways that the asteroids can be studied with the Hubble Space Telescope (HST) and the Space Infrared Telescope Facility (SIRTF) are examined. Spectrophotometry of asteroids and the study of asteroid surfaces, shape, spins, configuration, normal reflectance, and limb darkening of asteroids using the HST are addressed along with the detection of asteroid satellites and the discovery of small asteroids using the HST. The relation of the HST to its ground system is described, as are the spectrophotometric instruments of the HST. Imaging with the HST using the Faint Object Camera and the Wide Field and Planetary Camera is examined. Finally, the SIRTF observatory, instrumentation, and capabilities for solar system science are discussed.

Zellner, B.; Wells, Eddie N.; Chapman, Clark R.; Cruikshank, D. P.

201

Simulation of laser detection and ranging (LADAR) and forward-looking infrared (FLIR) data for autonomous tracking of airborne objects  

NASA Astrophysics Data System (ADS)

This paper presents the results of an investigation leading into an implementation of FLIR and LADAR data simulation for use in a multi sensor data fusion automated target recognition system. At present the main areas of application are in military environments but systems can easily be adapted to other areas such as security applications, robotics and autonomous cars. Recent developments have been away from traditional sensor modeling and toward modeling of features that are external to the system, such as atmosphere and part occlusion, to create a more realistic and rounded system. We have implemented such techniques and introduced a means of inserting these models into a highly detailed scene model to provide a rich data set for later processing. From our study and implementation we are able to embed sensor model components into a commercial graphics and animation package, along with object and terrain models, which can be easily used to create a more realistic sequence of images.

Powell, Gavin; Markham, Keith C.; Marshall, David

2000-06-01

202

Ultra{endash}steep-spectrum radio sources. II. Radio, infrared, optical, and {ital HST} imaging of high-redshift 4C objects  

SciTech Connect

We present radio, infrared, optical, and {ital HST} imaging data on eight high-redshift ({ital z}{gt}2) ultra{endash}steep-spectrum 4C radio sources. The radio polarization morphologies are highly asymmetric, indicating large rotation measures across the objects. The optical morphologies are all aligned with the radio axis. The multicolor images show strong asymmetric gradients in the color of the continuum along the radio axes. No optical emission is detected from the radio lobes. Narrowband images of the redshifted Ly{alpha} emission show that the emission-line morphology is generally aligned with the radio source but does not necessarily correspond to the apparent morphology of the rest-frame ultraviolet continuum. {copyright} {ital 1996 The American Astronomical Society.}

Chambers, K.C. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaiian Islands 96822 (United States); Miley, G.K. [Sterrewacht, Leiden, Postbus 9513, NL-2300 RA, Leiden (Netherlands); van Breugel, W.J. [Institute for Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Bremer, M.A. [Sterrewacht Leiden, and SRON, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands); Huang, J.; Trentham, N.A. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaiian Islands 96822 (United States)

1996-10-01

203

Design and development of MOSFIRE: the multi-object spectrometer for infrared exploration at the Keck Observatory  

NASA Astrophysics Data System (ADS)

MOSFIRE is a unique multi-object spectrometer and imager for the Cassegrain focus of the 10 m Keck 1 telescope. A refractive optical design provides near-IR (0.97 to 2.45 ?m) multi-object spectroscopy over a 6.14' x 6.14' field of view with a resolving power of R~3,270 for a 0.7" slit width (2.9 pixels in the dispersion direction), or imaging over a field of view of 6.8' diameter with 0.18" per pixel sampling. A single diffraction grating can be set at two fixed angles, and order-sorting filters provide spectra that cover the K, H, J or Y bands by selecting 3rd, 4th, 5th or 6th order respectively. A folding flat following the field lens is equipped with piezo transducers to provide tip/tilt control for flexure compensation at the 0.1 pixel level. A special feature of MOSFIRE is that its multiplex advantage of up to 46 slits is achieved using a cryogenic Configurable Slit Unit or CSU developed in collaboration with the Swiss Centre for Electronics and Micro Technology (CSEM). The CSU is reconfigurable under remote control in less than 5 minutes without any thermal cycling of the instrument. Slits are formed by moving opposable bars from both sides of the focal plane. An individual slit has a length of 7.1" but bar positions can be aligned to make longer slits. When masking bars are removed to their full extent and the grating is changed to a mirror, MOSFIRE becomes a wide-field imager. Using a single, ASIC-driven, 2K x 2K H2-RG HgCdTe array from Teledyne Imaging Sensors with exceptionally low dark current and low noise, MOSFIRE will be extremely sensitive and ideal for a wide range of science applications. This paper describes the design and testing of the instrument prior to delivery later in 2010.

McLean, Ian S.; Steidel, Charles C.; Epps, Harland; Matthews, Keith; Adkins, Sean; Konidaris, Nicholas; Weber, Bob; Aliado, Ted; Brims, George; Canfield, John; Cromer, John; Fucik, Jason; Kulas, Kristin; Mace, Greg; Magnone, Ken; Rodriguez, Hector; Wang, Eric; Weiss, Jason

2010-07-01

204

MEASURING THE UNDETECTABLE: PROPER MOTIONS AND PARALLAXES OF VERY FAINT SOURCES  

SciTech Connect

The near future of astrophysics involves many large solid-angle, multi-epoch, multiband imaging surveys. These surveys will, at their faint limits, have data on a large number of sources that are too faint to be detected at any individual epoch. Here, we show that it is possible to measure in multi-epoch data not only the fluxes and positions, but also the parallaxes and proper motions of sources that are too faint to be detected at any individual epoch. The method involves fitting a model of a moving point source simultaneously to all imaging, taking account of the noise and point-spread function (PSF) in each image. By this method it is possible to measure the proper motion of a point source with an uncertainty close to the minimum possible uncertainty given the information in the data, which is limited by the PSF, the distribution of observation times (epochs), and the total signal-to-noise in the combined data. We demonstrate our technique on multi-epoch Sloan Digital Sky Survey (SDSS) imaging of the SDSS Southern Stripe (SDSSSS). We show that with our new technique we can use proper motions to distinguish very red brown dwarfs from very high-redshift quasars in these SDSS data, for objects that are inaccessible to traditional techniques, and with better fidelity than by multiband imaging alone. We rediscover all 10 known brown dwarfs in our sample and present nine new candidate brown dwarfs, identified on the basis of significant proper motion.

Lang, Dustin [Department of Computer Science, University of Toronto, 6 King's College Road, Toronto, Ontario M5S 3G4 (Canada); Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Jester, Sebastian; Rix, Hans-Walter [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)], E-mail: david.hogg@nyu.edu

2009-05-15

205

On The Nature of Faint Galaxies with Strong UV Excess  

NASA Astrophysics Data System (ADS)

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 H? 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 H? 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 H? emission line width for CG 1331 is 7350 km/sec (FWHM). Lines corresponding to H? and H? have also been identified. This research has been supported in part by NASA through the Nevada Space Grant Consortium.

Cruzen, S.; Weistrop, D.; Angione, R.

1993-05-01

206

Methods for Estimating Fluxes and Absorptions of Faint X-ray Sources  

NASA Astrophysics Data System (ADS)

X-ray sources with very few counts can be identified with low-noise X-ray detectors such as the Advanced CCD Imaging Spectrometer on board the Chandra X-ray Observatory. These sources are often too faint for parametric spectral modeling using well-established methods such as fitting with XSPEC. We discuss the estimation of apparent and intrinsic broadband X-ray fluxes and soft X-ray absorption from gas along the line of sight to these sources, using nonparametric methods. Apparent flux is estimated from the ratio of the source count rate to the instrumental effective area averaged over the chosen band. Absorption, intrinsic flux, and errors on these quantities are estimated from comparison of source photometric quantities with those of high signal-to-noise spectra that were simulated using spectral models characteristic of the class of astrophysical sources under study. The concept of this method is similar to the long-standing use of color-magnitude diagrams in optical and infrared astronomy, with X-ray median energy replacing color index and X-ray source counts replacing magnitude. Our nonparametric method is tested against the apparent spectra of ~2000 faint sources in the Chandra observation of the rich young stellar cluster in the M 17 H II region. We show that the intrinsic X-ray properties can be determined with little bias and reasonable accuracy using these observable photometric quantities without employing often uncertain and time-consuming methods of nonlinear parametric spectral modeling. Our method is calibrated for thermal spectra characteristic of stars in young stellar clusters, but recalibration should be possible for some other classes of faint X-ray sources such as extragalactic active galactic nuclei.

Getman, Konstantin V.; Feigelson, Eric D.; Broos, Patrick S.; Townsley, Leisa K.; Garmire, Gordon P.

2010-01-01

207

The Formation History of the Ultra-Faint Dwarf Galaxies  

NASA Astrophysics Data System (ADS)

We present initial results from an HST survey of the ultra-faint dwarf galaxies. These Milky Way satellites were recently discovered in the Sloan Digital Sky Survey, and appear to be an extension of the classical dwarf spheroidals to low luminosities, offering a new front in the efforts to understand the missing satellite problem. Because they are the least luminous, most dark matter dominated, and least chemically evolved galaxies known, the ultra-faint dwarfs are the best candidate fossils from the early universe. The primary goal of the survey is to measure the star-formation histories of these galaxies and discern any synchronization due to the reionization of the universe.

Brown, Thomas M.; Tumlinson, J.; Geha, M. C.; Munoz, R.; Kirby, E.; Kalirai, J. S.; VandenBerg, D. A.; Avila, R.; Simon, J. D.; Ferguson, H. C.; GuhaThakurta, P.

2012-05-01

208

Faint High-Latitude Carbon Stars Discovered by the Sloan Digital Sky Survey: Methods and Initial Results  

Microsoft Academic Search

We report the discovery of 39 faint high-latitude carbon stars (FHLCs) from Sloan Digital Sky Survey (SDSS) commissioning data. The objects, each selected photometrically and verified spectroscopically, range over 16.6objects are, in general, too

Bruce Margon; Scott F. Anderson; Hugh C. Harris; Xiaohui Fan; Donald P. Schneider; Daniel E. Vanden Berk; David J. Schlegel; Eric W. Deutsch; Zeljko Ivezic; Patrick B. Hall; Benjamin F. Williams; Arthur F. Davidsen; J. Brinkmann; István Csabai; Jeffrey J. E. Hayes; Greg Hennessy; Ellyne K. Kinney; S. J. Kleinman; Don Q. Lamb; Dan Long; Eric H. Neilsen; Robert Nichol; Atsuko Nitta; Stephanie A. Snedden; Donald G. York

2002-01-01

209

Cataclysmic Variables from the Faint Sky Variability Survey  

Microsoft Academic Search

The Faint Sky Variability Survey is a large, deep field, optical, photometric survey using the Wide-Field Camera at the Isaac Newton Telescope on La Palma. Approximately 18 square degrees have been observed photometrically in BVI colors with variability sampling of 10's of minutes to years. Current population synthesis models for cataclysmic variables (CVs) predict the majority (70%) have passed the

M. E. Huber; S. B. Howell

2001-01-01

210

Faint Galaxies in Deep Advanced Camera for Surveys Observations  

Microsoft Academic Search

We present the analysis of the faint galaxy population in the Advanced Camera for Surveys (ACS) Early Release Observation fields VV 29 (UGC 10214) and NGC 4676. These observations cover a total area of 26.3 arcmin2 and have depths close to that of the Hubble Deep Fields in the deepest part of the VV 29 image, with 10 sigma detection

N. Benítez; H. Ford; R. Bouwens; F. Menanteau; J. Blakeslee; C. Gronwall; G. Illingworth; G. Meurer; T. J. Broadhurst; M. Clampin; M. Franx; G. F. Hartig; D. Magee; M. Sirianni; D. R. Ardila; F. Bartko; R. A. Brown; C. J. Burrows; E. S. Cheng; N. J. G. Cross; P. D. Feldman; D. A. Golimowski; L. Infante; R. A. Kimble; J. E. Krist; M. P. Lesser; Z. Levay; A. R. Martel; G. K. Miley; M. Postman; P. Rosati; W. B. Sparks; H. D. Tran; Z. I. Tsvetanov; R. L. White; W. Zheng

2004-01-01

211

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-Hoonah-Angoon Census Area, AK

212

Confirmation of Faint Dwarf Galaxies in the M81 Group  

NASA Astrophysics Data System (ADS)

We have followed up on the results of a 65 deg2 CFHT/MegaCam imaging survey of the nearby M81 Group searching for faint and ultra-faint dwarf galaxies. The original survey turned up 22 faint candidate dwarf members. Based on two-color HST ACS/WFC and WFPC2 photometry, we now confirm 14 of these as dwarf galaxy members of the group. Distances and stellar population characteristics are discussed for each. To a completeness limit of M_{r^{\\prime }} = -10, we find a galaxy luminosity function slope of –1.27 ± 0.04 for the M81 Group. In this region, there are now 36 M81 Group members known, including 4 blue compact dwarfs; 8 other late types including the interacting giants M81, NGC 3077, and M82; 19 early type dwarfs; and at least 5 potential tidal dwarf galaxies. We find that the dSph galaxies in M81 appear to lie in a flattened distribution, similar to that found for the Milky Way and M31. One of the newly discovered dSph galaxies has properties similar to the ultra-faint dwarfs being found in the Local Group with a size Re ~ 100 pc and total magnitude estimates M_{r^{\\prime }} = -6.8 and MI ~ –9.1.

Chiboucas, Kristin; Jacobs, Bradley A.; Tully, R. Brent; Karachentsev, Igor D.

2013-11-01

213

Faint-end quasar luminosity functions from cosmological hydrodynamic simulations  

NASA Astrophysics Data System (ADS)

We investigate the predictions for the faint-end quasar luminosity function (QLF) and its evolution using fully cosmological hydrodynamic simulations which self-consistently follow star formation, black hole growth and associated feedback processes. We find remarkably good agreement between the predicted and observed faint end of the optical and X-ray QLFs (the bright end is not accessible in our simulated volumes) at z < 2. At higher redshifts, our simulations tend to overestimate the QLF at the faintest luminosities. We show that although the low- (high)-luminosity ranges of the faint-end QLF are dominated by low- (high)-mass black holes, a wide range of black hole masses still contributes to any given luminosity range. This is consistent with the complex light curves of black holes resulting from the detailed hydrodynamics followed in the simulations. Consistent with the results on the QLFs, we find a good agreement for the evolution of the comoving number density (in optical, soft and hard X-ray bands) of active galactic nuclei for luminosities >=1043ergs-1. However, the luminosity density evolution from the simulation appears to imply a peak at higher redshift than constrained from hard X-ray data (but not in optical). Our predicted excess at the faintest fluxes at z >= 2 does not lead to an overestimate to the total X-ray background and its contribution is at most a factor of 2 larger than the unresolved fraction of the 2-8 keV background. Even though this could be explained by some yet undetected, perhaps heavily obscured faint quasar population, we show that our predictions for the faint sources at high redshifts (which are dominated by the low-mass black holes) in the simulations are likely affected by resolution effects.

Degraf, Colin; Di Matteo, Tiziana; Springel, Volker

2010-03-01

214

Galaxy Evolution from Deep Optical and Near-Infrared Surveys  

NASA Astrophysics Data System (ADS)

We use very deep optical and near-infrared imaging surveys to set constraints on galaxy evolution models, based on the numbers, colors, and morphologies of infrared-excess galaxies that are found in the field. We concentrate on a curious population of extremely faint (K > 20) infrared-excess galaxies whose blue-optical colors are not consistent with the expectations of any passive evolution models. These ``faint red-outlier galaxies'' (FROGs) are distinct from the redder and brighter ``extremely red objects'' (EROs; R-K~=6 ). In a concerted effort to identify a good sample of FROG s and to study their properties, we used Keck/NIRC to image several independent high-galactic latitude fields. Much of the analysis presented here is drawn from a very deep 3.24 arcmin2 K-band ( Klim~24 at 3?) mosaic in the deep Westphal HST/WFPC2 pointing of the Groth Survey Strip, for which F606W and F814W data were publically available. The surface density of FROGs is found to be ~ 3.3 +/- 1 arcmin-2, more than ten times that of EROs. Whereas reliable photometric redshifts are not forthcoming without the development of more relevant models, the colors are broadly consistent with the redshift range 1.2 < z < 2.3. If placed at z ~ 1.5, FROGs occur at space densities of about 10% of the local f* space density of K-selected galaxies. To map wavelength-dependent morphologies of two FROGs, we observed a portion of our main survey field with HST/NICMOS imaging through the F160W (1.6 ?m) filter. The target was resolved into two r~=0''.6 objects with similar colors, separated by ~0''.7. This is suggestive of old and dynamically-relaxed systems. The colors of FROGs are not satisfactorily fit by dust-reddened Bruzual-Charlot models at any redshift and for a broad range of assumed star formation histories. The best possible fits are consistent with very large amounts of reddening, E(B - V) ~ 1. If the infrared-excess in EROs and FROGs is taken to be entirely due to the effects of dust, then we can estimate the upper limit of their contribution to the far infrared background. We use a range of star formation histories at different ages and representative reddening values. The integral contribution of EROs and FROGs is calculated to be no greater than ~ 1 - 10 nW m-2 sr-1. At ? ~ 100?m, 1 nW m-2 sr-1 corresponds to ~ 10% of the total measured infrared background.

Moustakas, Leonidas Alexander

1998-09-01

215

Spectroscopy of faint T dwarf calibrators: understanding the substellar mass function and the coolest brown dwarfs  

NASA Astrophysics Data System (ADS)

More than 100 methane brown dwarfs, or T dwarfs, have now been discovered in the local field with 2MASS, SLOAN and UKIDSS, opening up a new area of physics describing objects at 450-1400 K. However, very few calibrator objects exist with well established ages and metallicities. A very surprising result from the UKIDSS sample {supported by 2MASS and SLOAN} is that the substellar mass function in the local field appears to decline to lower masses, in marked contrast to the rising initial mass function {IMF} observed in young clusters. Given that such a difference between the present day IMF and the Galactic time-averaged IMF is unlikely, it is very possible that the apparently falling IMF is an artifact of serious errors in either T model atmospheres or the evolutionary isochrones. We propose WFC3 spectroscopy of 4 faint T dwarf calibrators with well established ages and metallicities in the Pleiades and Sigma Ori clusters, and 2 faint field T dwarfs from UKIDSS for comparison. These spectra will constitute vital calibration data for T dwarf atmospheres with a wide range of surface gravities, which will be used to test and improve the model atmospheres. They will also aid preparation for future spectroscopy of the much larger numbers of field T dwarfs to soon be found by VISTA and WISE. These new surveys will permit a more precise measurement of the mass function and detection of even cooler objects.;

Lucas, Philip

2009-07-01

216

Extremely Metal-poor Stars In The Ultra-faint Dwarf Galaxies And Their Relation To The First Galaxies  

NASA Astrophysics Data System (ADS)

Recent works have shown that the ultra-faint dwarf galaxies (with L<10^5Lsun) contain a relatively large fraction of extremely metal-poor stars and are devoid of solar-type stars. Furthermore, these faint, fully DM dominated galaxies show large [Fe/H] abundances spreads of nearly 3 dex. I will present detailed chemical abundances of 15 stars with -3.8 < [Fe/H] < -1.4 in six of the ultra-faint dwarf galaxies, including the faintest known galaxy Segue 1. By now, the dwarf galaxies host 30% of the known metal-poor stars with [Fe/H]<-3.5, making them ideal objects for carrying out stellar archaeology and near-field cosmology. Generally, the abundance signatures of the dwarf galaxy stars closely resemble those of equivalent halo stars, suggesting that the metal-poor tail of the Galactic halo was assembled from early analogs of the ultra-faint dwarfs. Especially the most metal-poor halo stars may all originate from such small, old systems, and future interpretations of the stellar chemical signatures should take this into account. Furthermore, I will show preliminary evidence for a possible connection between these primitive metal-poor survivor galaxies, and the first galaxies (e.g. atomic cooling halos). Based on hydrodynamical simulations, we have established the nucleosynthetic signatures governing a first galaxy. We compare the predictions with the stellar abundances and conclude that some ultra-faint dwarfs could indeed be surviving first galaxies. The stratgey of closely combining observations with simulation results is already helping to learn more details about the relation between the first galaxies, the surviving dwarfs and their role in building the Milky Way stellar halo.

Frebel, Anna

2012-05-01

217

Infrared observations of highly variable radio sources in the galactic plane  

NASA Astrophysics Data System (ADS)

We have performed a comprehensive infrared imaging survey of 29 radio sources which were first detected by the UBC radio patrol survey of the galactic plane. The sources in our sample are the subset of variable and nonvariable 'control' objects which were mapped with the VLA by Duric & Gregory (1988). Since other sources in the original variability survey have been shown to be associated with unusual galactic X-ray and gamma-ray sources, the aim of the present work was to make the first steps towards discovering whether the remaining radio variables represent a hitherto undetected sample of faint, unusual X-ray binary stars. As a result, we have detected infrared sources coincident with seven of these radio objects and have varying degrees of confidence in their status as true counterparts. The infrared objects are typically far redder than surrounding stars in the same fields (J-K is approximately equal to 2.5), and are generally invisible on the optical sky survey plates. In addition to this, as a result of scanning the POSS plates, we have uncovered optical candidates coincident with five radio positions. Most of these optical sources are close to the plate limiting magnitudes and only two objects are common between the sets of infrared and optical candidates.

Norton, A. J.; Coe, M. J.; Unger, S. J.; Margon, B.; Phillips, A. C.

1993-02-01

218

Looking Deep with Infrared Eyes  

NASA Astrophysics Data System (ADS)

Today, British astronomers are releasing the first data from the largest and most sensitive survey of the heavens in infrared light to the ESO user community. The UKIRT Infrared Deep Sky Survey (UKIDSS) has completed the first of seven years of data collection, studying objects that are too faint to see at visible wavelengths, such as very distant or very cool objects. New data on young galaxies is already challenging current thinking on galaxy formation, revealing galaxies that are massive at a much earlier stage of development than expected. These first science results already show how powerful the full survey will be at finding rare objects that hold vital clues to how stars and galaxies in our Universe formed. UKIDSS will make an atlas of large areas of the sky in the infrared. The data become available to the entire ESO user community immediately after they are entered into the archive [2]. Release to the world follows 18 months after each release to ESO. "Astronomers across Europe will jump on these exciting new data. We are moving into new territory - our survey is both wide and deep, so we are mapping huge volumes of space. That's how we will locate rare objects - the very nearest and smallest stars, and young galaxies at the edge of the universe," said Andy Lawrence from the University of Edinburgh, UKIDSS Principal Investigator. The UKIDSS data are collected by the United Kingdom Infrared Telescope [3] situated near the summit of Mauna Kea in Hawaii using the Wide Field Camera (WFCAM) built by the United Kingdom Astronomy Technology Centre (UKATC) in Edinburgh. WFCAM is the most powerful infrared imager in the world, generating enormous amounts of data - 150 gigabytes per night (equivalent to more than 200 CDs) - and approximately 10.5 Terabytes in total so far (or 15,000 CDs). Mark Casali, now at ESO, was the Project Scientist in charge of the WFCAM instrument construction at the UKATC. "WFCAM was a bold technological undertaking," said Mark Casali. "Nothing quite like it has ever been built before. The fact that it is working reliably and reaching its theoretical sensitivity is a testament to the hard work and skill of the engineering team at the UKATC." ESO PR Photo 24a/06 ESO PR Photo 26a/06 Faint Red Galaxy in the UKIDSS Ultra-Deep Survey A small amount of data was released in January 2006 and already teams led by Omar Almaini at the University of Nottingham and Nigel Hambly of the Institute for Astronomy at the University of Edinburgh are beginning to reveal some of the secrets of star and galaxy formation. Omar Almaini, Ross McLure and the Ultra Deep Survey team have been looking at distant galaxies by surveying the same region of sky night after night to see deeper and to find these very faint objects. This survey will be one hundred times larger than any similar survey attempted to date and will cover an area four times the size of the full Moon. So far several hundred thousand galaxies have been detected and among the early discoveries, nine remarkable galaxies have been found that appear to be 12 billion light years away. As it has taken 12 billion years for the light to travel from these galaxies to Earth, we are seeing them as they were when they were very young - only a billion years after the Big Bang. The newly discovered galaxies are unusual as they appear to be very massive for their age. This challenges thinking on how galaxies form, since it was thought that large galaxies form gradually over billions of years as smaller components merge together. "We're surveying an enormous volume of the distant Universe, which allows us to discover rare massive galaxies that were previously almost impossible to find. Understanding how these galaxies form is one of the Holy Grails of modern astronomy, and now we can trace them back to the edge of the known Universe" said Omar Almaini. ESO PR Photo 26b/06 ESO PR Photo 26b/06 Brown Dwarf Candidates in the Pleiades Cluster (UKIDSS) Nigel Hambly and Nicolas Lodieu have been using the UKIDSS data to discover more about ve

2006-07-01

219

The Morphologically Divided Redshift Distribution of Faint Galaxies  

Microsoft Academic Search

We have constructed a morphologically divided redshift distribution of faint field galaxies using a statistically unbiased sample of 196 galaxies brighter than I=21.5 for which detailed morphological information (from the Hubble Space Telescope) as well as ground-based spectroscopic redshifts are available. Galaxies are classified into three rough morphological types according to their visual appearance (E\\/S0s, spirals, Sdm\\/dE\\/Irr\\/Pec galaxies), and redshift

Myungshin Im; Richard E. Griffiths; Avi Naim; Kavan U. Ratnatunga; Nathan Roche; Richard F. Green; Vicki L. Sarajedini

1999-01-01

220

Near infrared observations of TNOs with SINFONI  

NASA Astrophysics Data System (ADS)

The trans-Neptunian objects are probably the most primitive objects in the Solar System and their study carries important clues about the history of formation and evolution of our planetary system. From 2001 the Meudon group started an observational campaign at VLT/ESO to observe by spectroscopy these faint and distant objects to investigate their surface composition. Recently, a new instrument has been installed, the Spectrograph for INtegral Field Observations in the Near Infrared, SINFONI. This instrument allows to obtain cubes of data with spectra of medium resolution of TNOs, useful to search for subtle absorption features. Here we present data for three plutinos: 26375 (1999 DE9), 38628 Huya, and 47932 (2000 GN171) searching for possible rotational inhomogeneities and/or features on their spectra. We also present data of the distant TNO 90377 Sedna searching for absorption bands, such as the band at 2.3 ?m, probably due to methane ice, proposed by Barucci et al. (2005, A&A, 439, L1). A comparison with previous published observations is performed and the results discussed. A parallel presentation of SINFONI data is presented in this same conference by de Bergh et al. in the frame of the study of 136108 (2003 EL61).

Alvarez-Candal, A.; Barucci, M. A.; Merlin, F.; Guibert, A.; de Bergh, C.

2007-08-01

221

Resurrection of traditional luminosity evolution models to explain faint fields galaxies  

NASA Astrophysics Data System (ADS)

We explore the nature of the evolution of faint field galaxies by assuming that the local luminosity function is not well-defined. We use a non-negative least-squares technique to derive a near optimal set of local luminosity functions for different spectral types of galaxies by fitting to the observed optical and near-infrared counts, B-R colors, and redshift distributions for galaxies with 15 less than or equal to B less than or equal to 27. Our previous work showed that a no-evolution model for the luminosity functions was able to match the observed blue galaxy counts to within a factor of less than 50% by B approximately 25 versus the 5x to 15x (e.g., Tyson 1988) of other nonevolving models. We report here the results of using only traditional luminosity evolution (i.e., the photometric evolution of stars in a galaxy over time given reasonable assumptions of the form of the star-formation history for various galaxy types), and find excellent fits to the observed data to B approximately 23. The addition of simple reddening with an SMC extinction law to our model spectral energy distributions extends the almost perfect fits to the faintest limits. While prior luminosity evolution models required both a law q0 and a high galaxy formation redshift to fit the observed data, the quality of our fits is not significantly degraded by changing the value of q0 to 0.5. We conclude that models more exotic than traditional luminosity evolution are not yet required to explain existing faint galaxy data and thus the need for contributions by mergers or new populations of galaxies is at least 5x less than previously estimated (e.g., Broadhurst et al. 1992).

Gronwall, Caryl; Koo, David C.

1995-02-01

222

FAINT NEAR-ULTRAVIOLET/FAR-ULTRAVIOLET STANDARDS FROM SWIFT/UVOT, GALEX, AND SDSS PHOTOMETRY  

SciTech Connect

At present, the precision of deep ultraviolet photometry is somewhat limited by the dearth of faint ultraviolet standard stars. In an effort to improve this situation, we present a uniform catalog of 11 new faint (u {approx} 17) ultraviolet standard stars. High-precision photometry of these stars has been taken from the Sloan Digital Sky Survey and Galaxy Evolution Explorer archives and combined with new data from the Swift Ultraviolet Optical Telescope to provide precise photometric measures extending from the near-infrared to the far-ultraviolet. These stars were chosen because they are known to be hot (20, 000 < T{sub eff} < 50, 000 K) DA white dwarfs with published Sloan spectra that should be photometrically stable. This careful selection allows us to compare the combined photometry and Sloan spectroscopy to models of pure hydrogen atmospheres to both constrain the underlying properties of the white dwarfs and test the ability of white dwarf models to predict the photometric measures. We find that the photometry provides good constraints on white dwarf temperatures, which demonstrates the ability of Swift/UVOT to investigate the properties of hot luminous stars. We further find that the models reproduce the photometric measures in all 11 passbands to within their systematic uncertainties. Within the limits of our photometry, we find the standard stars to be photometrically stable. This success indicates that the models can be used to calibrate additional filters to our standard system, permitting easier comparison of photometry from heterogeneous sources. The largest source of uncertainty in the model fitting is the uncertainty in the foreground reddening curve, a problem that is especially acute in the UV.

Siegel, Michael H.; Hoversten, Erik A.; Roming, Peter W. A.; Brown, Peter, E-mail: siegel@astro.psu.ed, E-mail: hoversten@astro.psu.ed, E-mail: roming@astro.psu.ed, E-mail: brown@astro.psu.ed [Department of Astronomy, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

2010-12-10

223

The human fear-circuitry and fear-induced fainting in healthy individuals--the paleolithic-threat hypothesis.  

PubMed

The Paleolithic-Threat hypothesis reviewed here posits that habitual efferent fainting can be traced back to fear-induced allelic polymorphisms that were selected into some genomes of anatomically, mitochondrially, and neurally modern humans (Homo sapiens sapiens) in the Mid-Paleolithic because of the survival advantage they conferred during periods of inescapable threat. We posit that during Mid-Paleolithic warfare an encounter with "a stranger holding a sharp object" was consistently associated with threat to life. A heritable hardwired or firm-wired (prepotentiated) predisposition to abruptly increase vagal tone and collapse flaccidly rather than freeze or attempt to flee or fight in response to an approaching sharp object, a minor injury, or the sight of blood, may have evolved as an alternative stress-induced fear-circuitry response. Such a stable (balanced) polymorphism for the hemodynamically "paradoxical" flaccid-immobility in response to these stimuli may have increased some non-combatants' chances of survival. This is consistent with the unusual age and sex pattern of fear-induced fainting. The Paleolithic-Threat hypothesis also predicts a link to various hypo-androgenic states (e. g. low dehydroxy-epiandrosterone-sulfate. We offer five predictions testable via epidemiological, clinical, and ethological/ primatological methods. The Paleolithic-Threat hypothesis has implications for research in the aftermath of man-made disasters, such as terrorism against civilians, a traumatic event in which this hypothesis predicts epidemics of fear-induced fainting. PMID:15944875

Bracha, H Stefan; Bracha, Adam S; Williams, Andrew E; Ralston, Tyler C; Matsukawa, Jennifer M

2005-06-01

224

The First Science Flight of the Faint Intergalactic medium Redshifted Emission Balloon (FIREBALL)  

NASA Astrophysics Data System (ADS)

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.

Martin, Christopher; Milliard, Bruno; Schiminovich, David; Tuttle, Sarah; Matuszewski, Matt; Rahman, Shahin; Evrard, Jean; Frank, Stephan; Deharveng, Jean-Michel; Peroux, Celine

225

Faint blue counts from formation of dwarf galaxies at Z approximately equals 1  

NASA Astrophysics Data System (ADS)

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.

Babul, Arif; Rees, Martin J.

1993-01-01

226

Visible and Near-Infrared Diffuse Reflectance Spectra of Pyroxenes as Applied to Remote Sensing of Solid Objects in the Solar System  

Microsoft Academic Search

Spin-allowed Fe z+ absorption bands occur in the visible and near-infrared diffuse reflectance spectra of most pyroxenes. The wavelengths of the bands centered near 1 #m and 2 #m vary as functions of pyroxene composition, making possible mineralogical and chemical deductions based on spectral reflectance curves. Typically, pyroxene bands are well developed in relation to absorption features in the spectra

John B. Adams

1974-01-01

227

Colors and taxonomy of Centaurs and trans-Neptunian objects  

NASA Astrophysics Data System (ADS)

Context. The study of the surface properties of Centaurs and trans-Neptunian objects (TNOs) provides essential information about the early conditions and evolution of the outer Solar System. Due to the faintness of most of these distant and icy bodies, photometry currently constitutes the best technique to survey a statistically significant number of them. Aims: Our aim is to investigate color properties of a large sample of minor bodies of the outer Solar System, and set their taxonomic classification. Methods: We carried out visible and near-infrared photometry of Centaurs and TNOs, making use, respectively, of the FORS2 and ISAAC instruments at the Very Large Telescope (European Southern Observatory). Using G-mode analysis, we derived taxonomic classifications according to the Barucci et al. (2005a, AJ, 130, 1291) system. Results: We report photometric observations of 31 objects, 10 of them have their colors reported for the first time ever. 28 Centaurs and TNOs have been assigned to a taxon. Conclusions: We combined the entire sample of 38 objects taxonomically classified in the framework of our programme (28 objects from this work; 10 objects from DeMeo et al. 2009a, A&A, 493, 283) with previously classified TNOs and Centaurs, looking for correlations between taxonomy and dynamics. We compared our photometric results to literature data, finding hints of heterogeneity for the surfaces of 4 objects. Based on observations carried out at the European Southern Observatory (ESO), Chile (Programmes 178.C-0036 and 178.C-0867).

Perna, D.; Barucci, M. A.; Fornasier, S.; DeMeo, F. E.; Alvarez-Candal, A.; Merlin, F.; Dotto, E.; Doressoundiram, A.; de Bergh, C.

2010-02-01

228

Deceleration of faint photographic meteors and the density of meteoroids  

SciTech Connect

The authors have performed mathematical modeling of observed deceleration of faint photographic meteors, and their heights of disappearance, in the framework of a simplified theory of quasicontinuous crushing of meteoroids. This modeling has enabled them to estimate the density of the parent meteoroids and the mass of large fragments. Out of 92 sporadic meteors which they have considered, they have found that 57 were created by meteoroids with characteristic similar to those of carbonaceous chondrites, 20 came from meteoroids similar to ordinary stony meteorites (chondrites) 8 came from iron meteoroids, 4 from stony-iron meteoroids, and 3 of the meteors came from very porous meteoroids of the dust clump type.

Lebedinets, V.N.

1987-07-01

229

The Infrared Properties of Dwarf Galaxies: New Results from SINGS and THINGS  

Microsoft Academic Search

We present new observations of dwarf galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS) Legacy Program dataset. The unprecedented sensitivity of these data offers a unique opportunity for a detailed exploration of the properties of these faint systems in the infrared. We compare these data to sensitive HI observations obtained in The HI Nearby Galaxies Survey (THINGS) to study

J. M. Cannon; F. Walter; R. C. Kennicutt; G. Bendo; E. Brinks; D. Calzetti; W. J. G. de Blok; C. Engelbracht; K. D. Gordon; L. Kewley; A. Li; M. Meyer; M. Regan; H. Roussel; J. D. T. Smith; M. Thornley

2005-01-01

230

On the relation of mid-infrared emission with the gamma-ray properties of Fermi-detected BL Lac objects  

NASA Astrophysics Data System (ADS)

We present the Wide-field Infrared Survey Explorer (WISE) photometric data of 158 Fermi-detected BL Lacs and investigate the nature of their mid-infrared (MIR) continuum emission. In the [3.4]-[4.6]-[12] ?m color-color diagram, nearly all their colors lie within the WISE Blazar strip (WBS), which is an effective diagnostic tool to separate sources dominated by non-thermal radiation from those dominated by thermal radiation. This feature indicates that their MIR emission is predominantly non-thermal. This argument is further supported by the strong radio-MIR flux correlation. We derive their MIR spectral indices and compare them with the near-infrared (NIR) spectral indices. We find that there is a prevalent steepening from MIR spectrum to NIR spectrum. The low-frequency-peaked BL Lacs (LBLs) have on average a larger MIR spectral index and a higher MIR luminosity than the high-frequency-peaked BL Lacs (HBLs), and the intermediate-frequency-peaked BL Lacs (IBLs) appear to bridge them. The MIR- ?-ray flux correlation is highly significant. A strong positive correlation is also found between the MIR and ?-ray spectral indices. The ?-ray-MIR loudness is significantly correlated with the synchrotron peak frequency. Finally we propose that the ?-rays are highly associated with the MIR emission from the jet, and the ?-ray emission is likely from the synchrotron self-Compton process for the Fermi-detected BL Lacs in our sample.

Mao, Li-Sheng

2012-08-01

231

A deep imaging and spectroscopic survey of faint galaxies  

SciTech Connect

Deep images in four optical passbands with limiting magnitudes for galactic images of roughly 27th AB magnitudes are used here to study the population of faint galaxies. While confirming the existence of a blueward trend of galaxy colors at faint magnitudes, it is found that the colors of the faintest galaxies are generally not as blue as found by Tyson (1988). The slope of the B-band source counts appears to decrease below the bright-end slope of 0.465 for magnitudes fainter than B about 24, thus removing the potential divergence of the integrated night-sky brightness. Spectroscopy of a small but representative sample of galaxies with B(AB) less than 24.1 yields a high success rate of spectroscopic identification and redshift determination. It is confirmed that significant evolution must be occurring between B(AB) about 21.5 and about 23.5. The evolution is best characterized as an increase of Phi-asterisk rather than L-asterisk. 42 refs.

Lilly, S.J.; Cowie, L.L.; Gardner, J.P. (Hawaii Univ., Honolulu (USA))

1991-03-01

232

A model atmosphere analysis of the faint early-type halo star PHL 346  

NASA Astrophysics Data System (ADS)

Stellar equivalent widths and hydrogen line profiles, measured from high-resolution optical spectra obtained with the 2.5 m Issac Newton Telescope, are used in conjunction with model atmosphere calculations to determine the atmospheric parameters and chemical composition of the faint, high galactic latitude early-type star PHL 346. The effective temperature (Teff = 22,600 + or - 1000 K) and surface gravity (log g = 3.6 + or - 0.2), as well as the chemical composition, are found to be similar to those of normal OB stars. Therefore, it is concluded that PHL 346 is an ordinary Population I object, at a z distance of 8.7 + or - 1.5 kpc. The relatively small stellar velocity in the z-direction (Vz = +56 + or - 10 km/s) then implies that PHL 346 must have been formed in the halo, possibly from galactic fountain material at a z distance of about 6 kpc.

Keenan, F. P.; Lennon, D. J.; Brown, P. J. F.; Dufton, P. L.

1986-08-01

233

FAINT, EVOLVING RADIO ACTIVE GALACTIC NUCLEI IN SDSS LUMINOUS RED GALAXIES  

SciTech Connect

We detect and study the properties of faint radio active galactic nuclei (AGNs) in luminous red galaxies (LRGs). The LRG sample comprises 760,000 objects from a catalog of LRG photometric redshifts constructed from the Sloan Digital Sky Survey (SDSS) imaging data, and 65,000 LRGs from the SDSS spectroscopic sample. These galaxies have typical 1.4 GHz flux densities in the 10s-100s of {mu}Jy, with the contribution from a low-luminosity AGN dominating any contribution from star formation. To probe the radio properties of such faint objects, we employ a stacking technique whereby FIRST survey image cutouts at each optical LRG position are sorted by the parameter of interest and median-combined within bins. We find that median radio luminosity scales with optical luminosity (L {sub opt}) as L {sub 1.4GHz} {proportional_to} L {sup {beta}} {sub opt}, where {beta} depends on the redshift being probed. Above z {approx_equal} 0.4, {beta} appears to decrease from {beta} {approx_equal} 1 at z = 0.4 to {beta} {approx_equal} 0 at z = 0.7, a result which could be indicative of AGN cosmic downsizing. We also find that the overall LRG population, which is dominated by low-luminosity AGNs, experiences significant cosmic evolution between z = 0.2 and z = 0.7. A simultaneous fit to untangle the redshift and luminosity dependences yields redshift evolution of the form L {sub 1.4GHz} {proportional_to} (1 + z){sup 3.15{+-}}{sup 0.07}, implying a considerable increase in total AGN heating for these massive ellipticals with redshift. By matching against the FIRST catalog, we investigate the incidence and properties of LRGs associated with double-lobed (FR I/II) radio galaxies.

Hodge, J. A.; Zeimann, G. R.; Becker, R. H. [University of California, 1 Shields Ave, Davis, CA 95616 (United States); White, R. L. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)], E-mail: hodge@physics.ucdavis.edu

2009-09-15

234

Accuracy analysis of a Hartmann-Shack wavefront sensor operated with a faint object  

Microsoft Academic Search

A detailed analysis of the characteristics, regularities, and relationships of the centroiding errors of image spots caused by discrete and limited sampling, photon noise, and readout noise of the detector in a Hartmann-Shack wavefront sensor, wherein an image intensified charge-coupled device used as a photon detector is presented. The theoretical analysis and experimental results herein prove useful for optimum design

Genrui Cao; Xing Yu

1994-01-01

235

Ultraviolet Faint Object Spectrograph Observations of the Hot Post-Nova GQ MUSCAE  

NASA Astrophysics Data System (ADS)

Low resolution, time-resolved ultraviolet spectra were obtained with the Hubble Space Telescope for the post--nova GQ Muscae on September 2, 1994. We obtained satisfactory data during 3 HST orbits which together cover about 90% of the GQ Mus 85.5 min binary orbital period. The mean spectrum shows a strong, blue continuum which is only slightly flatter than a Rayleigh-Jeans spectra energy distribution. The UV luminosity is LUV ~10(35) erg s(-1) . Moderately strong emission lines from He II, C IV and possibly other high ionization species are present. No significant variability is found as a function of orbital phase and the random variability is <= 10 % throughout the 1300--2100 Angstroms spectral region. The results from these observations are discussed in terms of a cooling white dwarf model for this post--nova.

Shanley, L.; Gallagher, J. S.; Orio, M.; Ogelman, H.

1996-05-01

236

THE FAINT-END SLOPE OF THE REDSHIFT 5.7 Ly{alpha} LUMINOSITY FUNCTION  

SciTech Connect

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.

Henry, Alaina L.; Martin, Crystal L. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Dressler, Alan; McCarthy, Patrick [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Sawicki, Marcin, E-mail: ahenry@physics.ucsb.edu [Department of Astronomy and Physics, Saint Mary's University, Halifax, NS B3H 3C3 (Canada)

2012-01-10

237

Structural parameters of 11 faint Galactic globular clusters derived with 2MASS  

NASA Astrophysics Data System (ADS)

Context: Structural parameters and the total MV magnitude are important properties for the characterisation of individual globular clusters. With the growth in statistics, especially of the intrinsically faint objects, the collective properties of the Galactic globular cluster system will be better defined, leading to a deeper understanding of the Galaxy formation processes. Aims: We determine the structural parameters of 11 faint Galactic globular clusters that, in most cases, had not been previously studied in this context: IC 1257, Lyngå 7, Terzan 4, Terzan 10, BH 176, ESO 452-SC11, ESO 280-SC08, 2MASS-GC01, 2MASS-GC02, GLIMPSE-C01, and AL 3. They are projected not far from the central region of the Galaxy. Field-star contamination is significant in the colour-magnitude diagrams. Half of the sample has an absorption AV ?7, in some cases reaching AV ?15. Methods: Stellar radial number-density and surface-brightness profiles were built with 2MASS photometry that, for the present clusters, corresponds to giant-branch stars. Field-star decontamination is essential for clusters in dense fields, so an algorithm that we had previously developed for open clusters in rich fields was employed to better define cluster sequences. With decontaminated photometry we also computed the total MV of four such globular clusters, using M 4 as a template. King-like functions were fitted to the radial profiles, from which the core, half-light, half-star count, and tidal radii were derived, together with the concentration parameter. The derived parameters were then compared to equivalent ones available in the literature for other Galactic globular clusters. Results: Compared to massive globular clusters, those in the present sample have smaller tidal and larger core radii for a given Galactocentric distance, which is consistent with rather loose structures. Globular cluster radii derived from number-density and surface-brightness profiles have similar values. The present magnitude estimates are MV ? -4.9 (ESO 280-SC08), MV ? -5.8 (2MASS-GC01), and MV ? -5.6 (2MASS-GC02). We also estimate MV ? -6.1 for GLIMPSE-C01, which is somewhat less luminous than previously given. The density profiles of Tz 4 and 2MASS-GC01 show evidence of post-core collapse clusters. Conclusions: The structural parameters and luminosity of most of the faint globular clusters dealt with in this paper are consistent with those of Palomar-like (low mass and loose structure) globular clusters. This work helps to improve the coverage of the globular cluster parameter space.

Bonatto, C.; Bica, E.

2008-03-01

238

Infrared Observations of Periodic Comets.  

National Technical Information Service (NTIS)

Selected comets are observed in the infrared with the NASA Infrared Telescope Facility (IRTF) and other telescopes as appropriate. The scientific objectives are to characterize the thermal emission from the dust coma, derive dust productions rates, detect...

S. Hanner

1988-01-01

239

Clustering Effect on the Number Count of Faint Galaxies  

NASA Astrophysics Data System (ADS)

We have tested the cosmological model of ?0 = 1 and ? = 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.

Yamashita, K.

1992-08-01

240

Two Magellanic Cloud Star-Forming Clusters from Optical to Infrared  

NASA Astrophysics Data System (ADS)

We present analysis of the young stellar and proto-stellar populations in star-forming clusters NGC 602 in the SMC and N206 (Henize 206) in the LMC. Deep, photometric data over the wavelength range 0.36 to 24 ?m allow us to probe stellar populations and recent star formation using a combination of Color-Magnitude Diagram analysis, model Spectral Energy Distribution fitting, and image inspection. We combine both ground- and space-based observations to develop a more complete picture of star formation and its progression in these regions, from embedded, infrared bright YSOs (Young Stellar Objects) to faint optical Pre-Main Sequence sources to optically bright O and B type stars. Infrared data are drawn from the Spitzer Legacy Projects Surveying the Agents of a Galaxy's Evolution (SAGE-LMC and SAGE-SMC). Near infrared data are from InfraRed Survey Facility (IRSF) Magellanic Clouds Point Source Catalog of Kato, et al. (2007). N206 optical data are taken from the Magellanic Cloud Photometric Survey (MCPS), and NGC 602 optical data are from Hubble/ACS (Advanced Camera for Surveys) and ground-based SMARTS (Small and Moderate Aperture Research Telescope System) observations. The SAGE Project is supported by NASA/Spitzer grant 1275598 and NASA NAG5-12595.

Romita, Krista; Carlson, L. R.; Sewilo, M.; Meixner, M.; Sabbi, E.; Gordon, K.; Nota, A.; Sirianni, M.; Smith, L. J.; Leither, C.; Hora, J. L.; Robitaille, T.; Whitney, B.; Block, M.; Engelbracht, C.; Misselt, K.; Indebetouw, R.; Kato, D.; Gallagher, J. S.; Babler, B.; Meade, M.; Oey, M. S.; Cignoni, M.; Tosi, M.; Vijh, U.; Walterbos, R.

2010-01-01

241

Discovery of optically faint obscured quasars with Virtual Observatory tools  

NASA Astrophysics Data System (ADS)

We use Virtual Observatory (VO) tools to identify optically faint, obscured (i.e., type 2) active galactic nuclei (AGN) in the two Great Observatories Origins Deep Survey (GOODS) fields. By employing publicly available X-ray and optical data and catalogues we discover 68 type 2 AGN candidates. The X-ray powers of these sources are estimated by using a previously known correlation between X-ray luminosity and X-ray-to-optical flux ratio. Thirty-one of our candidates have high estimated powers (Lx > 1044 erg/s) and therefore qualify as optically obscured quasars, the so-called ``QSO 2''. Based on the derived X-ray powers, our candidates are likely to be at relatively high redshifts, z˜ 3, with the QSO 2 at z˜4. By going ˜3 mag fainter than previously known type 2 AGN in the two GOODS fields we are sampling a region of redshift - power space which was previously unreachable with classical methods. Our method brings to 40 the number of QSO 2 in the GOODS fields, an improvement of a factor ˜ 4 when compared to the only 9 such sources previously known. We derive a QSO 2 surface density down to 10-15 erg cm-2 s-1 in the 0.5-8 keV band of ?330 deg-2, ˜30% of which is made up of previously known sources. This is larger than current estimates and some predictions and suggests that the surface density of QSO 2 at faint flux limits has been underestimated. This work demonstrates that VO tools are mature enough to produce cutting-edge science results by exploiting astronomical data beyond ``classical'' identification limits (R ? 25) with interoperable tools for statistical identification of sources using multiwavelength information.

Padovani, P.; Allen, M. G.; Rosati, P.; Walton, N. A.

2004-09-01

242

The Milky Way: A Significant Asymmetric Distribution of Faint Halo\\/Thick Disk Stars  

Microsoft Academic Search

We present a star count analysis of the faint stars on either side of the Sun-Center line, from l = +\\/- 20 deg to +\\/- 75 deg and b = +20 deg to +50 deg with data from 40 POSS I fields. Larsen and Humphreys [1996] found a significant asymmetry in the number of faint blue stars on either side

J. E. Parker; R. M. Humphreys; J. A. Larsen

2001-01-01

243

Hunting for faint INTEGRAL AGN in the direction of the Galactic poles: IGR J02341+0228  

NASA Astrophysics Data System (ADS)

We recently started an observational program aimed at searching for soft X-ray counterparts of faint unidentified sources detected in the direction of the Galactic poles with the hard X-ray imager IBIS/ISGRI on-board INTEGRAL. The first object identified in our program is IGR J02341+0228. This source is detected in the 17-80 keV IBIS/ISGRI mosaic at a significance level of 6.5 (on source exposure time ~610 ks).

Ricci, C.; Bozzo, E.; Walter, R.; Paltani, S.; Stella, L.

2012-05-01

244

Performance of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) high-resolution near-infrared multi-object fiber spectrograph  

NASA Astrophysics Data System (ADS)

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) uses a dedicated 300-fiber, narrow-band near-infrared (1.51-1.7 ?m), high resolution (R~22,500) spectrograph to survey approximately 100,000 giant stars across the Milky Way. This three-year survey, in operation since late-summer 2011 as part of the Sloan Digital Sky Survey III (SDSS III), will revolutionize our understanding of the kinematical and chemical enrichment histories of all Galactic stellar populations. We present the performance of the instrument from its first year in operation. The instrument is housed in a separate building adjacent to the 2.5-m SDSS telescope and fed light via approximately 45-meter fiber runs from the telescope. The instrument design includes numerous innovations including a gang connector that allows simultaneous connection of all fibers with a single plug to a telescope cartridge that positions the fibers on the sky, numerous places in the fiber train in which focal ratio degradation had to be minimized, a large mosaic-VPH (290 mm x 475 mm elliptically-shaped recorded area), an f/1.4 six-element refractive camera featuring silicon and fused silica elements with diameters as large as 393 mm, three near-infrared detectors mounted in a 1 x 3 mosaic with sub-pixel translation capability, and all of these components housed within a custom, LN2-cooled, stainless steel vacuum cryostat with dimensions 1.4-m x 2.3-m x 1.3-m.

Wilson, John C.; Hearty, F.; Skrutskie, M. F.; Majewski, S. R.; Schiavon, R.; Eisenstein, D.; Gunn, J.; Holtzman, J.; Nidever, D.; Gillespie, B.; Weinberg, D.; Blank, B.; Henderson, C.; Smee, S.; Barkhouser, R.; Harding, A.; Hope, S.; Fitzgerald, G.; Stolberg, T.; Arns, J.; Nelson, M.; Brunner, S.; Burton, A.; Walker, E.; Lam, C.; Maseman, P.; Barr, J.; Leger, F.; Carey, L.; MacDonald, N.; Ebelke, G.; Beland, S.; Horne, T.; Young, E.; Rieke, G.; Rieke, M.; O'Brien, T.; Crane, J.; Carr, M.; Harrison, C.; Stoll, R.; Vernieri, M.; Shetrone, M.; Allende-Prieto, C.; Johnson, J.; Frinchaboy, P.; Zasowski, G.; Garcia Perez, A.; Bizyaev, D.; Cunha, K.; Smith, V. V.; Meszaros, Sz.; Zhao, B.; Hayden, M.; Chojnowski, S. D.; Andrews, B.; Loomis, C.; Owen, R.; Klaene, M.; Brinkmann, J.; Stauffer, F.; Long, D.; Jordan, W.; Holder, D.; Cope, F.; Naugle, T.; Pfaffenberger, B.; Schlegel, D.; Blanton, M.; Muna, D.; Weaver, B.; Snedden, S.; Pan, K.; Brewington, H.; Malanushenko, E.; Malanushenko, V.; Simmons, A.; Oravetz, D.; Mahadevan, S.; Halverson, S.

2012-09-01

245

Centaur and TNO near-infrared spectroscopy program at ESO-VLT  

NASA Astrophysics Data System (ADS)

Centaur and Trans-Neptunian objects contain important information on the formation and evolution of the Solar System. To study the surface composition of these faint and elusive objects, we have started an observational program at ESO-VLT with the infrared spectrometer ISAAC. The observations were made with the Antu telescope (the first 8 meter telescope of the VLT built on Mount Paranal, Chile). The spectra were recorded with ISAAC at low resolution in the J, H and K regions. These are the spectral ranges where the most diagnostic features of ices are present. The observations, initially made at a resolution of 500, were degraded in order to increase the S/N ratio. We obtained near-infrared spectra of two Centaurs: 1950 GO, now named 8405 Asbolus, and 1995 DW2 and of the Trans-Neptunian 1996 TP66. At present only 8405 Asbolus spectra have been reduced and interpreted. The spectra show a rather featureless behaviour with, in particular, no absorption due to water ice. We have combined our near-infrared spectrum with a visible spectrum, and have performed some preliminar spectral modelling attempts.

Barucci, M. A.; de Bergh, C.; Romon, J.; Cuby, J. G.; Le Bras, A.; Schmitt, B.

2000-10-01

246

Crystalline water ice on the Kuiper belt object (50000) Quaoar.  

PubMed

The Kuiper belt is a disk-like structure consisting of solid bodies orbiting the Sun beyond Neptune. It is the source of the short-period comets and the likely repository of the Solar System's most primitive materials. Surface temperatures in the belt are low ( approximately 50 K), suggesting that ices trapped at formation should have been preserved over the age of the Solar System. Unfortunately, most Kuiper belt objects are too faint for meaningful compositional study, even with the largest available telescopes. Water ice has been reported in a handful of objects, but most appear spectrally featureless. Here we report near-infrared observations of the large Kuiper belt object (50000) Quaoar, which reveal the presence of crystalline water ice and ammonia hydrate. Crystallinity indicates that the ice has been heated to at least 110 K. Both ammonia hydrate and crystalline water ice should be destroyed by energetic particle irradiation on a timescale of about 10(7) yr. We conclude that Quaoar has been recently resurfaced, either by impact exposure of previously buried (shielded) ices or by cryovolcanic outgassing, or by a combination of these processes. PMID:15592406

Jewitt, David C; Luu, Jane

2004-12-01

247

Object Oriented Learning Objects  

ERIC Educational Resources Information Center

|We apply the object oriented software engineering (OOSE) design methodology for software objects (SOs) to learning objects (LOs). OOSE extends and refines design principles for authoring dynamic reusable LOs. Our learning object class (LOC) is a template from which individualised LOs can be dynamically created for, or by, students. The properties…

Morris, Ed

2005-01-01

248

The Electromagnetic Spectrum: Infrared Waves  

NSDL National Science Digital Library

This webpage, part of a NASA site on the electromagnetic spectrum, presents information on infrared light. An explanation of how objects emit infrared is provided, along with a diagram of the electromagnetic spectrum. The site contains a number of photos made with infrared light.

2007-06-24

249

Helium shells and faint emission lines from slitless flash spectra  

NASA Astrophysics Data System (ADS)

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.

Bazin, Cyril; Koutchmy, Serge

2013-05-01

250

THE PRIMEVAL POPULATIONS OF THE ULTRA-FAINT DWARF GALAXIES  

SciTech Connect

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.

Brown, Thomas M.; Tumlinson, Jason; Kalirai, Jason S.; Avila, Roberto J.; Ferguson, Henry C., E-mail: tbrown@stsci.edu, E-mail: tumlinson@stsci.edu, E-mail: jkalirai@stsci.edu, E-mail: avila@stsci.edu, E-mail: ferguson@stsci.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); and others

2012-07-01

251

No climate paradox under the faint early Sun  

NASA Astrophysics Data System (ADS)

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 CO2 and/or CH4 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.

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

2010-04-01

252

Luminosity Function of Faint Globular Clusters in M87  

SciTech Connect

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.

Waters, Christopher Z.; Zepf, Stephen E.; /Michigan State U.; Lauer, Tod R.; /NOAO, Tucson; Baltz, Edward A.; /KIPAC, Menlo Park; Silk, Joseph; /Oxford U.

2006-07-14

253

ARE THE ULTRA-FAINT DWARF GALAXIES JUST CUSPS?  

SciTech Connect

We develop a technique to investigate the possibility that some of the recently discovered ultra-faint dwarf satellites of the Milky Way might be cusp caustics rather than gravitationally self-bound systems. Such cusps can form when a stream of stars folds, creating a region where the projected two-dimensional surface density is enhanced. In this work, we construct a Poisson maximum likelihood test to compare the cusp and exponential models of any substructure on an equal footing. We apply the test to the Hercules dwarf (d {approx} 113 kpc, M{sub V} {approx} -6.2, e {approx} 0.67). The flattened exponential model is strongly favored over the cusp model in the case of Hercules, ruling out at high confidence that Hercules is a cusp catastrophe. This test can be applied to any of the Milky Way dwarfs, and more generally to the entire stellar halo population, to search for the cusp catastrophes that might be expected in an accreted stellar halo.

Zolotov, Adi; Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Willman, Beth, E-mail: az481@nyu.edu [Department of Astronomy, Haverford College, 370 Lancaster Avenue, Haverford, PA 19041 (United States)

2011-01-20

254

No climate paradox under the faint early Sun.  

PubMed

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. PMID:20360739

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

2010-04-01

255

Supernova 2003ie Was Likely a Faint Type IIP Event  

NASA Astrophysics Data System (ADS)

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 ?) 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 ~ - 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 ?). 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.

Arcavi, Iair; Gal-Yam, Avishay; Sergeev, Sergey G.

2013-04-01

256

The Primeval Populations of the Ultra-faint Dwarf Galaxies  

NASA Astrophysics Data System (ADS)

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 ~1 Gyr of each other, as might be expected if their star formation was truncated by a global event, such as reionization. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

Brown, Thomas M.; Tumlinson, Jason; Geha, Marla; Kirby, Evan N.; VandenBerg, Don A.; Muñoz, Ricardo R.; Kalirai, Jason S.; Simon, Joshua D.; Avila, Roberto J.; Guhathakurta, Puragra; Renzini, Alvio; Ferguson, Henry C.

2012-07-01

257

Infrared Investigations.  

ERIC Educational Resources Information Center

|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)|

Lascours, Jean; Albe, Virginie

2001-01-01

258

Evolution of faint radio sources in the VIDEO-XMM3 field  

NASA Astrophysics Data System (ADS)

It has been speculated that low-luminosity radio-loud active galactic nuclei (AGN) have the potential to serve as an important source of AGN feedback, and may be responsible for suppressing star formation activity in massive elliptical galaxies at late times. As such the cosmic evolution of these sources is vitally important to understand the significance of such AGN feedback processes and their influence on the global star formation history of the Universe. In this paper, we present a new investigation of the evolution of faint radio sources out to z ˜ 2.5. We combine a 1 square degree Very Large Array radio survey, complete to a depth of 100 ?Jy, with accurate 10 band photometric redshifts from the following surveys: Visible and Infrared Survey Telescope for Astronomy Deep Extragalactic Observations and Canada-France-Hawaii Telescope Legacy Survey. The results indicate that the radio population experiences mild positive evolution out to z ˜ 1.2 increasing their space density by a factor of ˜3, consistent with results of several previous studies. Beyond z = 1.2, there is evidence of a slowing down of this evolution. Star-forming galaxies drive the more rapid evolution at low redshifts, z < 1.2, while more slowly evolving AGN populations dominate at higher redshifts resulting in a decline in the evolution of the radio luminosity function at z > 1.2. The evolution is best fitted by pure luminosity evolution with star-forming galaxies evolving as (1 + z)2.47 ± 0.12 and AGN as (1 + z)1.18 ± 0.21.

McAlpine, K.; Jarvis, M. J.; Bonfield, D. G.

2013-09-01

259

The Planck-ATCA Coeval Observations project: the faint sample  

NASA Astrophysics Data System (ADS)

The Planck-ATCA Coeval Observations (PACO) project collected data between 4.5 and 40 GHz for 482 sources selected within the Australia Telescope 20 GHz (AT20G) catalogue and observed with the Australia Telescope Compact Array. Observations were done almost simultaneously with the Planck satellite, in the period between 2009 July and 2010 August. In this paper, we present and discuss the data for the complete sample of 159 sources with SAT20G > 200 mJy in the South Ecliptic Pole region. The Planck Early Release Compact Source Catalogue (ERCSC) contains 57 of our sources. A comparison between the PACO catalogue and the ERCSC confirms that the reliability of the latter is better than 95 per cent. The missing ERCSC sources are typically associated with the Large Magellanic Cloud, the Milky Way or are otherwise extended. The spectral analysis of the PACO faint catalogue shows a spectral steepening of the sources at high frequencies, confirming the results obtained from the PACO bright sample. A comparison with AT20G measurements, carried out, on average, a few years earlier, has demonstrated that, on these time-scales, our sources show a rather high variability with an rms amplitude of ?40 per cent at 20 GHz. The source spectral properties are found not to vary substantially with flux density, except for an increase in the fraction of steep spectrum sources at fainter flux densities. Our data also allow us to extend by a factor of ?5 downwards in flux density the source counts at ?33 and ?40 GHz obtained from the ERCSC. This allows us to substantially improve our control on the contribution of unresolved extragalactic sources to the power spectrum of small-scale fluctuations in cosmic microwave background maps.

Bonavera, Laura; Massardi, Marcella; Bonaldi, Anna; González-Nuevo, Joaquin; de Zotti, Gianfranco; Ekers, Ronald D.

2011-09-01

260

Heating by Catalytic Gas Infrared Rays  

Microsoft Academic Search

Infrared (IR) is a form of electromagnetic radiation that has a wavelength slightly longer than the color red in the visible light spectrum. Infrared radiation is created when objects are heated at temperatures not quite high enough to make them glow. You can detect infrared radiation by the heating effect it has on your skin.Infrared heating systems rely upon the

Mohammed Awwad Al-Dabbas

2011-01-01

261

Adaptive Optics Imaging Survey of Luminous Infrared Galaxies  

SciTech Connect

We present high resolution imaging observations of a sample of previously unidentified far-infrared galaxies at z < 0.3. The objects were selected by cross-correlating the IRAS Faint Source Catalog with the VLA FIRST catalog and the HST Guide Star Catalog to allow for adaptive optics observations. We found two new ULIGs (with L{sub FIR} {ge} 10{sup 12} L{sub {circle_dot}}) and 19 new LIGs (with L{sub FIR} {ge} 10{sup 11} L{sub {circle_dot}}). Twenty of the galaxies in the sample were imaged with either the Lick or Keck adaptive optics systems in H or K{prime}. Galaxy morphologies were determined using the two dimensional fitting program GALFIT and the residuals examined to look for interesting structure. The morphologies reveal that at least 30% are involved in tidal interactions, with 20% being clear mergers. An additional 50% show signs of possible interaction. Line ratios were used to determine powering mechanism; of the 17 objects in the sample showing clear emission lines--four are active galactic nuclei and seven are starburst galaxies. The rest exhibit a combination of both phenomena.

Laag, E A; Canalizo, G; van Breugel, W; Gates, E L; de Vries, W; Stanford, S A

2006-03-13

262

Infrared viewing apparatus  

SciTech Connect

An apparatus known as a common module for converting a thermal scene into a visible image. The apparatus comprises an infrared objective, a pivotal mirror which can be pivoted back and forth about an axis, an infrared detection array comprising a plurality of detectors, and a linear display array which is connected to the infrared detection array via an amplifier arrangement. The radiation emitted by the display array is imaged in a plane of observation, preferably via the back of the pivotal mirror and via at least one diverting mirror. For omnidirectional viewing in the horizontal and the vertical direction the infrared objective, the pivotal mirror, the detector array and the display array are combined to form a constructional unit, which is arranged to be pivotable about a horizontal and about a vertical axis. Between the diverting mirror and the eyepiece an erecting prism is arranged. The erecting prism is rotated in conformity with the rotation of the constructional unit.

Christiansen, H.; Schnieder, H.

1984-10-02

263

THE AROMATIC FEATURES IN VERY FAINT DWARF GALAXIES  

SciTech Connect

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.

Wu Ronin; Hogg, David W.; Moustakas, John [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)

2011-04-01

264

Application of infrared thermal imaging in blade system temperature monitoring  

Microsoft Academic Search

All objects emit infrared radiation at differing levels, depending on their temperature. Infrared thermal imaging is the technique of producing an image from infrared radiation. This thermal image represents two-dimensional distribution of the infrared radiation emitted by object displaying the object's temperatures. High performance computing data centres deploy high-density blade servers that have high power and cooling requirements. Thermal management

Darko Kolaric; Tomislav Lipic; Ivan Grubisic; Luko Gjenero; Karolj Skala

2011-01-01

265

The enigmatic young object: Walker 90/V590 Monocerotis  

NASA Astrophysics Data System (ADS)

Aims: We assess the evolutionary status of the intriguing object Walker 90/V590 Mon, which is located about 20 arcmin northwest of the Cone Nebula near the center of the open cluster NGC 2264. This object, according to its most recent optical spectral type determination (B7), which we confirmed, is at least 3 mag too faint in V for the cluster distance, but it shows the classical signs of a young pre-main sequence object, such as highly variable H? emission, Mg II emission, IR excess, UV continuum, and optical variability. Methods: We analyzed a collection of archival and original data on Walker 90, covering 45 years including photometry, imaging, and spectroscopic data ranging from ultraviolet to near-infrared wavelengths. Results: According to star formation processes, it is expected that, as this object clears its primordial surroundings, it should become optically brighter, show a weakening of its IR excess and present decreasing line emissions. This behavior is supported by our observations and analysis, but timescales are expected to be longer than the one observed here. Based on photometric data secured in 2007, we find Walker 90 at its brightest recorded optical magnitude (overline{12.47} ± 0.06). We document an evolution in spectral type over the past five decades (from A2/A3 to currently B7 and as early as B4), along with a decrease in the near-infrared K fluxes. From near-infrared VISIR images secured in 2004, Walker 90 appears as a point source placing an upper limit of < 0.1 arcsec for its diameter. Evidence of turbulent inflows is found in rapidly changing inverse P-Cygni profiles in the lower Balmer lines, with a broadening of ±400 km s-1 in H? and a redshifted component in H? with a terminal velocity of 600 km s-1. The measured steep UV continuum fluxes (mimicking a star as early as B4), added to a tentative identification of N V emission, suggest a strong non-photospheric component, typically of fluxes arising from a thermally inhomogeneous accretion disk. We detect a well defined 2200 Å bump, indicative of dense material in the line-of-sight. We conclude that many observational features are explained if W90 is a flared disk system, surrounded by an inclined optically thick accretion disk. Based on observations made with ESO Telescopes at Paranal Observatory under programme ID 075.C-0528(A). Tables 1-5 are only available in electronic form at http:/www.aanda.org

Pérez, M. R.; McCollum, B.; van den Ancker, M. E.; Joner, M. D.

2008-08-01

266

Exozodiacal discs with ALADDIN: how faint can we detect them?  

NASA Astrophysics Data System (ADS)

In this paper, we describe the expected performance of ALADDIN, a nulling interferometer project optimised for operation at Dome C. After reviewing the main atmospheric parameters pertaining to infrared interferometry on the high Antarctic plateau, we shortly describe the ALADDIN instrument and compute its estimated performance in terms of the smallest exozodiacal dust disc density that can be detected. Our estimations are based on a thorough end-to-end software simulator previously developed for the GENIE nulling interferometer project at VLTI. We then propose a possible mission scenario, where the southern target stars of future exo-Earth characterisation missions can be surveyed for the presence of bright exozodiacal discs (>50 zodi) within one winter-over at Concordia.

Absil, O.; Coudé du Foresto, V.; Barillot, M.; Daudigeos, X.; Defrère, D.; den Hartog, R.; di Folco, E.; Surdej, J.

267

Orbital Dynamics and the Structure of Faint Dusty Rings  

Microsoft Academic Search

The orbital perturbations that act on objects circling a planet vary in strength depending on the sizes of both the particle and its orbit. We examine three cases that are difficult to treat with the standard tools of celestial mechanics: (i) large distant satellites, (ii) small objects on distant orbits, and (iii) tiny particles orbiting near a planet. The dominant

Douglas Peary Hamilton

1994-01-01

268

3D: The next generation near-infrared imaging spectrometer.  

NASA Astrophysics Data System (ADS)

The new MPE near infrared imaging spectrometer 3D represents a new generation of astronomical instrumentation. It is based on a 256^2^ NICMOS-3 Rockwell array and can simultaneously obtain 256 H- or K-band spectra at R=1100 or 2100 from a square 16x16 pixel field on the sky. Typical pixel scales are 0.3"/pixel or 0.5"/pixel. 3D is a combination of a novel image slicer and a liquid nitrogen cooled long slit spectrometer. It includes high definition on-axis lens optics, a high efficiency directly ruled KRS-5 grism as well as a cold closed-loop piezo-driven tilt mirror allowing full spectral sampling. The instrument efficiency including detector is 15%. Combining the advantages of imaging and spectroscopy increases the observing efficiency on key astronomical objects (e.g. galactic nuclei) by such a large factor over existing grating or Fabry-Perot spectrometers that subarcsecond near-IR spectroscopy of faint Seyferts, starbursts, quasars, or distant galaxy clusters becomes feasible for the first time with 4m-class telescopes. As a portable instrument 3D has already been successfully deployed on several 2 and 4m-class telescopes.

Weitzel, L.; Krabbe, A.; Kroker, H.; Thatte, N.; Tacconi-Garman, L. E.; Cameron, M.; Genzel, R.

1996-11-01

269

Chandra X-ray Observations of the X-ray Faint Elliptical Galaxy NGC 4697  

Microsoft Academic Search

(abridged) A Chandra ACIS S3 observation of the X-ray faint elliptical galaxy\\u000aNGC 4697 resolves much of the X-ray emission (61% of the counts from within one\\u000aeffective radius) into 90 point sources, of which ~80 are low mass X-ray\\u000abinaries (LMXBs) associated with this galaxy. The dominance of LMXBs indicates\\u000athat X-ray faint early-type galaxies have lost much of

Craig L. Sarazin; Jimmy A. Irwin; Joel N. Bregman

2001-01-01

270

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

NASA Astrophysics Data System (ADS)

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.

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

271

On the nature of faint low surface brightness galaxies in the Coma cluster  

NASA Astrophysics Data System (ADS)

Context: This project is the continuation of our study of faint Low Surface Brightness Galaxies (fLSBs) in one of the densest nearby (z = 0.023) galaxy regions known, the Coma cluster. Aims: Our goal is to improve our understanding of the nature of these objects by comparing the broad band spectral energy distribution with population synthesis models, in order to infer ages, dust extinction and spectral characteristics. Methods: The data were obtained with the MEGACAM and CFH12K cameras at the CFHT. We used the resulting photometry in 5 broad band filters (u*, B, V, R, and I) that included new u*-band data to fit spectral models. With these spectral fits we inferred a cluster membership criterium, as well as the ages, dust extinctions, and photometric types of these fLSBs. Results: We show that about half of the Coma cluster fLSBs have a spectral energy distribution well represented in our template library (best fit fLSBs, BF) while the other half present a flux deficit at ultraviolet wavelengths (moderately good fit fLSBs, MGF). Among the BF fLSBs, ~80% are probably part of the Coma cluster based on their spectral energy distribution. BF fLSBs are relatively young (younger than 2.3 Gyr for 90% of the sample) non-starburst objects. The later their type, the younger the fLSBs are. A significant part of the BF fLSBs are quite dusty objects (1/3 have AV greater than 1.5). BF fLSBs are low stellar mass objects (the later their type the less massive they are), with stellar masses comparable to globular clusters for the faintest ones. Their characteristics are partly correlated with infall directions, confirming the disruptive origin for at least part of them. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institute National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

Adami, C.; Pelló, R.; Ulmer, M. P.; Cuillandre, J. C.; Durret, F.; Mazure, A.; Picat, J. P.; Scheidegger, R.

2009-02-01

272

Infrared Detectors.  

National Technical Information Service (NTIS)

The bibliography contains unclassified and unlimited citations on Infrared Detectors. These citations are studies and analyses pertaining to detection techniques, equipment, refrigeration systems, instrumentation, sensitivity, reliability, design, measure...

1974-01-01

273

FIRST-2MASS RED QUASARS: TRANSITIONAL OBJECTS EMERGING FROM THE DUST  

SciTech Connect

We present a sample of 120 dust-reddened quasars identified by matching radio sources detected at 1.4 GHz in the Faint Images of the Radio Sky at Twenty Centimeters survey with the near-infrared Two Micron All Sky Survey catalog and color-selecting red sources. Optical and/or near-infrared spectroscopy provide broad wavelength sampling of their spectral energy distributions that we use to determine their reddening, characterized by E(B - V). We demonstrate that the reddening in these quasars is best described by Small-Magellanic-Cloud-like dust. This sample spans a wide range in redshift and reddening (0.1 {approx}< z {approx}< 3, 0.1 {approx}< E(B - V) {approx}< 1.5), which we use to investigate the possible correlation of luminosity with reddening. At every redshift, dust-reddened quasars are intrinsically the most luminous quasars. We interpret this result in the context of merger-driven quasar/galaxy co-evolution where these reddened quasars are revealing an emergent phase during which the heavily obscured quasar is shedding its cocoon of dust prior to becoming a 'normal' blue quasar. When correcting for extinction, we find that, depending on how the parent population is defined, these red quasars make up {approx}< 15%-20% of the luminous quasar population. We estimate, based on the fraction of objects in this phase, that its duration is 15%-20% as long as the unobscured, blue quasar phase.

Glikman, Eilat [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Urrutia, Tanya [Leibniz Institut fuer Astrophysik, An der Sternwarte 16, D-14482 Potsdam (Germany); Lacy, Mark [National Radio Astronomy Observatory, Charlottesville, VA (United States); Djorgovski, S. George; Mahabal, Ashish [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); Petitjean, Patrick [Institut d'Astrophysique de Paris, UMR7095 CNRS, Universite Pierre et Marie Curie, 98 bis bd Arago, F-75014 Paris (France); Ge, Jian [Astronomy Department, University of Florida, 211 Bryant Space Science Center, P.O. Box 112055, Gainesville, FL 32611 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); York, Donald G., E-mail: eilat.glikman@yale.edu [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

2012-09-20

274

EROs found behind lensing clusters. I. Stellar populations and dust properties of optical dropout EROs and comparison with related objects  

Microsoft Academic Search

Context: On the nature, redshift, stellar populations and dust properties of optically faint or non-detected extremely red objects. Aims: Determining the nature, redshift, stellar populations and dust properties of optically faint or non-detected, extremely red objects (ERO) found from our survey of the lensing clusters A1835 and AC114 (Richard et al. 2006, A&A, 456, 861). Comparison with properties of related

D. Schaerer; A. Hempel; E. Egami; R. Pelló; J. Richard; J.-F. Le Borgne; J.-P. Kneib; M. Wise; F. Boone

2007-01-01

275

A Catalog of Faint Interacting Galaxies in Pairs and Groups: Erratum  

NASA Astrophysics Data System (ADS)

In the paper "A Catalog of Faint Interacting Galaxies in Pairs and Groups" by Duilia F. de Mello, Leopoldo Infante, and Felipe Menanteau (ApJS, 108, 99 [1997]), a correction should be made to Table 2. No sextet was found in this survey. The total number of groups is 29.

de Mello, Duilia F.; Infante, Leopoldo; Menanteau, Felipe

1997-08-01

276

Study on the faint star extraction technology with MEMS gyro aided APS star tracker  

NASA Astrophysics Data System (ADS)

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.

Xing, Fei; Zhao, Borui; Sun, Ting; Xu, Wei; You, Zheng

2013-08-01

277

The early faint sun paradox: Organic shielding of ultraviolet-labile greenhouse gases  

Microsoft Academic Search

Atmospheric mixing ratios of â¼10{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

C. Sagan; C. Chyba

1997-01-01

278

The FIRST survey: Faint Images of the Radio Sky at Twenty centimeters  

Microsoft Academic Search

The FIRST survey to produce Faint Images of the Radio Sky at Twenty centimeters is now underway using the NRAO Very Large Array. We describe here the scientific motivation for a large-area sky survey at radio frequencies which has a sensitivity and angular resolution comparable to the Palomar Observatory Sky Survey, and we recount the history that led to the

Robert H. Becker; Richard L. White; David J. Helfand

1995-01-01

279

New faint planetary nebulae from the DSS and SDSS  

NASA Astrophysics Data System (ADS)

Having surveyed ~ 10% of the sky, we have identified more than 130 PN candidates by surveying multicolour Digitized Sky Survey (DSS), Sloan Digitized Sky Survey (SDSS), and combined [O III], H? and [S II] images. In a first imaging and spectroscopy campaign, 51 objects were identified as true and probable PNe. This work presents an additional 17 probable or possible PNe identified since that study. The majority of these candidates are situated at Galactic latitudes |b| > 5^, with the exception of seven objects located closer to the Galactic plane. Using the techniques described here that do not require any new survey data, we anticipate that many more PNe are waiting to be found, perhaps as many as 90.

Kronberger, Matthias; Jacoby, George H.; Ciardullo, Robin; Crisp, Richard D.; De Marco, Orsola; Douchin, Dimitri; Frew, David J.; Harmer, Dianne; Howell, Mike; Howell, Steve B.; Parker, Quentin A.; Patchick, Dana; Rector, Travis; Riddle, Dave; Teutsch, Philipp

2012-08-01

280

Infrared Vidicon Development.  

National Technical Information Service (NTIS)

The objective of the program was to demonstrate the feasibility of using metal-silicon Schottky barrier diode arrays in the retina of an infrared vidicon. Such arrays promise to be substantially more uniform in this application than other available approa...

J. P. Spratt

1974-01-01

281

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

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.

Marchesini, Danilo [Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Stefanon, Mauro [Observatori Astronomic Universitat de Valencia, C/Catedratico Agustin Escardino Benlloch, 7, 46980, Valencia (Spain); Brammer, Gabriel B. [European Southern Observatory (ESO), Santiago (Chile); Whitaker, Katherine E. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States)

2012-04-01

282

Infrared and Optical Observations of GRB 030115 and its ExtremelyRed Host Galaxy: Implications for Dark Bursts  

SciTech Connect

We present near-infrared (NIR) and optical observations ofthe afterglow of GRB 030115. Discovered in aninfrared search at Kitt Peak5 hr after the burst trigger, this afterglow is the faintest everobserved in the R band at such an early epoch and exhibits very redcolors, with R-K~;6. The optical magnitude of the afterglow of GRB 030115is fainter than many upper limits for other bursts, suggesting thatwithout early NIR observations it would have been classified as a "dark"burst. Both the color and optical magnitude of the afterglow are likelydue to dust extinction atmoderate redshift z>2 and indicate that atleast some optical afterglows are very faint due to dust along the lineof sight.Multicolor Hubble Space Telescope observations were also takenof the host galaxy and the surrounding field. Photometric redshifts implythat the host and a substantial number of faint galaxies in the field areat z 2:5. The overdensity of galaxies is sufficiently great that GRB030115 may have occurred in a rich high-redshift cluster. The host galaxyshows extremely red colors (R-K = 5) and is the first GRB host to beclassified as an extremely red object (ERO). Some of the galaxiessurrounding the host also show very red colors, while the majority of theclusterare much bluer, indicating ongoing unobscured star formation. Asit is thought that much of high-redshift starformation occurs in highlyobscured environments, it may well be that GRB 030115 represents atransition object, between the relatively unobscured afterglows seen todate and a population of objects that are very heavily extinguished, evenin the NIR.

Levan, Andrew; Fruchter, Andrew; Rhoads, James; Mobasher, Bahram; Tanvir, Nial; Gorosabel, Javier; Rol, Evert; Kouveliotou, Chryssa; Dell'Antonio, Ian; Merrill, Michael; Bergeron, Eddie; Castro Ceron, JosMar a; Masetti, Nicola; Vreeswijk, Paul; Antonelli, Angelo; Bersier,David; Castro-Tirado, Alberto; Fynbo, Johan; Garnavich, Peter; Holland,Stephen; Hjorth, Jens; Nugent, Peter; Pian, Elena; Smette, Alain; Thomsen, Bjarne; Thorsett, Stephen E.; Wijers, Ralph

2006-05-01

283

Infrared Astronomy  

NASA Astrophysics Data System (ADS)

List of participants; Preface; 1. Star formation Francesco Palla; 2. Last stages of stellar evolution Stuart R. Pottasch; 3. The Milky Way galaxy and the galactic centre Gerard Gilmore; 4. Galaxies in the infrared Charles M. Telesco; 5. Cosmology Robert D. Joseph; 6. G25.2+0.2, a new ring nebula around a luminous blue star: case study for the importance of IR observations Eric E. Becklin; 7. Two colloquia on cosmic dust N. Chandra Wickramasingle; 8. Infrared instrumentation Ian S. McLean; 9. Infrared astronomy with satellites Thijs de Graauw.

Mampaso, A.; Prieto, M.; Sánchez, F.

2004-01-01

284

A Search for Faint Planetary Nebulae Using the DSS  

NASA Astrophysics Data System (ADS)

A group of amateur astronomers (Deep Sky Hunters) has identified ˜50 candidate PNe by visually searching the 1st and 2nd generation red Digital Sky Survey images. Candidate PNe are then observed in H? with larger telescopes, primarily the WIYN 3.5-m on Kitt Peak, and the 1.2-m and 1.5-m at Haute-Provence Observatory (OHP). Thus far, ˜20 new PNe have been found. These objects have a strong tendency to have low surface brightness and to be relatively round.

Jacoby, G. H.; Kronberger, M.; Patchick, D.; Teutsch, P.; Saloranta, J.; Acker, A.; Frew, D.

2007-06-01

285

Why Infrared?  

ERIC Educational Resources Information Center

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)

Harris, J. R.

1973-01-01

286

Optical Selection of Faint Active Galactic Nuclei in the COSMOS Field  

NASA Astrophysics Data System (ADS)

We outline a strategy to select faint (iAB<24.5) type 1 active galactic nucleus (AGN) candidates down to the Seyfert/QSO boundary for spectroscopic targeting in the COSMOS field. Our selection process picks candidates by their nonstellar colors in uBVRizK broadband photometry from the Subaru and CFH Telescopes and morphological properties extracted from Hubble Space Telescope (HST) ACS i-band data. Although the COSMOS field has been used extensively to survey the faint galaxy population out to z~6, AGN optical color selection has not been applied to so faint a level in such a large continuous part of the sky. Hot stars are known to be the dominant contaminant for bright AGN candidate selection at z<2, but we anticipate the highest color contamination rate at all redshifts to be from faint starburst and compact galaxies. Morphological selection via the Gini Coefficient separates most potential AGNs from these faint blue galaxies. Recent models of the quasar luminosity function (QLF) from Hopkins et al. are used to estimate quasar surface densities, and a recent study of stellar populations in the COSMOS field is applied to infer stellar surface densities and contamination. We use 292 spectroscopically confirmed type 1 broad-line AGN and quasar templates to predict AGN colors as a function of redshift, and then contrast those predictions with the colors of known contaminating populations. Since the number of galaxy contaminants cannot be reliably identified with respect to stellar and predicted QLF numbers, the completeness and efficiency of the selection cannot be calculated before gathering confirming spectroscopic observations. Instead we offer an upper limit estimate to selection efficiency (about 50% for low-z and 20%-40% for intermediate-z and high-z) as well as the completeness and efficiency with respect to an X-ray point source population (from the COSMOS AGN Survey), in the range 20%-50%. The motivation of this study and subsequent spectroscopic follow-up is to populate and refine the faint end of the QLF, at both low and high redshifts, where the population of type 1 AGNs is presently not well known. The anticipated AGN observations will add to the ~300 already known AGNs in the COSMOS field, making COSMOS a densely packed field of quasars to be used to understand supermassive black holes and probe the structure of the intergalactic medium in the intervening volume.

Casey, C. M.; Impey, C. D.; Trump, J. R.; Gabor, J.; Abraham, R. G.; Capak, P.; Scoville, N. Z.; Brusa, M.; Schinnerer, E.

2008-07-01

287

THE FAINT END OF THE QUASAR LUMINOSITY FUNCTION AT z {approx} 4  

SciTech Connect

The evolution of the quasar luminosity function (QLF) is one of the basic cosmological measures providing insight into structure formation and mass assembly in the universe. We have conducted a spectroscopic survey to find faint quasars (-26.0 < M{sub 1450} < -22.0) at redshifts z = 3.8-5.2 in order to measure the faint end of the QLF at these early times. Using available optical imaging data from portions of the NOAO Deep Wide-Field Survey and the Deep Lens Survey, we have color-selected quasar candidates in a total area of 3.76 deg{sup 2}. Thirty candidates have R <= 23 mag. We conducted spectroscopic follow-up for 28 of our candidates and found 23 QSOs, 21 of which are reported here for the first time, in the 3.74 < z < 5.06 redshift range. We estimate our survey completeness through detailed Monte Carlo simulations and derive the first measurement of the density of quasars in this magnitude and redshift interval. We find that the binned luminosity function (LF) is somewhat affected by the K-correction used to compute the rest-frame absolute magnitude at 1450 A. Considering only our R <= 23 sample, the best-fit single power law (PHI {proportional_to} L {sup beta}) gives a faint-end slope beta = -1.6 +- 0.2. If we consider our larger, but highly incomplete sample going 1 mag fainter, we measure a steeper faint-end slope -2 < beta < -2.5. In all cases, we consistently find faint-end slopes that are steeper than expected based on measurements at z {approx} 3. We combine our sample with bright quasars from the Sloan Digital Sky Survey to derive parameters for a double-power-law LF. Our best fit finds a bright-end slope, alpha = -2.4 +- 0.2, and faint-end slope, beta = -2.3 +- 0.2, without a well-constrained break luminosity. This is effectively a single power law, with beta = -2.7 +- 0.1. We use these results to place limits on the amount of ultraviolet radiation produced by quasars and find that quasars are able to ionize the intergalactic medium at these redshifts.

Glikman, Eilat; Bogosavljevic, Milan; Djorgovski, S. G.; Mahabal, Ashish [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Dey, Arjun; Jannuzi, Buell T., E-mail: eilat.glikman@yale.ed [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States)

2010-02-20

288

CCD time-resolved photometry of faint cataclysmic variables. II  

SciTech Connect

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.

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

1989-10-01

289

UBVRI photometry of faint field stars (Skiff, 2007)  

NASA Astrophysics Data System (ADS)

This file, originally prepared for the needs of the Lowell Observatory Near-Earth Object Search (LONEOS), contains a rough working collection of Johnson-Cousins UBVRI photometry assembled mainly from the published literature or from publicly available datasets. The V-R and V-I colors are all on the Cousins system. Most of the stars are fainter than V=10.0; the median magnitude is V=13.9, and significant numbers of stars are listed below 20mag. Besides several large surveys, several hundred small sequences in the regions of variable stars, star clusters, galaxies hosting supernovae, quasars, etc were built by determining coordinates for the sequence stars using the published finder charts. At minimum the data include V magnitudes and at least one ordinary photometric color, most commonly B-V. The data were collected for use in determining approximate photometric zero-points in wide-field imaging, with external accuracy of 0.05 mag or better. Though each dataset was vetted for consistency in magnitude and colors, neither high accuracy nor high precision is guaranteed. Obvious variable stars were omitted, but some unknown variables are inevitably included. In any given field, it is advisable use all the available stars for calibration rather than a single comparison. Several large datasets are included. The Guide Star Photometric Catalogue (GSPC, Lasker et al 1988, Cat. II/143) provides BV sequences near the centers of all the Schmidt sky survey plates. At high latitudes in the southern sky, additional data on the 5-degree Schmidt grid were obtained by Platais et al (1998, Cat. I/277) that extend the GSPC sequences to V=~16. More southern fields were observed by Demers et al (1993A&AS...99..437D and 1993A&AS...99..461D); coordinates for these stars have been determined for the first time. Nearly a thousand high-quality sequences in the northern sky have been observed by Henden, partly published in relation to work on cataclysmic variables (e.g. Cat. J/PASP/107/324) and symbiotic stars (e.g. Cat. J/A+A/143/343). Additional Henden sequences have been adopted from the files cited below at the AAVSO ftp site. These large sequences were trimmed to include only a few stars per magnitude interval, and also to omit crowded stars (no significant companions closer than 15" radius). The star coordinates are mainly from early versions of the GSC or USNO series. As such they are given to 1" precision, and in some cases small systematic errors and (now) proper motion mean their accuracy is in the 1" to 5" range. Thus for automated linkage to CCD frames, some modest search radius should be adopted to match with the catalogue. Because the file was originally intended for private use, bibliographic references were not included except in a very few instances. Usually it is straightforward to recover the source paper by inspection of the SIMBAD bibliography for specific objects. Problematic cases can be directed to the compiler (Brian Skiff). (1 data file).

Skiff, B. A.

2007-03-01

290

THE FAINT END OF THE QUASAR LUMINOSITY FUNCTION AT z {approx} 4: IMPLICATIONS FOR IONIZATION OF THE INTERGALACTIC MEDIUM AND COSMIC DOWNSIZING  

SciTech Connect

We present an updated determination of the z {approx} 4 QSO luminosity function (QLF), improving the quality of the determination of the faint end of the QLF presented by Glikman et al. (2010). We have observed an additional 43 candidates from our survey sample, yielding one additional QSO at z = 4.23 and increasing the completeness of our spectroscopic follow-up to 48% for candidates brighter than R = 24 over our survey area of 3.76 deg{sup 2}. We study the effect of using K-corrections to compute the rest-frame absolute magnitude at 1450 A compared with measuring M{sub 1450} directly from the object spectra. We find a luminosity-dependent bias: template-based K-corrections overestimate the luminosity of low-luminosity QSOs, likely due to their reliance on templates derived from higher luminosity QSOs. Combining our sample with bright quasars from the Sloan Digital Sky Survey and using spectrum-based M{sub 1450} for all the quasars, we fit a double power law to the binned QLF. Our best fit has a bright-end slope, {alpha} = 3.3 {+-} 0.2, and faint-end slope, {beta} = 1.6{sup +0.8}{sub -0.6}. Our new data revise the faint-end slope of the QLF down to flatter values similar to those measured at z {approx} 3. The break luminosity, though poorly constrained, is at M* = -24.1{sup +0.7}{sub -1.9}, approximately 1-1.5 mag fainter than at z {approx} 3. This QLF implies that QSOs account for about half the radiation needed to ionize the intergalactic medium at these redshifts.

Glikman, Eilat; Lee, Kyoung-Soo [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Djorgovski, S. G. [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Dey, Arjun; Jannuzi, Buell T., E-mail: eilat.glikman@yale.edu [National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ 85719 (United States)

2011-02-20

291

A faint galaxy redshift survey behind massive clusters  

SciTech Connect

This thesis is concerned with the gravitational lensing effect by massive galaxy clusters. We have explored a new technique for measuring galaxy masses and for detecting high-z galaxies by their optical colors. A redshift survey has been obtained at the Keck for a magnitude limited sample of objects (I<23) behind three clusters, A1689, A2390, and A2218 within a radius of 0.5M pc. For each cluster we see both a clear trend of increasing flux and redshift towards the center. This behavior is the result of image magnifications, such that at fixed redshift one sees further down the luminosity function. The gradient of this magnification is, unlike measurements of image distortion, sensitive to the mass profile, and found to depart strongly from a pure isothermal halo. We have found that V RI color selection can be used effectively as a discriminant for finding high-z galaxies behind clusters and present five 4.1 < z < 5.1 spectra which are of very high quality due to their high mean magnification of {approximately}20, showing strong, visibly-saturated interstellar metal lines in some cases. We have also investigated the radio ring lens PKS 1830-211, locating the source and multiple images and detected molecular absorption at mm wavelengths. Broad molecular absorption of width 1/40kms is found toward the southwest component only, where surprisingly it does not reach the base of the continuum, which implies incomplete coverage of the SW component by molecular gas, despite the small projected size of the source, less than 1/8h pc at the absorption redshift.

Frye, Brenda

1999-12-01

292

the Metal Abundance of X-ray Faint Early-Type Galaxies: Effects of Dilution?  

NASA Astrophysics Data System (ADS)

The metallicity of hot gas in E/S0 galaxies is known to vary widely, in the sense that galaxies with only small amounts of hot gas often have very low hot gas metallicities. One solution is that what little hot gas X-ray faint systems have has been diluted by pristine hydrogen gas in the vicinity of the galaxy. There is a growing body of evidence suggesting that some early-type galaxies harbor sizable large-scale HI halos, presumably left over from the epoch of galaxy formation. If this pristine HI is accreted, the existing hot gas in the galaxy will be diluted. We propose to test this by measuring the metallicities of a sample of X-ray faint galaxies with a range of HI-to-hot gas ratios. If the dilution hypothesis is correct, galaxies with more HI will have lower hot gas metallicities.

Su, Yuanyuan

2010-10-01

293

A Catalog of Faint Interacting Galaxies in Pairs and Groups. II.  

NASA Astrophysics Data System (ADS)

We have completed the second part of an extensive survey of faint pairs and groups of galaxies in order to study galaxy evolution at intermediate redshifts. In this paper we present the second catalog of faint interacting galaxies of 49 equatorial fields taken with the Cerro Tololo Inter-American Observatory 4 m prime focus camera. The data set contains 11,297 galaxies within 19 < mR < 22, covering a total area of 2.63 deg2. We have found 1461 isolated pairs and 30 groups with separations 2" < theta < 6". Our results confirm the excess of galaxies in pairs and groups found in the first catalog (Infante, de Mello, & Menanteau 1996; de Mello, Infante, & Menanteau 1997). The two catalogs together cover an area of 4.86 deg2 in the sky.

de Mello, Duilia F.; Infante, Leopoldo; Menanteau, Felipe; Vieira, Gladys

1997-06-01

294

The Taiwan ECDFS Near-Infrared Survey: Ultra-deep J and KS Imaging in the Extended Chandra Deep Field-South  

NASA Astrophysics Data System (ADS)

We present ultra-deep J and KS imaging observations covering a 30' × 30' area of the Extended Chandra Deep Field-South (ECDFS) carried out by our Taiwan ECDFS Near-Infrared Survey (TENIS). The median 5? limiting magnitudes for all detected objects in the ECDFS reach 24.5 and 23.9 mag (AB) for J and KS , respectively. In the inner 400 arcmin2 region where the sensitivity is more uniform, objects as faint as 25.6 and 25.0 mag are detected at 5?. Thus, this is by far the deepest J and KS data sets available for the ECDFS. To combine TENIS with the Spitzer IRAC data for obtaining better spectral energy distributions of high-redshift objects, we developed a novel deconvolution technique (IRACLEAN) to accurately estimate the IRAC fluxes. IRACLEAN can minimize the effect of blending in the IRAC images caused by the large point-spread functions and reduce the confusion noise. We applied IRACLEAN to the images from the Spitzer IRAC/MUSYC Public Legacy in the ECDFS survey (SIMPLE) and generated a J+KS -selected multi-wavelength catalog including the photometry of both the TENIS near-infrared and the SIMPLE IRAC data. We publicly release the data products derived from this work, including the J and KS images and the J+KS -selected multi-wavelength catalog.

Hsieh, Bau-Ching; Wang, Wei-Hao; Hsieh, Chih-Chiang; Lin, Lihwai; Yan, Haojing; Lim, Jeremy; Ho, Paul T. P.

2012-12-01

295

Faint recombination lines in Galactic PNe with a [WC] nucleus  

NASA Astrophysics Data System (ADS)

Aims: We present spatially resolved high-resolution spectrophotometric data for the planetary nebulae PB 8, NGC 2867, and PB 6. We have analyzed two knots in NGC 2867 and PB 6 and one in PB 8. The three nebulae are ionized by [WC] type nuclei: early [WO] for PB 6 and NGC 2867 and [WC 5-6] in the case of PB 8. Our aim is to study the behavior of the abundance discrepancy problem (ADF) in this type of planetary nebula. Methods: We measured a large number of optical recombination (ORL) and collisionally excited lines (CEL), from different ionization stages (many more than in any previous work), thus, we were able to derive physical conditions from many different diagnostic procedures. We determined ionic abundances from the available collisionally excited and recombination lines. Based on both sets of ionic abundances, we derived total chemical abundances in the nebulae using suitable ionization correction factors. Results: From CELs, we have found abundances typical of Galactic disk planetary nebulae. Moderate ADF(O++) were found for PB 8 (2.57) and NGC 2867 (1.63). For NGC 2867, abundances from ORLs are higher but still consistent with Galactic disk planetary nebulae. On the contrary, PB 8 presents a very high O/H ratio from ORLs. A high C/O was obtained from ORLs for NGC 2867; this ratio is similar to C/O obtained from CELs and with the chemical composition of the wind of the central star, indicating that there was no further C-enrichment in the star, relative to O, after the nebular material ejection. On the contrary, we found C/O<1 in PB 8. Interestingly, we obtain (C/O)ORLs/(C/O)CELs < 1 in PB 8 and NGC 2867; this added to the similarity between the heliocentric velocities measured in [O iii] and O ii lines for our three objects argue against the presence of H-deficient metal-rich knots coming from a late thermal pulse event. Based on data obtained at Las Campanas Observatory, Carnegie Institution. Table 3 is only available in electronic form at http://www.aanda.org

García-Rojas, J.; Peña, M.; Peimbert, A.

2009-03-01

296

Swallowed Object  

MedlinePLUS

... toys, coins, safety pins, buttons, bones, wood, glass, magnets, batteries or other foreign objects. Problems may arise ... toys, coins, safety pins, buttons, bones, wood, glass, magnets, batteries or other foreign objects. These objects often ...

297

Can thin cirrus clouds in the tropics provide a solution to the faint young Sun paradox?  

Microsoft Academic Search

In this paper we present radiative-convective simulations to test the idea that tropical cirrus clouds, acting as a negative feedback on climate, can provide a solution to the faint young Sun paradox. We find that global mean surface temperatures above freezing can indeed be found for luminosities larger than about 0.8 (corresponding to ?2.9 Ga and nearly complete tropical cirrus

Roberto Rondanelli; Richard S. Lindzen

2010-01-01

298

Increased phase synchronization and decreased cerebral autoregulation during fainting in the young  

PubMed Central

Vasovagal syncope may be due to a transient cerebral hypoperfusion that accompanies frequency entrainment between arterial pressure (AP) and cerebral blood flow velocity (CBFV). We hypothesized that cerebral autoregulation fails during fainting; a phase synchronization index (PhSI) between AP and CBFV was used as a nonlinear, nonstationary, time-dependent measurement of cerebral autoregulation. Twelve healthy control subjects and twelve subjects with a history of vasovagal syncope underwent 10-min tilt table testing with the continuous measurement of AP, CBFV, heart rate (HR), end-tidal CO2 (ETco2), and respiratory frequency. Time intervals were defined to compare physiologically equivalent periods in fainters and control subjects. A PhSI value of 0 corresponds to an absence of phase synchronization and efficient cerebral autoregulation, whereas a PhSI value of 1 corresponds to complete phase synchronization and inefficient cerebral autoregulation. During supine baseline conditions, both control and syncope groups demonstrated similar oscillatory changes in phase, with mean PhSI values of 0.58 ± 0.04 and 0.54 ± 0.02, respectively. Throughout tilt, control subjects demonstrated similar PhSI values compared with supine conditions. Approximately 2 min before fainting, syncopal subjects demonstrated a sharp decrease in PhSI (0.23 ± 0.06), representing efficient cerebral autoregulation. Immediately after this period, PhSI increased sharply, suggesting inefficient cerebral autoregulation, and remained elevated at the time of faint (0.92 ± 0.02) and during the early recovery period (0.79 ± 0.04) immediately after the return to the supine position. Our data demonstrate rapid, biphasic changes in cerebral autoregulation, which are temporally related to vasovagal syncope. Thus, a sudden period of highly efficient cerebral autoregulation precedes the virtual loss of autoregulation, which continued during and after the faint.

Ocon, Anthony J.; Kulesa, John; Clarke, Debbie; Taneja, Indu; Medow, Marvin S.

2009-01-01

299

Increased phase synchronization and decreased cerebral autoregulation during fainting in the young.  

PubMed

Vasovagal syncope may be due to a transient cerebral hypoperfusion that accompanies frequency entrainment between arterial pressure (AP) and cerebral blood flow velocity (CBFV). We hypothesized that cerebral autoregulation fails during fainting; a phase synchronization index (PhSI) between AP and CBFV was used as a nonlinear, nonstationary, time-dependent measurement of cerebral autoregulation. Twelve healthy control subjects and twelve subjects with a history of vasovagal syncope underwent 10-min tilt table testing with the continuous measurement of AP, CBFV, heart rate (HR), end-tidal CO2 (ETCO2), and respiratory frequency. Time intervals were defined to compare physiologically equivalent periods in fainters and control subjects. A PhSI value of 0 corresponds to an absence of phase synchronization and efficient cerebral autoregulation, whereas a PhSI value of 1 corresponds to complete phase synchronization and inefficient cerebral autoregulation. During supine baseline conditions, both control and syncope groups demonstrated similar oscillatory changes in phase, with mean PhSI values of 0.58+/-0.04 and 0.54+/-0.02, respectively. Throughout tilt, control subjects demonstrated similar PhSI values compared with supine conditions. Approximately 2 min before fainting, syncopal subjects demonstrated a sharp decrease in PhSI (0.23+/-0.06), representing efficient cerebral autoregulation. Immediately after this period, PhSI increased sharply, suggesting inefficient cerebral autoregulation, and remained elevated at the time of faint (0.92+/-0.02) and during the early recovery period (0.79+/-0.04) immediately after the return to the supine position. Our data demonstrate rapid, biphasic changes in cerebral autoregulation, which are temporally related to vasovagal syncope. Thus, a sudden period of highly efficient cerebral autoregulation precedes the virtual loss of autoregulation, which continued during and after the faint. PMID:19820196

Ocon, Anthony J; Kulesa, John; Clarke, Debbie; Taneja, Indu; Medow, Marvin S; Stewart, Julian M

2009-10-09

300

Identification of a faint X-ray source with the W Ursae Majoris star VW Cephei  

NASA Astrophysics Data System (ADS)

The NRL instrument aboard the HEAO 1 satellite has detected a faint X-ray source, which has been identified tentatively with the contact binary star (W UMa variable) VW Cephei. Its luminosity is between 3 x 10 to the 30th and 4 x 10 to the 31st ergs/sec (0.1-10 keV), and the results suggest some variation of the X-ray flux with phase.

Carroll, R. W.; Cruddace, R. G.; Friedman, H.; Byram, E. T.; Wood, K.; Meekins, J.; Yentis, D.; Share, G. H.; Chubb, T. A.

1980-01-01

301

Concordance models of reionization: implications for faint galaxies and escape fraction evolution  

NASA Astrophysics Data System (ADS)

Recent observations have constrained the galaxy ultraviolet (UV) luminosity function up to z˜ 10. However, these observations alone allow for a wide range of reionization scenarios due to uncertainties in the abundance of faint galaxies and the escape fraction of ionizing photons. We show that requiring continuity with post-reionization (z < 6) measurements, where the Ly? forest provides a complete probe of the cosmological emissivity of ionizing photons, significantly reduces the permitted parameter space. Models that are simultaneously consistent with the measured UV luminosity function, the Thomson optical depth to the microwave background and the Ly? forest data require either (1) extrapolation of the galaxy luminosity function down to very faint UV magnitudes Mlim˜-10, corresponding roughly to the UV background suppression scale; (2) an increase of the escape fraction by a factor ?10 from z= 4 (where the best fit is 4 per cent) to 9; or (3) more likely, a hybrid solution in which undetected galaxies contribute significantly and the escape fraction increases more modestly. Models in which star formation is strongly suppressed in low-mass, reionization-epoch haloes of mass up to Mh˜ 1010 M? (e.g. owing to a metallicity dependence) are only allowed for extreme assumptions for the redshift evolution of the escape fraction. However, variants of such models in which the suppression mass is reduced (e.g. assuming an earlier or higher metallicity floor) are in better agreement with the data. Interestingly, concordance scenarios satisfying the available data predict a consistent redshift of 50 per cent ionized fraction zreion(50 per cent) ˜ 10. On the other hand, the duration of reionization is sensitive to the relative contribution of bright versus faint galaxies, with scenarios dominated by faint galaxies predicting a more extended reionization event. Scenarios relying too heavily on high-redshift dwarfs are disfavoured by kinetic Sunyaev-Zeldovich measurements, which prefer a short reionization history.

Kuhlen, Michael; Faucher-Giguère, Claude-André

2012-06-01

302

Faint Radio Sources in the NOAO Bootes Field. VLBA Imaging And Optical Identifications  

SciTech Connect

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.

Wrobel, J.M.; /NRAO, Socorro; Taylor, Greg B.; /NRAO, Socorro /KIPAC, Menlo Park; Rector, T.A.; /NRAO, Socorro /Alaska U.; Myers, S.T.; /NRAO, Socorro; Fassnacht, C.D.; /UC, Davis

2005-06-13

303

Large Ground-Based Telescopes with High Order Adaptive Optics for Imaging Faint Objects and ExtraSolar Planets  

Microsoft Academic Search

\\u000a The new 6-8 m class ground based telescopes equiped with very high-resolution adaptive optics have the potential to detect\\u000a Jupiter-like planets around nearby stars. Direct detection will allow discoveries of planets, beyond the angular radius where\\u000a Doppler spectroscopy achieves maximum sensitivity. In addition, direct imaging (and spectroscopy) will allow confirmation\\u000a for those indirect detections which lie within 0.3–2 arcseconds in

M. Langlois; D. Sandler; D. McCarthy

1999-01-01

304

Nucleosynthesis in Hypernovae and Faint Supernovae and Abundance Patterns of Extremely Metal-Poor Stars  

NASA Astrophysics Data System (ADS)

With the Subaru telescope, we have been revealing several new properties of various types of supernovae (SNe). Here we report on the properties and nucleosynthesis of the two distinct new classes of massive SNe: 1) very energetic Hypernovae, whose kinetic energy (KE) is more than 10 times the KE of normal core-collapse SNe, and 2) very faint and low energy SNe (Faint SNe). These two new classes of SNe are likely to be "black-hole-forming" SNe with rotating or non-rotating black holes. Nucleosynthesis in Hypernovae is characterized by larger abundance ratios (Zn,Co,V,Ti)/Fe and smaller (Mn,Cr)/Fe than normal SNe, which can explain the observed trends of these ratios in extremely metal-poor (EMP) stars. Nucleosynthesis in Faint SNe is characterized by a large amount of fall-back, which explains the abundance pattern of the most Fe-poor stars. These comparisons suggest that black-hole-forming SNe made important contributions to the early Galactic (and cosmic) chemical evolution. We discuss how nucleosynthetic properties resulted from such unusual supernovae are connected with the unusual abundance patterns of extremely metal-poor stars. Such connections may provide important constraints on the properties of first stars.

Nomoto, K.

2012-08-01

305

FAINT COLLIMATED HERBIG-HARO JETS FROM VISIBLE STARS IN L1641  

SciTech Connect

A population of 11 faint, collimated jets has been discovered in the northern part of the L1641 cloud in the region of HH 1/2, HH 34, and the L1641-N cluster. These jets were missed in previous imaging surveys on account of their weak emission, and they were discovered only on deep exposures with the Subaru 8 m telescope. With these new faint jets, the number of HH flows within the area surveyed has doubled. This suggests that collimated jets from young stars may be more common than previously assumed. It is noteworthy that all of the jets are associated with optically visible stars with r magnitudes ranging from 13.8 to 22.0. The driving sources of jets in regions flooded by ultraviolet radiation from nearby OB stars are known to be excavated by photoionization, and in three cases remnant H{alpha} emission envelopes are found associated with the sources, although the more benign environment in the region observed here, about 10 pc distant from the Orion Nebula Cluster, makes the optical visibility of all these sources rather surprising. Such faint jets from visible stars represent either the final vestiges of the outflow phenomenon, or they are triggered by disturbances of the remnant disks, possibly initiated by the orbital evolution of binaries that spiral in to form close binaries. Among the known H{alpha} emission stars within the region surveyed, 8% are found to be associated with jets.

Reipurth, Bo; Aspin, Colin; Walawender, Josh [Institute for Astronomy, University of Hawaii at Manoa, 640 N. Aohoku Place, HI 96720 (United States); Bally, John [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309 (United States); Tobin, John J., E-mail: reipurth@ifa.hawaii.ed, E-mail: caa@ifa.hawaii.ed, E-mail: joshw@ifa.hawaii.ed, E-mail: John.Bally@colorado.ed, E-mail: jjtobin@umich.ed [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)

2010-09-15

306

On the sensitivity of closure phases to faint companions in optical long baseline interferometry  

NASA Astrophysics Data System (ADS)

Aims: We explore the sensitivity and completeness of long baseline interferometric observations for detecting unknown, faint companions around bright unresolved stars. Methods: We derive a linear expression for the closure phase signature of a faint companion in the high contrast regime (? 0.1), and provide a quantitative estimation of the detection efficiency for the currently offered four-telescope configurations at the Very Large Telescope Interferometer. The results are compared to the performances provided by linear and Y-shaped interferometric configurations in order to identify the ideal array. Results: We find that all configurations have a similar efficiency in discovering companions wider than 10 mas. Assuming a closure phase accuracy of 0.25deg that is typical of state-of-the-art instruments, we predict a median dynamic range of up to six magnitudes when stacking observations obtained at five different hour angles. Conclusions: Surveying bright stars to search for faint companions can be considered as an ideal filler programme for modern interferometric facilities because that places few constraints on the choice of the interferometric configuration.

Le Bouquin, J.-B.; Absil, O.

2012-05-01

307

Comment on "Clouds and the Faint Young Sun Paradox" by Goldblatt and Zahnle (2011)  

NASA Astrophysics Data System (ADS)

Goldblatt and Zahnle (2011) raise a number of issues related to the possibility that cirrus clouds can provide a solution to the faint young sun paradox. Here, we argue that: (1) climates having a lower than present mean surface temperature cannot be discarded as solutions to the faint young sun paradox, (2) the detrainment from deep convective clouds in the tropics is a well-established physical mechanism for the formation of high clouds that have a positive radiative forcing (even if the possible role of these clouds as a negative climate feedback remains controversial) and (3) even if some cloud properties are not mutually consistent with observations in radiative transfer parameterizations, the most relevant consistency (for the purpose of hypothesis testing) is with observations of the cloud radiative forcing. Therefore, we maintain that cirrus clouds, as observed in the current climate and covering a large region of the tropics, can provide a solution to the faint young sun paradox, or at least ease the amount of CO2 or other greenhouse substances needed to provide temperatures above freezing during the Archean.

Rondanelli, R.; Lindzen, R. S.

2012-03-01

308

The SCUBA HAlf Degree Extragalactic Survey (SHADES) - V. Submillimetre properties of near-infrared-selected galaxies in the Subaru/XMM -Newton deep field  

NASA Astrophysics Data System (ADS)

We have studied the submillimetre (submm) properties of the following classes of near-infrared-selected (NIR-selected) massive galaxies at high redshifts: BzK-selected star-forming galaxies (BzKs); distant red galaxies (DRGs); and extremely red objects (EROs). We used the SCUBA HAlf Degree Extragalactic Survey (SHADES), the largest uniform submm survey to date. Partial overlap of SIRIUS/NIR images and SHADES in Subaru/XMM-Newton deep field has allowed us to identify four submm-bright NIR-selected galaxies, which are detected in the mid-IR, 24? m, and the radio, 1.4GHz. We find that all of our submm-bright NIR-selected galaxies satisfy the BzK selection criteria, i.e. BzK ? (z - K)AB - (B - z)AB >= -0.2, except for one galaxy whose B - z and z - K colours are however close to the BzK colour boundary. Two of the submm-bright NIR-selected galaxies satisfy all of the selection criteria we considered, i.e. they belong to the BzK-DRG-ERO overlapping population, or `extremely red' BzKs. Although these extremely red BzKs are rare (0.25 arcmin-2), up to 20 per cent of this population could be submm galaxies. This fraction is significantly higher than that found for other galaxy populations studied here. Via a stacking analysis, we have detected the 850-? m flux of submm-faint BzKs and EROs in our SCUBA maps. While the contribution of z ~ 2 BzKs to the submm background is about 10-15 per cent and similar to that from EROs typically at z ~ 1, BzKs have a higher fraction (~30 per cent) of submm flux in resolved sources compared with EROs and submm sources as a whole. From the spectral energy distribution (SED) fitting analysis for both submm-bright and submm-faint BzKs, we found no clear signature that submm-bright BzKs are experiencing a specifically luminous evolutionary phase, compared with submm-faint BzKs. An alternative explanation might be that submm-bright BzKs are more massive than submm-faint ones.

Takagi, T.; Mortier, A. M. J.; Shimasaku, K.; Coppin, K.; Pope, A.; Ivison, R. J.; Hanami, H.; Serjeant, S.; Clements, D. L.; Priddey, R. S.; Dunlop, J. S.; Takata, T.; Aretxaga, I.; Chapman, S. C.; Eales, S. A.; Farrah, D.; Granato, G. L.; Halpern, M.; Hughes, D. H.; van Kampen, E.; Scott, D.; Sekiguchi, K.; Smail, I.; Vaccari, M.

2007-11-01

309

Cool White Dwarfs Found in the UKIRT Infrared Deep Sky Survey  

NASA Astrophysics Data System (ADS)

We present the results of a search for cool white dwarfs in the United Kingdom InfraRed Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). The UKIDSS LAS photometry was paired with the Sloan Digital Sky Survey to identify cool hydrogen-rich white dwarf candidates by their neutral optical colors and blue near-infrared colors, as well as faint reduced proper motion magnitudes. Optical spectroscopy was obtained at Gemini Observatory and showed the majority of the candidates to be newly identified cool degenerates, with a small number of G- to K-type (sub)dwarf contaminants. Our initial search of 280 deg2 of sky resulted in seven new white dwarfs with effective temperature T eff ? 6000 K. The current follow-up of 1400 deg2 of sky has produced 13 new white dwarfs. Model fits to the photometry show that seven of the newly identified white dwarfs have 4120 K <=T eff <= 4480 K, and cooling ages between 7.3 Gyr and 8.7 Gyr; they have 40 km s-1 <= v tan <= 85 km s-1 and are likely to be thick disk 10-11 Gyr-old objects. The other half of the sample has 4610 K <=T eff <= 5260 K, cooling ages between 4.3 Gyr and 6.9 Gyr, and 60 km s-1 <= v tan <= 100 km s-1. These are either thin disk remnants with unusually high velocities, or lower-mass remnants of thick disk or halo late-F or G stars.

Leggett, S. K.; Lodieu, N.; Tremblay, P.-E.; Bergeron, P.; Nitta, A.

2011-07-01

310

COOL WHITE DWARFS FOUND IN THE UKIRT INFRARED DEEP SKY SURVEY  

SciTech Connect

We present the results of a search for cool white dwarfs in the United Kingdom InfraRed Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). The UKIDSS LAS photometry was paired with the Sloan Digital Sky Survey to identify cool hydrogen-rich white dwarf candidates by their neutral optical colors and blue near-infrared colors, as well as faint reduced proper motion magnitudes. Optical spectroscopy was obtained at Gemini Observatory and showed the majority of the candidates to be newly identified cool degenerates, with a small number of G- to K-type (sub)dwarf contaminants. Our initial search of 280 deg{sup 2} of sky resulted in seven new white dwarfs with effective temperature T{sub eff} {approx} 6000 K. The current follow-up of 1400 deg{sup 2} of sky has produced 13 new white dwarfs. Model fits to the photometry show that seven of the newly identified white dwarfs have 4120 K {<=}T{sub eff} {<=} 4480 K, and cooling ages between 7.3 Gyr and 8.7 Gyr; they have 40 km s{sup -1} {<=} v{sub tan} {<=} 85 km s{sup -1} and are likely to be thick disk 10-11 Gyr-old objects. The other half of the sample has 4610 K {<=}T{sub eff} {<=} 5260 K, cooling ages between 4.3 Gyr and 6.9 Gyr, and 60 km s{sup -1} {<=} v{sub tan} {<=} 100 km s{sup -1}. These are either thin disk remnants with unusually high velocities, or lower-mass remnants of thick disk or halo late-F or G stars.

Leggett, S. K.; Nitta, A. [Gemini Observatory, Northern Operations Center, 670 North A'ohoku Place, Hilo, HI 96720 (United States); Lodieu, N. [Instituto de Astrofisica de Canarias (IAC), C/ Via Lactea s/n, E-38200 La Laguna, Tenerife (Spain); Tremblay, P.-E.; Bergeron, P. [Departement de Physique, Universite de Montreal, C. P. 6128, Succursale Centre-Ville, Montreal, QC H3C 3J7 (Canada)

2011-07-01

311

Fluctuations In The Cosmic Infrared Background Using the Cosmic Infrared Background ExpeRiment (CIBER).  

NASA Astrophysics Data System (ADS)

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.

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

312

1-cm collimated source for use in infrared calibrations  

Microsoft Academic Search

Collimated infrared sources covering the 2 micrometer to 30 micrometer range of wavelengths are necessary to simulate infrared radiation from distant objects. This is important because on-orbit servo and tracking systems make extensive use of infrared radiation for remote sensing. Collimators are used to calibrate infrared detectors in terms of absolute power within a given spectral range. The National Institute

Beverly J. Klemme; Timothy M. Jung; Adriaan C. Carter; Eric L. Shirley; Steven R. Lorentz; Raju V. Datla

2000-01-01

313

Infrared Thermometer  

NASA Astrophysics Data System (ADS)

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.

1991-01-01

314

SN 2009N: Another Supernova in between the Normal and Faint Type II-P SNe  

NASA Astrophysics Data System (ADS)

Type II-P supernovae represent the most numerous class of type II SNe. An interesting subgroup is that of the sub-luminous events, which are typified by fainter absolute magnitudes, lower expansion velocities and smaller ejected Ni-mass than the majority of SNe II-P. However, only a couple of SNe falling into the ``gap'' between the sub-luminous and the normal SNe II-P populations have been discovered so far. We present optical and near-infrared photometric and spectroscopic observations of such object, SN 2009N in NGC 4487. The observed characteristics of SN 2009N (plateau length, expansion velocity, ejected Ni-mass) are compared to those of another intermediate-luminosity supernova, SN 2008in. We estimate the physical parameters of the progenitor at the explosion (explosion energy, progenitor radius, ejected mass) through hydrodynamical modelling of the main observables and discuss the results.

Takats, Katalin

2013-06-01

315

Resolving the Mystery of X-ray Faint Elliptical Galaxies: Chandra X-ray Observations of NGC 4697  

Microsoft Academic Search

Chandra observations of the X-ray faint elliptical galaxy NGC 4697 resolve most of the X-ray emission (69% within one effective radius) into ~80 point sources, of which most are low mass X-ray binaries (LMXBs). NGC 4697 is the nearest optically normal and bright but X-ray faint elliptical galaxy. Most of the emission is resolved even in the softest band, which

C. L. Sarazin; J. A. Irwin; J. N. Bregman

2000-01-01

316

THE WFC3 INFRARED SPECTROSCOPIC PARALLEL (WISP) SURVEY  

SciTech Connect

We present the WFC3 Infrared Spectroscopic Parallel (WISP) Survey. WISP is obtaining slitless, near-infrared grism spectroscopy of {approx}90 independent, high-latitude fields by observing in the pure-parallel mode with the Wide Field Camera Three on the Hubble Space Telescope for a total of {approx}250 orbits. Spectra are obtained with the G{sub 102} ({lambda} = 0.8-1.17 {mu}m, R {approx}210) and G{sub 141} grisms ({lambda} = 1.11-1.67 {mu}m, R {approx}130), together with direct imaging in the J and H bands (F110W and F140W, respectively). In the present paper, we present the first results from 19 WISP fields, covering approximately 63 arcmin{sup 2}. For typical exposure times ({approx}6400 s in G{sub 102} and {approx}2700 s in G{sub 141}), we reach 5{sigma} detection limits for emission lines of f {approx} 5 x 10{sup -17} erg s{sup -1} cm{sup -2} for compact objects. Typical direct imaging 5{sigma} limits are 26.3 and 26.1 mag. (AB) in F110W and F140W, respectively. Restricting ourselves to the lines measured with the highest confidence, we present a list of 328 emission lines, in 229 objects, in a redshift range 0.3 < z < 3. The single-line emitters are likely to be a mix of H{alpha} and [O III]5007,4959 A, with H{alpha} predominating. The overall surface density of high-confidence emission-line objects in our sample is approximately 4 per arcmin{sup 2}. These first fields show high equivalent width sources, active galactic nucleus, and post-starburst galaxies. The median observed star formation rate (SFR) of our H{alpha}-selected sample is 4 M{sub sun} yr{sup -1}. At intermediate redshifts, we detect emission lines in galaxies as faint as H{sub 140} {approx} 25, or M{sub R} < -19, and are sensitive to SFRs down to less than 1 M{sub sun} yr{sup -1}. The slitless grisms on WFC3 provide a unique opportunity to study the spectral properties of galaxies much fainter than L* at the peak of the galaxy assembly epoch.

Atek, H.; Scarlata, C.; Colbert, J. W.; Shim, H. [Spitzer Science Center, Caltech, Pasadena, CA 91125 (United States); Malkan, M.; Ross, N. R. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90024 (United States); McCarthy, P.; Dressler, A. [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Teplitz, H. I. [Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States); Siana, B.; Bridge, C. [Department of Astronomy, Caltech, Pasadena, CA 91125 (United States); Henry, A.; Martin, C. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Bunker, A. J. [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, OX13RH (United Kingdom); Fosbury, R. A. E. [Space Telescope-European Coordinating Facility, Garching (Germany)

2010-11-01

317

Deep Optical and Near Infrared Observations in ELAIS Areas  

NASA Astrophysics Data System (ADS)

We present deep optical and near infrared imaging over half square degree of sky in the centres of the ELAIS regions N1 and N2 and coincident with deep XMM/Chandra observations. The data have been obtained with the Wide Field Camera (WFC) and the Cambridge InfraRed Survey Instrument (CIRSI) both at the Isaac Newton Telescope (Observatorio del Roque de los Muchachos, Canary Islands). Limiting magnitudes achieved are g'=26.7, r'=26.2, i'=25.0 and H=20.2 (3 sigma). These data have been used to identify the faint optical counterparts of the Infrared Space Observatory (ISO), radio and X-ray sources in these areas.

González-Solares, E. A.; Pérez-Fournon, I.; McMahon, R.; Sabbey, C.; Almaini, O.; Manners, J.; Willott, C.; Cabrera-Guerra, F.; Ciliegi, P.; Lawrence, A.; Mann, B.; Oliver, S. J.; Rowan-Robinson, M.; Serjeant, S.; Verma, A.

2001-07-01

318

Thermal measurements using infrared thermometry - A new generation of infrared thermometers  

Microsoft Academic Search

Advances in infrared thermometry are discussed. The efficiency of the infrared radiation of an object is measured with the emissivity control of the thermometer and is then converted to a digital signal. The need to have the proper emissivity setting to detect radiation efficiency is examined. The use of dual-mirror systems, lasers, or light sighting systems to aim the infrared

C. E. Everest; M. M. Everest

1985-01-01

319

Spaceplace: See the Infrared Photo Album!  

NSDL National Science Digital Library

Younger students will enjoy viewing these images of ordinary objects rendered in the infrared part of the electromagnetic spectrum. They can access a virtual "camera" and see pictures of animals, people, and other objects in either infrared or visible light. The camera allows them to magnify the images; a color map provides a relative scale for temperatures. A Spanish translation is available.

320

THE FAINT END OF THE GALAXY LUMINOSITY FUNCTION IN A1689: A STEEP RED FAINT END UPTURN AT z = 0.18  

SciTech Connect

We present a deep and wide I luminosity function (LF) for galaxies in A1689 (z = 0.183) from a mosaic of Hubble Space Telescope WFPC2 images covering 10' on the side. The main result of this work is the detection of a steep upturn in the dwarf galaxy LF, with {alpha} {approx} -2. The dwarf-to-giant ratio appears to increase outward, but this is because giant galaxies are missing in the cluster outskirts, indicating luminosity segregation. The red sequence LF has the same parameters, within errors, as the total LF, showing that the faint end upturn consists of red quiescent galaxies. We speculate that the upturn is connected to the 'filling-in' of the red sequence at z < 0.4 and may represent the latest installment of 'downsizing' as the least massive galaxies are being quenched at the present epoch.

Banados, Eduardo [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Hung Liwei [Department of Astronomy, Ohio State University, Columbus, OH (United States); De Propris, Roberto [Cerro Tololo Inter-American Observatory, La Serena (Chile); West, Michael J. [European Southern Observatory, Santiago (Chile)

2010-09-20

321

Infrared radiometry  

Microsoft Academic Search

The observation of infrared radiation from the Earth to space is important in the study of meteorology and climatology. A high resolution radiometer was projected and constructed for this purpose. The spectral range was from the wavelength of 1.8 microns to 22 microns, including the 'atmospheric window' (8 to 14 microns and various bands of absorbers like water vapor, carbon

A. S. Montes; C. C. Ghizoni

1982-01-01

322

Infrared Thermometers  

ERIC Educational Resources Information Center

|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…

Schaefers, John

2006-01-01

323

FASTTRAC I: A High Resolution Infrared Tip-Tilt Imager  

NASA Astrophysics Data System (ADS)

The Center for Astronomical Adaptive Optics (CAAO) at Steward Observatory is implementing instrumentation to enable high resolution imaging in the infrared. The FASTTRAC I instrumentation suite achieves diffraction limited imaging (or spectroscopy) in the near infrared (1-2.4 microns ) by rapid (100 Hz) tip-tilt correction in typical seeing conditions (ro=10 cm at 0.5 microns ). FASTTRAC I removes image motion by rapidly steering a reactionless tip-tilt secondary mirror cell which economically accommodates existing IR secondaries at both the Observatory's 2.3m and 1.5m Cassegrains. Image motion is reduced to less than 0.05" rms during long exposures resulting in final image resolutions of 0.2-0.6" FWHM. Science targets can be acquired by utilizing faint visible (<= 17(th) V) or infrared (<= 8(th) K) guide stars (a unique dual capability). These guide stars must be within a 3' FOV which allows nearly full sky coverage for science target acquisition. A few examples of science targets already acquired by FASTTRAC I are: the first real time images (J, H, & K) of the massive black hole candidate Sgr A* FWHM <= 0.5", the first high resolution HeI (2.06 microns ) image of the Galactic Center, high resolution infrared images of faint (K ~ 22) field galaxies imaged by HST in the visible, Seyfert galaxy morphologies, and high redshift sub-arcsecond gravitational lenses. We will soon obtain tip-tilt corrected near infrared spectra of Sgr A* and other interesting infrared sources. This research is supported by grants from the NSF (AST 88-22465; AST 92-03336) and NASA (NAGW-2254). L.M. Close is supported by a NSERC Fellowship.

Close, Laird M.; Wittman, David; McCarthy, Donald W.; Rieke, Marica

1994-12-01

324

Far Infrared Sky Survey Experiment  

Microsoft Academic Search

The present experiment extends the spectral band of the infrared sky survey to 120 microns through the use of a sounding-rocketborne superfluid-helium-cooled telescope and high-sensitivity far-infrared photoconductive detectors. The objective of the experiment is to measure the spatial and brightness distribution of the celestial background and astronomical sources in the wavelength range 8-120 microns. The experiment, which will be flown

K. Shivanandan; D. P. McNutt; S. Price; T. Murdock

1978-01-01

325

Affective Objects  

Microsoft Academic Search

This paper will attempt t o d efine a new area of research: affective c ommunication through the use of affective objects. An affective object may be defined as any physical object which has the ability to sense emotional data from a person, map that information to an abstract form of expression and communicate that information expressively, either back to

Jocelyn Scheirer; Rosalind W. Picard

326

GOODS-Herschel: The Deepest Far-infrared View Of The Distant Universe  

Microsoft Academic Search

GOODS-Herschel is an open time key program using the Herschel Space Observatory to obtain the deepest far-infrared view of the distant universe. We have surveyed the GOODS-North field with PACS and SPIRE to very faint fluxes at 100-500 microns, and have also completed an ultradeep PACS observation at 100 and 160 microns covering about 1\\/4th of GOODS-South to the faintest

Mark Dickinson; D. Elbaz

2011-01-01

327

Galaxy number counts - IV. Surveying the Herschel Deep Field in the near-infrared  

Microsoft Academic Search

We present results from two new near-infrared imaging surveys. One survey covers 47.2arcmin2 to K(3sigma)=20mag whilst a second, deeper catalogue covers a subarea of 1.8arcmin2 to K(3sigma)=22.75mag. Over the entire area we have extremely deep optical photometry in four bandpasses (UBRI), allowing us to track the colour evolution of galaxies to very faint magnitude limits. Our K-band number counts are

H. J. McCracken; N. Metcalfe; T. Shanks; A. Campos; J. P. Gardner; R. Fong

2000-01-01

328

THE FAINT END OF THE CLUSTER-GALAXY LUMINOSITY FUNCTION AT HIGH REDSHIFT  

SciTech Connect

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.

Mancone, Conor L.; Baker, Troy; Gonzalez, Anthony H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Ashby, Matthew L. N.; Snyder, Greg [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Stanford, Spencer A. [Physics Department, University of California, Davis, CA 95616 (United States); Brodwin, Mark [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Eisenhardt, Peter R. M.; Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Wright, Edward L., E-mail: cmancone@astro.ufl.edu [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States)

2012-12-20

329

A temporal and spatial analysis of cavitation on mechanical heart valves by observing faint light emission.  

PubMed

Cavitation on mechanical heart valves (MHVs) could cause the mechanical failure of the occluder. A simple and reliable in vitro test method to evaluate cavitation potential must be developed. The bubble implosion damages the MHV material; thus, observing the behavior of the bubble implosion is essential. According to sonoluminescence, the collapsing cavity emits faint light. Therefore, in this study, the bubble collapse was analyzed both temporally and spatially by observing faint light emission. A photon counting system has been developed using a photomultiplier tube (H7360-01, Hamamatsu Photonics, Japan). The highest time resolution of this system is 5 microsec. A quartz optical fiber bundle of 2 mm diameter can be connected to this photomultiplier tube and traversed two-dimensionally over the MHV. The closure of the MHV triggers the photon counter, and the photons through 500 beats are recorded and integrated. A 20 mm Björk-Shiley valve was submerged in a water tank containing 10 L deionized water, and the pressure difference of 120 mm Hg was exerted on the valve at a rate of 60 bpm with a pulse duplicator. Approximately 700 microsec after the valve closure, light emission was detected along the edge of the occluder on the inflow side in the major orifice. Then, approximately 1,000 microsec after the closure, light along the occluder's edge in the minor orifice was recorded as well. Compared with the analysis, using a stroboscope and a high-speed camera, faint light was emitted from the collapsing cavities. In conclusion, sonoluminescnece was successfully observed around the MHV, and the photon counting technique and the traversing mechanism of the optical fiber bundle revealed the temporal and spatial distribution of the cavity collapse on the MHV. PMID:15171483

Takiura, Koki; Chinzei, Tsuneo; Abe, Yusuke; Isoyama, Takashi; Saito, Itsuro; Mochizuki, Shuichi; Imachi, Kou

330

Infrared retina  

DOEpatents

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.

Krishna, Sanjay (Albuquerque, NM); Hayat, Majeed M. (Albuquerque, NM); Tyo, J. Scott (Tucson, AZ); Jang, Woo-Yong (Albuquerque, NM)

2011-12-06

331

Method for imaging a concealed object  

DOEpatents

A method for imaging a concealed object is described and which includes a step of providing a heat radiating body, and wherein an object to be detected is concealed on the heat radiating body; imaging the heat radiating body to provide a visibly discernible infrared image of the heat radiating body; and determining if the visibly discernible infrared image of the heat radiating body is masked by the presence of the concealed object.

Davidson, James R [Idaho Falls, ID; Partin, Judy K [Idaho Falls, ID; Sawyers, Robert J [Idaho Falls, ID

2007-07-03

332

Summarizing ChaMPlane: Global Distributions And Nature Of Faint Chandra XRBs in the Galaxy  

NASA Astrophysics Data System (ADS)

We summarize the global properties of sources detected in our nearly 10y ChaMPlane survey of faint (<0.01 cts/s) Chandra sources in the Galactic plane. In this presentation, we focus on sources detected above 2 keV which are dominated by CVs and XRBs. Using the GCR hard sources with optical counterparts (Zhao et al), we derive constraints on luminosity and spatial distributions for sources out to 3 kpc (for NH < 3 E21) for comparison with all ChaMPlane fields with similar limiting NH to constrain the global distributions of CVs and qLMXBs in the Galaxy.

Grindlay, Jonathan E.; Hong, J.; van den Berg, M.; Servillat, M.; Zhao, P.; Allen, B.

2011-09-01

333

The early faint sun paradox: Organic shielding of ultraviolet-labile greenhouse gases  

SciTech Connect

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.

Sagan, C. [Cornell Univ., Ithaca, NY (United States); Chyba, C. [Univ. of Arizona, Tucson, AZ (United States)

1997-05-23

334

THE CALIBRATION OF MONOCHROMATIC FAR-INFRARED STAR FORMATION RATE INDICATORS  

SciTech Connect

Spitzer data at 24, 70, and 160 {mu}m and ground-based H{alpha} images are analyzed for a sample of 189 nearby star-forming and starburst galaxies to investigate whether reliable star formation rate (SFR) indicators can be defined using the monochromatic infrared dust emission centered at 70 and 160 {mu}m. We compare recently published recipes for SFR measures using combinations of the 24 {mu}m and observed H{alpha} luminosities with those using 24 {mu}m luminosity alone. From these comparisons, we derive a reference SFR indicator for use in our analysis. Linear correlations between SFR and the 70 {mu}m and 160 {mu}m luminosity are found for L(70) {approx_gt} 1.4 x 10{sup 42} erg s{sup -1} and L(160) {approx_gt} 2 x 10{sup 42} erg s{sup -1}, corresponding to SFR {approx_gt} 0.1-0.3 M{sub sun} yr{sup -1}, and calibrations of SFRs based on L(70) and L(160) are proposed. Below those two luminosity limits, the relation between SFR and 70 {mu}m (160 {mu}m) luminosity is nonlinear and SFR calibrations become problematic. A more important limitation is the dispersion of the data around the mean trend, which increases for increasing wavelength. The scatter of the 70 {mu}m (160 {mu}m) data around the mean is about 25% (factor {approx}2) larger than the scatter of the 24 {mu}m data. We interpret this increasing dispersion as an effect of the increasing contribution to the infrared emission of dust heated by stellar populations not associated with the current star formation. Thus, the 70 (160) {mu}m luminosity can be reliably used to trace SFRs in large galaxy samples, but will be of limited utility for individual objects, with the exception of infrared-dominated galaxies. The nonlinear relation between SFR and the 70 and 160 {mu}m emission at faint galaxy luminosities suggests a variety of mechanisms affecting the infrared emission for decreasing luminosity, such as increasing transparency of the interstellar medium, decreasing effective dust temperature, and decreasing filling factor of star-forming regions across the galaxy. In all cases, the calibrations hold for galaxies with oxygen abundance higher than roughly 12 +log(O/H) {approx} 8.1. At lower metallicity, the infrared luminosity no longer reliably traces the SFR because galaxies are less dusty and more transparent.

Calzetti, D.; Wu, S.-Y.; Hong, S. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Kennicutt, R. C.; Hao, C.-N.; Begum, A.; Johnson, B. [Institute of Astronomy, Cambridge University, Cambridge (United Kingdom); Lee, J. C. [Carnegie Observatories of Washington, Pasadena, CA (United States); Dale, D. A. [Department of Physics and Astronomy, University of Wyoming, WY (United States); Engelbracht, C. W.; Block, M. [Steward Observatory, University of Arizona, AZ (United States); Van Zee, L. [Department of Astronomy, University of Indiana, IN (United States); Draine, B. T. [Princeton University Observatory, Peyton Hall, Princeton, NJ (United States); Gordon, K. D.; Regan, M. [Space Telescope Science Institute, Baltimore, MD (United States); Moustakas, J. [Center for Astrophysics and Space Sciences, University of California, San Diego, CA (United States); Murphy, E. J. [Spitzer Science Center, Caltech, CA (United States); Dalcanton, J. [Department of Astronomy, University of Washington, WA (United States); Funes, J. [Vatican Observatory, University of Arizona, AZ (United States); Gil de Paz, A., E-mail: calzetti@astro.umass.ed [Departamento de Astrofisica, Universidad Computense de Madrid (Spain)

2010-05-10

335

Infrared Properties of Serendipitous X-Ray Quasars.  

National Technical Information Service (NTIS)

Near infrared measurements were obtained of 30 quasars originally found serendipitously as X-ray sources in fields of other objects. The observations show that the infrared characteristics of these quasars do not differ significantly from those of quasars...

G. Neugebauer B. T. Soifer K. Matthews B. Margon G. A. Chanan

1982-01-01

336

Infrared Luminosity Functions from the Chandra Deep Field-South: The Spitzer View on the History of Dusty Star Formation at 0 <~ z <~ 1  

NASA Astrophysics Data System (ADS)

We analyze a sample of ~2600 Spitzer MIPS 24 ?m sources brighter than ~80 ?Jy and located in the Chandra Deep Field-South to characterize the evolution of the comoving infrared (IR) energy density of the universe up to z~1. Using published ancillary optical data, we first obtain a nearly complete redshift determination for the 24 ?m objects associated with R<~24 mag counterparts at z<~1. These sources represent ~55%-60% of the total MIPS 24 ?m population with f24?m>~80 ?Jy, the rest of the sample likely lying at higher redshifts. We then determine an estimate of their total IR luminosities using various libraries of IR spectral energy distributions. We find that the 24 ?m population at 0.5<~z<~1 is dominated by ``luminous infrared galaxies'' (i.e., 1011 Lsolar<=LIR<=1012 Lsolar), the counterparts of which appear to be also luminous at optical wavelengths and tend to be more massive than the majority of optically selected galaxies. A significant number of fainter sources (5×1010 Lsolar<~LIR<=1011 Lsolar) are also detected at similar distances. We finally derive 15 ?m and total IR luminosity functions (LFs) up to z~1. In agreement with the previous results from the Infrared Space Observatory (ISO) and SCUBA and as expected from the MIPS source number counts, we find very strong evolution of the contribution of the IR-selected population with look-back time. Pure evolution in density is firmly excluded by the data, but we find considerable degeneracy between strict evolution in luminosity and a combination of increases in both density and luminosity [L*IR~(1+z)3.2+0.7-0.2, ?*IR~(1+z)0.7+0.2-0.6]. A significant steepening of the faint-end slope of the IR luminosity function is also unlikely, as it would overproduce the faint 24 ?m source number counts. Our results imply that the comoving IR energy density of the universe evolves as (1+z)3.9+/-0.4 up to z~1 and that galaxies luminous in the infrared (i.e., LIR>=1011 Lsolar) are responsible for 70%+/-15% of this energy density at z~1. Taking into account the contribution of the UV luminosity evolving as (1+z)~2.5, we infer that these IR-luminous sources dominate the star-forming activity beyond z~0.7. The uncertainties affecting these conclusions are largely dominated by the errors in the k-corrections used to convert 24 ?m fluxes into luminosities. Based on observations made with Spitzer, operated by the Jet Propulsion Laboratory under NASA contract 1407.

Le Floc'h, Emeric; Papovich, Casey; Dole, Hervé; Bell, Eric F.; Lagache, Guilaine; Rieke, George H.; Egami, Eiichi; Pérez-González, Pablo G.; Alonso-Herrero, Almudena; Rieke, Marcia J.; Blaylock, Myra; Engelbracht, Charles W.; Gordon, Karl D.; Hines, Dean C.; Misselt, Karl A.; Morrison, Jane E.; Mould, Jeremy

2005-10-01

337

Comparing Objects  

NSDL National Science Digital Library

Clifford, the big red dog, hosts an animated game where students click on the object that Clifford describes. The objects are in sets and students click on the smallest, tallest, shortest, etc. Clifford gives a "good job" reinforcement for the correct answer. Students are prompted to try again if they select the incorrect answer. No reading is required.

Pbskids.org

2011-06-28

338

Melting Objects  

Microsoft Academic Search

This paper describes a technique for producing realistic animations of melting objects. The work presented here introduces a method that accurately models both thermal flow and the latent heat during the phase change. The mechanism for energy transfer to the model is via both boundary conditions and radiation. Emphasis is made on accurately modelling the solid object and the method

Mark W. Jones

2003-01-01

339

With Objects  

Microsoft Academic Search

OSUIF is an extension to SUIF 2.0 that provides support for the compilation of object-oriented languages. OSUIF extends standard SUIF in three main areas: symbol table, intermediate language, and exception handling. The resulting system should be able to support compilers for many (but not all) object-oriented languages. The two initial OSUIF front ends will support C++ and Java.

Andrew Duncan; Bogdan Cocosel; Costin Iancu; Holger Kienle; Radu Rugina; Urs Hölzle; Martin Rinard

340

SYNCHROTRON BLOB MODEL OF INFRARED AND X-RAY FLARES FROM SAGITTARIUS A*  

SciTech Connect

Sagittarius A* in the Galactic center harbors a supermassive black hole and exhibits various active phenomena. Besides quiescent emission in radio and submillimeter radiation, flares in the near-infrared (NIR) and X-ray bands are observed to occur frequently. We study a time-dependent model of the flares, assuming that the emission is from a blob ejected from the central object. Electrons obeying a power law with the exponential cutoff are assumed to be injected in the blob for a limited time interval. The flare data of 2007 April 4 were used to determine the values of model parameters. The spectral energy distribution of flare emission is explained by nonthermal synchrotron radiation in the NIR and X-ray bands. The model light curves suggest that electron acceleration is still underway during the rising phase of the flares. GeV {gamma}-rays are also emitted by synchrotron self-Compton scattering, although their luminosity is not strictly constrained by the current model. If the GeV emission is faint, the plasma blob is dominated by the magnetic energy density over the electron kinetic energy density. Observations in the GeV band will clarify the origin of the blob.

Kusunose, Masaaki [Department of Physics, School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337 (Japan); Takahara, Fumio, E-mail: kusunose@kwansei.ac.jp, E-mail: takahara@vega.ess.sci.osaka-u.ac.jp [Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka 560-0043 (Japan)

2011-01-01

341

Infrared Monitoring of the Nearest Low-Mass T Tauri Binary: TWA 30AB  

NASA Astrophysics Data System (ADS)

The T Tauri phase of young stellar evolution is known to exist down to substellar masses. However, the intrinsic faintness of these objects and distances to star forming regions has limited detailed study of this critical phase. We propose monitoring observations of the nearest pair of low-mass T Tauri accretors, TWA 30A and B. Both of these 8 Myr sources exhibit spectroscopic signatures indicating actively accreting, nearly edge-on disks with jets and stellar outflows. However, their time-dependent behavior at optical and near-infrared wavelengths are distinct, suggesting differing geometries and differing sources for the observed emission. We propose to test these models through short-term (continuous over 6 hr) and medium-term (daily for 40 days) IRAC monitoring of both stars. These observations will allow us to simultaneously probe variations in the accretion on and warping of the outer disk of TWA 30A, and coherent scaleheight and opacity variations in the disk around TWA 30B in the region where planets may be forming. Combined with coincident ground-based follow-up, our program will provide the most detailed picture of disk evolution during the planet-building phase of the lowest-mass stars.

Burgasser, Adam; Faherty, Jacqueline; Mohanty, Subhanjoy; Gizis, John; Melis, Carl; Bochanski, John; Drake, Andrew; Looper, Dagny

2012-12-01

342

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

SciTech Connect

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.

Musella, Ilaria; Ripepi, Vincenzo; Marconi, Marcella, E-mail: ilaria@na.astro.it, E-mail: ripepi@na.astro.it, E-mail: marcella@na.astro.it [INAF, Osservatorio Astronomico di Capodimonte, I-8013 Napoli (Italy); and others

2012-09-10

343

Intrinsically faint quasars: evidence for meV axion dark matter in the universe  

NASA Astrophysics Data System (ADS)

Growing amount of observations indicate presence of intrinsically faint quasar subgroup (a few % of known quasars) with noncosmological quantized redshift. Here we find an analytical solution of Einstein equations describing bubbles made from axions with periodic interaction potential. Such particles are well-motivated cold dark matter candidate. The bubble interior possesses equal gravitational redshift which can have any value between zero and infinity. Quantum pressure supports the bubble against collapse and yields states stable on the scale more then hundreds million years. Our results explain the observed quantization of quasar redshift and suggest that intrinsically faint point-like quasars associated with nearby galaxies are axionic bubbles with masses 108-109Msolar and radii 103-104Rsolar. They are born in active galaxies and ejected into surrounding space. Properties of such quasars unambiguously indicate presence of axion dark matter in the Universe and yield the axion mass m?1 meV, which fits in the open axion mass window constrained by astrophysical and cosmological arguments.

Svidzinsky, Anatoly A.

344

Far-Infrared Galaxies in the Far-Ultraviolet  

NASA Astrophysics Data System (ADS)

In an effort to better understand the UV properties of ultraluminous infrared galaxies (ULIGs), and compare them to the rest-frame UV properties of high redshift submillimeter and Lyman-break galaxies, we have obtained far- and near-UV imaging observations (?eff=1457 and 2364 Å, respectively) of two luminous infrared galaxies (LIGs-VV 114 and IC 883) and five ULIGs (IRAS 08572+3915, Mrk 273, IRAS 15250+3609, Arp 220, and IRAS 19254-7245) using the Hubble Space Telescope. All the galaxies were detected in both channels. UV light, both diffuse and from star clusters, can be traced to within the inner kiloparsec of the dominant near-IR nuclei. However, in general, the brightest UV sources are clearly displaced from the I-band and near-IR peaks by at least hundreds of parsecs. Furthermore, only 0.07%-7.3% of the total near-UV light is projected within the inner 500 pc radius, even though this is the same region where most of the bolometric energy is generated. All nuclei are highly obscured by dust. Even after correction for dust reddening, the global UV emission fails to account for the total bolometric luminosities of these systems by factors of 3-75. The discrepancy is much worse if only the central regions, where the bolometric luminosities are generated, are included. In two cases (VV 114 and IRAS 08572+3915), the merging companion galaxies are more prominent in the UV than the more IR luminous member. While all our galaxies show possible signatures of active galactic nucleus (AGN) activity, only IRAS 19254-7245 yields even a possible detection of an AGN in our UV images. Simple calculations show that all but one of our galaxies would be expected to drop below the detection thresholds of, e.g., the Hubble Deep Fields at redshifts between 1.5 and 3, and we find that ~2 of our five ULIGs would be selected as extremely red objects in this redshift range. A typical ULIG in our sample would be too faint to be detected at high redshift in the deepest current optical or submillimeter deep surveys. Only VV 114 has UV luminosity and color similar to Lyman-break galaxies at z~3 the other galaxies would be too faint and/or red to be selected by current surveys. The low UV brightnesses of our ULIGs mean that they would not appear as optically bright (or bright ERO) submillimeter galaxy counterparts, although they might be similar to the fainter submillimeter galaxy counterparts. 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, Incorporated, under NASA contract NAS5-26555.

Goldader, Jeffrey D.; Meurer, Gerhardt; Heckman, Timothy M.; Seibert, Mark; Sanders, D. B.; Calzetti, Daniela; Steidel, Charles C.

2002-04-01

345

TryEngineering: Infrared Investigations  

NSDL National Science Digital Library

This is a lesson plan that explores principles of electromagnetic radiation, developed to help teachers integrate engineering practices in the secondary classroom. Students use a television remote control device to test the limitations of infrared and devise a plan for adapting infrared to work around a corner or between two rooms. The driving question of the lesson: How do engineers apply infrared technology in devices to satisfy different requirements? The lesson follows a module format that includes objectives and learner outcomes, recommended reading, illustrated procedures, and background information about the engineering connections. The TryEngineering collection is maintained by the Institute of Electrical and Electronics Engineers (IEEE). Editor's Note: We suggest supplementing this lab with interactive digital resources to help students visualize infrared radiation as part of the electromagnetic spectrum. See Related Materials for links to recommended simulations and video.

346

ChaMPlane Deep Galactic Bulge Survey. I. Faint Accretion-driven Binaries in the Limiting Window  

NASA Astrophysics Data System (ADS)

We have carried out a deep X-ray and optical survey with Chandra and HST of low-extinction regions in the Galactic bulge. Here we present the results of a search for low-luminosity (LX lsim 1034 erg s-1) accreting binaries among the Chandra sources in the region closest to the Galactic center, at an angular offset of 1fdg4, that we have named the Limiting Window. Based on their blue optical colors, excess H? fluxes, and high X-ray-to-optical flux ratios, we identify three likely accreting binaries; these are probably white dwarfs accreting from low-mass companions (cataclysmic variables; CVs) although we cannot exclude that they are quiescent neutron-star or black-hole low-mass X-ray binaries. Distance estimates put these systems farther than gsim 2 kpc. Based on their H?-excess fluxes and/or high X-ray-to-optical flux ratios, we find 22 candidate accreting binaries; however, the properties of some can also be explained if they are dMe stars or active galaxies. We investigate the CV number density toward the bulge and find that the number of observed candidate CVs is consistent with or lower than the number expected for a constant CV-to-star ratio that is fixed to the local value. Our conclusions are limited by uncertainties in the extinction (for which we see a ~ 30% variation in our 6farcm6 × 6farcm6 field) and selection effects. The X-ray properties of two likely CVs are similar to those of the faint, hard X-ray sources in the Galactic center region that have been suggested to be (mainly) magnetic CVs. If our candidates belong to the same population, they would be the first members to be optically identified; optical or infrared identification of their Galactic center analogs would be impossible due to the higher obscuration. We speculate that all Galactic hard X-ray sources in our field can be explained by magnetic CVs.

van den Berg, Maureen; Hong, Jae Sub; Grindlay, Jonathan E.

2009-08-01

347

ChaMPlane DEEP GALACTIC BULGE SURVEY. I. FAINT ACCRETION-DRIVEN BINARIES IN THE LIMITING WINDOW  

SciTech Connect

We have carried out a deep X-ray and optical survey with Chandra and HST of low-extinction regions in the Galactic bulge. Here we present the results of a search for low-luminosity (L{sub X} {approx}< 10{sup 34} erg s{sup -1}) accreting binaries among the Chandra sources in the region closest to the Galactic center, at an angular offset of 1.{sup 0}4, that we have named the Limiting Window. Based on their blue optical colors, excess H{alpha} fluxes, and high X-ray-to-optical flux ratios, we identify three likely accreting binaries; these are probably white dwarfs accreting from low-mass companions (cataclysmic variables; CVs) although we cannot exclude that they are quiescent neutron-star or black-hole low-mass X-ray binaries. Distance estimates put these systems farther than {approx}> 2 kpc. Based on their H{alpha}-excess fluxes and/or high X-ray-to-optical flux ratios, we find 22 candidate accreting binaries; however, the properties of some can also be explained if they are dMe stars or active galaxies. We investigate the CV number density toward the bulge and find that the number of observed candidate CVs is consistent with or lower than the number expected for a constant CV-to-star ratio that is fixed to the local value. Our conclusions are limited by uncertainties in the extinction (for which we see a {approx} 30% variation in our 6.'6 x 6.'6 field) and selection effects. The X-ray properties of two likely CVs are similar to those of the faint, hard X-ray sources in the Galactic center region that have been suggested to be (mainly) magnetic CVs. If our candidates belong to the same population, they would be the first members to be optically identified; optical or infrared identification of their Galactic center analogs would be impossible due to the higher obscuration. We speculate that all Galactic hard X-ray sources in our field can be explained by magnetic CVs.

Van den Berg, Maureen; Hong, Jae Sub; Grindlay, Jonathan E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)], E-mail: maureen@head.cfa.harvard.edu

2009-08-01

348

Extended Objects.  

National Technical Information Service (NTIS)

After some disconnected comments on the MIT bag and string models for extended hadrons, I review current understanding of extended objects in classical conventional relativistic field theories and their quantum mechanical interpretation. (ERA citation 02:...

M. Creutz

1976-01-01

349

Technologies for thermal infrared imaging from GEO  

NASA Astrophysics Data System (ADS)

Thermal infrared imaging from geostationary satellite can provide all time, real time and video observation, and it can achieve fast pointing and information acquisition of any object on the earth disk. It is more suitable for timely information acquisition of emergent event such as natural disaster. The paper introduces the development and related applications of GEO thermal infrared imaging technologies during the past several decades. It then introduces a concept of all time, real time and video observation from GEO using two thermal infrared staring imagers with different spatial resolution and field of view (FOV). The low spatial resolution and wide FOV thermal infrared staring imager is used to monitor objects within a large area concerned, while the high spatial resolution and narrow FOV thermal infrared staring imager is used to acquire detailed information of the interesting objects within a small area. The main characteristics and technical solutions about the proposed concept are described in the paper.

Ma, Wenpo

2013-09-01

350

The Universe's Most Distant Object  

NASA Video Gallery

This video is a zoom into the Hubble Space Telescope infrared Ultra Deep Field, first taken in 2009. It is a very small patch of sky in the southern constellation Fornax. The zoom centers on the farthest identified object in the field. The object, possibly a galaxy, looks red because its light has been stretched by the expansion of the universe. Credit: NASA/ESA/G. Bacon, STScI (no audio)

Robert Garner

2011-01-26

351

Objective fronts  

NASA Astrophysics Data System (ADS)

This paper addresses the long-standing problem of plotting atmospheric fronts objectively. A thermodynamic definition of a front is proposed. Time-independent diagnostic quantities are then devised according to this definition. These can be computed from any gridded dataset. Fronts are then plotted, without human intervention, by utilising standard graphics package facilities, such as contouring, to represent the diagnostics. The methodology includes applying threshold criteria to erase automatically fronts which are thermally weak. By tuning these criteria a good match with subjective fronts is obtained. In addition, the objective surface fronts very often coincide with troughs in surface pressure, implying that a thermodynamic definition is sufficient. The objective front-plotting is further developed to recognise split fronts, and ana- and kata-front characteristics. Many examples are presented; these illustrate how objective fronts are potentially a very powerful tool for both forecasting and research. At the Joint Centre for Mesoscale Meteorology plots and animations showing objective fronts have been produced on a daily basis for many months now.

Hewson, T. D.

1998-03-01

352

Infrared Sensing Techniques for Adaptive Robotic Welding.  

National Technical Information Service (NTIS)

The objective of this research is to investigate the feasibility of using infrared sensors to monitor the welding process. Data were gathered using an infrared camera which was trained on the molten metal pool during the welding operation. Several types o...

T. T. Lin K. Groom N. H. Madsen B. A. Chin

1986-01-01

353

Infrared fiber optics  

NASA Astrophysics Data System (ADS)

This interim technical report summarizes the first year's research efforts to fabricate optical communications fibers that are transmissive between 1 and 12 micrometers. The ultimate objective of this program is to prepare infrared transmitting fibers with losses less than 5 dB/km. In preparing infrared transparent fibers with these losses, we are emphasizing the extrusion into fiber of very pure KCl as this material has demonstrated bulk losses equal to or less than 5 dB/km in the 2 to 6 micrometers region. The primary approach used to meet the program goals, therefore, was the extrusion of reactive atmosphere process (RAP) grown KCl into 250 to 1000 micrometers-diameter optical fibers. After one year of effort, the best KCl fiber extruded had a loss of 4200 dB/km. This report also summarizes our efforts in fabricating a special infrared fiber prototype device for the detection of pulsed CO2 laser radiation. The prototype device, which is to be used in a battlefield identification friend or foe (BIFF) application, was successfully field tested in Germany.

Harrington, J. A.; Turk, R.; Henderson, M.; Myer, J.

1979-12-01

354

The Faint-End Slopes of Galaxy Luminosity Functions in the COSMOS Field  

NASA Astrophysics Data System (ADS)

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 (0.02faint-end slopes grow shallower with increasing redshift; in the highest redshift bin (0.4faint 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 Corporation, CEA/DAPNIA, the National Research Council of Canada, the Canadian Astronomy Data Centre, the Centre National de la Recherche Scientifique de France, TERAPIX, and the University of Hawaii; and the National Radio Astronomy Observatory, which is a facility of the National Science Foundation operated under cooperative agreement by AURA, Inc.

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

355

Hunting for extremely faint planetary nebulae in the SDSS spectroscopic database  

NASA Astrophysics Data System (ADS)

Using ˜1700 000 target- and sky-fibre spectra from the Sloan Digital Sky Survey (SDSS), we have carried out a systematic search for Galactic planetary nebulae (PNe) via detections of the [O III] ??4959, 5007 lines. Thanks to the excellent sensitivity of the SDSS spectroscopic surveys, this is by far the deepest search for PNe ever taken, reaching a surface brightness of the [O III] ?5007 line down to about 29.0 mag arcsec-2. The search leads to the recovery of 13 previously known PNe in the Northern and Southern Galactic Caps. In total, 44 new PN candidates are identified, including seven candidates of multiple detections and 37 candidates of single detection. The seven candidates of multiple detections are all extremely large (between 21 and 154 arcmin) and faint, located mostly in the low Galactic latitude region and with a kinematics similar to disc stars. After checking their images in H? and other bands, three of them are probably H II regions, one is probably associated with a new supernova remnant, another one is possibly a true PN and the remaining two could be either PNe or supernova remnants. Based on sky positions and kinematics, seven candidates of single detection probably belong to the halo population. If confirmed, they will increase the number of known PNe in the Galactic halo significantly. All the newly identified PN candidates are very faint, with a surface brightness of the [O III] ?5007 line between 27.0-30.0 mag arcsec-2, and very challenging to be discovered with previously employed techniques (e.g. slitless spectroscopy, narrow-band imaging), and thus may greatly increase the number of `missing' faint PNe. Our results demonstrate the power of large-scale fibre spectroscopy in hunting for ultrafaint PNe and other types of emission line nebulae. Combining the large spectral data bases provided by the SDSS and other on-going projects (e.g. the LAMOST Galactic surveys), it is possible to build a statistically meaningful sample of ultrafaint, large, evolved PNe, thus, improving the census of Galactic PNe.

Yuan, H. B.; Liu, X. W.

2013-11-01

356

Hunting for extremely faint planetary nebulae in the SDSS spectroscopic database  

NASA Astrophysics Data System (ADS)

Using ˜1700 000 target- and sky-fibre spectra from the Sloan Digital Sky Survey (SDSS), we have carried out a systematic search for Galactic planetary nebulae (PNe) via detections of the [O III] ??4959, 5007 lines. Thanks to the excellent sensitivity of the SDSS spectroscopic surveys, this is by far the deepest search for PNe ever taken, reaching a surface brightness of the [O III] ?5007 line down to about 29.0 mag arcsec-2. The search leads to the recovery of 13 previously known PNe in the Northern and Southern Galactic Caps. In total, 44 new PN candidates are identified, including seven candidates of multiple detections and 37 candidates of single detection. The seven candidates of multiple detections are all extremely large (between 21 and 154 arcmin) and faint, located mostly in the low Galactic latitude region and with a kinematics similar to disc stars. After checking their images in H? and other bands, three of them are probably H II regions, one is probably associated with a new supernova remnant, another one is possibly a true PN and the remaining two could be either PNe or supernova remnants. Based on sky positions and kinematics, seven candidates of single detection probably belong to the halo population. If confirmed, they will increase the number of known PNe in the Galactic halo significantly. All the newly identified PN candidates are very faint, with a surface brightness of the [O III] ?5007 line between 27.0-30.0 mag arcsec-2, and very challenging to be discovered with previously employed techniques (e.g. slitless spectroscopy, narrow-band imaging), and thus may greatly increase the number of `missing' faint PNe. Our results demonstrate the power of large-scale fibre spectroscopy in hunting for ultrafaint PNe and other types of emission line nebulae. Combining the large spectral data bases provided by the SDSS and other on-going projects (e.g. the LAMOST Galactic surveys), it is possible to build a statistically meaningful sample of ultrafaint, large, evolved PNe, thus, improving the census of Galactic PNe.

Yuan, H. B.; Liu, X. W.

2013-09-01

357

Objective functions.  

PubMed

Multiple sequence alignment involves alignment of more than two sequences and is an NP-complete problem. Therefore, heuristic algorithms that use different criteria to find an approximation to the optimal solution are employed. At the heart of these approaches lie the scoring and objective functions that a given algorithm uses to compare competing solutions in constructing a multiple sequence alignment. These objective functions are often motivated by the biological paradigms that govern functional similarities and evolutionary relations. Most existing approaches utilize a progressive process where the final alignment is constructed sequentially by adding new sequences into an existing multiple sequence alignment matrix, which is dynamically updated. In doing this, the core scoring function to assess accuracies of pairwise alignments generally remains the same, while the objective functions used in intermediary steps differ. Nevertheless, the overall assessment of the final multiple sequence alignment is generally calculated by an extension of pairwise scorings. In this chapter, we explore different scoring and objective functions used in calculating the accuracy and optimization of a multiple sequence alignment and provide utilization of these criteria in popularly used multiple sequence alignment algorithms. PMID:24170394

Do?an, Haluk; Otu, Hasan H

2014-01-01

358

Objectively Speaking  

NSDL National Science Digital Library

This resources is a column on how to write learning objectives for a course and why they make everything you do thereafter (e.g. planning syllabi and class sessions, making up assignments and exams, and reviewing departmental curricula) easier and more effective. Target Audience: 2-4 Year College Faculty/Administrators

Felder, Richard M., 1939-; Brent, Rebecca, 1956-

2009-12-18

359

Diagnoses made in a secondary care "fits, faints, and funny turns" clinic  

PubMed Central

Aims To investigate the diagnoses made for children referred to a “fits, faints, and funny turns” clinic. Methods Prospective study of 380 children referred to a dedicated secondary care clinic over an eight year period. Results Twenty three per cent of children were given a final diagnosis of one of the childhood epilepsies, with 48% of these having a specific epilepsy syndrome. Syncope was the commonest cause of a non?epileptic event (syncope and reflex anoxic seizures comprised 100/238, 42%) but there were a wide variety of other causes. Fifty three events (14%) were unclassified and managed without a diagnostic label or treatment. Conclusions In children with funny turns referred to secondary care, the diagnostic possibilities are numerous; among non?epileptic events, syncopes predominate. The majority do not have epilepsy. Unclassifiable events with no clear epileptic or non?epileptic cause are common and can be safely managed expectantly.

Hindley, D; Ali, A; Robson, C

2006-01-01

360

Blue and visual photometry of the Rubin et al. (1976) sample of faint galaxies  

NASA Astrophysics Data System (ADS)

Blue and visual multiaperture photoelectric photometry of 112 faint spiral galaxies from the list of Rubin et al. (1976) is presented. Total galaxy magnitudes for an aperture/diameter ratio of 1.0, according to the precepts of Graham (1976) are compared with the photographic magnitudes of the Zwicky et al. (1961-1968) Catalogue of Galaxies and Clusters of Galaxies. From a reanalysis for the motion of the Local Group, it is found that use of the new galaxy magnitudes increases the difference between the motion vector derived from Rubin et al. and the motions derived from other samples of galaxies and that implied by the anisotropy of the cosmic background radiation.

Peterson, C. J.; Baumgart, C. W.

1986-03-01

361

Some features of digital kinematic and photometrical processing of faint TV meteors  

NASA Astrophysics Data System (ADS)

Some features of digital kinematic and photometrical processing of TV faint meteors are discussed. For these purposes a computer original program has been worked out. The program uses data obtained by TV devices equipped by izokon TV tubes. The observed images are recorded on videotape and digitized with the help of a framegrabber. Precision of measurements of meteor coordinates in the frame is estimated. The kinematic processing is based on a original method using elements of vector analysis and calculating both meteor trajectory parameters in Earth's atmosphere and orbit elements. The errors of these parameters are also computed. Photometrical characteristics of TV systems were investigated. Some experiments for photometrical field correction, spectral sensitivity of TV tube cathode and correction for the motion of a meteor were carried out. The method was approbated on the results of double-station observations of meteors in Kyiv for the last years.

Kozak, Pavlo M.; Rozhilo, Alexander A.; Taranukha, Yury G.

2001-11-01

362

Infrared studies of star formation  

Microsoft Academic Search

Infrared observations at wavelengths of a few microns to 1 mm are reviewed which pertain to the problem of star formation. The data considered include observations of large gas and dust clouds within which stars may be forming and detailed studies of individual objects within these clouds. Stages of star formation are outlined, the IR luminosity of forming stars is

M. W. Werner; E. E. Becklin; G. Neugebauer

1977-01-01

363

Radio, optical and infrared observations of CLASS B0128+437  

NASA Astrophysics Data System (ADS)

We present new observations of the gravitational lens system CLASS B0128+437 made in the optical, infrared and radio regimes. Hubble Space Telescope observations detect only a very faint, extended object in the I band with no obvious emission from the lensed images visible; no detection at all is made in the V band. The lens system is detected with a much higher signal-to-noise ratio with the United Kingdom Infrared Telescope in the K band and, although resolved, the resolution is not sufficient to allow the lensed images and the lens galaxy to be separated. A careful astrometric calibration, however, suggests that the peak of the infrared emission corresponds to the two merging images A and B and therefore that the lensed images dominate at infrared wavelengths. The new radio data consist of high-resolution very long baseline interferometry radio images at three frequencies, 2.3, 5 and 8.4 GHz, made with the Very Long Baseline Array (VLBA) and the 100-m Effelsberg telescope. These reveal that the lensed source consists of three well-defined subcomponents that are embedded in a more extended jet. Due to the fact that the subcomponents have different spectral indices, it is possible to determine, unambiguously, which part of each image corresponds to the same source subcomponent. Our main finding is that one of the images, B, looks very different to the others, there being no obvious division into separate subcomponents and the image being apparently both broader and smoother. This is a consequence, we believe, of scatter-broadening in the interstellar medium of the lensing galaxy. The large number of multiply imaged source subcomponents also provides an abundance of modelling constraints and we have attempted to fit a singular isothermal ellipsoid + external shear model to the data, as well as utilizing the novel method of Evans and Witt. It proves difficult in both cases, however, to obtain a satisfactory fit, which strongly suggests the presence of substructure in the mass distribution of the lensing galaxy, perhaps of the kind that is predicted by cold dark matter theories of structure formation.

Biggs, A. D.; Browne, I. W. A.; Jackson, N. J.; York, T.; Norbury, M. A.; McKean, J. P.; Phillips, P. M.

2004-05-01

364

Stellar Archeology in the Galactic Halo with Ultra-faint Dwarfs. VII. Hercules  

NASA Astrophysics Data System (ADS)

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, langP abrang = 0.68 days (? = 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)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 ~ 25 mag and extends beyond the galaxy's half-light radius over a total area of 40' × 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. Based on data collected at the 2.5 m Isaac Newton Telescope, La Palma, Canary Islands, Spain, at the 4.2 m William Herschel Telescope, Roche de los Muchachos, Canary Islands, Spain, at the 2.2 m ESO/MPI telescope, La Silla, Chile, Proposal 079.D-0587, at the 2 m Liverpool Telescope, Roche de los Muchachos, Canary Islands, Spain, and at the 2 m Faulkes Telescope North, Haleakala Observatory, Hawaii, USA.

Musella, Ilaria; Ripepi, Vincenzo; Marconi, Marcella; Clementini, Gisella; Dall'Ora, Massimo; Scowcroft, Victoria; Moretti, Maria Ida; Di Fabrizio, Luca; Greco, Claudia; Coppola, Giuseppina; Bersier, David; Catelan, Márcio; Grado, Aniello; Limatola, Luca; Smith, Horace A.; Kinemuchi, Karen

2012-09-01

365

Color and Variability Characteristics of Point Sources in the Faint Sky Variability Survey  

SciTech Connect

The authors present an analysis of the color and variability characteristics for point sources in the Faint Sky Variability Survey (FSVS). The FSVS cataloged {approx} 23 square degrees in BVI filters from {approx} 16-24 mag to investigate variability in faint sources at moderate to high Galactic latitudes. Point source completeness is found to be >83% for a selected representative sample (V - 17.5-22.0 mag, B-V = 0.0-1.5) containing both photometric B, V detections and 80% of the time-sampled V data available compared to a basic internal source completeness of 99%. Multi-epoch (10-30) observations in V spanning minutes to years modeled by light curve simulations reveal amplitude sensitivities to {approx} 0.015-0.075 mag over a representative V = 18-22 mag range. Periodicity determinations appear viable to time-scales of an order 1 day or less using the most sampled fields ({approx} 30 epochs). The fraction of point sources is found to be generally variable at 5-8% over V = 17.5-22.0 mag. For V brighter than 19 mag, the variable population is dominated by low amplitude (< 0.05 mag) and blue (B-V < 0.35) sources, possibly representing a population of {gamma} Doradus stars. Overall, the dominant population of variable sources are bluer than B-V = 0.65 and have Main Sequence colors, likely reflecting larger populations of RR Lyrae, SX Phe, {gamma} Doradus, and W UMa variables.

Huber, M E; Everett, M E; Howell, S B

2005-03-07

366

Infrared Radiative Heat Transfer in Nongray Gases.  

National Technical Information Service (NTIS)

The object of this investigation was to study various approximate methods of analyzing infrared radiative heat transfer in nongray nonisothermal gases. For this purpose, a very simple physical system was chosen consisting of a gas bounded by two infinite ...

R. D. Cess P. Mighdoll S. N. Tiwari

1967-01-01

367

The Infrared Counterpart of the Bright X-ray Source GX340+0  

NASA Astrophysics Data System (ADS)

The intense X-ray source GX340+0, a ``Z source" of characteristics similar to Sco X-1, has been observed since the sounding rockets days of X-ray astronomy, but remains optically unidentified despite an accurate X-ray position. The inferred distance of many kpc and galactic latitude of b=0(deg) imply that the counterpart may be very heavily reddened. Recently Penninx et al. (A&A, in press) have reported detection of a variable radio source associated with the X-ray object, providing a new position of subarcsecond accuracy for the system. Using IRIS at the Anglo-Australian telescope, we have obtained a series of brief K-band images of the field. We detect an unresolved IR source of K=17.3 at a position precisely coincident (<1'') with that of the radio and X-ray source; uncertainties in the radio versus IR astrometric frames dominate the measuring errors. Poor observing conditions imply that the measured flux is probably uncertain by at least +/-0.5 mag. A comparison of our measured K-band flux with that typical for Sco X-1 indicates a (highly uncertain) distance ratio of ~ 12times for GX340+0 to Sco X-1, neglecting extinction differences. Although the distances to both of these X-ray sources are highly uncertain, this plausible ratio implies that the observed IR source at GX340+0 is consistent with that expected from the simplest possible model, where all Sco-like sources have similar IR luminosity. It is likely that this infrared object is at last the counterpart of GX340+0. However, the observed surface density of faint IR sources at this low galactic latitude implies a small but non-negligible probability of a chance superposition of an unrelated object upon the X-ray/radio source. Spectral or variability observations will therefore probably be required to irrevocably confirm the identification.

Miller, B.; Margon, B.; Burton, M. G.

1992-12-01

368

The Faint Sky Variability Survey: Searching for Low-Luminosity Cataclysmic Variables and Very Low-Mass Dwarfs  

Microsoft Academic Search

The Faint Sky Variability Survey is a large, deep field, optical, photometric survey using the Wide-Field Camera at the Isaac Newton Telescope on La Palma. Approximately 15 square degrees have been observed photometrically in BVI colors with variability sampling of 10s of minutes to a year. In line with two of the design goals, we are actively searching the photometry

M. E. Huber; S. B. Howell

2001-01-01

369

Search for Faint Companions to Nearby Solar-like Stars using the Adaptive Optics System at Mount Wilson Observatory  

Microsoft Academic Search

We present results of a search for faint companions to nearby (d \\\\ 25 pc) solar-like (F and G spectral type) stars using the natural guide star adaptive optics system on the Mount Wilson 100 inch (2.5 m) telescope during the period from 1996 June to 1999 August. The observing list, based on the third edition (1991) of the Catalogue

Nils H. Turner; Theo A. ten Brummelaar; Harold A. McAlister; Brian D. Mason; William I. Hartkopf

2001-01-01

370

Infrared Astronomy: More Than Our Eyes Can See Lithograph  

NSDL National Science Digital Library

This lithograph uses images of the Orion constellation to illustrate how a common astronomical object appears in both visible light and in the infrared. The back of the lithograph tells the history of infrared light and explains the benefits of infrared astronomy.

2000-01-01

371

The significance of faint visualization of the superior sagittal sinus in brain scintigraphy for the diagnosis of brain death  

SciTech Connect

Brain death is associated with cessation of blood flow to the brain. Tc-99m brain flow studies are used as a laboratory confirmatory test for the establishment of the diagnosis of brain death. Criteria for the diagnosis of cessation of blood flow to the brain are 1) visualization of carotid artery activity in the neck of the patient and 2) no visualization of activity in the distribution of the anterior and middle cerebral arteries. The authors noticed that in a significant number of patients, although there was no visualization of arterial blood flow to the brain the static images demonstrated faint accumulation of activity in the region of the superior sagittal sinus (SSS). In a four year period 212 brain flow studies were performed in 154 patients for diagnosis of brain death; of them 137 studies (65%) showed no evidence of arterial flow. In 103 out of the 137 studies (75%) there was no visualization of the SSS; in the remaining 34 studies (3l patients) however three patterns of faint activity attributed to partial and or faint visualization of the SSS could be recognized at the midline of the immediate anterior static view: a) linear from the cranial vault floor up b) disk shaped at the apex of the vault and c) disk shaped at the apex tailing caudad. All of the 3l patients in this group satisfied brain death criteria within four days of the last study which showed faint visualization of the superior sagittal sinus. The authors conclude that even in the presence of a faint visualization of the superior sagittal sinus on static post brain flow scintigraphy, the diagnosis of cessation of blood flow to the brain can be made if there is no evidence of arterial blood flow.

Bisset, R.; Sfakianakis, G.; Ihmedian, I.; Holzman, B.; Curless, R.; Serafini, A.

1985-05-01

372

POLDER instrument: mission objectives  

NASA Astrophysics Data System (ADS)

Polarization and directionality of Earth reflectances (POLDER) is an optical imaging radiometer developed by CNES for flight on NASA's ADEOS mission (launch date 1995). It is a wide field of view (50 degree(s)) and moderate spatial resolution (6 km) instrument, giving an almost daily coverage of the Earth. It gives access to the bidirectional reflectance and polarization distribution functions (BRDFs and BPDFs) by acquiring, for a given target, measurements in variable viewing configurations along the track of the satellite. These measurements are acquired in nine spectral bands of the visible-near infrared spectrum, and at three polarization angles at 443, 665, and 865 nm. Its main scientific objectives are: (1) tropospheric aerosols -- determination of the characteristics of the aerosols; (2) ocean color -- accurate determination of the sea surface reflectances, due in particular to improved capabilities of atmospheric corrections; (3) land surface -- determination of surface BRDFs and improvement of the correction of surface bidirectional effects and atmospheric effects on vegetation indices; (4) Earth radiation budget and clouds -- determination of clouds BRDF and classification of clouds according to bidirectional radiative properties, but also on cloud altitude and phase. The objective of the paper is to present and discuss these mission objectives.

Deschamps, P. Y.; Herman, M.; Podaire, A.; Ratier, A.

1992-12-01

373

Does disgust increase parasympathetic activation in individuals with a history of fainting? A psychophysiological analysis of disgust stimuli with and without blood-injection-injury association.  

PubMed

People with blood-injection-injury fear can faint when being confronted with blood, injections or injuries. Page (1994) holds that people with blood-injury phobia faint, because they are disgust sensitive and disgust facilitates fainting by eliciting parasympathetic activity. We tested the following two hypotheses: (1) Disgusting pictures elicit more disgust in blood-injection-injury-anxious people with a history of fainting than they do in controls. (2) Disgust causes parasympathetic activation. Subjects were 24 participants with high blood-injection-injury fear and a history of fainting in anxiety relevant situations and 24 subjects with average blood-injection-injury fear and no fainting history. We analyzed self-reported feelings of disgust, anxiety and faintness and reactions in heart rate, skin conductance, blood pressure and respiratory sinus arrhythmia during the confrontation with disgusting pictures with and without blood content. We did not find any evidence that the blood-injection-injury anxious subjects were more disgust sensitive than the control subjects and we also did not find any evidence that disgust elicits parasympathetic activation. PMID:23023164

Vossbeck-Elsebusch, Anna N; Steinigeweg, Katrin; Vögele, Claus; Gerlach, Alexander L

2012-07-31

374

Reducing malaria misdiagnosis: the importance of correctly interpreting Paracheck Pf® "faint test bands" in a low transmission area of Tanzania  

PubMed Central

Background Although malaria rapid diagnostic tests (RDTs) have been extensively evaluated since their introduction in the early 1990's, sensitivity and specificity vary widely limiting successful integration into clinical practice. This paper reviews specific issues surrounding RDT use in field settings and presents results of research investigating how to interpret "faint test bands" on ParaCheck Pf® in areas of low transmission in order to reduce malaria misdiagnosis. Methods A multi-phase cross-sectional study was conducted at a remote hospital in the northern Tanzanian highlands. Capillary blood samples were taken from consenting participants (n = 319) for blood smear and ParaCheck Pf® testing. Primary outcome variables were sensitivity, specificity and proportion misdiagnosed by ParaCheck Pf® and local microscopy. ParaCheck Pf® "faint bands" were classified as both true positives or true negatives during evaluation to determine appropriate clinical interpretation. Multivariate logistic regression adjusted for age and gender was conducted to determine odds of misdiagnosis for local microscopy and ParaCheck Pf®. Results Overall, 23.71% of all ParaCheck Pf® tests resulted in a "faint band" and 94.20% corresponded with true negatives. When ParaCheck Pf® "faint bands" were classified as positive, specificity was 75.5% (95% CI = 70.3% - 80.6%) as compared to 98.9% (95% CI = 97.0% - 99.8%) when classified as negative. The odds of misdiagnosis by local microscopy for those > 5 years as compared to those ? 5 years are 0.370 (95% CI = 0.1733 - 0.7915, p = 0.010). In contrast, even when ParaCheck Pf® faint bands are considered positive, the odds of misdiagnosis by ParaCheck Pf® for those > 5 years as compared to those ? 5 years are 0.837 (95% CI = 0.459 - 1.547, p = 0.5383). Conclusions We provide compelling evidence that in areas of low transmission, "faint bands" should be considered a negative test when used to inform clinical decision-making. Correct interpretation of RDT test bands in a clinical setting plays a central role in successful malaria surveillance, appropriate patient management and most importantly reducing misdiagnosis.

2011-01-01

375

AKARI Mid-Infrared All-Sky Survey Diffuse Map  

NASA Astrophysics Data System (ADS)

AKARI, the Japanese infrared astronomical satellite launched in February 2006, exhausted its liquid helium cryogen in August 2007. For about one and a half years of the cold mission phase, AKARI performed all-sky surveys in the two mid-infrared photometric bands centered at 9 and 18 microns with higher spatial resolutions and sensitivities than IRAS. Both bands cover slightly shorter wavelength ranges than the IRAS 12 and 25 micron bands and thus provide different information on the infrared sky. In particular, the AKARI 9 micron band map has unique advantage in tracing the distribution of polycyclic aromatic hydrocarbons (PAHs) for the whole sky. To enable discussion on faint diffuse interstellar emission, we have improved the AKARI mid-infrared all-sky diffuse maps by correcting artifacts such as those caused by space ionizing radiation and scattered light from the moon and very bright sources. The quality of these diffuse maps are now being checked within the AKARI team. We plan to release them to the public in near future.

Ishihara, Daisuke; Onaka, Takashi; Akari Team; Kaneda, Hidehiro; Oyabu, Shinki; Mouri, Akio; Kondo, Toru; Suzuki, Satoshi; Yamagishi, Mitsuyoshi

2012-07-01

376

THE TAIWAN ECDFS NEAR-INFRARED SURVEY: ULTRA-DEEP J AND K{sub S} IMAGING IN THE EXTENDED CHANDRA DEEP FIELD-SOUTH  

SciTech Connect

We present ultra-deep J and K{sub S} imaging observations covering a 30' Multiplication-Sign 30' area of the Extended Chandra Deep Field-South (ECDFS) carried out by our Taiwan ECDFS Near-Infrared Survey (TENIS). The median 5{sigma} limiting magnitudes for all detected objects in the ECDFS reach 24.5 and 23.9 mag (AB) for J and K{sub S} , respectively. In the inner 400 arcmin{sup 2} region where the sensitivity is more uniform, objects as faint as 25.6 and 25.0 mag are detected at 5{sigma}. Thus, this is by far the deepest J and K{sub S} data sets available for the ECDFS. To combine TENIS with the Spitzer IRAC data for obtaining better spectral energy distributions of high-redshift objects, we developed a novel deconvolution technique (IRACLEAN) to accurately estimate the IRAC fluxes. IRACLEAN can minimize the effect of blending in the IRAC images caused by the large point-spread functions and reduce the confusion noise. We applied IRACLEAN to the images from the Spitzer IRAC/MUSYC Public Legacy in the ECDFS survey (SIMPLE) and generated a J+K{sub S} -selected multi-wavelength catalog including the photometry of both the TENIS near-infrared and the SIMPLE IRAC data. We publicly release the data products derived from this work, including the J and K{sub S} images and the J+K{sub S} -selected multi-wavelength catalog.

Hsieh, Bau-Ching; Wang, Wei-Hao; Hsieh, Chih-Chiang; Lin, Lihwai; Lim, Jeremy; Ho, Paul T. P. [Institute of Astrophysics and Astronomy, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Yan Haojing [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)

2012-12-15

377

Geological sulfur isotopes indicate elevated OCS in the Archean atmosphere, solving faint young sun paradox  

PubMed Central

Distributions of sulfur isotopes in geological samples would provide a record of atmospheric composition if the mechanism producing the isotope effects could be described quantitatively. We determined the UV absorption spectra of 32SO2, 33SO2, and 34SO2 and use them to interpret the geological record. The calculated isotopic fractionation factors for SO2 photolysis give mass independent distributions that are highly sensitive to the atmospheric concentrations of O2, O3, CO2, H2O, CS2, NH3, N2O, H2S, OCS, and SO2 itself. Various UV-shielding scenarios are considered and we conclude that the negative ?33S observed in the Archean sulfate deposits can only be explained by OCS shielding. Of relevant Archean gases, OCS has the unique ability to prevent SO2 photolysis by sunlight at ? >202 nm. Scenarios run using a photochemical box model show that ppm levels of OCS will accumulate in a CO-rich, reducing Archean atmosphere. The radiative forcing, due to this level of OCS, is able to resolve the faint young sun paradox. Further, the decline of atmospheric OCS may have caused the late Archean glaciation.

Ueno, Yuichiro; Johnson, Matthew S.; Danielache, Sebastian O.; Eskebjerg, Carsten; Pandey, Antra; Yoshida, Naohiro

2009-01-01

378

Faint Extended OH Emission from the Local Interstellar Medium in the Direction l ? 108°, b ? 5°  

NASA Astrophysics Data System (ADS)

We have mapped faint 1667 OH line emission (TA ? 20-40 mK in our ?30' beam) along many lines of sight in the Galaxy covering an area of ?4° × 4° in the general direction of l ? 108°, b ? 5°. The OH emission is widespread, similar in extent to the local H I (r <~ 2 kpc) both in space and in velocity. The OH profile amplitudes show a good general correlation with those of H I in spectral channels of ?1 km s-1 this relation is described by TA (OH) ?1.50 × 10-4 TB (H I) for values of TB (H I) <~ 60-70 K. Beyond this the H I line appears to "saturate," and few values are recorded above ?90 K. However, the OH brightness continues to rise, by a further factor ?3. The OH velocity profiles show multiple features with widths typically 2-3 km s-1, but less than 10% of these features are associated with CO(1-0) emission in existing surveys of the area smoothed to comparable resolution.

Allen, Ronald J.; Ivette Rodríguez, Mónica; Black, John H.; Booth, Roy S.

2012-04-01

379

A new analysis strategy for detection of faint ?-ray sources with Imaging Atmospheric Cherenkov Telescopes  

NASA Astrophysics Data System (ADS)

A new background rejection strategy for ?-ray astrophysics with stereoscopic Imaging Atmospheric Cherenkov Telescopes (IACT), based on Monte Carlo (MC) simulations and real background data from the H.E.S.S. [High Energy Stereoscopic System, see [1].] experiment, is described. The analysis is based on a multivariate combination of both previously-known and newly-derived discriminant variables using the physical shower properties, as well as its multiple images, for a total of eight variables. Two of these new variables are defined thanks to a new energy evaluation procedure, which is also presented here. The method allows an enhanced sensitivity with the current generation of ground-based Cherenkov telescopes to be achieved, and at the same time its main features of rapidity and flexibility allow an easy generalization to any type of IACT. The robustness against Night Sky Background (NSB) variations of this approach is tested with MC simulated events. The overall consistency of the analysis chain has been checked by comparison of the real ?-ray signal obtained from H.E.S.S. observations with MC simulations and through reconstruction of known source spectra. Finally, the performance has been evaluated by application to faint H.E.S.S. sources. The gain in sensitivity as compared to the best standard Hillas analysis ranges approximately from 1.2 to 1.8 depending on the source characteristics, which corresponds to an economy in observation time of a factor 1.4 to 3.2.

Becherini, Y.; Djannati-Ataï, A.; Marandon, V.; Punch, M.; Pita, S.

2011-07-01

380

T he Faint Drifting Decameter Radio Bursts From The Solar Corona  

NASA Astrophysics Data System (ADS)

The radio observations of solar corona at decameter wavelengths reveal the presence of numerous faint, frequency drifting structures. We analyse observations performed on July 13th , 2002 with the DSP wideband spectrometer instrument implemented at the UTR-2 radiote- lescope. The main characteristics of these structures are statistically studied. Three populations of bursts are iden- tifies. The largest one presents negative frequency drifts of about -0.89 MHz.s-1 and a lifetime extending up to 11 sec (median value 2.72 sec). A second one shows positive frequency drifts of about +0.95 MHz.s-1 and a life- time extending up to 3 sec. The last population consists in structures with very small frequency drifts of about -0.1 MHz.s-1 and a shorter lifetime (about 1 sec). Assuming that those emissions are the signature of elec- tron beams propagating through the solar corona, we deduce that they have a velocity of about 3-5 times the electron thermal velocity. A new mechanism is proposed to explain the formation of plasma waves with such low beam velocity: spatially localized, temporal fluctuations of the electron distribution function width (heating).

Briand, C.; Zaslavsky, A.; Lecacheux, A.; Zarka, P.; Maksimovic, M.; Mangeney, A.

2007-01-01

381

THE OLD ENVIRONMENT OF THE FAINT CALCIUM-RICH SUPERNOVA SN 2005cz  

SciTech Connect

The supernova SN 2005cz has recently attracted some attention due to the fact that it was spectroscopically similar to type Ib supernovae (SNe Ib), a class that is presumed to result from the core collapse of massive stars, yet it occurred in an elliptical galaxy, where one expects very few massive stars to exist. Two explanations for this remarkable event were put forward. Perets et al. associate SN 2005cz with the class of Ca-rich, faint SNe Ib, which likely result from old double-white-dwarf systems with an He-rich secondary. On the other hand, Kawabata et al. suggest that SN 2005cz is indeed a core-collapse event (in a binary system), albeit of a star at the lower end of the mass range, 10-12 M{sub sun}. The existence of this star in its elliptical host is explained as resulting from low-level star formation (SF) activity in that galaxy. Here we present extensive observations of the location of SN 2005cz, sensitive to a variety of SF tracers, including optical spectroscopy, H{alpha} emission, UV emission, and Hubble Space Telescope photometry. We show that NGC 4589, the host galaxy of SN 2005cz, does not show any signatures of a young stellar population or recent SF activity either close to or far from the location of SN 2005cz.

Perets, Hagai B. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02338 (United States); Gal-yam, Avishay [Weizmann Institute of Science, POB 26, Rehovot (Israel); Crockett, R. Mark; Sullivan, Mark [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Anderson, Joseph P. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); James, Phil A. [Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom); Neill, James D. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Leonard, Douglas C. [Department of Astronomy, San Diego State University, San Diego, CA 92182 (United States)

2011-02-20

382

New Horizons Mission Planning Support: A Deep Search for Faint Rings of Pluto  

NASA Astrophysics Data System (ADS)

With the discoveries of Hydra and Nix, dwarf planet Pluto centers a more extensive satellite system than any terrestrial planet. Small moons are usually accompanied by rings of faint dust, which arise from impacts into their surfaces. Such rings show interesting dynamics including the influence of non-gravitational forces such as radiation pressure and Poynting-Robertson drag. A previous search for rings of Pluto in HST images was negative, but was limited by the scattered light from Pluto and Charon. Our more optimized plan will enable us to model and subtract out the scattered light pattern, yielding a detection threshold 10-30 times fainter than the prior limit. If Pluto sports a ring comparable to the major dust rings of the giant planets, our observing plan should detect it. This work supports the New Horizons mission by potentially revealing a dust hazard that might endanger the spacecraft during its 2015 flyby. It could also enhance the science return by allowing planners to target a known feature rather than conducting a more resource-intensive general search for rings. We request Director's Discretionary time because the Pluto observing sequence will be finalized in 2011; thus the observing window in June represents our last chance to obtain results that could influence the mission.;

Showalter, Mark

2009-07-01

383

SN 2011hs: A Fast and Faint Type IIb SN from a Supergiant Progenitor  

NASA Astrophysics Data System (ADS)

Type IIb Supernovae are the final evolutionary stage of massive stars that were able to retain only a thin (about 0.1 Mo) H/He external envelope at the time of the explosion. The nature of such progenitor stars (were they compact or extended stars?) and the mechanism of mass-loss that made such final structure possible (e.g. stellar winds, binary mass transfer, etc.) are still open issues. We present the preliminary results obtained from the study of a sample of Type IIb SNe. In particular, we present SN 2011hs, a IIb SN with peculiar properties: very high velocities from the spectroscopic lines and a faint and narrow bolometric light curve. Such observables suggest, as confirmed by the comparison with hydrodinamical numerical models, a small 56Ni mass ejected from a low-mass He core star. Finally, from the models, we obtain evidence for a progenitor with a radius of the order of 500 Ro, corresponding to an extended star as in the case of SNe 1993J and 2011dh.

Bufano, Filomena

2013-06-01

384

A faint type of supernova from a white dwarf with a helium-rich companion  

NASA Astrophysics Data System (ADS)

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 (~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 44Ti.

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.

2010-05-01

385

Archean Earth Atmosphere Fractal Haze Aggregates: Light Scattering Calculations and the Faint Young Sun Paradox  

NASA Astrophysics Data System (ADS)

As part of an ongoing undergraduate research project of light scattering calculations involving fractal carbonaceous soot aggregates relevant to current anthropogenic and natural sources in Earth's atmosphere, we have read with interest a recent paper [E.T. Wolf and O.B Toon,Science 328, 1266 (2010)] claiming that the Faint Young Sun paradox discussed four decades ago by Carl Sagan and others can be resolved without invoking heavy CO2 concentrations as a greenhouse gas warming the early Earth enough to sustain liquid water and hence allow the origin of life. Wolf and Toon report that a Titan-like Archean Earth haze, with a fractal haze aggregate nature due to nitrogen-methane photochemistry at high altitudes, should block enough UV light to protect the warming greenhouse gas NH3 while allowing enough visible light to reach the surface of the Earth. To test this hypothesis, we have employed a rigorous T-Matrix arbitrary-particle light scattering technique, to avoid the simplifications inherent in Mie-sphere scattering, on haze fractal aggregates at UV and visible wavelenths of incident light. We generate these model aggregates using diffusion-limited cluster aggregation (DLCA) algorithms, which much more closely fit actual haze fractal aggregates than do diffusion-limited aggregation (DLA) algorithms.

Boness, D. A.; Terrell-Martinez, B.

2010-12-01

386

A Search for Parsec-scale Radio Jets in Faint Quasar and Radio Galaxy Nuclei  

NASA Astrophysics Data System (ADS)

Parsec-scale radio jets in bright active galaxy nuclei have been well-studied, but they are generally directed toward Earth. To test relativistic jet models over a wide range in orientation, we are studying nuclei 10-1000 times weaker. Observations of four very faint nuclei in classical doubles were made at 8.4 GHz in December 2004 and March 2006 using the High Sensitivity Array (HSA). The radio galaxy 3C132 has a 5- mJy elliptical structure, but it is not clear if this might represent a one- or two-sided jet. The radio galaxy 3C34 shows a 1.5-mJy circular core with no jet. The radio galaxy 3C441 was not detected (< 1 mJy). The quasar 3C68.1 has a 1.2-mJy circular core with no jet. Thus, despite the HSA's extreme sensitivity, we have not made a clear detection of a single jet. This is somewhat surprising based on an extrapolation of a known core-jet brightness correlation to fainter nuclei, but core and jet Lorentz factors of 5-10 could explain the missing jets if a substantial fraction of the core emission is unbeamed at large orientation angles.

Hough, David; Aars, Christian

2007-10-01

387

A Search for Parsec-scale Radio Jets in Faint Quasar and Radio Galaxy Nuclei  

NASA Astrophysics Data System (ADS)

Parsec-scale radio jets in bright active galaxy nuclei have been well-studied, but they are generally directed toward Earth. To test relativistic jet models over a wide range in orientation, we are studying nuclei 10-1000 times weaker. Observations of four very faint nuclei in classical doubles were made at 8.4 GHz in December 2004 and March 2006 using the High Sensitivity Array (HSA). The radio galaxy 3C132 has a 5-mJy elliptical structure, but it is not clear if this might represent a one- or two-sided jet. The radio galaxy 3C34 shows a 1.5-mJy circular core with no jet. The radio galaxy 3C441 was not detected (less than 1 mJy). The quasar 3C68.1 has a 1.2-mJy circular core with no jet. Thus, despite the extreme sensitivity of the HSA, we have not made a clear detection of a single jet. This is somewhat surprising based on an extrapolation of a known core-jet brightness correlation to fainter nuclei, but core and jet Lorentz factors of 5-10 could explain the missing jets if a substantial fraction of the core emission is unbeamed at large orientation angles. We thank the AAS for a Small Research Grant.

Hough, David H.; Aars, C. E.

2007-12-01

388

ACCURATE STELLAR KINEMATICS AT FAINT MAGNITUDES: APPLICATION TO THE BOOeTES I DWARF SPHEROIDAL GALAXY  

SciTech Connect

We develop, implement, and characterize an enhanced data reduction approach which delivers precise, accurate, radial velocities from moderate resolution spectroscopy with the fiber-fed VLT/FLAMES+GIRAFFE facility. This facility, with appropriate care, delivers radial velocities adequate to resolve the intrinsic velocity dispersions of the very faint dwarf spheroidal (dSph) galaxies. Importantly, repeated measurements let us reliably calibrate our individual velocity errors (0.2 kms{sup -1} {<=} {delta}{sub V} {<=} 5 km s{sup -1}) and directly detect stars with variable radial velocities. We show, by application to the Booetes I dSph, that the intrinsic velocity dispersion of this system is significantly below 6.5 km s{sup -1} reported by previous studies. Our data favor a two-population model of Booetes I, consisting of a majority 'cold' stellar component, with velocity dispersion 2.4{sup +0.9}{sub -0.5} km s{sup -1}, and a minority 'hot' stellar component, with velocity dispersion {approx}9 km s{sup -1}, although we cannot completely rule out a single component distribution with velocity dispersion 4.6{sup 0.8}{sub -0.6} km s{sup -1}. We speculate that this complex velocity distribution actually reflects the distribution of velocity anisotropy in Booetes I, which is a measure of its formation processes.

Koposov, Sergey E.; Gilmore, G.; Walker, M. G.; Belokurov, V.; Evans, N. Wyn; Okamoto, S.; Penarrubia, J. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Fellhauer, M.; Gieren, W.; Geisler, D.; Monaco, L. [Departamento de Astronomia, Universidad de Concepcion (Chile); Norris, J. E. [Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia); Wilkinson, M. [Department of Physics and Astronomy, University of Leicester, Leics (United Kingdom); Wyse, R. F. G. [Department of Physics and Astronomy, The Johns Hopkins University, 3900 N. Charles Street, Baltimore, MD 21218 (United States); Zucker, D. B. [Department of Physics and Astronomy, Macquarie University, North Ryde, NSW 2109 (Australia)

2011-08-01

389

The H I column density distribution function in faint dwarf galaxies  

NASA Astrophysics Data System (ADS)

We present the H I column density distribution function, f(NHI), as measured from dwarf galaxies observed as part of the Faint Irregular Galaxy Giant Metrewave Radio Telescope (GMRT) Survey (FIGGS). We find that the shape of the dwarf galaxy f(NHI) is significantly different from the f(NHI) for high-redshift damped Lyman ? absorbers (DLAs) or the f(NHI) for a representative sample of z = 0 gas-rich galaxies. The dwarf f(NHI) falls much more steeply at high H I column densities as compared to the other determinations. While ˜10 per cent of the cross-section above NHI = 1020.3 atoms cm-2 at z = 0 is provided by dwarf galaxies, the fraction falls to ?1 per cent by NHI ˜ 1021.5 atoms cm-2. In the local universe, the contribution to the high NHI end of the f(NHI) distribution comes predominantly from the inclined discs of large galaxies. Dwarf galaxies, both because of their smaller scalelengths and their larger intrinsic axial ratios, do not produce large H I column densities even when viewed edge-on. If high-column-density DLAs/Gamma Ray Burst (GRB) hosts correspond to galaxies like the local dwarfs, this would require that either (i) the absorption arises from merging and not isolated systems or (ii) the observed lines of sight are strongly biased towards high-column-density regions.

Patra, Narendra Nath; Chengalur, Jayaram N.; Begum, Ayesha

2013-02-01

390

Passive Evolution: Are the Faint Blue Galaxy Counts Produced by a Population of Eternally Young Galaxies?  

NASA Astrophysics Data System (ADS)

A constant-age population of blue galaxies, postulated in the model of Gronwall & Koo, seems to provide an attractive explanation of the excess of very blue galaxies in the deep galaxy counts. Such a population may be generated by a set of galaxies with cycling star formation rates or, at the other extreme, be maintained by the continual formation of new galaxies that fade after they reach the age specified in the Gronwall & Koo model. For both of these hypotheses, we have calculated the luminosity functions, including the respective selection criteria, the redshift distributions, and the number counts in the BJ and K bands. We find a substantial excess in the number of galaxies at low redshift (0 < z < 0.05) over that observed in the Canada-France-Hawaii redshift survey (Lilly et al.) and at the faint end of the Las Campanas luminosity function (Lin et al.). Passive or mild evolution fails to account for the deep galaxy counts because of the implications for low-redshift determinations of the I-selected redshift distribution and the r-selected luminosity function in samples where the faded counterparts of the star-forming galaxies would be detectable.

Bouwens, Rychard J.; Silk, Joseph

1996-11-01

391

Near-infrared low-resolution spectroscopy of Pleiades L-type brown dwarfs  

NASA Astrophysics Data System (ADS)

Context. The fundamental properties of brown dwarfs evolve with age. Models describing the evolution of luminosities and effective temperatures, among other physical parameters, can be empirically constrained using brown dwarfs of various masses in star clusters of well-determined age and metallicity. Aims: We aim to carry out a spectroscopic and photometric characterization of low-mass brown dwarfs in the ~120 Myr old Pleiades open cluster. Methods: We obtained low-resolution, near-infrared spectra of the J = 17.4-18.8 mag candidate L-type brown dwarfs PLIZ 28 and 35, BRB 17, 21, 23, and 29, which are Pleiades members by photometry and proper motion. We also obtained spectra of the well-known J = 15.4-16.1 mag late M-type cluster members PPl 1, Teide 1, and Calar 3. Results: We find that the first six objects have early- to mid-L spectral types and confirm previously reported M-types for the three other objects. The spectra of the L0-type BRB 17 and PLIZ 28 present a triangular H-band continuum shape, indicating that this peculiar spectral feature persists until at least the age of the Pleiades. We add to our sample 36 reported M5-L0-type cluster members and collect their IC- and UKIDSS ZYJHK-band photometry. We confirm a possible interleaving of the Pleiades and field L-type sequences in the JHK absolute magnitude versus spectral type diagrams, and quantify marginally redder Pleiades J-K colours, by 0.11 ± 0.20 mag, possibly related to both reddening and youth. Using field dwarf bolometric correction - and effective temperature - spectral type relations, we obtain the Hertzsprung-Russell diagram of the Pleiades sample. Theoretical models reproduce the spectral sequence at M5.5-9, but appear to overestimate the luminosity or underestimate the effective temperature at L0-5. Conclusions: We classify six faint Pleiades brown dwarfs as early to mid L-type objects using low-resolution near-infrared spectra. We compare their properties to field dwarfs and theoretical models and estimate their masses to be in the range 0.025-0.035 M?.

Bihain, G.; Rebolo, R.; Zapatero Osorio, M. R.; Béjar, V. J. S.; Caballero, J. A.

2010-09-01

392

Search for Faint Companions to Nearby Solar-like Stars using the Adaptive Optics System at Mount Wilson Observatory  

Microsoft Academic Search

We present results of a search for faint companions to nearby (d<25 pc) solar-like (F and G spectral type) stars using the natural guide star adaptive optics system on the Mount Wilson 100 inch (2.5 m) telescope during the period from 1996 June to 1999 August. The observing list, based on the third edition (1991) of the Catalogue of Nearby

Nils H. Turner; Theo A. ten Brummelaar; Harold A. McAlister; Brian D. Mason; William I. Hartkopf; Lewis C. Roberts Jr.

2001-01-01

393

Advances in applications and methodology for aerial infrared thermography  

Microsoft Academic Search

Most aerial infrared (IR) is performed by the military, but there are commercial uses. Some of these non-military applications are the focus of this paper. Generally speaking, the farther away one can get from the object of an infrared survey, while maintaining the needed spatial resolution and thermal sensitivity, the more usable the data is. Wide areas and large objects

Gregory R. Stockton

2004-01-01

394

Passive Infrared Resolution Target.  

National Technical Information Service (NTIS)

According to this patent application an infrared measurement system is provided for determining the resolution of infrared sensors wherein perforated aluminum panels are positioned in a conventional target array for determining photographic resolution. Th...

L. O. Vroombout

1976-01-01

395

Infrared Motion Sensor Evaluation.  

National Technical Information Service (NTIS)

This report describes the test program performed by MERADCOM to determine the performance and reliability of model 19-115 Infrared Intrusion Sensor (IRIS). Three commercial infrared sensors were included in the test program to establish a base for compari...

W. C. Garrett

1978-01-01

396

Kinematic properties and stellar populations of faint early-type galaxies - I. Velocity dispersion measurements of central Coma galaxies  

NASA Astrophysics Data System (ADS)

We present velocity dispersion measurements for 69 faint early-type galaxies in the core of the Coma cluster, spanning -22.0 <~MR<~-17.5 mag. We examine the L-? relation for our sample and compare it to that of bright elliptical galaxies (Es) from the literature. The distribution of the the faint early-type galaxies in the L-? plane follows the relation L~?2.01+/-0.36, which is significantly shallower from L~?4 as defined for the bright Es. While increased rotational support for fainter early-type galaxies could account for some of the difference in slope, we show that it cannot explain it. We also investigate the colour-? relation for our Coma galaxies. Using the scatter in this relation, we constrain the range of galaxy ages as a function of their formation epoch for different formation scenarios. Assuming a strong coordination in the formation epoch of faint early-type systems in Coma, we find that most had to be formed at least 6 Gyr ago and over a short 1-Gyr period.

Matkovi?, A.; Guzmán, R.

2005-09-01