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1

NIFTE: The Near Infrared Faint-Object Telescope Experiment  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

2

Faint Infrared-Excess Field Galaxies: FROGs  

E-print Network

Deep near-infrared and optical imaging surveys in the field reveal a curious population of galaxies that are infrared-bright (I-K>4), yet with relatively blue optical colors (V-I20, is high enough that if placed at z>1 as our models suggest, their space densities are about one-tenth of phi-*. The colors of these ``faint red outlier galaxies'' (fROGs) may derive from exceedingly old underlying stellar populations, a dust-embedded starburst or AGN, or a combination thereof. Determining the nature of these fROGs, and their relation with the I-K>6 ``extremely red objects,'' has implications for our understanding of the processes that give rise to infrared-excess galaxies in general. We report on an ongoing study of several targets with HST & Keck imaging and Keck/LRIS multislit spectroscopy.

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

1997-12-10

3

Faint Infrared-Excess Field Galaxies FROGs  

E-print Network

Deep near-infrared and optical imaging surveys in the field reveal a curious population of galaxies that are infrared-bright (I-K>4), yet with relatively blue optical colors (V-I20, is high enough that if placed at z>1 as our models suggest, their space densities are about one-tenth of phi-*. The colors of these ``faint red outlier galaxies'' (fROGs) may derive from exceedingly old underlying stellar populations, a dust-embedded starburst or AGN, or a combination thereof. Determining the nature of these fROGs, and their relation with the I-K>6 ``extremely red objects,'' has implications for our understanding of the processes that give rise to infrared-excess galaxies in general. We report on an ongoing study of several targets with HST & Keck imaging and Keck/LRIS multislit spectroscopy.

Moustakas, L A; Zepf, S E; Bunker, A J

1997-01-01

4

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

5

Hubble Space Telescope, Faint Object Camera  

NASA Technical Reports Server (NTRS)

This drawing illustrates Hubble Space Telescope's (HST's), Faint Object Camera (FOC). The FOC reflects light down one of two optical pathways. The light enters a detector after passing through filters or through devices that can block out light from bright objects. Light from bright objects is blocked out to enable the FOC to see background images. The detector intensifies the image, then records it much like a television camera. For faint objects, images can be built up over long exposure times. The total image is translated into digital data, transmitted to Earth, and then reconstructed. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The HST detects objects 25 times fainter than the dimmest objects seen from Earth and provides astronomers with an observable universe 250 times larger than visible from ground-based telescopes, perhaps as far away as 14 billion light-years. The HST views galaxies, stars, planets, comets, possibly other solar systems, and even unusual phenomena such as quasars, with 10 times the clarity of ground-based telescopes. The HST was deployed from the Space Shuttle Discovery (STS-31 mission) into Earth orbit in April 1990. The Marshall Space Flight Center had responsibility for design, development, and construction of the HST. The Perkin-Elmer Corporation, in Danbury, Cornecticut, developed the optical system and guidance sensors.

1981-01-01

6

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

7

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

8

X-ray Counterparts of Infrared Faint Radio Sources  

NASA Astrophysics Data System (ADS)

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

Schartel, Norbert

2011-10-01

9

Fainting  

MedlinePLUS

... Lessons Social Media: Connect With Us First Aid: Fainting KidsHealth > Parents > First Aid & Safety > Printable Safety Guides > ... from falling. Contact your child's doctor about any fainting episode. Seek Emergency Medical Care If Your Child: ...

10

The Faint Infrared Grism Survey (FIGS)  

NASA Astrophysics Data System (ADS)

We propose uniquely deep near-infrared spectroscopy using the WFC3 IR grism down to a continuum limit of J=26.5, and line flux limit 4e-18 ergs/cm^2/s, yielding spectra of 6000 sources in 4 fields. Only Hubble can achieve such sensitivity, as we have demonstrated in our previous deep grism surveys with ACS.With the deep spectra obtained in the FIGS survey we will:(1) Probe the reionization epoch by spectroscopy of galaxies at z = 5.5-8.5, whether or not they show Lyman-alpha (LyA) line emission. Continuum breaks are hard to detect from the ground and LyA lines may be scarce at these redshifts. Spectroscopic redshifts will probe galaxy clustering and improve luminosity measurements, thereby improving estimatesof reionizing photons by at least 40%.(2) Robustly measure the fraction of galaxies with high EW LyA, to measure the neutral fraction of the IGM. We will be sensitive to LyA lines in the central period of reionization where we expect to see a change in LyA fraction.(3) Illuminate the formation processes of early type galaxies at 1

Malhotra, Sangeeta

2014-10-01

11

Faint Object Classification and Analysis System standard test image results  

Microsoft Academic Search

A set of standard test images has been analyzed using the Faint Object Classification and Analysis System (FOCAS). This paper presents an outline of the FOCAS software and algorithms followed by a summary of the results and a description of the archive containing the detailed analysis. The archive is available on magnetic tape. The detailed results may be used to

Francisco Valdes

1989-01-01

12

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

13

Fainting  

MedlinePLUS

... a person loses consciousness and falls over. After lying down, a person's head is at the same ... or getting up too quickly after sitting or lying down can cause someone to faint. Emotional stress. ...

14

Fainting  

MedlinePLUS

... brain does not get enough oxygen. You lose consciousness, or "pass out," for a brief time (usually ... Taking longer than a few seconds to regain consciousness Fainting when you turn your head to the ...

15

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

16

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

17

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

18

DEEP SPITZER OBSERVATIONS OF INFRARED-FAINT RADIO SOURCES: HIGH-REDSHIFT RADIO-LOUD ACTIVE GALACTIC NUCLEI?  

SciTech Connect

Infrared-faint radio sources (IFRSs) are a rare class of objects which are relatively bright at radio wavelengths but very faint at infrared and optical wavelengths. Here we present sensitive near-infrared observations of a sample of these sources taken as part of the Spitzer Extragalactic Representative Volume Survey. Nearly all the IFRSs are undetected at a level of {approx}1 {mu}Jy in these new deep observations, and even the detections are consistent with confusion with unrelated galaxies. A stacked image implies that the median flux density is S{sub 3.6{mu}m} {approx} 0.2 {mu}Jy or less, giving extreme values of the radio-infrared flux density ratio. Comparison of these objects with known classes of object suggests that the majority are probably high-redshift radio-loud galaxies, possibly suffering from significant dust extinction.

Norris, Ray P.; Mao, Minnie [CSIRO Australia Telescope National Facility, P.O. Box 76, Epping, NSW, 1710 (Australia); Afonso, Jose [Observatorio Astronomico de Lisboa, Faculdade de Ciencias, Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisbon (Portugal); Cava, Antonio [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Farrah, Duncan; Oliver, Seb [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Huynh, Minh T.; Mauduit, Jean-Christophe; Surace, Jason [Infrared Processing and Analysis Center, MS220-6, California Institute of Technology, Pasadena, CA 91125 (United States); Ivison, R. J. [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Jarvis, Matt [Centre for Astrophysics, Science and Technology Research Institute, University of Hertfordshire, Hatfield, Herts, AL10 9AB (United Kingdom); Lacy, Mark [NRAO, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Maraston, Claudia [Institute of Cosmology and Gravitation, Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom); Middelberg, Enno [Astronomisches Institut, Ruhr-Universitaet Bochum, Universitaetsstr. 150, 44801 Bochum (Germany); Seymour, Nick, E-mail: Ray.Norris@csiro.au [Mullard Space Science Laboratory, UCL, Holmbury St Mary, Dorking, Surrey, RH5 6NT (United Kingdom)

2011-07-20

19

Discovery of Faint Kuiper Belt Objects with the MOSIAC Camera  

NASA Astrophysics Data System (ADS)

Prior to 1992, most astronomers believed that all significant bodies in the Solar System were known. They were wrong. The discovery of 1992 QB_1 (Jewitt and Luu, 1993) and subsequent searches by these and other investigators have shown that a vast population of small - and perhaps some not so small - bodies exists in an annular region extending from 30 to at least 130 AU. This region, commonly called the Kuiper Belt, is believed to contain roughly 100,000 objects larger than 100 km diameter. To date, however, only 68 Kuiper Belt Objects (KBOs) have been securely discovered. These objects hold important clues to the dynamical and physical evolution of the Solar System. To make progress in our understanding of the Kuiper Belt, a much larger sample of its members must be discovered. Because small bodies at these distances are very faint and the area of the sky to be searched is vast, progress in discovering KBOs has been slow. The 4-m telescope with MOSAIC and WIYN are uniquely suited to rapidly improve this situation. Here, we request two 2-night runs on the 4-m, each followed by 4 quarter-night blocks of queue-scheduled time on WIYN to search for KBOs.

Millis, Robert L.; Buie, Marc W.; Wagner, R. Mark; Elliot, James L.

1999-02-01

20

Serendipitous Background Monitoring of the Hubble Space Telescope's Faint Object Spectrograph  

E-print Network

Serendipitous Background Monitoring of the Hubble Space Telescope's Faint Object Spectrograph John Baltimore, MD 21218 ABSTRACT The nature of the Hubble Space Telescope's (HST) low Earth orbit imposes The Faint Object Spectrograph on board the Hubble Space Telescope contains two digicon detectors each

Schneider, Glenn

21

Faint Object Camera imaging and spectroscopy of NGC 4151  

NASA Technical Reports Server (NTRS)

We describe ultraviolet and optical imaging and spectroscopy within the central few arcseconds of the Seyfert galaxy NGC 4151, obtained with the Faint Object Camera on the Hubble Space Telescope. A narrowband image including (O III) lambda(5007) shows a bright nucleus centered on a complex biconical structure having apparent opening angle approximately 65 deg and axis at a position angle along 65 deg-245 deg; images in bands including Lyman-alpha and C IV lambda(1550) and in the optical continuum near 5500 A, show only the bright nucleus. In an off-nuclear optical long-slit spectrum we find a high and a low radial velocity component within the narrow emission lines. We identify the low-velocity component with the bright, extended, knotty structure within the cones, and the high-velocity component with more confined diffuse emission. Also present are strong continuum emission and broad Balmer emission line components, which we attribute to the extended point spread function arising from the intense nuclear emission. Adopting the geometry pointed out by Pedlar et al. (1993) to explain the observed misalignment of the radio jets and the main optical structure we model an ionizing radiation bicone, originating within a galactic disk, with apex at the active nucleus and axis centered on the extended radio jets. We confirm that through density bounding the gross spatial structure of the emission line region can be reproduced with a wide opening angle that includes the line of sight, consistent with the presence of a simple opaque torus allowing direct view of the nucleus. In particular, our modelling reproduces the observed decrease in position angle with distance from the nucleus, progressing initially from the direction of the extended radio jet, through our optical structure, and on to the extended narrow-line region. We explore the kinematics of the narrow-line low- and high-velocity components on the basis of our spectroscopy and adopted model structure.

Boksenberg, A.; Catchpole, R. M.; Macchetto, F.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Crane, P.; Deharveng, J. M.; Disney, M. J.; Jakobsen, P.

1995-01-01

22

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

23

FOCAS: The Faint Object Camera and Spectrograph for the Subaru Telescope  

Microsoft Academic Search

The Faint Object Camera and Spectrograph (FOCAS) is a Cassegrain optical instrument for the Subaru Telescope. Its capabilities include 6'phi FOV direct imaging, low-resolution spectroscopy (R=250 - 2000 with 0\\

Nobunari Kashikawa; Kentaro Aoki; Ryo Asai; Noboru Ebizuka; Motoko Inata; Masanori Iye; Koji S. Kawabata; George Kosugi; Youichi Ohyama; Kiichi Okita; Tomohiko Ozawa; Yoshihiko Saito; Toshiyuki Sasaki; Kazuhiro Sekiguchi; Yasuhiro Shimizu; Hiroko Taguchi; Tadafumi Takata; Yasushi Yadoumaru; Michitoshi Yoshida

2002-01-01

24

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

25

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

26

The Subaru/XMM-Newton Deep Survey (SXDS). V. Optically Faint Variable Object Survey  

NASA Astrophysics Data System (ADS)

We present our survey for optically faint variable objects using multiepoch (8-10 epochs over 2-4 years) i'-band imaging data obtained with Subaru Suprime-Cam over 0.918 deg2 in the Subaru/XMM-Newton Deep Field (SXDF). We found 1040 optically variable objects by image subtraction for all the combinations of images at different epochs. This is the first statistical sample of variable objects at depths achieved with 8-10 m class telescopes or the Hubble Space Telescope. The detection limit for variable components is i'vari~25.5 mag. These variable objects were classified into variable stars, supernovae (SNe), and active galactic nuclei (AGNs), based on the optical morphologies, magnitudes, colors, and optical-mid-infrared colors of the host objects, spatial offsets of variable components from the host objects, and light curves. Detection completeness was examined by simulating light curves for periodic and irregular variability. We detected optical variability for 36%+/-2% (51%+/-3% for a bright sample with i'<24.4 mag) of X-ray sources in the field. Number densities of variable objects as functions of time intervals ?t and variable component magnitudes i'vari are obtained. Number densities of variable stars, SNe, and AGNs are 120, 489, and 579 objects deg-2, respectively. Bimodal distributions of variable stars in the color-magnitude diagrams indicate that the variable star sample consists of bright (V~22 mag) blue variable stars of the halo population and faint (V~23.5 mag) red variable stars of the disk population. There are a few candidates of RR Lyrae providing a possible number density of ~10-2 kpc-3 at a distance of >150 kpc from the Galactic center. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based on observations (program GN-2002B-Q-30) obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (US), the Particle Physics and Astronomy Research Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina).

Morokuma, Tomoki; Doi, Mamoru; Yasuda, Naoki; Akiyama, Masayuki; Sekiguchi, Kazuhiro; Furusawa, Hisanori; Ueda, Yoshihiro; Totani, Tomonori; Oda, Takeshi; Nagao, Tohru; Kashikawa, Nobunari; Murayama, Takashi; Ouchi, Masami; Watson, Mike G.; Richmond, Michael W.; Lidman, Christopher; Perlmutter, Saul; Spadafora, Anthony L.; Aldering, Greg; Wang, Lifan; Hook, Isobel M.; Knop, Rob A.

2008-03-01

27

Detection Algorithm of Small and Fast orbital objects using Faint Streaks; application to geosynchronous orbit objects  

NASA Astrophysics Data System (ADS)

This paper proposes an algorithm to detect small or apparently fast orbital objects from optical images making use of their faint streaks. In the conventional algorithm, a high signal-to-background-noise-ratio (e.g., 3 or more) is required to detect objects. In our algorithm, we sum signals along the streak direction to improve sensitivity. By applying this algorithm to multi-images, we can detect lower signal-to-noise ratio objects. The algorithm consists of following steps; 1) take local sums of signal intensity on each pixel along preliminarily predicted streak direction, 2) find middle point candidates of streaks on each image, 3) search candidates of a sequence of points aligning in a straight line, and 4) select the candidate with the best linearity and reliability. In this paper, we focus on objects around geosynchronous orbit where most of streaks are oriented to South-North direction. We note that it is not reasonable to apply this algorithm to low Earth orbit objects having no specific streak direction because of limited computational resources. It requires orbit information from other facilities (e.g., space-based sensors). We confirmed that we can detect a streak appeared on images with approximately 1 signal-to-background-noise-ratio with applying the algorithm.

Tagawa, Makoto; Hanada, Toshiya; Oda, Hiroshi; Kurosaki, Hirohisa; Yanagisawa, Toshifumi

28

a SUBARU Archival Search for Faint Trans-Neptunian Objects  

Microsoft Academic Search

We present the results of a survey for trans-Neptunian objects (TNOs) based on Subaru archival images, originally collected by Sheppard et al. in 2005 as part of a search for irregular satellites of Uranus. The survey region covers 2.8 deg2, centered on Uranus and observed near opposition on two adjacent nights. Our survey reaches half its maximum detection efficiency at

Cesar I. Fuentes; Matthew J. Holman

2008-01-01

29

Astrometry and Photometry of Faint, High Priority Solar System Objects  

NASA Astrophysics Data System (ADS)

We propose to use MOSAIC 1.1 on the Mayall 4-meter telescope to improve knowledge of the orbits and magnitudes of high priority classes of Near Earth Objects (NEOs) and other small solar system bodies that cannot be reached with our Spacewatch telescopes. Many asteroids and comets are being lost owing to insufficient followup astrometry, but only the most important ones can continue to be observed with the limited resources available. Objects flagged as high scientific priority and urgently in need of further observations include freshly discovered virtual impactors (VIs) and NEOs discovered by the soon-to-be reactivated WISE spacecraft. It is better to follow objects longer during their discovery apparitions than to search tens of degrees of arc for them when they return years later, hence our need to reach fainter magnitudes. Other targets for recovery include future targets of radar, NEOs previously detected by WISE with orbits or albedos suggesting potential for cometary activity, potential destinations for spacecraft, and returning NEOs with hard-won albedos and diameters previously determined by WISE in need of astrometry.

McMillan, Robert S.; Larsen, Jeffrey A.; Scotti, James V.; Bressi, Terrence H.; Maleszewski, Chester K.

2014-02-01

30

Astrometry and Photometry of Faint, High Priority Solar System Objects  

NASA Astrophysics Data System (ADS)

We request MOSAIC 1.1 on the Mayall 4-meter telescope to improve knowledge of the orbits and magnitudes of high priority classes of Near Earth Objects (NEOs) and other small solar system bodies that cannot be reached with our Spacewatch telescopes. Targets include freshly discovered virtual impactors (VIs), other close approachers, and NEOs discovered by the NEOWISE spacecraft. It is better to follow objects longer during their discovery apparitions than to search tens of degrees of arc for them when they return years later, hence the need to reach fainter magnitudes on short notice. About half of our targets are therefore unknown at the time of this proposal. Other targets for recovery include future targets of radar, NEOs previously detected by WISE with orbits or albedos suggesting potential for cometary activity, potential destinations for spacecraft, and returning NEOs with hard-won albedos and diameters determined by WISE that need astrometry. Our past use of the Mayall telescope has been determined by Co-Investigator Tim Spahr of the Minor Planet Center to provide ``dramatic improvement'' to orbits.

McMillan, Robert S.; Larsen, Jeff; Scotti, Jim; Bressi, Terry; Spahr, Tim; Maleszewski, Chet

2014-08-01

31

Object tracking in infrared imagery  

Microsoft Academic Search

In this paper, we propose a robust approach for object tracking in infrared imagery. Our method mainly applies the image intensity histogram distribution and intensity projection distributions and computes a likelihood measure between the candidate and the model distributions by evaluating the Mean Shift Vector. In addition, Gabor filters are applied here to enhance the contrast of the object with

Hui Chen; Ming Tang; Hanqing Lu

2003-01-01

32

Hubble Space Telescope Faint Object Camera calculated point-spread functions.  

PubMed

A set of observed noisy Hubble Space Telescope Faint Object Camera point-spread functions is used to recover the combined Hubble and Faint Object Camera wave-front error. The low-spatial-frequency wave-front error is parameterized in terms of a set of 32 annular Zernike polynomials. The midlevel and higher spatial frequencies are parameterized in terms of set of 891 polar-Fourier polynomials. The parameterized wave-front error is used to generate accurate calculated point-spread functions, both pre- and post-COSTAR (corrective optics space telescope axial replacement), suitable for image restoration at arbitrary wavelengths. We describe the phase-retrieval-based recovery process and the phase parameterization. Resultant calculated precorrection and postcorrection point-spread functions are shown along with an estimate of both pre- and post-COSTAR spherical aberration. PMID:18250862

Lyon, R G; Dorband, J E; Hollis, J M

1997-03-10

33

The faint limit of the Hubble Space Telescope faint object spectrograph and rejection of the cosmic-ray background  

NASA Technical Reports Server (NTRS)

The faintest object which can be observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) is set by the detector cosmic-ray background and not by object flux. We use data from Beaver and Lyons to show that 48% of the background counts are from cosmic rays which each generate a near instantaneous burst of two or more counts. Setting the FOS threshold parameter REJLIM = 1, which rejects all frames with more than one count increases the ratio of signal-to-dark counts (S/D) by a factor of 1.94, regardless of the frame time or the object signal, because half of the dark counts which arrive in single counts (from either cosmic-ray bursts or thermal dark current photoemission) are rejected at the same rate as the object signal. But the signal-to-noise ratio (SNR proportional to S/square root of S + D) increases by at most a factor of 1.35, and for realistic parameters and taking into account dead time, we expect a gain in SNR of only 1.18. If a diode has failed and now emits noise, no data at all will be recorded. The chance of this occurring is approximately = 10% , and for this reason we do not recommend the use of REJLIM. The two-point correlation function of dark counts per pixel has strong peaks every four pixels, caused by the action of quarter-stepping on the counts from large bursts. The counts from such bursts spread over at least 80-100 diodes, and we show that such bursts can be rejected during data reduction if the data are recorded in RAPID mode with individual exposures of about 35 seconds. The SNR of the spectrum can also be improved by weighting each exposure by its SNR (a function ofthe mean dark count rate at that time), since dark varies by a factor of 2 around an orbit. These two procedures together increase the SNR by a factor of 1.1.3 (a 28% gain in exposure time) in regions of a spectrum where the object is much fainter than the background. We find that the Ly-alpha and O I sky emission lines give at most 4 (counts/array/s/sq arcsec), and typically half this number. With a small frame time and a small entrance aperture, these counts cause REJLIM = 1 to reject only a few percent of the data. We discuss only the HST FOS blue side detector, but the same ideas apply to any photon counter which records bursts of noise, and the calculations resemble those for the loss of signal due to coincidences in photon counters. In the ideal photon counter the dark counts are readily distinguished from photons. One way to do this is to add detectors which records only dark current, so that every cosmic ray produces more than one count and the instrument can be operated in an anti-coincidence mode.

Tytler, David; Davis, Christopher

1995-01-01

34

Infrared-faint radio sources: a new population of high-redshift radio galaxies  

NASA Astrophysics Data System (ADS)

We present a sample of 1317 Infrared-faint radio sources (IFRSs) that, for the first time, are reliably detected in the infrared, generated by cross-correlating the Wide-field Infrared Survey Explorer (WISE) all-sky survey with major radio surveys. Our IFRSs are brighter in both radio and infrared than the first-generation IFRSs that were undetected in the infrared by the Spitzer Space Telescope. We present the first spectroscopic redshifts of IFRSs, and find that all but one of the IFRSs with spectroscopy have z > 2. We also report the first X-ray counterparts of IFRSs, and present an analysis of radio spectra and polarization, and show that they include gigahertz peaked-spectrum, compact steep-spectrum and ultra-steep-spectrum sources. These results, together with their WISE infrared colours and radio morphologies, imply that our sample of IFRSs represents a population of radio-loud active galactic nuclei at z > 2. We conclude that our sample consists of lower redshift counterparts of the extreme first-generation IFRSs, suggesting that the fainter IFRSs are at even higher redshift.

Collier, J. D.; Banfield, J. K.; Norris, R. P.; Schnitzeler, D. H. F. M.; Kimball, A. E.; Filipovi?, M. D.; Jarrett, T. H.; Lonsdale, C. J.; Tothill, N. F. H.

2014-03-01

35

WFC3 Spectroscopy of Faint Young Companions to Orion Young Stellar Objects  

NASA Astrophysics Data System (ADS)

We propose G141 grism spectroscopy of faint young companions to young stellar objects (YSOs) in the Orion molecular cloud which were recently identified in a WFC3/HST 1.6 micron survey of 320 YSOs in Orion. We will target the ten faintest companions detected between 80-1000 AU which have F160W magnitudes between 19 and 22.6 mag; these are too faint to obtain spectra from ground-based telecopes. The faint magnitudes of these ten companions suggest that they have masses as small as 5 Mjupiter depending on their age and reddening. To determine spectral types and masses for these sources, we will use grism spectroscopy to detect broad water features in the photospheric spectrum. These observations are part of a coordinated spectroscopy campaign; the remaining 50 brighter companions will be observed using spectrographs on the IRTF and SUBARU. These data will constrain the companion mass function at projected separations of 80-1000 AU from Orion young stellar objects. Given their faint magnitudes, as many as half of the 60 companions may be below the Hydrogen burning limit. With spectra, we can determine whether there is an excess of sub-stellar companions relative to the field IMF at these separations; the detection of such an excess would be evidence for the formation of sub-stellar objects in the outer regions of protostellar disks. Furthermore, the observed fraction of companions at these separations increases from 7.8 to 14.1% between low and high stellar density region in Orion; suggesting that the formation of multiple sytems is dependent on the birth environment. With spectra, we can explore the dependence of the companion mass function on the birth environment.

Megeath, S.

2014-10-01

36

Infrared spectroscopy of Sakurai's object  

NASA Astrophysics Data System (ADS)

We present near (ground-based) and far (ISO) infrared spectroscopy of Sakurai's object. As in the case of the optical spectrum, between 1996 and 1997 April the near-infrared spectrum underwent a dramatic change to later spectral type, and there is some evidence that the spectrum continued to evolve during 1997. Molecular features of carbon-bearing molecules (CN, C_2, CO) - corresponding to those seen in cool carbon stars - are now prominent in the 1-2.5mum range, and the ^12C/^13C ratio is low. The ISO data demonstrate the presence of hot circumstellar dust at a temperature of ~680K. If the dust shell is optically thin, the dust mass is ~2.8x10^-8Msolar.

Eyres, S. P. S.; Evans, A.; Geballe, T. R.; Salama, A.; Smalley, B.

1998-08-01

37

The Faint Stellar Object SDSS J1257+3419 is a Dark Matter Dominated System  

E-print Network

A recent study has revealed SDSS J1257+3419 is either a faint and small dwarf galaxy or a faint and widely extended globular cluster. In this Letter, the author suggests this stellar system is a dwarf spheroidal (dSph). Adopting an observational relation between binding energy and mass of old stellar systems, we derive a relation between mass and size of dSphs by assuming that they are dark matter dominated and virialized objects. Letting half-light radius represent size of SDSS J1257+3419, we find that its mass is $\\sim 7\\times 10^6$ solar mass. This indicates mass-to-light ratio ($M/L$) of SDSS J1257+3419 is about 1000 in the solar unit. This large $M/L$ is expected from a Mateo plot of dSphs. Thus, we insist SDSS J1257+3419 is a dSph.

Hideyuki Kamaya

2007-09-04

38

Hubble Space Telescope: Faint object camera instrument handbook. Version 2.0  

NASA Technical Reports Server (NTRS)

The Faint Object Camera (FOC) is a long focal ratio, photon counting device designed to take high resolution two dimensional images of areas of the sky up to 44 by 44 arcseconds squared in size, with pixel dimensions as small as 0.0007 by 0.0007 arcseconds squared in the 1150 to 6500 A wavelength range. The basic aim of the handbook is to make relevant information about the FOC available to a wide range of astronomers, many of whom may wish to apply for HST observing time. The FOC, as presently configured, is briefly described, and some basic performance parameters are summarized. Also included are detailed performance parameters and instructions on how to derive approximate FOC exposure times for the proposed targets.

Paresce, Francesco (editor)

1990-01-01

39

Hubble Space Telescope faint object camera instrument handbook (Post-COSTAR), version 5.0  

NASA Technical Reports Server (NTRS)

The faint object camera (FOC) is a long-focal-ratio, photon-counting device capable of taking high-resolution two-dimensional images of the sky up to 14 by 14 arc seconds squared in size with pixel dimensions as small as 0.014 by 0.014 arc seconds squared in the 1150 to 6500 A wavelength range. Its performance approaches that of an ideal imaging system at low light levels. The FOC is the only instrument on board the Hubble Space Telescope (HST) to fully use the spatial resolution capabilities of the optical telescope assembly (OTA) and is one of the European Space Agency's contributions to the HST program.

Nota, A. (editor); Jedrzejewski, R. (editor); Greenfield, P. (editor); Hack, W. (editor)

1994-01-01

40

Far-infrared properties of submillimeter and optically faint radio galaxies  

NASA Astrophysics Data System (ADS)

We use deep observations obtained with the Photodetector Array Camera and Spectrometer (PACS) onboard the Herschel Space Observatory to study the far-infrared (FIR) properties of submillimeter and optically faint radio galaxies (SMGs and OFRGs). From literature we compiled a sample of 35 securely identified SMGs and nine OFRGs located in the GOODS-N and the A2218 fields. This sample is cross-matched with our PACS 100 ?m and 160 ?m multi-wavelength catalogs based on sources-extraction using prior detections at 24 ?m. About half of the galaxies in our sample are detected in at least the PACS 160 ?m bandpass. The dust temperatures and the infrared luminosities of our galaxies are derived by fitting their PACS and SCUBA 850 ?m (only the upper limits for the OFRGs) flux densities with a single modified (? = 1.5) black body function. The median dust temperature of our SMG sample is Tdust = 36±8 K while for our OFRG sample it is Tdust = 47±3 K. For both samples, median dust temperatures derived from Herschel data agree well with previous estimates. In particular, Chapman et al. (2005, ApJ, 622, 772) found a dust temperature of Tdust = 36±7 K for a large sample of SMGs assuming the validity of the FIR/radio correlation (i.e., q= log10(LFIR[W]/L1.4 GHz[W Hz-1] /3.75×1012)). The agreement between our studies confirms that the local FIR/radio correlation effectively holds at high redshift even though we find < q > = 2.17±0.19, a slightly lower value than that observed in local systems. The median infrared luminosities of SMGs and OFRGs are 4.6×1012 L? and 2.6×1012 L?, respectively. We note that for both samples the infrared luminosity estimates from the radio part of the spectral energy distribution (SED) are accurate, while estimates from the mid-IR are considerably (~×3) more uncertain. Our observations confirm the remarkably high luminosities of SMGs and thus imply median star-formation rates of 960 M? yr-1 for SMGs with S(850 ?m)>5 mJy and 460 M? yr-1 for SMGs with S(850 ?m)>2 mJy, assuming a Chabrier IMF and no dominant AGN contribution to the far-infrared luminosity. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Magnelli, B.; Lutz, D.; Berta, S.; Altieri, B.; Andreani, P.; Aussel, H.; Castañeda, H.; Cava, A.; Cepa, J.; Cimatti, A.; Daddi, E.; Dannerbauer, H.; Dominguez, H.; Elbaz, D.; Förster Schreiber, N.; Genzel, R.; Grazian, A.; Gruppioni, C.; Magdis, G.; Maiolino, R.; Nordon, R.; Pérez Fournon, I.; Pérez García, I.; Poglitsch, A.; Popesso, P.; Pozzi, F.; Riguccini, L.; Rodighiero, G.; Saintonge, A.; Santini, P.; Sanchez-Portal, M.; Shao, L.; Sturm, E.; Tacconi, L.; Valtchanov, I.; Wieprecht, E.; Wiezorrek, E.

2010-07-01

41

Improving the Ability of Image Sensors to Detect Faint Stars and Moving Objects Using Image Deconvolution Techniques  

PubMed Central

In this paper we show how the techniques of image deconvolution can increase the ability of image sensors as, for example, CCD imagers, to detect faint stars or faint orbital objects (small satellites and space debris). In the case of faint stars, we show that this benefit is equivalent to double the quantum efficiency of the used image sensor or to increase the effective telescope aperture by more than 30% without decreasing the astrometric precision or introducing artificial bias. In the case of orbital objects, the deconvolution technique can double the signal-to-noise ratio of the image, which helps to discover and control dangerous objects as space debris or lost satellites. The benefits obtained using CCD detectors can be extrapolated to any kind of image sensors. PMID:22294896

Fors, Octavi; Nunez, Jorge; Otazu, Xavier; Prades, Albert; Cardinal, Robert D.

2010-01-01

42

Tracking motion objects in infrared videos  

Microsoft Academic Search

We propose motion detection and object tracking method that is particularly suitable for infrared videos. Detection of moving objects in infrared videos is based on changing texture in parts of the view field. We estimate the speed of texture change by measuring the spread of texture vectors in the texture space. This method allows us to robustly detect very fast

Longin Jan Latecki; Roland Miezianko; Dragoljub Pokrajac

2005-01-01

43

Adaptive Feature Selection for Infrared Object Tracking  

Microsoft Academic Search

This paper proposes a novel object tracking algorithm for the infrared object tracking. To improve the discrimination ability of the object model, the gray features which can be used to distinguish the object from its surrounding background is chosen to represent the object. This algorithm defines a discrimination function of gray features, and the \\

ShuPeng Wang

2010-01-01

44

Faint Object Camera observations of M87 - The jet and nucleus  

NASA Technical Reports Server (NTRS)

UV and optical images of the central region and jet of the nearby elliptical galaxy M87 have been obtained with about 0.1 arcsec resolution in several spectral bands with the Faint Object Camera (FOC) on the HST, including polarization images. Deconvolution enhances the contrast of the complex structure and filamentary patterns in the jet already evident in the aberrated images. Morphologically there is close similarity between the FOC images of the extended jet and the best 2-cm radio maps obtained at similar resolution, and the magnetic field vectors from the UV and radio polarimetric data also correspond well. We observe structure in the inner jet within a few tenths arcsec of the nucleus which also has been well studied at radio wavelengths. Our UV and optical photometry of regions along the jet shows little variation in spectral index from the value 1.0 between markedly different regions and no trend to a steepening spectrum with distance along the jet.

Boksenberg, A.; Macchetto, F.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Crane, P.; Deharveng, J. M.; Disney, M. J.; Jakobsen, P.; Kamperman, T. M.

1992-01-01

45

Infrared-based object tracking  

Microsoft Academic Search

Often it is necessary to track moving objects on horizontal paths. Human error and the associated cost and dangers of using humans lead to a requirement to automate this task. The system presented here was designed, built and tested. The system uses an IR beacon and a microcontroller receiver\\/controller module. The design consists of a field programmable gate array (FPGA)

Jon Gervais; Austin Youngblood; Walter H. Delashmit

2009-01-01

46

Electron-Multiplying CCD Imaging: Effectiveness for Stellar Occultations by Faint Objects  

NASA Astrophysics Data System (ADS)

Our Portable Occultation, Eclipse, and Transit Systems (POETS; Souza et al. 2006, PASP 118, 1550) have been successfully employed for multiple stellar occultation observations: (i) four systems obtained data in South America during the 11 July 2005 occultation of C313.2 (2UCAC 26257135) by Charon (Gulbis et al. 2006, Nature 439, 48; Person et al. 2006, AJ 132 1575); (ii) four systems obtained data in Australia during the 2006 June 12 occultation of P384.2 (2UCAC 26039859) by Pluto (Elliot et al. 2007, AJ 134, 1), and (iii) three systems were utilized in the Southwestern U.S. for the 2007 March 18 occultation of P445.2 (2UCAC 25823784) by Pluto (Person et al. 2007, this meeting). Pluto and Charon have apparent V magnitudes of 14 and 16, and the stars for these events had UCAC magnitudes of 14.99 to 15.25. These events were bright enough to achieve fair to excellent signal-to-noise ratios (SNRs) at cadences between 2 and 10 Hz by using "conventional” camera modes. POETS also possess electron-multiplying (EM) readout modes, which we have not yet employed for occultation observations because conventional modes have been more than adequate. EM modes have higher read noise, generate an excess noise factor, and limit dynamic range; however, signal can be increased by a factor of up to 1000x, and read noise is effectively eliminated at high EM gain. Here, we explore the benefits and disadvantages of using EM capability for observations of stellar occultations by faint bodies. We focus on prospective occultations by Kuiper Belt objects, predictions of which are increasingly numerous as fainter stars are considered. We identify regimes in which EM modes are most effective by analyzing SNR as a function of exposure time and object/star magnitudes. This work is supported by NASA Planetary Astronomy grants NNG04GF25G and NNG04GE48G.

Gulbis, Amanda A.; Elliot, J. L.; Person, M. J.; Souza, S. P.; Babcock, B. A.; Pasachoff, J. M.; McKay, A. J.; Zuluaga, C. A.

2007-10-01

47

Far-ultraviolet spectroscopy of the quasar UM 675 with the faint object spectrograph on the Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

To investigate the far-UV spectral properties of a QSO and to look for evidence of He I 584 A emission and absorption the Faint Object Spectrograph aboard the HST was used to observed UM 675. Light is detected down to 520 A in the object in the rest frame and limits are set to He I emission, the He I Gunn-Peterson effect at z = 2.148, and Ly-alpha absorption at z roughly 0.5.

Beaver, E. A.; Burbidge, E. M.; Cohen, Ross D.; Junkkarinen, Vesa T.; Lyons, Ronald W.

1991-01-01

48

Infrared Search for Young Brown Dwarf Companions around Young Stellar Objects in the rho Ophiuchi and the Serpens Molecular Clouds  

Microsoft Academic Search

We conducted an infrared search for faint companions around 351 young stellar objects in the rho Ophiuchi molecular cloud and the Serpens molecular cloud. Nine objects in the Spitzer\\/IRAC archival images were identified as being young stellar companion candidates. They showed an intrinsic infrared excess; one object was extremely red both in the [3.6] - [4.5] color and in the

Chiaki Shirono; Yoichi Itho; Yumiko Oasa

2011-01-01

49

Infrared stationary object acquisition and moving object tracking  

Microsoft Academic Search

Currently, there is much interest in developing electro-optic and infrared stationary and moving object acquisition and tracking algorithms for Intelligence, Surveillance, and Reconnaissance (ISR) and other applications. Many of the existing EO\\/IR object acquisition and tracking techniques work well for goodquality images, when object parameters such as size are well-known. However, when dealing with noisy and distorted imagery many techniques

Sengvieng Amphay; David Gray

2010-01-01

50

Mars ozone measurements near the 1995 aphelion: Hubble space telescope ultraviolet spectroscopy with the faint object spectrograph  

Microsoft Academic Search

Ultraviolet (225-330 nm) spectral scans of Mars were obtained with the Hubble space telescope (HST) faint object spectrograph (FOS) in February of 1995. These spectra yield ozone column abundances, cloud opacities (0.2-0.4 at low latitudes), and polar seasonal ice albedos from southern midlatitudes to northern high latitudes on Mars. At the time of these measurements, Mars was at a solar

R. Todd Clancy; Michael J. Wolff; Philip B. James; Ed Smith; Youssef N. Billawala; Steven W. Lee; Michael Callan

1996-01-01

51

JHK Observations of Faint Standard Stars in the Mauna Kea Near-Infrared Photometric System  

E-print Network

JHK photometry in the Mauna Kea Observatory (MKO) near-IR system is presented for 115 stars. Of these, 79 are UKIRT standards and 42 are LCO standards. The average brightness is 11.5 mag, with a range of 10 to 15. The average number of nights each star was observed is 4, and the average of the internal error of the final results is 0.011 mag. These JHK data agree with those reported by other groups to 0.02 mag. The measurements are used to derive transformations between the MKO JHK photometric system and the UKIRT, LCO and 2MASS systems. The 2MASS-MKO data scatter by 0.05 mag for redder stars: 2MASS-J includes H2O features in dwarfs and MKO-K includes CO features in giants. Transformations derived for stars whose spectra contain only weak features cannot give accurate transformations for objects with strong absorption features within a filter bandpasses. We find evidence of systematic effects at the 0.02 mag level in the photometry of stars with J<11 and H,K<10.5. This is due to an underestimate of the linearity correction for stars observed with the shortest exposure times; very accurate photometry of stars approaching the saturation limits of infrared detectors which are operated in double-read mode is difficult to obtain. Four stars in the sample, GSPC S705-D, FS 116 (B216-b7), FS 144 (Ser-EC84) and FS 32 (Feige 108), may be variable. 84 stars in the sample have 11< J< 15 and 10.5objects be employed as primary standards for that system [abridged].

S. K. Leggett; M. J. Currie; W. P. Varricatt; T. G. Hawarden; A. J. Adamson; J. Buckle; T. Carroll; J. K. Davies; C. J. Davis; T. H. Kerr; O. P. Kuhn; M. S. Seigar; T. Wold

2006-09-16

52

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

NASA Technical Reports Server (NTRS)

R136 is the luminous central object of the giant H II region 30 Doradus in the LMC. The first high-resolution observations of R136 with the Faint Object Camera on board the Hubble Space Telescope are reported. The physical nature of the brightest component R136a has been a matter of some controversy over the last few years. The UV images obtained show that R136a is a very compact star cluster consisting of more than eight stars within 0.7 arcsec diameter. From these high-resolution images a mass upper limit can be derived for the most luminous stars observed in R136.

Weigelt, G.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.; Crane, P.; Deharveng, J. M.; Disney, M. J.; Jakobsen, P.; Kamperman, T. M.

1991-01-01

53

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

54

Faint and peculiar objects in GAIA: results from GSC-II  

Microsoft Academic Search

The one billion objects in the GSC-II make up a formidable data set for the hunt of peculiar and rare targets such as late type stars, white dwarfs, carbon dwarfs, asteroids, variable stars, etc. Here we present a survey to search for ancient cool white dwarfs, which led to the discovery of several stars with peculiar spectral distributions and extreme

D. Carollo; A. Spagna; M. G. Lattanzi; R. L. Smart; S. T. Hodgkin; B. J. McLean

2003-01-01

55

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

Microsoft Academic Search

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'

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

2005-01-01

56

Imaging of four planetary nebulae in the Magellanic Clouds using the Hubble Space Telescope Faint Object Camera  

NASA Technical Reports Server (NTRS)

Using the Faint Object Camera on-board the Hubble Space Telescope, we have obtained images of four planetary nebulae (PNe) in the Magellanic Clouds, namely N2 and N5 in the SMC and N66 and N201 in the LMC. Each nebula was imaged through two narrow-band filters isolating forbidden O III 5007 and H-beta, for a nominal exposure time of 1000 s in each filter. In forbidden O III, SMC N5 shows a circular ring structure, with a peak-to-peak diameter of 0.26 arcsec and a FWHM of 0.35 arcsec while SMC N2 shows an elliptical ring structure with a peak-to-peak diameter of 0.26 x 0.21. The expansion ages corresponding to the observed structures in SMC N2 and N5 are of the order of 3000 yr. LMC N201 is very compact, with a FWHM of 0.2 arcsec in H-beta. The Type I PN LMC N66 is a multipolar nebula, with the brightest part having an extent of about 2 arcsec and with fainter structures extending over 4 arcsec.

Blades, J. C.; Barlow, M. J.; Albrecht, R.; Barbieri, C.; Boksenberg, A.; Crane, P.; Deharveng, J. M.; Disney, M. J.; Jakobsen, P.; Kamperman, T. M.

1992-01-01

57

Infrared Search for Young Brown Dwarf Companions around Young Stellar Objects in the ? Ophiuchi and the Serpens Molecular Clouds  

NASA Astrophysics Data System (ADS)

We conducted an infrared search for faint companions around 351 young stellar objects in the ? Ophiuchi molecular cloud and the Serpens molecular cloud. Nine objects in the Spitzer/IRAC archival images were identified as being young stellar companion candidates. They showed an intrinsic infrared excess; one object was extremely red both in the [3.6] - [4.5] color and in the [4.5] - [5.8] color, and two objects were red in the [4.5] - [5.8] color. They were as faint as 15 mag in the [3.6] band. Follow-up K-band spectroscopy revealed that the three objects had deep water absorption bands, indicative of low effective temperatures. By comparing their spectra and infrared spectral energy distributions with synthesized spectra of low-temperature objects, we derived the effective temperatures and continuum excesses for these objects. It is very likely that one is a low-mass stellar companion, and two others are young brown dwarf companions associated with young stellar objects.

Shirono, Chiaki; Itho, Yoichi; Oasa, Yumiko

2011-10-01

58

Real-Time Infrared Object Tracking Based on Mean Shift  

Microsoft Academic Search

\\u000a Themean shift algorithm is an efficient method for tracking object in the color image sequence. However, in the infrared object-tracking\\u000a scenario, there is a singular feature space, i.e. the grey space, for representing the infrared object. Due to the lack of\\u000a the information for the object representation, the object tracking based on the mean shift algorithm may be lost in

Jian Cheng; Jie Yang

2004-01-01

59

Fainting (Syncope)  

MedlinePLUS

... Tools & Tips Getting More Help Related Topics Arrhythmias Balance ... to younger adults, syncope—the medical term for fainting—occurs twice as often in adults older than 70, and three to four times as ...

60

An infrared search for substellar objects  

NASA Technical Reports Server (NTRS)

Preliminary results from a systematic search for nearby substellar objects in the IRAS data bases has revealed only a single candidate among the 12 micron sources in the region of the polar caps. This object appears to be a distant carbon star. All 5700 sources were positionally associated with stars or galaxies.

Low, F. J.

1987-01-01

61

Object Tracking using Joint Visible and Thermal Infrared  

E-print Network

is sensitive to changes in the lighting conditions of the scene. The use of thermal infrared image sequences can help the tracking process, as thermal infrared imagery is not sensitive to lighting conditions robot applications, tracking is needed to handle occlusions and disappeared objects [

Boyer, Edmond

62

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

63

Infrared Search for Young Brown Dwarf Companions around Young Stellar Objects in the rho Ophiucus Molecular Cloud and the Serpens Molecular Cloud  

E-print Network

We conducted an infrared search for faint companions around 351 young stellar objects in the rho Ophiucus molecular cloud and the Serpens molecular cloud. Nine objects in the Spitzer/IRAC archival images were identified as young stellar companion candidates. They showed an intrinsic infrared excess; one object was extremely red both in the [3.6] - [4.5] color and in the [4.5] - [5.8] color, and two objects were red in the [4.5] - [5.8] color. They were as faint as 15 mag in the [3.6] band. Follow-up K-band spectroscopy revealed that three objects had deep water absorption bands, indicative of low effective temperatures. By comparing the spectra and infrared spectral energy distributions with synthesized spectra of low-temperature objects, we derived the effective temperatures and continuum excess for these objects. It seems highly likely that one of the three objects is a low-mass stellar companion and two objects are young brown dwarf companions associated with the young stellar objects.

Shirono, Chiaki; Oasa, Yumiko

2011-01-01

64

Hubble Space Telescope faint object spectrograph Quasar Absorption System Snapshot Survey (AbSnap). 1: Astrometric optical positions and finding charts of 269 bright QSO  

NASA Technical Reports Server (NTRS)

We present finding charts and optical positions accurate to less than 1 arcsec for 269 bright (V less than or = 18.5) Quasi-Stellar Objects (QSOs). These objects were selected as candidates for the Hubble Space Telescope (HST) Quasar Absorption System Snapshot Survey (AbSnap), a program designed to use the Faint Object Spectrograph (FOS) to obtain short exposure ultraviolet (UV) spectra of bright QSOs. Many quasars were included because of their proximity to bright, low redshift galaxies and positions of these QSOs are measured accurately for the first time. Data were obtained using the digitized sky survey produced by the Space Telescope Science Institute's Guide Stars Selection System Astrometric Support Program.

Bowen, David V.; Osmer, Samantha J.; Blades, J. Chris; Tytler, David; Cottrell, Lance; Fan, Xiao-Ming; Lanzetta, Kenneth M.

1994-01-01

65

MOIRCS: multi-object infrared camera and spectrograph for SUBARU  

Microsoft Academic Search

MOIRCS is a new Cassegrain instrument of Subaru telescope, dedicated for wide field imaging and multi-object spectroscopy in near-infrared. MOIRCS has been constructed jointly by Tohoku University and the Subaru Telescope and saw the first light in Sept., 2004. The commissioning observations to study both imaging and spectroscopic performance were conducted for about one year. MOIRCS mounts two 2048 ×

Takashi Ichikawa; Ryuji Suzuki; Chihiro Tokoku; Yuka Katsuno Uchimoto; Masahiro Konishi; Tomohiro Yoshikawa; Toru Yamada; Ichi Tanaka; Koji Omata; Tetsuo Nishimura

2006-01-01

66

Classifying Tracked Objects and their Interactions from Infrared Imagery  

Microsoft Academic Search

For many intelligent security systems the use of infrared technology is becoming essential and is a challenging issue. This paper outlines a framework for exploiting spatio-temporal tracking parameters to classify multiple moving objects and recognize their interactions using low quality thermal imagery. For outdoor scenes, motion segmentation is automatically performed using a novel dynamic background-subtraction technique which robustly adapts detection

El Maadi Amar; Xavier Maldague

2006-01-01

67

Cygnids and Taurids - Two classes of infrared objects.  

NASA Technical Reports Server (NTRS)

In a study of the anonymous objects from the IRC Survey, we have found that about 10 percent have large long wave excesses. These infrared stars seem to belong to two classes, one group like NML Cygni (Cygnids) and the other like NML Tauri (Taurids).

Strecker, D. W.; Ney, E. P.; Murdock, T. L.

1973-01-01

68

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

69

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

70

Pyroelectric infrared sensor-based thermometer for monitoring indoor objects  

NASA Astrophysics Data System (ADS)

This article describes a system for measuring temperature by monitoring an object's radiation in the infrared spectrum. Using a measuring device by passing through a data acquisition interface, a long-term observation of the temperature variance of objects on a personal computer by the LabVIEW software is conducted. A special mechanism joined with a pyroelectric infrared (PIR) sensor, optical chopper, and Fresnel lens is presented in this system. This separable architecture makes the lens easily replaceable and portable. In this study, the PIR sensor into a quantitative measurement for long-term and long-distance applications with calibration equipment based on a blackbody and some electrometers was successfully applied. Experimental results show that the measuring device only has an average error rate of 1.21% in the overall range from 40 to 200 °C, and field of view is 4.58°. The results confirm that noncontacted temperature measurement using a PIR sensor is feasible.

Tsai, C. F.; Young, M. S.

2003-12-01

71

Object tracking in a stereo and infrared vision system  

Microsoft Academic Search

In this paper, we deal with the problem of real-time detection, recognition and tracking of moving objects in open and unknown environments using an infrared (IR) and visible vision system. A thermo-camera and two stereo visible-cameras synchronized are used to acquire multi-source information: three-dimensional data about target geometry and its thermal information are combined to improve the robustness of the

S. Colantonio; M. Benvenuti; M. G. Di Bono; G. Pieri; O. Salvetti

2007-01-01

72

The AKARI Far-Infrared Surveyor young stellar object catalog  

NASA Astrophysics Data System (ADS)

We demonstrate the use of the AKARI all-sky survey photometric data in the study of galactic star formation. Our aim was to select young stellar objects (YSOs) in the AKARI Far-Infrared Surveyor (FIS) Bright Source Catalogue. We used AKARI/FIS and Wide-field Infrared Survey Explorer (WISE) data to derive mid- and far-infrared colors of YSOs. Classification schemes based on quadratic discriminant analysis (QDA) have been given for YSOs and the training catalog for QDA was the whole-sky selection of previously known YSOs (i.e., listed in the SIMBAD database). A new catalog of AKARI FIS YSO candidates including 44001 sources has been prepared; the reliability of the classification is over 90%, as tested in comparison to known YSOs. As much as 76% of our YSO candidates are from previously uncatalogued types. The vast majority of these sources are Class I and II types according to the Lada classification. The distribution of AKARI FIS YSOs is well correlated with that of the galactic ISM; local over-densities were found on infrared loops and towards the cold clumps detected by Planck.

Tóth, L. Viktor; Marton, Gábor; Zahorecz, Sarolta; Balázs, Lajos G.; Ueno, Munetaka; Tamura, Motohide; Kawamura, Akiko; Kiss, Zoltán T.; Kitamura, Yoshimi

2014-02-01

73

Near-infrared spectroscopy of primitive solar system objects  

NASA Astrophysics Data System (ADS)

We have obtained near-infrared (H and K band at lambda/Delta(lambda) is approximately 480 to 600) spectra of a sample of primitive objects including 2 Centaur objects (2060 Chiron and 5145 Pholus) and 16 P- and D-type asteroids. The spectra were obtained at the United Kingdom Infrared Telescope using the cooled grating spectrometer CGS4, and were used to search for chemically diagnostic vibrational features in these primitive objects. Pholus exhibits broad adsorption features at 2.07 and 2.27 micrometers, as well as a weak feature at 1.72 micrometers. The 1.72- and 2.27-micrometer features are similar to those seen in a laboratory tar sand sample. No distinct absorption features are found in other objects, including Chiron, which displays a spectrally neutral continuum. A comparison of the P- and D-type asteroid spectra with laboratory measurements of organic solids shows no compelling evidence for hydrocarbon overtones seen in terrestrial bituminous tar sands.

Luu, Jane; Jewitt, David; Cloutis, Edward

1994-05-01

74

Near-infrared spectroscopy of primitive solar system objects  

NASA Technical Reports Server (NTRS)

We have obtained near-infrared (H and K band at lambda/Delta(lambda) is approximately 480 to 600) spectra of a sample of primitive objects including 2 Centaur objects (2060 Chiron and 5145 Pholus) and 16 P- and D-type asteroids. The spectra were obtained at the United Kingdom Infrared Telescope using the cooled grating spectrometer CGS4, and were used to search for chemically diagnostic vibrational features in these primitive objects. Pholus exhibits broad adsorption features at 2.07 and 2.27 micrometers, as well as a weak feature at 1.72 micrometers. The 1.72- and 2.27-micrometer features are similar to those seen in a laboratory tar sand sample. No distinct absorption features are found in other objects, including Chiron, which displays a spectrally neutral continuum. A comparison of the P- and D-type asteroid spectra with laboratory measurements of organic solids shows no compelling evidence for hydrocarbon overtones seen in terrestrial bituminous tar sands.

Luu, Jane; Jewitt, David; Cloutis, Edward

1994-01-01

75

Preliminary analysis of an ultraviolet Hubble Space Telescope faint object camera image of the center of M31  

NASA Technical Reports Server (NTRS)

A 5161 s exposure was taken with the FOC on the central 44 arcsec of M31, through a filter centered at 1750 A. Much of the light is redleak from visible wavelengths, but nearly half of it is genuine UV. The image shows the same central peak found earlier by Stratoscope, with a somewhat steeper dropoff outside that peak. More than 100 individual objects are seen, some pointlike and some slightly extended. We identify them as post-asymptotic giant branch stars, some of them surrounded by a contribution from their accompanying planetary nebulae. These objects contribute almost a fifth of the total UV light, but fall far short of accounting for all of it. We suggest that the remainder may result from the corresponding evolutionary tracks in a population more metal-rich than solar.

King, I. R.; Deharveng, J. M.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.; Crane, P.; Disney, M. J.; Jakobsen, P.; Kamperman, T. M.

1992-01-01

76

Discovery of Associated Absorption Lines in an X-Ray Warm Absorber: Hubble Space Telescope Faint Object Spectrograph Observations of MR 2251-178  

NASA Technical Reports Server (NTRS)

The presence of a 'warm absorber' was first suggested to explain spectral variability in an X-ray spectrum of the radio-quiet quasi-stellar object (QSO) MR 2251-178. A unified picture, in which X-ray warm absorbers and 'intrinsic' UV absorbers are the same, offers the opportunity to probe the nuclear environment of active galactic nuclei. To test this scenario and understand the physical properties of the absorber, we obtained a UV spectrum of MR 2251-178 with the Faint Object Spectrograph on board the Hubble Space Telescope (HST). The HST spectrum clearly shows absorption due to Lyalpha, N v, and C IV, blueshifted by 300 km s(exp -1) from the emission redshift of the QSO. The rarity of both X-ray and UV absorbers in radio-quiet QSOs suggests these absorbers are physically related, if not identical. Assuming the unified scenario, we place constraints on the physical parameters of the absorber and conclude the mass outflow rate is essentially the same as the accretion rate in MR 2251-178.

Monier, Eric M.; Mathur, Smita; Wilkes, Belinda; Elvis, Martin

2001-01-01

77

A study of ultraviolet absorption lines through the complete Galactic halo by the analysis of HST faint object spectrograph spectra of active Galactic nuclei, 1  

NASA Technical Reports Server (NTRS)

The ultraviolet (1150 - 2850 A) spectra of a number of active galactic nuclei (AGNs) observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) have been used to study the properties of the Galactic halo. The objects that served as probes are 3C 273, PKS 0454-220, Pg 1211+143, CSO 251, Ton 951, and PG 1351+640. The equivalent widths of certain interstellar ions have been measured, with special attention paid to the C IV/C II and Si IV/Si II ratios. These ratios have been intercompared, and the highest values are found in the direction of 3C 273, where C IV/C II = 1.2 and Si IV/Si II greater than 1. These high ratios may be due to a nearby supernova remnant, rather than to ionized gas higher up in the Galactic halo. Our data give some support to the notion that QSO metal-line systems may arise from intervening galaxies which contain high supernova rates, galactic fountains, and turbulent mixing layers.

Burks, Geoffrey S.; Bartko, Frank; Shull, J. Michael; Stocke, John T.; Sachs, Elise R.; Burbidge, E. Margaret; Cohen, Ross D.; Junkkarinen, Vesa T.; Harms, Richard J.; Massa, Derck

1994-01-01

78

THE GLOBULAR CLUSTER SYSTEM OF THE VIRGO GIANT ELLIPTICAL GALAXY NGC 4636. I. SUBARU/FAINT OBJECT CAMERA AND SPECTROGRAPH SPECTROSCOPY AND DATABASE  

SciTech Connect

We present a spectroscopic study of the globular clusters (GCs) in the giant elliptical galaxy NGC 4636 in the Virgo Cluster. We selected target GC candidates using the Washington photometry derived from the deep CCD images taken at the KPNO 4 m Telescope. Then we obtained the spectra of 164 target objects in the field of NGC 4636 using the Multi-Object Spectroscopy mode of Faint Object Camera and Spectrograph on the Subaru 8.2 m Telescope. We have measured the velocities for 122 objects: 105 GCs in NGC 4636, the nucleus of NGC 4636, 11 foreground stars, two background galaxies, and three probable intracluster GCs in the Virgo Cluster. The GCs in NGC 4636 are located in the projected galactocentric radius within 10' (corresponding to 43 kpc). The measured velocities for the GCs range from approx300 km s{sup -1} to approx1600 km s{sup -1}, with a mean value of 932{sup +25}{sub -22} km s{sup -1}, which is in good agreement with the velocity for the nucleus of NGC 4636, 928 +- 45 km s{sup -1}. The velocity dispersion of the GCs in NGC 4636 is derived to be 231{sup +15}{sub -17} km s{sup -1}, and the velocity dispersion of the blue GCs is slightly larger than that of the red GCs. Combining our results with data in the literature, we produce a master catalog of radial velocities for 238 GCs in NGC 4636. The velocity dispersion of the GCs in the master catalog is found to be 225{sup +12}{sub -9} km s{sup -1} for the entire sample, 251{sup +18}{sub -12} km s{sup -1} for 108 blue GCs, and 205{sup +11}{sub -13} km s{sup -1} for 130 red GCs.

Park, Hong Soo; Lee, Myung Gyoon; Hwang, Ho Seong [Astronomy Program, Department of Physics and Astronomy, Seoul National University (Korea, Republic of); Arimoto, Nobuo [National Astronomical Observatory of Japan, Tokyo (Japan); Tamura, Naoyuki [Subaru Telescope, National Astronomical Observatory of Japan, Hilo (United States); Onodera, Masato, E-mail: hspark@astro.snu.ac.k, E-mail: mglee@astro.snu.ac.k, E-mail: hoseong.hwang@cea.f, E-mail: masato.onodera@cea.f, E-mail: arimoto.n@nao.ac.j, E-mail: naoyuki@subaru.naoj.or [CEA, Laboratoire AIM, Irfu/SAp, F-91191 Gif-sur-Yvette (France)

2010-01-20

79

Rapid response near-infrared spectrophotometric characterization of Near Earth Objects  

NASA Astrophysics Data System (ADS)

Small NEOs are, as a whole, poorly characterized, and we know nothing about the physical properties of the majority of all NEOs. The rate of NEO discoveries is increasing each year, and projects to determine the physical properties of NEOs are lagging behind. NEOs are faint, and generally even fainter by the time that follow-up characterizations can be made days or weeks later. There is a need for a high-throughput, high-efficiency physical characterization strategy in which hundreds of faint NEOs can be characterized each year. Broadband photometry in the near-infrared is sufficiently diagnostic to assign taxonomic types, and hence constrain both the individual and ensemble properties of NEOs. We will present results from our recently initiated program of rapid response near-infrared spectrophotometric characterization of NEOs. We are using UKIRT (on Mauna Kea) and the RATIR instrument on the 1.5m telescope at the San Pedro Martir Observatory (Mexico) to allow us to make observations most nights of the year in robotic/queue mode. This technique is powerful and fast. We have written automated software that allows us to observe NEOs very soon after discovery. Our targets are NEOs that are generally too faint for other characterization techniques. We are on pace to characterize hundreds of NEOs per year.

Mommert, Michael; Trilling, David; Axelrod, Tim; Butler, Nat; Jedicke, Robert; Moskovitz, Nicholas; Pichardo, Barbara; Reyes, Mauricio

2014-11-01

80

Object Tracking and QOS Control Using Infrared Sensor and Video Cameras  

Microsoft Academic Search

Object tracking and the quality of service (QOS) control is one of key issues in sensor networks. In order to track objects and provide information about the location, trajectory and identity for each object, we propose a new object tracking scheme using both infrared sensors and video cameras, where infrared sensors are used to detect and locate moving objects, while

Can Zhang; Jiankang Wu; Guofang Tu

2006-01-01

81

Discovery of Two New Faint Cataclysmic Variables  

E-print Network

We report on the discovery of two new faint cataclysmic variables. The objects were selected as candidates from two different imaging surveys aimed at the discovery of such faint systems. One survey used color and variability while the other used color and H$_\\alpha$ emission as selection criteria. We present our spectra of the two new variables and discuss their properties. A discussion of the implication of these discoveries on the space density of faint cataclysmic variables is presented.

S. B. Howell; E. Mason; M. Huber; R. Clowes

2002-10-18

82

A 21 Centimeter Absorber Identified with a Spiral Galaxy: Hubble Space Telescope Faint Object Spectrograph and Wide-Field Camera Observations of 3CR 196  

NASA Technical Reports Server (NTRS)

We present imaging and spectroscopy of the quasar 3CR 196 (z(sub e) = 0.871), which has 21 cm and optical absorption at z(sub a) = 0.437. We observed the region of Ly alpha absorption in 3CR 196 at z(sub a) = 0.437 with the Faint Object Spectrograph on the Hubble Space Telescope. This region of the spectrum is complicated because of the presence of a Lyman limit and strong lines from a z(sub a) approx. z(sub e) system. We conclude that there is Ly alpha absorption with an H I column density greater than 2.7 x 10(exp 19) cm(exp -2) and most probably 1.5 x 10(exp 20) cm(exp -2). Based on the existence of the high H I column density along both the optical and radio lines of sight, separated by more than 15 kpc, we conclude that the Ly alpha absorption must arise in a system comparable in size to the gaseous disks of spiral galaxies. A barred spiral galaxy, previously reported as a diffuse object in the recent work of Boisse and Boulade, can be seen near the quasar in an image taken at 0.1 resolution with the Wide Field Planetary Camera 2 on the HST. If this galaxy is at the absorption redshift, the luminosity is approximately L(sub *) and any H I disk should extend in front of the optical quasar and radio lobes of 3CR 196, giving rise to both the Ly alpha and 21 cm absorption. In the z(sub a) approx. z(sub e) system we detect Lyman lines and the Lyman limit, as well as high ion absorption lines of C III, N V, S VI, and O VI. This absorption probably only partially covers the emission-line region. The ionization parameter is approximately 0.1. Conditions in this region may be similar to those in broad absorption line QSOs.

Cohen, Ross D.; Beaver, E. A.; Diplas, Athanassios; Junkkarinen, Vesa T.; Barlow, Thomas A.; Lyons, Ronald W.

1996-01-01

83

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

Microsoft Academic Search

Galaxy counts in the K band, (J-K) colors, and apparent size distributions of faint galaxies in the Subaru Deep Field (SDF) down to K~24.5 were studied in detail. Special attention has been paid to take into account various selection effects, including the cosmological dimming of surface brightness, to avoid any systematic bias that may be the origin of controversy in

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

2001-01-01

84

Tracking visual and infrared objects using joint Riemannian manifold appearance and affine shape modeling  

Microsoft Academic Search

This paper addresses the problem of object tracking from visual and infrared videos captured either by a dynamic or stationary camera where objects contain large pose changes. We propose a novel object tracking scheme that exploits the geometrical structure of Riemannian manifold and piecewise geodesics under a Bayesian framework. Two particle filters are alternatingly employed for tracking dynamic objects. One

Zulfiqar Hasan Khan; Irene Yu-Hua Gu

2011-01-01

85

Moving Object Detection on a Runway Prior to Landing Using an Onboard Infrared Camera  

E-print Network

Moving Object Detection on a Runway Prior to Landing Using an Onboard Infrared Camera Cheng-Hua Pai 55418 rida.hamza@honeywell.com Abstract Determining the status of a runway prior to landing is essential- jects on the runway from an onboard infrared camera prior to the landing phase. Since the runway

Southern California, University of

86

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

Microsoft Academic Search

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\\

Yoichi Itoh; Motohide Tamura; Tadashi Nakajima

1999-01-01

87

OBJECTIVE: Investigate the use of microbolometer infrared technology for real time imaging at THz frequencies.  

E-print Network

OBJECTIVE: Investigate the use of microbolometer infrared technology for real time imaging at THz microbolometer pixels for sensing at THz frequencies. PHASE 1: During the initial phase of research, a detailed study of real-time THz imaging character- istics of a microbolometer infrared camera will be carried out

88

Herbig-Haro Objects and Mid-infrared Outflows in the Vela C Molecular Cloud  

NASA Astrophysics Data System (ADS)

We have performed a deep [S II] ??6717/6731 wide field Herbig-Haro (HH) object survey toward the Vela C molecular cloud with a sky coverage of about 2 deg2. In total, 18 new HH objects, HH 1090-1107, are discovered and the two previously known HH objects, HH 73-74, are also detected in our [S II] images. We also present an investigation of mid-infrared outflows in the Vela C molecular cloud using the Wide-field Infrared Survey Explorer images taken from AllWISE data release. Using the method suggested by Zhang & Wang, 11 extended green objects (EGOs) are identified to be the mid-infrared outflows, including 6 new mid-infrared outflows that have not been detected previously at other wavelengths and 5 mid-infrared counterparts of the HH objects detected in this work. Using the AllWISE Source Catalog and the source classification scheme suggested by Koenig et al., we have identified 56 young stellar object (YSO) candidates in the Vela C molecular cloud. The possible driving sources of the HH objects and EGOs are discussed based on the morphology of HH objects and EGOs and the locations of HH objects, EGOs and YSO candidates. Finally we associate 12 HH objects and 5 EGOs with 10 YSOs and YSO candidates. The median length of the outflows in Vela C is 0.35 pc and the outflows seem to be oriented randomly.

Zhang, Miaomiao; Wang, Hongchi; Henning, Thomas

2014-08-01

89

Near-infrared Properties of the X-ray-emitting Young Stellar Objects in the Carina Nebula  

NASA Astrophysics Data System (ADS)

The Great Nebula in Carina (NGC 3372) is the best target to study in detail the process of violent massive star formation and the resulting feedback effects of cloud dispersal and triggered star formation. While the population of massive stars is rather well studied, the associated low-mass stellar population was largely unknown up to now. The near-infrared study in this paper builds on the results of the Chandra Carina Complex Project, that detected 14,368 X-ray sources in the 1.4 deg2 survey region, an automatic source classification study that classified 10,714 of these X-ray sources as very likely young stars in Carina, and an analysis of the clustering properties of the X-ray-selected Carina members. In order to determine physical properties of the X-ray-selected stars, most of which were previously unstudied, we used HAWK-I at the ESO Very Large Telescope to conduct a very deep near-IR survey with subarcsecond angular resolution, covering an area of about 1280 arcmin2. The HAWK-I images reveal more than 600,000 individual infrared sources, whereby objects as faint as J ? 23, H ? 22, and K s ? 21 are detected at signal-to-noise ratio (S/N) >=3. While less than half of the Chandra X-ray sources have counterparts in the Two Micron All Sky Survey catalog, the ~5 mag deeper HAWK-I data reveal infrared counterparts to 6636 (=88.8%) of the 7472 Chandra X-ray sources in the HAWK-I field. We analyze near-infrared color-color and color-magnitude diagrams to derive information about the extinctions, infrared excesses (as tracers for circumstellar disks), ages, and masses of the X-ray-selected objects. The near-infrared properties agree well with the results of the automatic X-ray source classification, showing that the remaining contamination in the X-ray-selected sample of Carina members is very low (lsim7%). The shape of the K-band luminosity function of the X-ray-selected Carina members agrees well with that derived for the Orion Nebula Cluster, suggesting that, down to the X-ray detection limit around 0.5-1 M sun, the shape of the initial mass function (IMF) in Carina is consistent with that in Orion (and thus the field IMF). The fraction of stars with near-infrared excesses is rather small, lsim10%, but shows considerable variations between individual parts of the complex. The distribution of extinctions for the diskless stars ranges from ~1.6 mag to ~6.2 mag (central 80th percentile), clearly showing a considerable range of differential extinction between individual stars in the complex.

Preibisch, Thomas; Hodgkin, Simon; Irwin, Mike; Lewis, James R.; King, Robert R.; McCaughrean, Mark J.; Zinnecker, Hans; Townsley, Leisa; Broos, Patrick

2011-05-01

90

NEAR-INFRARED PROPERTIES OF THE X-RAY-EMITTING YOUNG STELLAR OBJECTS IN THE CARINA NEBULA  

SciTech Connect

The Great Nebula in Carina (NGC 3372) is the best target to study in detail the process of violent massive star formation and the resulting feedback effects of cloud dispersal and triggered star formation. While the population of massive stars is rather well studied, the associated low-mass stellar population was largely unknown up to now. The near-infrared study in this paper builds on the results of the Chandra Carina Complex Project, that detected 14,368 X-ray sources in the 1.4 deg{sup 2} survey region, an automatic source classification study that classified 10,714 of these X-ray sources as very likely young stars in Carina, and an analysis of the clustering properties of the X-ray-selected Carina members. In order to determine physical properties of the X-ray-selected stars, most of which were previously unstudied, we used HAWK-I at the ESO Very Large Telescope to conduct a very deep near-IR survey with subarcsecond angular resolution, covering an area of about 1280 arcmin{sup 2}. The HAWK-I images reveal more than 600,000 individual infrared sources, whereby objects as faint as J {approx} 23, H {approx} 22, and K{sub s} {approx} 21 are detected at signal-to-noise ratio (S/N) {>=}3. While less than half of the Chandra X-ray sources have counterparts in the Two Micron All Sky Survey catalog, the {approx}5 mag deeper HAWK-I data reveal infrared counterparts to 6636 (=88.8%) of the 7472 Chandra X-ray sources in the HAWK-I field. We analyze near-infrared color-color and color-magnitude diagrams to derive information about the extinctions, infrared excesses (as tracers for circumstellar disks), ages, and masses of the X-ray-selected objects. The near-infrared properties agree well with the results of the automatic X-ray source classification, showing that the remaining contamination in the X-ray-selected sample of Carina members is very low ({approx}<7%). The shape of the K-band luminosity function of the X-ray-selected Carina members agrees well with that derived for the Orion Nebula Cluster, suggesting that, down to the X-ray detection limit around 0.5-1 M{sub sun}, the shape of the initial mass function (IMF) in Carina is consistent with that in Orion (and thus the field IMF). The fraction of stars with near-infrared excesses is rather small, {approx}<10%, but shows considerable variations between individual parts of the complex. The distribution of extinctions for the diskless stars ranges from {approx}1.6 mag to {approx}6.2 mag (central 80th percentile), clearly showing a considerable range of differential extinction between individual stars in the complex.

Preibisch, Thomas [Universitaets-Sternwarte Muenchen, Ludwig-Maximilians-Universitaet, Scheinerstr. 1, 81679 Muenchen (Germany); Hodgkin, Simon; Irwin, Mike; Lewis, James R. [Cambridge Astronomical Survey Unit, Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); King, Robert R. [Astrophysics Group, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QL (United Kingdom); McCaughrean, Mark J. [European Space Agency, Research and Scientific Support Department, ESTEC, Postbus 299, 2200 AG Noordwijk (Netherlands); Zinnecker, Hans [Deutsches SOFIA Institut, Universitaet Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany); Townsley, Leisa; Broos, Patrick [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park PA 16802 (United States)

2011-05-01

91

Geodesic Active Contour Based Fusion of Visible and Infrared Video for Persistent Object Tracking  

Microsoft Academic Search

Persistent object tracking in complex and adverse environments can be improved by fusing information from multiple sensors and sources. We present a new moving object detection and tracking system that robustly fuses infrared and visible video within a level set framework. We also introduce the concept of the flux tensor as a generalization of the 3D structure tensor for fast

Filiz Bunyak; Kannappan Palaniappan; Sumit Kumar Nath; Guna Seetharaman

2007-01-01

92

Automatic Registration of Color and Infrared Videos Using Trajectories Obtained from a Multiple Object Tracking Algorithm  

Microsoft Academic Search

The registration of images from multiple types of sensors (particularly infrared sensors and color sensors) is the first step to achieving multi-sensor fusion. This is the subject of this paper. Registration is performed by using the trajectories of the moving objects obtained by a novel multiple object tracking algorithm. The trajectories are matched using a RANSAC-based algorithm. The registration criteria

François Morin; Atousa Torabi; Guillaume-alexandre Bilodeau

2008-01-01

93

Multiple cues fusion for object tracking with particle filter in infrared image  

Microsoft Academic Search

Object tracking in infrared image sequences is a challenging research topic due to the extremely low signal to noise ratio of IR image. In this paper, a new tracking method based on multiple cues fusion particle filter framework is proposed. In order to make full use of the object appearance information, both the spatial distribution and the gray distribution of

Ting Jin; Fu-Gen Zhou; Xiang-Zhi Bai; Ken Chen

2009-01-01

94

The Near Infrared Camera and Multi-Object Spectrometer, Ready for Launch  

Microsoft Academic Search

The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is a second- generation instrument to be installed on the Hubble Space Telescope (HST) during the February 13, 1997 on-orbit servicing mission. NICMOS will provide infrared imaging and spectroscopic observations of astronomical targets in the spectral range 0.8-2.5 microns. Integration, testing, and ground-calibration of NICMOS was completed in September, 1996. Expected instrumental

G. Schneider; R. I. Thompson; M. Rieke; E. Mentzell

1996-01-01

95

The development of ground-based infrared multi-object spectrograph based on the microshutter array  

NASA Astrophysics Data System (ADS)

We report on our development of a near-infrared multi-object spectrograph for ground-based applications using the micro-shutter array, which was originally developed for the Near Infrared Spectrograph of the James Webb Space Telescope. The micro-shutter array in this case acts as a source selector at a reimaged telescope focal plane. The developed spectrograph will be implemented either with ground-layer adaptive optics system or multi-conjugate adaptive optics system on a large telescope. This will enable for the first time fully reconfigurable infrared multi-object spectroscopy with adaptive optics systems. We envision studying diverse astronomical objects with our spectrograph, including high-redshift galaxies, galaxy clusters and super star clusters.

Moon, Dae-Sik; Sivanandam, Suresh; Kutyrev, Alexander S.; Moseley, Samuel H.; Graham, James R.; Roy, Aishwarya

2014-07-01

96

Characterization and Application of a Grazing Angle Objective for Quantitative Infrared Reflection Microspectroscopy  

NASA Technical Reports Server (NTRS)

A grazing angle objective on an infrared microspectrometer is studied for quantitative spectroscopy by considering the angular dependence of the incident intensity within the objective's angular aperture. The assumption that there is no angular dependence is tested by comparing the experimental reflectance of Si and KBr surfaces with the reflectance calculated by integrating the Fresnel reflection coefficient over the angular aperture under this assumption. Good agreement was found, indicating that the specular reflectance of surfaces can straight-forwardly be quantitatively integrated over the angular aperture without considering non-uniform incident intensity. This quantitative approach is applied to the thickness determination of dipcoated Krytox on gold. The infrared optical constants of both materials are known, allowing the integration to be carried out. The thickness obtained is in fair agreement with the value determined by ellipsometry in the visible. Therefore, this paper illustrates a method for more quantitative use of a grazing angle objective for infrared reflectance microspectroscopy.

Pepper, Stephen V.

1995-01-01

97

SIFT-based object recognition for tracking in infrared imaging system  

Microsoft Academic Search

In this paper, we propose an automatic object tracking and recognition in unknown environments by using scale-invariant feature transform (SIFT) in PowerPC-based infrared (IR) imaging system. Proposed method consists of two stages. First, we must localize the interest point in position and scale of moving objects. Second, we must build a description of the interest point and recognize moving objects.

Sunghun Jung

2009-01-01

98

Development of multi-object spectroscopy unit for simultaneous-color wide-field infrared multi-object spectrograph  

NASA Astrophysics Data System (ADS)

SWIMS (Simultaneous-color Wide-field Infrared Multi-object Spectrograph) has a multi-object spectroscopic function including IFU in addition to the imaging capability. The mechanism in order to achieve this function is Multi-Object Spectroscopy Unit. This is the function that can derive spectra of simultaneous 20-30 objects over range from 0.9 to 2.5?mm. To set or exchange a slit mask on telescope focal plane, MOSU consists of the slit-mask dewar (carrousel), focal plane dewar, and robotic arm called mask catcher. There are many structural and mechanical features in MOSU to achieve its performance in cooling system, positional repeatability of slit mask and so on. We present here its unique components and its specifications and performance.

Takahashi, Hidenori; Konishi, Masahiro; Motohara, Kentaro; Kato, Natsuko M.; Tateuchi, Ken; Kitagawa, Yurato; Todo, Soya

2014-08-01

99

A novel layered object tracking algorithm for forward-looking infrared imagery based on mean shift and feature matching  

Microsoft Academic Search

A novel layered object tracking algorithm for FLIR imagery is proposed based on mean shift algorithm and feature matching. First, infrared object is modeled by kernel histogram. Bhattacharyya coefficient is used to measure the similarity between object model and candidate model. The object is then localized by mean shift algorithm rapidly and efficiently. Because of the low contrast between infrared

Wei Yang; Junshan Li; Jing Liu; Deqin Shi

2009-01-01

100

The Nature of Faint Submillimeter Galaxies  

E-print Network

We summarise the main results on the faint submillimeter (submm) galaxy population which have come from the SCUBA Cluster Lens Survey. We detail our current understanding of the characteristics of these submm-selected galaxies across wavebands from X-rays to radio. After presenting the main observational properties of this population we conclude by discussing the nature of these distant, ultraluminous infrared galaxies and their relationship to other high-redshift populations.

Ian Smail; Rob Ivison; Andrew Blain; Jean-Paul Kneib

2000-08-16

101

Herbig-Haro objects 1 and 2 - Another infrared candidate for their energy source  

Microsoft Academic Search

A possible source for the excitation energy of Herbig-Haro objects 1 and 2 has been detected at wavelengths of 1 - 4 mum. Its position coincides with a recent detection of a 6-cm radio continuum source and the centre of an NH3 torus orientated perpendicularly to the line joining H-H 1 and 2. Its infrared (1 - 200 mum) luminosity

L. F. Rodriguez; M. Roth; M. Tapia

1985-01-01

102

Moving Object Detection and Tracking in Forward Looking InfraRed Aerial Imagery  

Microsoft Academic Search

This chapter discusses the challenges of automating surveillance and reconnaissance tasks for infra-red visual data obtained from aerial platforms. These problems have gained significant importance over the years, especially with the advent of light weight and reliable imaging devices. Detection and tracking of objects of interest has traditionally been an area of interest in the computer vision literature. These tasks

Subhabrata Bhattacharya; Imran Saleemi; Mubarak Shah

2011-01-01

103

The effect of infrared and visible image fusion on object tracking using correlation matching  

Microsoft Academic Search

This paper studies on how the performance of object tracking using correlation matching can be affected by the pixel-level infrared and visible image fusion approaches, as compared to tracking using single modality source images. Several classic grayscale and color image fusion approaches have been investigated, with the former including traditional DWT method and our proposed adaptive weighted average method based

Songfeng Yin; Liangcai Cao; Guofan Jin

2011-01-01

104

NEOWISE: Proposed Discovery of Near-Earth Objects in the Infrared by the WISE Mission  

Microsoft Academic Search

The Wide-field Infrared Survey Explorer will make hundreds of thousands of incidental detections of asteroids. Main belt asteroids as small as 3 km in diameter and hundreds of Near-Earth Objects (NEOs) as small as a few hundred meters in diameter will be above WISE's detection thresholds at 12 and 23 microns wavelength. Standard data products will include accurate positions and

Robert S. McMillan; A. K. Mainzer; R. G. Walker; E. L. Wright; P. R. Eisenhardt; R. M. Cutri; T. Grav

2009-01-01

105

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

106

Technical considerations for designing low-cost, long-wave infrared objectives  

NASA Astrophysics Data System (ADS)

With the growth of uncooled infrared imaging in the consumer market, the balance between cost implications and performance criteria in the objective lens must be examined carefully. The increased availability of consumer-grade, long-wave infrared cameras is related to a decrease in military usage but it is also due to the decreasing costs of the cameras themselves. This has also driven up demand for low-cost, long-wave objectives that can resolve smaller pixels while maintaining high performance. Smaller pixels are traditionally associated with high cost objectives because of higher resolution requirements but, with careful consideration of all the requirements and proper selection of materials, costs can be moderated. This paper examines the cost/performance trade-off implications associated with optical and mechanical requirements of long-wave infrared objectives. Optical performance, f-number, field of view, distortion, focus range and thermal range all affect the cost of the objective. Because raw lens material cost is often the most expensive item in the construction, selection of the material as well as the shape of the lens while maintaining acceptable performance and cost targets were explored. As a result of these considerations, a low-cost, lightweight, well-performing objective was successfully designed, manufactured and tested.

Desroches, Gerard; Dalzell, Kristy; Robitaille, Blaise

2014-06-01

107

Characterization of High Proper Motion Objects from the Wide-field Infrared Survey Explorer  

NASA Astrophysics Data System (ADS)

We present an analysis of high proper motion objects that we have found in a recent study and in this work with multi-epoch astrometry from the Wide-field Infrared Survey Explorer (WISE). Using photometry and proper motions from the Two Micron All-Sky Survey and WISE, we have identified the members of this sample that are likely to be late-type, nearby, or metal-poor. We have performed optical and near-infrared spectroscopy on 41 objects, from which we measure spectral types that range from M4-T2.5. This sample includes 11 blue L dwarfs and 5 subdwarfs; the latter were also classified as such in the recent study by Kirkpatrick and coworkers. Based on their spectral types and photometry, several of our spectroscopic targets may have distances of <20 pc with the closest at ~12 pc. The tangential velocities implied by the spectrophotometric distances and proper motions indicate that four of the five subdwarfs are probably members of the Galactic halo while several other objects, including the early-T dwarf WISE J210529.08-623558.7, may belong to the thick disk. Based on data from the Wide-field Infrared Survey Explorer, the Two Micron All-Sky Survey, the NASA Infrared Telescope Facility, Gemini Observatory, the SOAR Telescope, and the Magellan Telescopes.

Luhman, K. L.; Sheppard, Scott S.

2014-06-01

108

Object tracking in infrared image sequence by Monte-Carlo method  

Microsoft Academic Search

This paper presents a robust tracking algorithm for infrared objects in the image sequence, which is based on particle filer. Particle filter is a powerful tool for tracking especially in non-Gaussian condition, but the selection of samples is still a challenging problem. According to the frame-to-frame correlation, two basic assumptions are proposed. Borrowing the idea from Sequence Importance Sampling, Monte-Carlo

Qianli Ma; Min Wang

2010-01-01

109

Detection of buried objects using infrared imaging of impulse laser heated soils  

Microsoft Academic Search

In this work we examine the time-dependent aspects of thermal imaging of buried metallic and non-metallic objects, when impulse heating of the soil surface is performed. A 1500W carbon dioxide laser is used to provide the thermal impulse. Time-dependent thermal images are obtained using an infrared focal plane array camera and a gated data acquisition\\/analysis system. Experimental studies are conducted

D. E. Poulain; D. R. Alexander; S. A. Schaub; J. K. Krause

1999-01-01

110

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

111

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

E-print Network

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 ($\\sim10^2$) of BL Lac objects --- low-luminosity Active Galactic Nuclei (AGN) 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 vs. 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; Brandt, W N; Markoff, Sera; Shemmer, Ohad; Wu, Jianfeng

2011-01-01

112

Multiple object and integral field near-infrared spectroscopy using fibers  

E-print Network

We describe a new system for multiple object spectroscopy and integral field spectroscopy at near-infrared wavelengths using optical fibers. Both modes of the SMIRFS instrument have been tested at the UK Infrared Telescope with the CGS4 infrared spectrograph. The modular system includes a common optical system to image the fiber slit onto the cold slit inside the CGS4 cryostat. The multiobject mode consists of 14 interchangeable fused silica or zirconium fluoride fibers each with a field of 4 arcsec. The integral field mode consists of 72 fused silica fibers coupled with a lenslet array to give a contiguous field of 6x4 arcsec with 0.6 arcsec sampling. We describe the performance of both modes. For the multiobject mode, the feasibility and desirability of using fluoride fibers to extend the wavelength range into the K-band is discussed. For the integral field mode, the performance is compared with theoretical expectation with particular attention to the effect of Focal Ratio Degradation in the fibers. These results demonstrate the feasibility of multiobject and integral field spectroscopy in the near-infrared using lenslet-coupled fiber systems. Although SMIRFS in an experimental system working with a spectrograph not designed for this purpose, the throughput and uniformity of response are good. SMIRFS points the way forward to systems with much larger numbers of elements.

Roger Haynes; David Lee; Jeremy Allington-Smith; Robert Content; George Dodsworth; Ian Lewis; Ray Sharples; James Turner; John Webster; Christine Done; Reynier Peletier; Ian Parry; Scott Chapman

1999-09-01

113

Near- and Mid-Infrared Imaging Study of Young Stellar Objects around LkH? 234  

NASA Astrophysics Data System (ADS)

We present high-resolution (0''.2) near-infrared images of the area surrounding the Herbig Be star LkH? 234 taken with the Coronagraphic Imager with Adaptive Optics (CIAO) and the adaptive optics on the Subaru Telescope. The near-infrared (J, H, K, L', and M' bands) images reveal circumstellar structures around LkH? 234 in detail. Eight young stellar object (YSO) candidates (Object B, C, D, E, F, G, NW1, and NW2) were detected at 2''-11'' from LkH? 234. Objects B and C are likely variable stars, which is consistent with a young evolutionary status. Three objects (LkH? 234, NW1, and NW2) were identified in the 11.8 µm (SiC) and 17.65µm images obtained with the Long Wavelength Spectrometer (LWS) on the Keck Telescope. NW1 and NW2 are thought to be embedded young stars. We suggest that NW1, and not LkH? 234, is the source illuminating the reflection nebula west of LkH? 234, although Object G may be another candidate. In our images, these objects are located at the center of the 2 µm polarization, and NW1 resides at the center of a monopolar cavity. The SED of NW1 suggests that it is a YSO with a spectral type of B6-B7. Object F and G were discovered by our observations at 1''.9 and 2''.3, respectively, from LkH? 234, and their proximity to LH? 234 suggests that they may be its lower-mass companions.

Kato, Eri; Fukagawa, Misato; Perrin, Marshall D.; Shibai, Hiroshi; Itoh, Yusuke; Ootsubo, Takafumi

2011-08-01

114

Optically faint X-ray sources in the Chandra deep field North: Spitzer constraints  

NASA Astrophysics Data System (ADS)

We investigate the properties of the most optically faint sources in the GOODS-N area (RAB > 26.5). These extremely optically faint populations present an uncharted territory although they represent an appreciable fraction of the X-ray sources in the GOODS-N field. The optically faint sources are believed to contain either red active galactic nuclei (AGN) at moderate redshifts or possibly quasi stellar objects (QSOs) at very high redshift. We compile our sample by first finding the 3.6 ?m IRAC counterparts of the X-ray sources and in turn by searching for the optical counterparts of the IRAC sources. No counterparts were found for 35 objects in the R-band Subaru optical images. Of these, 18 have HST ACS counterparts, while the remaining have no optical counterparts. The vast majority of our 35 sources are classified as extremely red objects (EROs) on the basis of their V606-KS lower limits. Their derived photometric redshifts show that these populate moderate redshifts (median z ~ 2.8), being at markedly different redshifts from the already spectroscopically identified population which peaks at z ~ 0.7. The Spitzer IRAC mid-IR colours of the sources without HST counterparts tend to lie within the mid-IR colour diagram AGN “wedge”, suggesting either QSO, ultra luminous infrared galaxy (ULIRG; Mrk231) templates or early-type galaxy templates at z > 3. A large fraction of our sources (17/35), regardless of whether they have HST counterparts, can be classified as mid-IR bright/optically faint sources (dust obscured galaxies) a class of sources which is believed to include many heavily absorbed AGN. The co-added X-ray spectrum of the optically faint sources is very flat, with a spectral index of ? ? 0.87, significantly flatter than the spectrum of the X-ray background. The optically faint (R > 26.5) X-ray sources constitute more than 50 per cent of the total X-ray population at redshifts z > 2, bearing important implications for the luminosity function and its evolution. Considering X-ray sources with 2 < z < 4 we find good agreement with a modified pure luminosity evolution (PLE) model.

Rovilos, E.; Georgantopoulos, I.; Akylas, A.; Fotopoulou, S.

2010-11-01

115

On the Nature of Faint Fuzzies in M81  

NASA Astrophysics Data System (ADS)

We report the discovery of 32 faint fuzzy objects in M81, the maximum number of objects of this kind detected in any spiral galaxy. The majority of these objects have colors similar to those of globular clusters, but are fainter and more extended. In this contribution, we discuss the nature of these objects using their structural, photometric and spectroscopic properties.

Mayya, Y. D.; Santiago-Cortes, M.; Rosa-González, D.; Gómez-González, M.; Rodríguez, L.; Carrasco, L.

2014-09-01

116

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

117

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

118

Infrared Spectroscopy and Analysis of Brown Dwarf and Planetary Mass Objects in the Orion Nebula Cluster  

E-print Network

We present near-infrared long slit and multi-slit spectra of low mass brown dwarf candidates in the Orion Nebula Cluster. The long slit data were observed in the H- & K-bands using NIRI on the Gemini North Telescope. The multi-object spectroscopic observations were made using IRIS2 on the Anglo Australian Telescope at H-band. We develop a spectral typing scheme based on optically calibrated, near infrared spectra of young sources in the Taurus and IC 348 star forming regions with spectral types M3.0 to M9.5. We apply our spectral typing scheme to 52 sources, including previously published UKIRT and GNIRS spectra. 40 objects show strong water absorption with spectral types of M3 to >M9.5. The latest type objects are provisionally classified as early L types. We plot our sources on H-R diagrams overlaid with theoretical pre-main-sequence isochrones. The majority of our objects lie close to or above the 1 Myr isochrone, leading to an average cluster age that is masses below the deuterium burning limit (0.012 Msun). We use a Monte Carlo approach to model the observed luminosity function with a variety of cluster age and mass distributions. The lowest chi^2 values are produced by an age distribution centred at 1 Myr, with a mass function that declines at sub-stellar masses according to an M^alpha power law in the range alpha=0.3 to 0.6. We find that truncating the mass function at 0.012 Msun produces luminosity functions that are starved of the faintest magnitudes, even when using bimodal age populations that contain 10 Myr old sources. The results of these Monte Carlo simulations therefore support the existence of a planetary mass population in the ONC.

D. J. Weights; P. W. Lucas; P. F. Roche; D. J. Pinfield; F. Riddick

2008-10-20

119

[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

120

Proc. IEEE Int. Conf. on Advanced Video and Signal Based Surveillance, Como, Italy, September 2005 Tracking Motion Objects in Infrared Videos  

E-print Network

Tracking Motion Objects in Infrared Videos Longin Jan Latecki1 , Roland Miezianko1 , Dragoljub Pokrajac2 1@desu.edu Abstract We propose motion detection and object tracking method that is particularly suitable for infrared videos. Detection of moving objects in infrared videos is based on changing texture in parts of the view

Latecki, Longin Jan

121

Faint Field Galaxies around Bright Stars: A New Strategy for Imaging at the Diffraction Limit  

NASA Astrophysics Data System (ADS)

This paper presents a new strategy for observing faint galaxies with high-order natural guide star systems. We have imaged five high Galactic latitude fields within the isoplanatic patch of bright stars (8.5 magfaint field galaxies that are observable with a natural guide star adaptive optics (AO) system on a large telescope. Because of the small fields of many AO science cameras, these preliminary images are necessary to identify candidate galaxies. We present the photometry and positions for 78 objects (at least 40 galaxies) near five bright stars, appropriate for diffraction-limited studies with the Keck and other AO systems on large ground-based telescopes. The K-band seeing conditions in each field were excellent (0.4"-0.7"), allowing us to identify stars and estimate galaxy sizes. We also simulate AO images of field galaxies to determine the feasibility of infrared morphological studies at the diffraction limit. With new high-order AO systems coming on line with 8-10 m class telescopes, we believe these observations are invaluable in beginning to study faint galaxy populations at the diffraction limit.

Larkin, J. E.; Glassman, T. M.

1999-11-01

122

Near-infrared Variability among Young Stellar Objects in the Star Formation Region Cygnus OB7  

NASA Astrophysics Data System (ADS)

We present an analysis of near-infrared time-series photometry in J, H, and K bands for about 100 epochs of a 1° × 1° region of the Lynds 1003/1004 dark cloud in the Cygnus OB7 region. Augmented by data from the Wide-field Infrared Survey Explorer, we identify 96 candidate disk bearing young stellar objects (YSOs) in the region. Of these, 30 are clearly Class I or earlier. Using the Wide-Field Imaging Camera on the United Kingdom Infrared Telescope, we were able to obtain photometry over three observing seasons, with photometric uncertainty better than 0.05 mag down to J ? 17. We study detailed light curves and color trajectories of ~50 of the YSOs in the monitored field. We investigate the variability and periodicity of the YSOs and find the data are consistent with all YSOs being variable in these wavelengths on timescales of a few years. We divide the variability into four observational classes: (1) stars with periodic variability stable over long timescales, (2) variables which exhibit short-lived cyclic behavior, (3) long-duration variables, and (4) stochastic variables. Some YSO variability defies simple classification. We can explain much of the observed variability as being due to dynamic and rotational changes in the disk, including an asymmetric or changing blocking fraction, changes to the inner disk hole size, as well as changes to the accretion rate. Overall, we find that the Class I:Class II ratio of the cluster is consistent with an age of <1 Myr, with at least one individual, wildly varying source ~100, 000 yr old. We have also discovered a Class II eclipsing binary system with a period of 17.87 days.

Wolk, Scott J.; Rice, Thomas S.; Aspin, Colin

2013-08-01

123

NESSI: an optimized Near-Infrared (NIR) Multi-Object Spectrograph (MOS) for exoplanet studies  

NASA Astrophysics Data System (ADS)

NESSI: the New Mexico Tech Extra(solar)planet Spectroscopic Survey Instrument is a ground-based multi-object spectrograph that operates in the near-infrared and is being deployed this fall at the Magdalena Ridge Observatory 2.4 m telescope. When completed later this year, it is expected to be used to characterize the atmospheres of transiting exoplanets with unprecedented ground-based accuracies down to about K = 9 magnitude. The superior capabilities of NEESI for this type of work lay, in part, in the design philosophy used for the instrument which is well-focused on the exoplanet case. We report here on this design philosophy, detail and status of the design and assembly, and preparation for first light in the fall of 2012.

Creech-Eakman, M. J.; Jurgenson, C. A.; Santoro, F. G.; Bloemhard, H.; Boston, P. J.; Deroo, P. D.; Hrynevych, M.; Jimenez, S. R.; Olivares, A. M.; Napolitano, M.; Salcido, C. D.; Schmidt, L. M.; Selina, R.; Swain, M. R.; Vasisht, G.

2012-09-01

124

A Mid-Infrared Imaging Survey of Embedded Young Stellar Objects in the (rho) Ophiuchi Cloud Core  

NASA Technical Reports Server (NTRS)

Results of a comprehensive, new, ground-based mid-infrared imaging survey of the young stellar population of the (rho) Ophiuchi cloud are presented. Data were acquired at the Palomar 5m and at the Keck 10m telescopes with the MIRLIN and LWS instruments, at 0'.5 and 0'.25 resolutions, respectively. Of 172 survey objects, 85 were detected. Among the 22 multiple systems observed, 15 were resolved and their individual component fluxes determined. A plot of the frequency distribution of the detected objects with SED spectral slope shows that YSOs spend approx.4 x 10(exp 5) yr in the flat-spectrum phase, clearing out their remnant infall envelopes. Mid-infrared variability is found among a significant fraction of the surveyed objects and is found to occur for all SED classes with optically thick disks. Large-amplitude near-infrared variability, also found for all SED classes with optically thick disks, seems to occur with somewhat higher frequency at the earlier evolutionary stages. Although a general trend of mid-infrared excess and near-infrared veiling exists progressing through SED classes, with Class I objects generally exhibiting r(sub K) >= 1, flat-spectrum objects with r(sub K) >= 0.58, and Class III objects with r(sub K) =0, Class II objects exhibit the widest range of r(sub K) values, ranging from 0 <= r(sub K) <= 4.5. However, the highly variable value of veiling that a single source can exhibit in any of the SED classes in which active disk accretion can take place is striking and is direct observational evidence for highly time-variable accretion activity in disks. Finally, by comparing mid-infrared versus near-infrared excesses in a subsample with well-determined effective temperatures and extinction values, disk-clearing mechanisms are explored. The results are consistent with disk clearing proceeding from the inside out.

Barsony, Mary; Ressler, Michael E.; Marsh, Kenneth A.

2005-01-01

125

Deep infrared galaxies  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

126

Young Stellar Object Variability (YSOVAR): Long Timescale Variations in the Mid-Infrared  

E-print Network

The YSOVAR (Young Stellar Object VARiability) Spitzer Space Telescope observing program obtained the first extensive mid-infrared (3.6 & 4.5 um) time-series photometry of the Orion Nebula Cluster plus smaller footprints in eleven other star-forming cores (AFGL490, NGC1333, MonR2, GGD 12-15, NGC2264, L1688, Serpens Main, Serpens South, IRAS 20050+2720, IC1396A, and Ceph C). There are ~29,000 unique objects with light curves in either or both IRAC channels in the YSOVAR data set. We present the data collection and reduction for the Spitzer and ancillary data, and define the "standard sample" on which we calculate statistics, consisting of fast cadence data, with epochs about twice per day for ~40d. We also define a "standard sample of members", consisting of all the IR-selected members and X-ray selected members. We characterize the standard sample in terms of other properties, such as spectral energy distribution shape. We use three mechanisms to identify variables in the fast cadence data--the Stetson ind...

Rebull, L M; Covey, K R; Guenther, H M; Hillenbrand, L A; Plavchan, P; Poppenhaeger, K; Stauffer, J R; Wolk, S J; Gutermuth, R; Morales-Calderon, M; Song, I; Barrado, D; Bayo, A; James, D; Hora, J L; Vrba, F J; de Oliveira, C Alves; Bouvier, J; Carey, S J; Carpenter, J M; Favata, F; Flaherty, K; Forbrich, J; Hernandez, J; McCaughrean, M J; Megeath, S T; Micela, G; Smith, H A; Terebey, S; Turner, N; Allen, L; Ardila, D; Bouy, H; Guieu, S

2014-01-01

127

A Mid-Infrared Imaging Survey of Embedded Young Stellar Objects in the Rho Ophiuchi Cloud Core  

E-print Network

Results of a comprehensive, new, ground-based mid-infrared imaging survey of the young stellar population of the Rho Ophiuchi cloud are presented. Data were acquired at the Palomar 5-m and at the Keck 10-m telescopes with the MIRLIN and LWS instruments, at 0.25 arcsec and 0.25 arcsec resolutions, respectively. Of 172 survey objects, 85 were detected. Among the 22 multiple systems observed, 15 were resolved and their individual component fluxes determined. A plot of the frequency distribution of the detected objects with SED spectral slope shows that YSOs spend ~400,000 yr in the Flat Spectrum phase, clearing out their remnant infall envelopes. Mid-infrared variability is found among a significant fraction of the surveyed objects, and is found to occur for all SED classes with optically thick disks. Large-amplitude near-infrared variability, also found for all SED classes with optically thick disks, seems to occur with somewhat higher frequency at the earlier evolutionary stages. Although a general trend of mid-infrared excess and NIR veiling exists proceeding through SED classes, with Class I objects generally exhibiting K-veilings > 1, Flat Spectrum objects with K-veilings > 0.58, and Class III objects with K-veilings =0, Class II objects exhibit the widest range of K-band veiling values, 0-4.5. However, the highly variable value of veiling that a single source can exhibit in any of the SED classes in which active disk accretion can take place is striking, and is direct observational evidence for highly time-variable accretion activity in disks. Finally, by comparing mid-infrared vs. near-infrared excesses in a subsample with well-determined effective temperatures and extinction values, disk clearing mechanisms are explored. The results are consistent with disk clearing proceeding from the inside-out.

Mary Barsony; Michael E. Ressler; Kenneth A. Marsh

2005-04-19

128

INFRARED AND KINEMATIC PROPERTIES OF THE SUBSTELLAR OBJECT G 196-3 B  

SciTech Connect

We report unusual near- and mid-infrared photometric properties of G 196-3 B, the young substellar companion at 16'' from the active M2.5-type star G 196-3 A, using data taken with the IRAC and MIPS instruments onboard Spitzer. G 196-3 B shows markedly redder colors at all wavelengths from 1.6 up to 24 {mu}m than expected for its spectral type, which is determined at L3 from optical and near-infrared spectra. We discuss various physical scenarios to account for its reddish nature and conclude that a low-gravity atmosphere with enshrouded upper atmospheric layers and/or a warm dusty disk/envelope provides the most likely explanations, the two of them consistent with an age in the interval 20-300 Myr. We also present new and accurate separate proper motion measurements for G 196-3 A and B confirming that both objects are gravitationally linked and share the same motion within a few mas yr{sup -1}. After integration of the combined spectrophotometric spectral energy distributions, we obtain the result that the difference in the bolometric magnitudes of G 196-3 A and B is 6.15 {+-} 0.10 mag. Kinematic consideration of the Galactic space motions of the system for distances in the interval 15-30 pc suggests that the pair is a likely member of the Local Association and that it lies near the past positions of young star clusters like {alpha} Persei less than 85 Myr ago, where the binary might have originated. At these young ages, the mass of G 196-3 B would be in the range 12-25 M {sub Jup}, close to the frontier between planets and brown dwarfs.

Zapatero Osorio, M. R.; Caballero, J. A. [Centro de AstrobiologIa (CSIC-INTA), Crta. Ajalvir km 4, E-28850 Torrejon de Ardoz, Madrid (Spain); Rebolo, R.; Bihain, G.; Bejar, V. J. S.; Alvarez, C., E-mail: mosorio@cab.inta-csic.e, E-mail: rrl@iac.e, E-mail: gbihain@iac.e, E-mail: vbejar@iac.e [Instituto de Astrofisica de Canarias (IAC), C. VIa Lactea s/n, E-38205 La Laguna, Tenerife (Spain)

2010-06-01

129

Young Stellar Object VARiability (YSOVAR): Long Timescale Variations in the Mid-infrared  

NASA Astrophysics Data System (ADS)

The YSOVAR (Young Stellar Object VARiability) Spitzer Space Telescope observing program obtained the first extensive mid-infrared (3.6 and 4.5 ?m) time series photometry of the Orion Nebula Cluster plus smaller footprints in 11 other star-forming cores (AFGL 490, NGC 1333, Mon R2, GGD 12-15, NGC 2264, L1688, Serpens Main, Serpens South, IRAS 20050+2720, IC 1396A, and Ceph C). There are ~29,000 unique objects with light curves in either or both IRAC channels in the YSOVAR data set. We present the data collection and reduction for the Spitzer and ancillary data, and define the "standard sample" on which we calculate statistics, consisting of fast cadence data, with epochs roughly twice per day for ~40 days. We also define a "standard sample of members" consisting of all the IR-selected members and X-ray-selected members. We characterize the standard sample in terms of other properties, such as spectral energy distribution shape. We use three mechanisms to identify variables in the fast cadence data—the Stetson index, a ?2 fit to a flat light curve, and significant periodicity. We also identified variables on the longest timescales possible of six to seven years by comparing measurements taken early in the Spitzer mission with the mean from our YSOVAR campaign. The fraction of members in each cluster that are variable on these longest timescales is a function of the ratio of Class I/total members in each cluster, such that clusters with a higher fraction of Class I objects also have a higher fraction of long-term variables. For objects with a YSOVAR-determined period and a [3.6]-[8] color, we find that a star with a longer period is more likely than those with shorter periods to have an IR excess. We do not find any evidence for variability that causes [3.6]-[4.5] excesses to appear or vanish within our data set; out of members and field objects combined, at most 0.02% may have transient IR excesses.

Rebull, L. M.; Cody, A. M.; Covey, K. R.; Günther, H. M.; Hillenbrand, L. A.; Plavchan, P.; Poppenhaeger, K.; Stauffer, J. R.; Wolk, S. J.; Gutermuth, R.; Morales-Calderón, M.; Song, I.; Barrado, D.; Bayo, A.; James, D.; Hora, J. L.; Vrba, F. J.; Alves de Oliveira, C.; Bouvier, J.; Carey, S. J.; Carpenter, J. M.; Favata, F.; Flaherty, K.; Forbrich, J.; Hernandez, J.; McCaughrean, M. J.; Megeath, S. T.; Micela, G.; Smith, H. A.; Terebey, S.; Turner, N.; Allen, L.; Ardila, D.; Bouy, H.; Guieu, S.

2014-11-01

130

Spectrum from Faint Galaxy IRAS F00183-7111  

NASA Technical Reports Server (NTRS)

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

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

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

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

The Spitzer spectrum is the result of only 14 minutes of integration time, highlighting the power of the infrared spectrograph to unlock the secrets of distant galaxies.

2003-01-01

131

The IRAS faint source survey  

Microsoft Academic Search

The principal features of the IRAS Faint Source Survey (FSS), a new product resulting from the extended IRAS mission, are reviewed. The FSS has achieved an increase in sensitivity of about a factor of 2.5 relative to the IRAS Point Source Catalog by coadding the data before extracting sources. The FSS was produced by point-source filtering the individual detector data

Mehrdad Moshir

1991-01-01

132

Subsystem Imaging Performance and Modeling of the Infrared Multi-Object Spectrograph  

NASA Technical Reports Server (NTRS)

The Infrared Multi-Object Spectrograph (IRMOS) is a facility instrument for the Kitt Peak National Observatory Mayall Telescope (3.8 meter). IRMOS is a near-IR (0.8 - 2.5 micron) spectrograph with low to mid resolution (R=lambda/delta, lambda = 300 - 3800). The IRMOS spectrograph produces simultaneous spectra of - 100 objects in its 2.8 x 2.0 arc-min field of view using a commercial MEMS multi-mirror array device (MMA). The IRMOS optical design consists of two imaging systems, or "stages." The focal reducer, stage one, images the focal plane of the telescope onto the MMA. The spectrograph, stage two, images the MMA onto the detector. We describe the breadboard alignment method and imaging and scattered light performance for both the focal reducer and spectrograph. This testing provides verification of the optomechanical alignment method, and a measurement of the contribution of scattered light in the system due to mirror small scale surface error. After the stage I and 2 optics are integrated with the instrument, our test results will make it possible to distinguish between scattered light from the mirrors and the MMA. Image testing will be done at four wavelengths in the visible and near-IR. A mercury-argon pencil lamp will provide spectral lines at 546.1 and 1012 nm, and a blackbody radiation source lines at 1600 and 2200 nm. A CCD camera will be used as a detector for the visible wavelengths, and an IR photodiode will be used for the IR wavelengths. We compare our data with a theoretical analysis using a commercial software package. Mirror surface error is modeled by treating each surface as a superposition of various gratings (e.g., diamond turning tool marks, features due to the impurities of Al 6061, and periodic mid-frequency errors due to drift during machining).

Connelly, Joseph A.; Tveekrem, June L.; Ohl, Raymond G.; Mink, Ronald; Chambers, V. John; Mentzell, J. Eric; Greenhouse, Matthew A.; MacKenty, John W.; Krebs, Carolyn (Technical Monitor)

2002-01-01

133

Target discrimination of man-made objects using passive polarimetric signatures acquired in the visible and infrared spectral bands  

NASA Astrophysics Data System (ADS)

Surveillance operations and search and rescue missions regularly exploit electro-optic imaging systems to detect targets of interest in both the civilian and military communities. By incorporating the polarization of light as supplementary information to such electro-optic imaging systems, it is possible to increase their target discrimination capabilities, considering that man-made objects are known to depolarized light in different manner than natural backgrounds. As it is known that electro-magnetic radiation emitted and reflected from a smooth surface observed near a grazing angle becomes partially polarized in the visible and infrared wavelength bands, additional information about the shape, roughness, shading, and surface temperatures of difficult targets can be extracted by processing effectively such reflected/emitted polarized signatures. This paper presents a set of polarimetric image processing algorithms devised to extract meaningful information from a broad range of man-made objects. Passive polarimetric signatures are acquired in the visible, shortwave infrared, midwave infrared, and longwave infrared bands using a fully automated imaging system developed at DRDC Valcartier. A fusion algorithm is used to enable the discrimination of some objects lying in shadowed areas. Performance metrics, derived from the computed Stokes parameters, characterize the degree of polarization of man-made objects. Field experiments conducted during winter and summer time demonstrate: 1) the utility of the imaging system to collect polarized signatures of different objects in the visible and infrared spectral bands, and 2) the enhanced performance of target discrimination and fusion algorithms to exploit the polarized signatures of man-made objects against cluttered backgrounds.

Lavigne, Daniel A.; Breton, Mélanie; Fournier, Georges; Charette, Jean-François; Pichette, Mario; Rivet, Vincent; Bernier, Anne-Pier

2011-10-01

134

MOSFIRE: a multi-object near-infrared spectrograph and wide-field camera for the Keck Observatory  

E-print Network

MOSFIRE: a multi-object near-infrared spectrograph and wide-field camera for the Keck Observatory of California/Santa Cruz, Santa Cruz, CA USA 95064 d W. M. Keck Observatory, 65-1120 Mamalahoa Highway, Kamuela of the third generation instrument program at the W. M. Keck Observatory (WMKO)1 . The optical design provides

Steidel, Chuck

135

MID-INFRARED SIZE SURVEY OF YOUNG STELLAR OBJECTS: DESCRIPTION OF KECK SEGMENT-TILTING EXPERIMENT AND BASIC RESULTS  

SciTech Connect

The mid-infrared properties of pre-planetary disks are sensitive to the temperature and flaring profiles of disks for the regions where planet formation is expected to occur. In order to constrain theories of planet formation, we have carried out a mid-infrared ({lambda} = 10.7 {mu}m) size survey of young stellar objects using the segmented Keck telescope in a novel configuration. We introduced a customized pattern of tilts to individual mirror segments to allow efficient sparse-aperture interferometry, allowing full aperture synthesis imaging with higher calibration precision than traditional imaging. In contrast to previous surveys on smaller telescopes and with poorer calibration precision, we find that most objects in our sample are partially resolved. Here, we present the main observational results of our survey of five embedded massive protostars, 25 Herbig Ae/Be stars, 3 T Tauri stars, 1 FU Ori system, and five emission-line objects of uncertain classification. The observed mid-infrared sizes do not obey the size-luminosity relation found at near-infrared wavelengths and a companion paper will provide further modeling analysis of this sample. In addition, we report imaging results for a few of the most resolved objects, including complex emission around embedded massive protostars, the photoevaporating circumbinary disk around MWC 361A, and the subarcsecond binaries T Tau, FU Ori, and MWC 1080.

Monnier, J. D.; Tannirkulam, A. [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Tuthill, P. G.; Ireland, M. [University of Sydney, NSW 2006 (Australia); Cohen, R. [W. M. Keck Observatory, Kamuela, HI 96743 (United States); Perrin, M. D. [University of California at Los Angeles, CA 90095 (United States)

2009-07-20

136

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

137

NEAR-INFRARED SPECTROSCOPY OF INFRARED-EXCESS STELLAR OBJECTS IN THE YOUNG SUPERNOVA REMNANT G54.1+0.3  

SciTech Connect

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 {approx}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 {approx}35 M{sub Sun} 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 [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Moon, Dae-Sik, E-mail: hjkim@astro.snu.ac.kr, E-mail: koo@astro.snu.ac.kr, E-mail: moon@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada)

2013-09-01

138

Young Stellar Object Search toward the Boundary of the Central Molecular Zone with Near-infrared Polarimetry  

NASA Astrophysics Data System (ADS)

We have carried out near-infrared polarimetry toward the boundary of the Central Molecular Zone, in the field of (-1.°4 <~ l <~ -0.°3 and 1.°0 <~ l <~ 2.°9, |b| <~ 0.°1), using the near-infrared polarimetric camera SIRPOL on the 1.4 m Infrared Survey Facility telescope. We have selected 112 intrinsically polarized sources on the basis of the estimate of interstellar polarization on Stokes Q/I - U/I planes. The selected sources are brighter than KS = 14.5 mag and have polarimetric uncertainty ?P < 1%. Ten of these distinctive polarized sources are fit well with spectral energy distributions of young stellar objects when using the photometry in the archive of the Spitzer Space Telescope mid-infrared data. However, many sources have spectral energy distributions of normal stars suffering from heavy interstellar extinction; these might be stars behind dark clouds. Due to the small number of distinctive polarized sources and candidates of young stellar objects, we cannot judge if they are declining in number outside the Central Molecular Zone. Many massive candidates for young stellar objects in the literature have only small intrinsic polarization. This might suggest that their masses are 4-15 M ?, whose intrinsic polarization has been expected to be small.

Yoshikawa, Tatsuhito; Nishiyama, Shogo; Tamura, Motohide; Kwon, Jungmi; Nagata, Tetsuya

2014-08-01

139

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

140

Long-term evolution of FU Orionis objects at infrared wavelengths  

E-print Network

We investigate the brightness evolution of 7 FU Orionis systems in the 1-100 micrometer wavelength range using data from the Infrared Space Observatory (ISO). The ISO measurements were supplemented with 2MASS and MSX observations performed in the same years as the ISO mission (1995-98). The spectral energy distributions (SEDs) based on these data points were compared with earlier ones derived from the IRAS photometry as well as from ground-based observations carried out around the epoch 1983. In 3 cases (Z CMa, Parsamian 21, V1331 Cyg) no difference between the two epochs was seen within the measurement uncertainties. V1057 Cyg, V1515 Cyg and V1735 Cyg have become fainter at near-infrared wavelengths while V346 Nor has become slightly brighter. V1057 Cyg exhibits a similar flux change also in the mid-infrared. At lambda >= 60 micrometer most of the sources remained constant; only V346 Nor seems to fade. Our data on the long-term evolution of V1057 Cyg agree with the model predictions of Kenyon & Hartmann (1991) and Turner et al. (1997) at near- and mid-infrared wavelengths, but disagree at lambda > 25 micrometer. We discuss if this observational result at far-infrared wavelengths could be understood in the framework of the existing models.

P. Ábrahám; Á. Kóspál; Sz. Csizmadia; M. Kun; A. Moór; T. Prusti

2004-08-03

141

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 ...

142

Faintness  

MedlinePLUS

... Schueler, MD How it Works Testimonials FAQ for Consumers FAQ for Physicians News Advertising Terms of Use Contact Us Site Map How ... yourself? About Stephen J. Schueler, M.D News Advertising How It Works FAQ for Consumers FAQ for Physicians Testimonials Site Map Terms of ...

143

MOONS: the Multi-Object Optical and Near-infrared Spectrograph for the VLT  

NASA Astrophysics Data System (ADS)

MOONS is a new Multi-Object Optical and Near-infrared Spectrograph selected by ESO as a third generation instrument for the Very Large Telescope (VLT). The grasp of the large collecting area offered by the VLT (8.2m diameter), combined with the large multiplex and wavelength coverage (optical to near-IR: 0.8?m - 1.8?m) of MOONS will provide the European astronomical community with a powerful, unique instrument able to pioneer a wide range of Galactic, Extragalactic and Cosmological studies and provide crucial follow-up for major facilities such as Gaia, VISTA, Euclid and LSST. MOONS has the observational power needed to unveil galaxy formation and evolution over the entire history of the Universe, from stars in our Milky Way, through the redshift desert, and up to the epoch of very first galaxies and re-ionization of the Universe at redshift z>8-9, just few million years after the Big Bang. On a timescale of 5 years of observations, MOONS will provide high quality spectra for >3M stars in our Galaxy and the local group, and for 1-2M galaxies at z>1 (SDSS-like survey), promising to revolutionise our understanding of the Universe. 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.

Cirasuolo, M.; Afonso, J.; Carollo, M.; Flores, H.; Maiolino, R.; Oliva, E.; Paltani, S.; Vanzi, Leonardo; Evans, Christopher; Abreu, M.; Atkinson, David; Babusiaux, C.; Beard, Steven; Bauer, F.; Bellazzini, M.; Bender, Ralf; Best, P.; Bezawada, N.; Bonifacio, P.; Bragaglia, A.; Bryson, I.; Busher, D.; Cabral, A.; Caputi, K.; Centrone, M.; Chemla, F.; Cimatti, A.; Cioni, M.-R.; Clementini, G.; Coelho, J.; Crnojevic, D.; Daddi, E.; Dunlop, J.; Eales, S.; Feltzing, S.; Ferguson, A.; Fisher, M.; Fontana, A.; Fynbo, J.; Garilli, B.; Gilmore, G.; Glauser, A.; Guinouard, I.; Hammer, F.; Hastings, P.; Hess, A.; Ivison, R.; Jagourel, P.; Jarvis, M.; Kaper, L.; Kauffman, G.; Kitching, A. T.; Lawrence, A.; Lee, D.; Lemasle, B.; Licausi, G.; Lilly, S.; Lorenzetti, D.; Lunney, D.; Maiolino, R.; Mannucci, F.; McLure, R.; Minniti, D.; Montgomery, D.; Muschielok, B.; Nandra, K.; Navarro, R.; Norberg, P.; Oliver, S.; Origlia, L.; Padilla, N.; Peacock, J.; Pedichini, F.; Peng, J.; Pentericci, L.; Pragt, J.; Puech, M.; Randich, S.; Rees, P.; Renzini, A.; Ryde, N.; Rodrigues, M.; Roseboom, I.; Royer, F.; Saglia, R.; Sanchez, A.; Schiavon, R.; Schnetler, H.; Sobral, D.; Speziali, R.; Sun, D.; Stuik, R.; Taylor, A.; Taylor, W.; Todd, S.; Tolstoy, E.; Torres, M.; Tosi, M.; Vanzella, E.; Venema, L.; Vitali, F.; Wegner, M.; Wells, M.; Wild, V.; Wright, G.; Zamorani, G.; Zoccali, M.

2014-07-01

144

Probing the envelopes of massive young stellar objects with diffraction limited mid-infrared imaging  

NASA Astrophysics Data System (ADS)

Context. Massive stars form whilst they are still embedded in dense envelopes. As a result, the roles of rotation, mass loss and accretion in massive star formation are not well understood. Aims: This study evaluates the source of the Q-band, ?c = 19.5 ?m, emission of massive young stellar objects (MYSOs). This allows us to determine the relative importance of rotation and outflow activity in shaping the circumstellar environments of MYSOs on 1000 AU scales. Methods: We obtained diffraction limited mid-infrared images of a sample of 20 MYSOs using the VLT/VISIR and Subaru/COMICS instruments. For these 8 m class telescopes and the sample selected, the diffraction limit, ~0.6'', corresponds to approximately 1000 AU. We compare the images and the spectral energy distributions (SEDs) observed to a 2D, axis-symmetric dust radiative transfer model that reproduces VLTI/MIDI observations of the MYSO W33A. We vary the inclination, mass infall rate, and outflow opening angle to simultaneously recreate the behaviour of the sample of MYSOs in the spatial and spectral domains. Results: The mid-IR emission of 70 percent of the MYSOs is spatially resolved. In the majority of cases, the spatial extent of their emission and their SEDs can be reproduced by the W33A model featuring an in-falling, rotating dusty envelope with outflow cavities. There is independent evidence that most of the sources which are not fit by the model are associated with ultracompact H ii regions and are thus more evolved. Conclusions: We find that, in general, the diverse ~20 ?m morphology of MYSOs can be attributed to warm dust in the walls of outflow cavities seen at different inclinations. This implies that the warm dust in the outflow cavity walls dominates the Q-band emission of MYSOs. In turn, this emphasises that outflows are an ubiquitous feature of massive star formation. This paper is based on data obtained using the ESO VLT at the Paranal Observatory with programme 083.C-0795 and the Subaru telescope, which is operated by the National Astronomical Observatory of Japan.Appendix A and Fig. 2 are available in electronic form at http://www.aanda.org

Wheelwright, H. E.; de Wit, W. J.; Oudmaijer, R. D.; Hoare, M. G.; Lumsden, S. L.; Fujiyoshi, T.; Close, J. L.

2012-04-01

145

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

146

Searching for Optically Faint GEO Debris  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

147

Long-term evolution of FU Orionis objects at infrared wavelengths  

NASA Astrophysics Data System (ADS)

We investigate the brightness evolution of seven FU Orionis systems in the 1-100 ?m wavelength range using data from the Infrared Space Observatory (ISO). The ISO measurements were supplemented by 2MASS and MSX observations performed in the same years as the ISO mission (1995-98). The spectral energy distributions (SEDs) based on these data points were compared with earlier ones derived from the IRAS photometry as well as from ground-based observations carried out around the epoch 1983. In three cases (Z CMa, Parsamian 21, V1331 Cyg) no difference between the two epochs was seen within the measurement uncertainties. V1057 Cyg, V1515 Cyg and V1735 Cyg have become fainter at near-infrared wavelengths while V346 Nor has become slightly brighter. V1057 Cyg exhibits a similar flux change in the mid-infrared. At ?? 60 ?m most of the sources remained constant; only V346 Nor seems to fade. Our data on the long-term evolution of V1057 Cyg agree with the model predictions of Kenyon & Hartmann (\\cite{Kenyonh91}) and Turner et al. (\\cite{Turner97}) at near- and mid-infrared wavelengths, but disagree at ?>25 ?m. We discuss if this observational result at far-infrared wavelengths could be understood in the framework of the existing models. Based on observations with ISO, an ESA project with instruments funded by ESA member states (especially the PI countries France, Germany, the Netherlands and the United Kingdom) with participation of ISAS and NASA.

Ábrahám, P.; Kóspál, Á.; Csizmadia, Sz.; Kun, M.; Moór, A.; Prusti, T.

2004-12-01

148

Mid-infrared size survey of Young Stellar Objects: Description of Keck segment-tilting experiment and basic results  

E-print Network

The mid-infrared properties of pre-planetary disks are sensitive to the temperature and flaring profiles of disks for the regions where planet formation is expected to occur. In order to constrain theories of planet formation, we have carried out a mid-infrared (wavelength 10.7 microns) size survey of young stellar objects using the segmented Keck telescope in a novel configuration. We introduced a customized pattern of tilts to individual mirror segments to allow efficient sparse-aperture interferometry, allowing full aperture synthesis imaging with higher calibration precision than traditional imaging. In contrast to previous surveys on smaller telescopes and with poorer calibration precision, we find most objects in our sample are partially resolved. Here we present the main observational results of our survey of 5 embedded massive protostars, 25 Herbig Ae/Be stars, 3 T Tauri stars, 1 FU Ori system, and 5 emission-line objects of uncertain classification. The observed mid-infrared sizes do not obey the siz...

Monnier, J D; Ireland, M; Cohen, R; Tannirkulam, A; Perrin, M D

2009-01-01

149

Invariant feature matching based adaptive bandwidth mean shift and its application to infrared object tracking  

Microsoft Academic Search

Mean shift algorithm has grained great success in object tracking domain due to its ease of implementation, real time response and robust tracking performance, however, the fixed kernel bandwidth may cause tracking failure for size changing objects. A novel object tracking algorithm for FLIR imagery is proposed based on mean shift with adaptive bandwidth. The scale invariant feature transform is

Fangzhou Zhaoi; Junshan Li; Yinghong Zhu; Wei Yang

2010-01-01

150

Aerial visible-thermal infrared hyperspectral feature extraction technology and its application to object identification  

NASA Astrophysics Data System (ADS)

Based on aerial visible-thermal infrared hyperspectral imaging system (CASI/SASI/TASI) data, field spectrometer data and multi-source geological information, this paper utilizes the hyperspectral data processing and feature extraction technology to identify uranium mineralization factors, the spectral features of typical tetravalent, hexavalent uranium minerals and mineralization factors are established, and hyperspectral logging technology for drill cores and trench also are developed, the relationships between radioactive intensity and spectral characteristics are built. Above methods have been applied to characterize uranium mineralization setting of granite-type and sandstone-type uranium deposits in south and northwest China, the successful outcomes of uranium prospecting have been achieved.

Jie-lin, Zhang; Jun-hu, Wang; Mi, Zhou; Yan-ju, Huang; Ding, Wu

2014-03-01

151

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

152

Object detection utilizing a linear retrieval algorithm for thermal infrared imagery  

SciTech Connect

Thermal infrared (TIR) spectroscopy and remote sensing have been proven to be extremely valuable tools for mineralogic discrimination. One technique for sub-pixel detection and data reduction, known as a spectral retrieval or unmixing algorithm, will prove useful in the analysis of data from scheduled TIR orbital instruments. This study represents the first quantitative attempt to identify the limits of the model, specifically concentrating on the TIR. The algorithm was written and applied to laboratory data, testing the effects of particle size, noise, and multiple endmembers, then adapted to operate on airborne Thermal Infrared Multispectral Scanner data of the Kelso Dunes, CA, Meteor Crater, AZ, and Medicine Lake Volcano, CA. Results indicate that linear spectral unmixmg can produce accurate endmember detection to within an average of 5%. In addition, the effects of vitrification and textural variations were modeled. The ability to predict mineral or rock abundances becomes extremely useful in tracking sediment transport, decertification, and potential hazard assessment in remote volcanic regions. 26 refs., 3 figs.

Ramsey, M.S. [Arizona State Univ., Tempe, AZ (United States)

1996-11-01

153

Near-Infrared Spectrum of Low-Inclination Classical Kuiper Belt Object (79360) 1997 CS29  

Microsoft Academic Search

The ``cold classical'' Kuiper Belt is the only part of the Kuiper Belt where objects show color statistics distinct from the rest of the trans-Neptunian population. Cold classical orbits are also likely to have been among the least dynamically perturbed since the time of accretion. As such, cold classical objects are especially interesting targets for compositional investigation by means of

W. M. Grundy; M. W. Buie; J. R. Spencer

2005-01-01

154

Nature of Faint Emission-Line Galaxies.  

National Technical Information Service (NTIS)

One of the results of faint galaxy redshift surveys is the increased fraction of galaxies which have strong emission-line spectra. These faint surveys find that roughly 50 percent of the galaxies have an equivalent width of (OII), W sub 3727, greater than...

J. J. Smetanka

1993-01-01

155

Infrared  

NASA Astrophysics Data System (ADS)

'Infrared' is a very wide field in physics and the natural sciences which has evolved enormously in recent decades. It all started in 1800 with Friedrich Wilhelm Herschel's discovery of infrared (IR) radiation within the spectrum of the Sun. Thereafter a few important milestones towards widespread use of IR were the quantitative description of the laws of blackbody radiation by Max Planck in 1900; the application of quantum mechanics to understand the rotational-vibrational spectra of molecules starting in the first half of the 20th century; and the revolution in source and detector technologies due to micro-technological breakthroughs towards the end of the 20th century. This has led to much high-quality and sophisticated equipment in terms of detectors, sources and instruments in the IR spectral range, with a multitude of different applications in science and technology. This special issue tries to focus on a few aspects of the astonishing variety of different disciplines, techniques and applications concerning the general topic of infrared radiation. Part of the content is based upon an interdisciplinary international conference on the topic held in 2012 in Bad Honnef, Germany. It is hoped that the information provided here may be useful for teaching the general topic of electromagnetic radiation in the IR spectral range in advanced university courses for postgraduate students. In the most general terms, the infrared spectral range is defined to extend from wavelengths of 780 nm (upper range of the VIS spectral range) up to wavelengths of 1 mm (lower end of the microwave range). Various definitions of near, middle and far infrared or thermal infrared, and lately terahertz frequencies, are used, which all fall in this range. These special definitions often depend on the scientific field of research. Unfortunately, many of these fields seem to have developed independently from neighbouring disciplines, although they deal with very similar topics in respect of the underlying physics. There are now at least six different disciplines that deal with infrared radiation in one form or another, and in one or several different spectral portions of the whole IR range. These are spectroscopy, astronomy, thermal imaging, detector and source development and metrology, as well the field of optical data transmission. Scientists working in these fields range from chemists and astronomers through to physicists and even photographers. This issue presents examples from some of these fields. All the papers—though some of them deal with fundamental or applied research—include interesting elements that make them directly applicable to university-level teaching at the graduate or postgraduate level. Source (e.g. quantum cascade lasers) and detector development (e.g. multispectral sensors), as well as metrology issues and optical data transmission, are omitted since they belong to fundamental research journals. Using a more-or-less arbitrary order according to wavelength range, the issue starts with a paper on the physics of near-infrared photography using consumer product cameras in the spectral range from 800 nm to 1.1 µm [1]. It is followed by a series of three papers dealing with IR imaging in spectral ranges from 3 to 14 µm [2-4]. One of them deals with laboratory courses that may help to characterize the IR camera response [2], the second discusses potential applications for nondestructive testing techniques [3] and the third gives an example of how IR thermal imaging may be used to understand cloud cover of the Earth [4], which is the prerequisite for successful climate modelling. The next two papers cover the vast field of IR spectroscopy [5, 6]. The first of these deals with Fourier transform infrared spectroscopy in the spectral range from 2.5 to 25 µm, studying e.g. ro-vibrational excitations in gases or optical phonon interactions within solids [5]. The second deals mostly with the spectroscopy of liquids such as biofuels and special techniques such as attenuated total reflectance [6]. The two final papers deal with what se

Vollmer, M.

2013-11-01

156

Changes in heart rate variability during fainting  

NASA Astrophysics Data System (ADS)

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.

Sheldon, Robert; Riff, Kenneth

1991-10-01

157

The High $\\mathrm{A_V}$ Quasar Survey: Reddened Quasi Stellar Objects selected from optical/near-infrared photometry - II  

E-print Network

Quasi Stellar Objects (QSOs) whose spectral energy distributions (SEDs) are reddened by dust either in their host galaxies or in intervening absorber galaxies are to a large degree missed by optical color selection criteria like the ones used by the SDSS. To overcome this bias against red QSOs, we employ a combined optical and near-infrared color selection. In this paper, we present a spectroscopic follow-up campaign of a sample of red candidate QSOs which were selected from the SDSS and the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and SDSS/UKIDSS photometry are supplemented by photometry from the Wide-field Infrared Survey Explorer (WISE). In our sample of 159 candidates, 154 (97 %) are confirmed to be QSOs. We use a statistical algorithm to identify sightlines with plausible intervening absorption systems and identify 9 such cases assuming dust in the absorber similar to Large Magellanic Cloud sightlines. We find absorption systems towards 30 QSOs, two of which are consistent with the...

Krogager, J -K; Fynbo, J P U; Venemans, B P; Ledoux, C; Møller, P; Noterdaeme, P; Vestergaard, M; Kangas, T; Pursimo, T; Saturni, F G; Smirnova, O

2014-01-01

158

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

159

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

NASA Technical Reports Server (NTRS)

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.

Stapelfeldt, Karl R.; Scoville, Nicholas Z.; Beichman, Charles A.; Hester, J. Jeff; Gautier, Thomas N., III

1991-01-01

160

Using near-infrared spectroscopy to assess neural activation during object processing in infants  

PubMed Central

The capacity to represent the world in terms of numerically distinct objects (i.e., object individuation) is a milestone in early cognitive development and forms the foundation for more complex thought and behavior. Over the past 10 to 15 yr, infant researchers have expended a great deal of effort to identify the origins and development of this capacity. In contrast, relatively little is known about the neural mechanisms that underlie the ability to individuate objects, in large part because there are a limited number of noninvasive techniques available to measure brain functioning in human infants. Recent research suggests that near-IR spectroscopy (NIRS), an optical imaging technique that uses relative changes in total hemoglobin concentration and oxygenation as an indicator of neural activation, may be a viable procedure for assessing the relation between object processing and brain function in human infants. We examine the extent to which increased neural activation, as measured by NIRS, could be observed in two neural areas known to be involved in object processing, the primary visual cortex and the inferior temporal cortex, during an object processing task. Infants aged 6.5 months are presented with a visual event in which two featurally distinct objects emerge successively to opposite sides of an occluder and neuroimaging data are collected. As predicted, increased neural activation is observed in both the primary visual and inferior cortex during the visual event, suggesting that these neural areas support object processing in the young infant. The outcome has important implications for research in cognitive development, developmental neuroscience, and optical imaging. PMID:15847576

Wilcox, Teresa; Bortfeld, Heather; Woods, Rebecca; Wruck, Eric; Boas, David A.

2006-01-01

161

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

162

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

NASA Astrophysics Data System (ADS)

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

163

Trajectory estimation of closely spaced objects (CSO) using infrared focal plane data of an STSS (space tracking and surveillance system) platform  

Microsoft Academic Search

A major challenge in tracking midcourse objects by means of an infrared (IR) sensor is that during a significant part of the trajectory they are closely spaced (Closely Spaced Objects, or CSO). The imprints of the CSOs on the IR focal plane create blurred unresolved clusters where the number, the coordinates, and the radiant intensities of the objects are not

Jonathan Korn; Howard Holtz; Morton S. Farber

2004-01-01

164

OPTICAL AND INFRARED REFLECTANCE SPECTRUM OF KUIPER BELT OBJECT 1996TL 66  

E-print Network

(Jewitt, Luu, and Chen 1996). Kuiper Belt Objects (hereafter 1 Visiting Astronomer, W. M. Keck Observatory reported in this paper were obtained at the Multiple Mirror Telescope Observatory, a facility operated, Arizona, and the Keck I 10­m telescope on Mauna Kea, Hawaii, respectively. (a) Keck observations The near

Jewitt, David C.

165

Are compact groups hostile towards faint galaxies?  

NASA Astrophysics Data System (ADS)

Aims: The goal of this work is to understand whether the extreme environment of compact groups (CGs) can affect the distribution and abundance of faint galaxies around them. Methods: We performed an analysis of the faint galaxy population in the vicinity of compact and normal groups. We built a light-cone mock galaxy catalogue constructed from the Millennium Run Simulation II plus a semi-analytical model of galaxy formation. We identified a sample of CGs in the mock catalogue as well as a control sample of normal galaxy groups and computed the projected number density profiles of faint galaxies around the first and the second ranked galaxies. We also compared the profiles obtained from the semi-analytical galaxies in CGs with those obtained from observational data. In addition, we investigated whether the ranking or the luminosity of a galaxy is the most important parameter in the determination of the centre around which the clustering of faint galaxies occurs. Results: There is no particular influence of the extreme compact group (CG) environment on the number of faint galaxies in such groups compared to control groups. When selecting normal groups with separations between the first and second ranked galaxies similar to what is observed in CGs, the faint galaxy projected number density profiles in CGs and normal groups are similar in shape and height. We observed a similar behaviour of the population of faint galaxies in observations and simulations in the regions closer to the first and second ranked galaxies. Finally, we find that the projected density of faint galaxies is higher around luminous galaxies, regardless of the ranking in the CG. Conclusions: The semi-analytical approach shows that CGs and their surroundings do not represent a hostile enough environment to make faint galaxies behave differently than in normal groups. Appendix A is available in electronic form at http://www.aanda.org

Zandivarez, Ariel; Díaz-Giménez, Eugenia; Mendes de Oliveira, Claudia; Gubolin, Henrique

2014-12-01

166

A Pan-Carina Young Stellar Object Catalog: Intermediate-mass Young Stellar Objects in the Carina Nebula Identified Via Mid-infrared Excess Emission  

NASA Astrophysics Data System (ADS)

We present a catalog of 1439 young stellar objects (YSOs) spanning the 1.42 deg2 field surveyed by the Chandra Carina Complex Project (CCCP), which includes the major ionizing clusters and the most active sites of ongoing star formation within the Great Nebula in Carina. Candidate YSOs were identified via infrared (IR) excess emission from dusty circumstellar disks and envelopes, using data from the Spitzer Space Telescope (the Vela-Carina survey) and the Two-Micron All Sky Survey. We model the 1-24 ?m IR spectral energy distributions of the YSOs to constrain physical properties. Our Pan-Carina YSO Catalog (PCYC) is dominated by intermediate-mass (2 M sun < m <~ 10 M sun) objects with disks, including Herbig Ae/Be stars and their less evolved progenitors. The PCYC provides a valuable complementary data set to the CCCP X-ray source catalogs, identifying 1029 YSOs in Carina with no X-ray detection. We also catalog 410 YSOs with X-ray counterparts, including 62 candidate protostars. Candidate protostars with X-ray detections tend to be more evolved than those without. In most cases, X-ray emission apparently originating from intermediate-mass, disk-dominated YSOs is consistent with the presence of low-mass companions, but we also find that X-ray emission correlates with cooler stellar photospheres and higher disk masses. We suggest that intermediate-mass YSOs produce X-rays during their early pre-main-sequence evolution, perhaps driven by magnetic dynamo activity during the convective atmosphere phase, but this emission dies off as the stars approach the main sequence. Extrapolating over the stellar initial mass function scaled to the PCYC population, we predict a total population of >2 × 104 YSOs and a present-day star formation rate (SFR) of >0.008 M sun yr-1. The global SFR in the Carina Nebula, averaged over the past ~5 Myr, has been approximately constant.

Povich, Matthew S.; Smith, Nathan; Majewski, Steven R.; Getman, Konstantin V.; Townsley, Leisa K.; Babler, Brian L.; Broos, Patrick S.; Indebetouw, Rémy; Meade, Marilyn R.; Robitaille, Thomas P.; Stassun, Keivan G.; Whitney, Barbara A.; Yonekura, Yoshinori; Fukui, Yasuo

2011-05-01

167

Faint blue galaxies - High or low redshift?  

NASA Astrophysics Data System (ADS)

The results of two new redshift surveys carried out with the Low Dispersion Survey Spectrograph (LDSS) on the Anglo-Austrian Telescope are presented. The first is an extension of the earlier LDSS deep survey, in which two of the original survey zones were reobserved and the 19 percent incompleteness in redshift identifications was reduced to just 4.5 percent. Redshifts for 19 new galaxies were obtained increasing the total number of redshifts to 104. It is concluded that at most 4.5 percent of galaxies brighter than 22.5 can have redshifs greater than 0.7. The second redshift survey studied the population of faint blue galaxies with R between 22 and 23. The redshifts of the six bluest galaxies with B-I less than 1, indicative of a near-flat spectrum in f(nu), were identified. Apart from one QSO, all the identified objects are galaxies with redshifts in the range between 0.3 and 0.9. These results are found to be consistent with both merging-dominated models for galaxy evolution and models postulating bursts of star formation in dwarf galaxies.

Colless, Matthew; Ellis, Richard S.; Broadhurst, T. J.; Taylor, Keith; Peterson, Bruce A.

1993-03-01

168

LUCIFER-MOS: a cryogenic multi-object infrared spectrograph for the LBT  

NASA Astrophysics Data System (ADS)

LUCIFER-MOS is a liquid nitrogen cooled near IR multi object spectrograph imaging 20 freely selectable sub-fields of about 2.2 inch by 1.8 inch and 6 by 4 image elements each on the entrance slit of the LUCIFER spectrograph. The image elements are re-arranged by 480 fused silica fibers of 50 micrometers core diameter and 100 micrometers total diameter with integrated, hexagonal lenslets of 0.6 mm width corresponding to a 0.3 inch field. The pre-optics magnifies the telescope image by a factor 3.3, thus adapting the telescope plate scale to the lenslet scale, and additionally providing a cold stop. The post-optics converts the f/3 fiber output beam to the f/15 beam accepted by the spectrograph. Each of the 20 6 by 4 fiber arrays together with its pre-optics is mounted in a spider arm which can be freely positioned within the 200 mm diameter field of view by a cryogenic robot. The robot performs three rotational movements to position the spider arms and is driven by cold stepper motors. The spider arms are locked in their positions by two permanent magnets each. Their magnetic field can be compensated by coils to unlock the arms and move them across the field of view.

Hofmann, Reiner; Thatte, Niranjan A.; Tecza, Matthias; Eisenhauer, Frank; Lehnert, Matthew

2000-08-01

169

Discovery of a Faint Old Stellar System at 150 kpc  

E-print Network

We report the detection of a faint old stellar system at $(\\alpha,\\delta)=(194.29^\\circ,~34.32^\\circ)$ (SDSS J1257+3419), based on the spatial distribution of bright red-giant branch stars in the Sloan Digital Sky Survey Data Release 4. SDSS J1257+3419 has a half-light radius of $38\\pm 12$ pc and an absolute integrated $V$-magnitude of $M_V=-4.8^{+1.4}_{-1.0}$ mag at a heliocentric distance of $150\\pm 15$ kpc. A comparison between SDSS J1257+3419 and known Galactic halo objects suggests that SDSS J1257+3419 is either (a) a faint and small dwarf galaxy or (b) a faint and widely extended globular cluster. In the former case, SDSS J1257+3419 could represent an entity of a postulated subhalo of the Milky Way. Further photometric and dynamical study of this stellar system is vital to discriminate these possibilities.

T. Sakamoto; T. Hasegawa

2006-10-29

170

A PAN-CARINA YOUNG STELLAR OBJECT CATALOG: INTERMEDIATE-MASS YOUNG STELLAR OBJECTS IN THE CARINA NEBULA IDENTIFIED VIA MID-INFRARED EXCESS EMISSION  

SciTech Connect

We present a catalog of 1439 young stellar objects (YSOs) spanning the 1.42 deg{sup 2} field surveyed by the Chandra Carina Complex Project (CCCP), which includes the major ionizing clusters and the most active sites of ongoing star formation within the Great Nebula in Carina. Candidate YSOs were identified via infrared (IR) excess emission from dusty circumstellar disks and envelopes, using data from the Spitzer Space Telescope (the Vela-Carina survey) and the Two-Micron All Sky Survey. We model the 1-24 {mu}m IR spectral energy distributions of the YSOs to constrain physical properties. Our Pan-Carina YSO Catalog (PCYC) is dominated by intermediate-mass (2 M{sub sun} < m {approx}< 10 M{sub sun}) objects with disks, including Herbig Ae/Be stars and their less evolved progenitors. The PCYC provides a valuable complementary data set to the CCCP X-ray source catalogs, identifying 1029 YSOs in Carina with no X-ray detection. We also catalog 410 YSOs with X-ray counterparts, including 62 candidate protostars. Candidate protostars with X-ray detections tend to be more evolved than those without. In most cases, X-ray emission apparently originating from intermediate-mass, disk-dominated YSOs is consistent with the presence of low-mass companions, but we also find that X-ray emission correlates with cooler stellar photospheres and higher disk masses. We suggest that intermediate-mass YSOs produce X-rays during their early pre-main-sequence evolution, perhaps driven by magnetic dynamo activity during the convective atmosphere phase, but this emission dies off as the stars approach the main sequence. Extrapolating over the stellar initial mass function scaled to the PCYC population, we predict a total population of >2 x 10{sup 4} YSOs and a present-day star formation rate (SFR) of >0.008 M{sub sun} yr{sup -1}. The global SFR in the Carina Nebula, averaged over the past {approx}5 Myr, has been approximately constant.

Povich, Matthew S.; Getman, Konstantin V.; Townsley, Leisa K.; Broos, Patrick S. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Smith, Nathan [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Majewski, Steven R.; Indebetouw, Remy [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Babler, Brian L.; Meade, Marilyn R.; Whitney, Barbara A. [Department of Astronomy, University of Wisconsin, 475 N. Charter Street, Madison, WI 53706 (United States); Robitaille, Thomas P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Stassun, Keivan G. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Yonekura, Yoshinori [Department of Physical Science, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531 (Japan); Fukui, Yasuo, E-mail: povich@astro.psu.edu [Department of Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)

2011-05-01

171

Near-infrared Spectroscopy Of Low Mass Compact Object X-ray Binaries : Accretion Disk Contamination And Mass Determination  

NASA Astrophysics Data System (ADS)

We present near-infrared (NIR) broadband (0.80--2.42 ?m) spectra of two low mass X-ray binaries: V404 Cyg and Cen X-4. One important parameter required in the determination of the mass of the compact object in these systems is the binary inclination. We can determine the inclination by modeling the ellipsoidal modulations of the Roche-lobe filling donor star, but the contamination of the donor star light from other components of the binary, particularly the accretion disk, must be taken into account. To this end, we determine the donor star contribution to the infrared flux by comparing the spectra of V404 Cyg and Cen X-4 to those of various field K-stars of known spectral type. For V404 Cyg, we determined that the donor star has a spectral type of K3III. We determined the fractional donor contribution to the NIR flux in the H- and K-bands as 0.98 ± .05 and 0.97 ± .09, respectively. We remodeled the H-band light curve from Sanwal et al. (1996) after correcting for the donor star contribution to obtain a new value for the binary inclination. From this, we determined the mass of the black hole in V404 Cyg to be 9.0±.7 M?. We performed the same spectral analysis for Cen X-4 and found the spectral type of the donor star to be in the range K7-M1V. The donor star contribution in Cen X-4 is 0.92±.02 in the H-band and 0.96±.15 in the K-band. We remodeled the H-band light curve from Shahbaz et al. (1993), again correcting for the fractional contribution of the donor star to obtain the inclination. From this, we determined the mass of the neutron star as 1.4±0.2 M?.

Khargharia, Juthika; Froning, C. S.; Robinson, E. L.

2010-01-01

172

A Chandra X-Ray Survey of Ultraluminous Infrared Galaxies  

E-print Network

We present results from Chandra observations of 14 ultraluminous infrared galaxies (ULIRGs; log(L_IR/L_Sun) >= 12) with redshifts between 0.04 and 0.16. The goals of the observations were to investigate any correlation between infrared color or luminosity and the properties of the X-ray emission and to attempt to determine whether these objects are powered by starbursts or active galactic nuclei (AGNs). The sample contains approximately the same number of high and low luminosity objects and ``warm'' and ``cool'' ULIRGs. All 14 galaxies were detected by Chandra. Our analysis shows that the X-ray emission of the two Seyfert 1 galaxies in our sample are dominated by AGN. The remaining 12 sources are too faint for conventional spectral fitting to be applicable. Hardness ratios were used to estimate the spectral properties of these faint sources. The photon indices for our sample plus the Chandra-observed sample from Ptak et al.(2003) peak in the range of 1.0-1.5, consistent with expectations for X-ray binaries in a starburst, an absorbed AGN, or hot bremsstrahlung from a starburst or AGN. The values of photon index for the objects in our sample classified as Seyferts (type 1 or 2) are larger than 2, while those classified as HII regions or LINERs tend to be less than 2. The hard X-ray to far-infrared ratios for the 12 weak sources are similar to those of starbursts, but we cannot rule out the possibility of absorbed, possibly Compton-thick, AGNs in some of these objects. Two of these faint sources were found to have X-ray counterparts to their double optical and infrared nuclei.

Stacy H. Teng; A. S. Wilson; S. Veilleux; A. J. Young; D. B. Sanders; N. M. Nagar

2005-08-03

173

Multiple beam combination for faint objects E. N. Ribak  

E-print Network

have a limited spectral band, so that they can extend far from the central, white-light fringe of the beam pairs. Keywords: Stellar interferometry, beam combination, achromatic fringes. 1. INTRODUCTION The problem how to combine beams in multiple-beam stellar interferometry has many solutions. A common way

Ribak, Erez

174

The LUCIFER MOS: a full cryogenic mask handling unit for a near-infrared multi-object spectrograph  

NASA Astrophysics Data System (ADS)

The LUCIFER-MOS unit is the full cryogenic mask-exchange unit for the near-infrared multi-object spectrograph LUCIFER at the Large Binocular Telescope. We present the design and functionality of this unique device. In LUCIFER the masks are stored, handled, and placed in the focal plane under cryogenic conditions at all times, resulting in very low thermal background emission from the masks during observations. All mask manipulations are done by a novel cryogenic mask handling robot that can individually address up to 33 fixed and user-provided masks and place them in the focal plane with high accuracy. A complete mask exchange cycle is done in less than five minutes and can be run in every instrument position and state reducing instrument setup time during science observations to a minimum. Exchange of old and new MOS masks is likewise done under cryogenic conditions using a unique exchange drive mechanism and two auxiliary cryostats that attach to the main instrument cryostat.

Buschkamp, Peter; Hofmann, Reiner; Gemperlein, Hans; Polsterer, Kai; Ageorges, Nancy; Eisenhauer, Frank; Lederer, Reinhard; Honsberg, Mathias; Haug, Marcus; Eibl, Johann; Seifert, Walter; Genzel, Reinhard

2010-07-01

175

Faint Satellites of Outer Planets  

Microsoft Academic Search

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

C. Veillet

1982-01-01

176

FAINT RADIO SOURCES AND STAR FORMATION HISTORY  

E-print Network

FAINT RADIO SOURCES AND STAR FORMATION HISTORY Deborah B. Haarsma 1 , R. Bruce Partridge 1 , Ian the global history of star formation. Sensitive radio observations of the Hubble Deep Field and other fields important information about global star formation history. Sensitive radio observations of the Hubble Deep

Waddington, Ian

177

Updated optical design and trade-off study for MOONS, the Multi-Object Optical and Near Infrared spectrometer for the VLT  

NASA Astrophysics Data System (ADS)

This paper presents the latest optical design for the MOONS triple-arm spectrographs. MOONS will be a Multi-Object Optical and Near-infrared Spectrograph and will be installed on one of the European Southern Observatory (ESO) Very Large Telescopes (VLT). Included in this paper is a trade-off analysis of different types of collimators, cameras, dichroics and filters.

Oliva, E.; Todd, S.; Cirasuolo, M.; Schnetler, H.; Lunney, D.; Rees, P.; Bianco, A.; Diolaiti, E.; Ferruzzi, D.; Fisher, M.; Guinouard, I.; Iuzzolino, M.; Parry, I.; Sun, X.; Tozzi, A.; Vitali, F.

2014-08-01

178

Updated optical design and trade-off study for MOONS, the Multi-Object Optical and Near Infrared spectrometer for the VLT  

E-print Network

This paper presents the latest optical design for the MOONS triple-arm spectrographs. MOONS will be a Multi-Object Optical and Near-infrared Spectrograph and will be installed on one of the European Southern Observatory (ESO) Very Large Telescopes (VLT). Included in this paper is a trade-off analysis of different types of collimators, cameras, dichroics and filters.

Oliva, E; Cirasuolo, M; Schnetler, H; Lunney, D; Rees, P; Bianco, A; Diolaiti, E; Ferruzzi, D; Fisher, M; Guinouard, I; Iuzzolino, M; Parry, I; Sun, X; Tozzi, A; Vitali, F

2014-01-01

179

Connecting X-Ray and Infrared Variability among Young Stellar Objects: Ruling out Potential Sources of Disk Fluctuations  

NASA Astrophysics Data System (ADS)

Variability in the infrared emission from disks around pre-main-sequence stars over the course of days to weeks appears to be common, but the physical cause of the changes in disk structure are not constrained. Here we present coordinated monitoring of one young cluster with the Spitzer and Chandra space telescopes aimed at studying the physical source of the variability. In fall 2011 we obtained 10 epochs of Chandra ACIS photometry over a period of 30 days with a roughly 3 day cadence contemporaneous with 20 epochs of Spitzer [3.6], [4.5] photometry over 40 days with a roughly 2 day cadence of the IC 348 cluster. This cadence allows us to search for week- to month-long responses of the infrared emission to changes in the high-energy flux. We find no strong evidence for a direct link between the X-ray and infrared variability on these timescales among 39 cluster members with circumstellar disks. There is no significant correlation between the shape of the infrared and X-ray light curves or between the sizes of the X-ray and infrared variability. Among the stars with an X-ray flare, none showed evidence of a correlated change in the infrared photometry on timescales of days to weeks following the flare. This lack of connection implies that X-ray heating of the planet-forming region of the disk is not significant, although we cannot rule out rapid or instantaneous changes in infrared emission.

Flaherty, K. M.; Muzerolle, J.; Wolk, S. J.; Rieke, G.; Gutermuth, R.; Balog, Z.; Herbst, W.; Megeath, S. T.; Furlan, E.

2014-09-01

180

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

181

OPTICAL/NEAR-INFRARED SELECTION OF RED QUASI-STELLAR OBJECTS: EVIDENCE FOR STEEP EXTINCTION CURVES TOWARD GALACTIC CENTERS?  

SciTech Connect

We present the results of a search for red QSOs using a selection based on optical imaging from the Sloan Digital Sky Survey (SDSS) and near-infrared imaging from UKIDSS. Our main goal with the selection is to search for QSOs reddened by foreground dusty absorber galaxies. For a sample of 58 candidates (including 20 objects fulfilling our selection criteria that already have spectra in the SDSS), 46 (79%) are confirmed to be QSOs. The QSOs are predominantly dust-reddened except for a handful at redshifts z {approx}> 3.5. However, the dust is most likely located in the QSO host galaxies (and for two, the reddening is primarily caused by Galactic dust) rather than in the intervening absorbers. More than half of the QSOs show evidence of associated absorption (BAL absorption). Four (7%) of the candidates turned out to be late-type stars, and another four (7%) are compact galaxies. We could not identify the remaining four objects. In terms of their optical spectra, these QSOs are similar to the QSOs selected in the FIRST-2MASS Red Quasar Survey except they are on average fainter, more distant, and only two are detected in the FIRST survey. As per the usual procedure, we estimate the amount of extinction using the SDSS QSO template reddened by Small-Magellanic-Cloud-(SMC) like dust. It is possible to get a good match to the observed (rest-frame ultraviolet) spectra, but it is not possible to match the observed near-IR photometry from UKIDSS for nearly all the reddened QSOs. The most likely reasons are that the SDSS QSO template is too red at optical wavelengths due to contaminating host galaxy light and because the assumed SMC extinction curve is too shallow. Three of the compact galaxies display old stellar populations with ages of several Gyr and masses of about 10{sup 10} M{sub Sun} (based on spectral energy distribution modeling). The inferred stellar densities in these galaxies exceed 10{sup 10} M{sub Sun} kpc{sup -2}, which is among the highest measured for early-type galaxies. Our survey has demonstrated that selection of QSOs based on near-IR photometry is an efficient way to select QSOs, including reddened QSOs, with only small contamination from late-type stars and compact galaxies. This will be useful with ongoing and future wide-field near-IR surveys such as the VISTA and EUCLID surveys.

Fynbo, J. P. U.; Krogager, J.-K.; Vestergaard, M.; Geier, S. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Venemans, B. [Max-Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Noterdaeme, P. [CNRS-UPMC, UMR7095, Institut d'Astrophysique de Paris, 98bis Bd. Arago, F-75014 Paris (France); Moller, P. [European Southern Observatory, Karl-Schwarzschildstrasse 2, D-85748 Garching bei Muenchen (Germany); Ledoux, C. [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19 (Chile)

2013-01-15

182

The Faint End of the HI Mass Function  

E-print Network

We study the faint end of the HI mass function (HIMF) in order to test the predictions of the CDM theory on the number density of objects with small (dark) masses. The neutral hydrogen is much better tracer of the underlying mass distribution compared to the luminous matter and can be used to test the existence of a population of small galaxies in which the star formation has been partially or completely suppressed during cosmic evolution. Due to technical limitations, the existing HI surveys are not very sensitive to HI masses below 10^8 M_sun. We designed a blind HI survey to be sensitive to objects with small HI masses. The surveyed area is in the Canis Venatici groups of galaxies and covers in total ~ 86 deg^2 of sky, with observed velocities in the range -350 HI. All new HI detections fall in the lower part of the mass-histogram, confirming our ability to detect galaxies with small HI masses. The calculated HIMF is flat in the faint end regime (slope ~ -1), different from the steep rise predicted by CDM models. Possible effects of the environment on the estimated HIMF parameters are discussed.

K. Kovac; T. A. Oosterloo; J. M. van der Hulst

2005-08-02

183

A faint galaxy redshift survey to B=24  

NASA Astrophysics Data System (ADS)

Using the multislit LDSS-2 spectrograph on the William Herschel Telescope, we have completed a redshift survey in the magnitude range 22.51 and includes the highest redshift galaxy (z=1.108) yet discovered in a field sample. The median redshift, z_MED=0.46, and form of the redshift distribution constitute compelling evidence against simple luminosity evolution as an explanation of the large excess of faint galaxies [~=(2-4)xno-evolution] seen in this magnitude range. Rather, we identify the excess population as blue objects with z~0.4 and B luminosities similar to local L^* galaxies, indicating a dramatic decrease in the density of such objects over the last Hubble time, and confirming the trends found in brighter redshift surveys. We also find a marked absence of very low-redshift galaxies (z<0.1) at faint limits, severely constraining any significant steepening of the local field galaxy luminosity function at low luminosities.

Glazebrook, Karl; Ellis, Richard; Colless, Matthew; Broadhurst, Tom; Allington-Smith, Jeremy; Tanvir, Nial

1995-03-01

184

GRAVITY: The adaptive optics assisted, two object beam combiner for the VLTI  

E-print Network

We present the adaptive optics assisted, near-infrared VLTI instrument - GRAVITY - for precision narrow-angle astrometry and interferometric phase referenced imaging of faint objects. Precision astrometry and phase-referenced interferometric imaging will realize the most advanced vision of optical/infrared interferometry with the VLT. Our most ambitious science goal is to study motions within a few times the event horizon size of the Galactic Center massive black hole and to test General Relativity in its strong field limit. We define the science reference cases for GRAVITY and derive the top level requirements for GRAVITY. The installation of the instrument at the VLTI is planned for 2012.

S. Gillessen; G. Perrin; W. Brandner; C. Straubmeier; F. Eisenhauer; S. Rabien; A. Eckart; P. Lena; R. Genzel; T. Paumard; S. Hippler

2006-07-17

185

A Constant Clustering Amplitude for Faint Galaxies?  

E-print Network

The angular clustering of faint field galaxies is investigated using deep imaging (I~25) obtained with the 10-m Keck-I telescope. The autocorrelation function is consistent with w(theta) ~ theta^-0.8 and, although less steep correlation functions cannot be ruled out with high confidence, we find no compelling evidence for a systematic decrease in the power law index at the faintest magnitude limits. Results from a number of independent observational studies are combined in order to investigate the variation of the correlation amplitude with median I-magnitude. At Imed~23 the results obtained by different studies are all in rough agreement and indicate that for Imed > 22 the correlation amplitude declines far less steeply than would be expected from an extrapolation of the trend in the brighter samples. In particular, at Imed~24 our data indicate w(theta) to be a factor ~7 higher than the extrapolation. A near-independence of magnitude is a general feature of the correlation amplitude in models in which the redshift distribution of the faint field population contains a substantial fraction of galaxies with z > 1. In order to reproduce the apparent abrupt flattening of the amplitude of w(theta) observed at faint limits, approximately 50% of the galaxies in a sample with a depth of I~25 must be at z > 1.

Tereasa G. Brainerd; Ian Smail

1997-12-19

186

A small-area faint KX redshift survey for QSOs in the ESO Imaging Survey Chandra Deep Field South  

NASA Astrophysics Data System (ADS)

In this paper we present preliminary spectroscopic results from a small-area faint K-excess (KX) survey, and compare KX selection against UVX selection. The aim of the KX method is to produce complete samples of QSOs that are flux-limited in the K band, in order to minimize any selection bias in samples of QSOs from the effects of reddening and extinction. Using the photometric catalogue of the ESO Imaging Survey Chandra Deep Field South (48arcmin2) we have identified compact objects with J-K colours redder than the stellar sequence that are brighter than K=19.5. We have obtained spectra of 33 candidates, using the LDSS++ spectrograph on the Anglo-Australian Telescope (AAT). Amongst the 11 bluer candidates, with V-J<3, three are confirmed as QSOs. Identification of the 22 redder candidates with V-J>=3 is substantially incomplete, but so far no reddened QSOs have been found. Near-infrared spectroscopy will be more effective in identifying some of these targets. Only two UVX (U-B<-0.2) sources brighter than K=19.5 are found that are not also KX selected. These are both identified as galactic stars. Thus KX selection appears to select all UVX QSOs. The surface density of QSOs in the blue subsample (V-J<3) at K<=19.5 is 325-177+316deg-2. Because identification of the red subsample (V-J>=3) is substantially incomplete, the 2? upper limit on the density of reddened QSOs is large, <1150deg-2. As anticipated, at these faint magnitudes the KX sample includes several compact galaxies. Of the 14 with measured redshifts, there are roughly equal numbers of early- and late-type objects. Nearly all the early-type galaxies are found in a single structure at z=0.66.

Croom, Scott M.; Warren, S. J.; Glazebrook, K.

2001-11-01

187

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

188

Optical/Near-infrared Selection of Red Quasi-stellar Objects: Evidence for Steep Extinction Curves toward Galactic Centers?  

NASA Astrophysics Data System (ADS)

We present the results of a search for red QSOs using a selection based on optical imaging from the Sloan Digital Sky Survey (SDSS) and near-infrared imaging from UKIDSS. Our main goal with the selection is to search for QSOs reddened by foreground dusty absorber galaxies. For a sample of 58 candidates (including 20 objects fulfilling our selection criteria that already have spectra in the SDSS), 46 (79%) are confirmed to be QSOs. The QSOs are predominantly dust-reddened except for a handful at redshifts z >~ 3.5. However, the dust is most likely located in the QSO host galaxies (and for two, the reddening is primarily caused by Galactic dust) rather than in the intervening absorbers. More than half of the QSOs show evidence of associated absorption (BAL absorption). Four (7%) of the candidates turned out to be late-type stars, and another four (7%) are compact galaxies. We could not identify the remaining four objects. In terms of their optical spectra, these QSOs are similar to the QSOs selected in the FIRST-2MASS Red Quasar Survey except they are on average fainter, more distant, and only two are detected in the FIRST survey. As per the usual procedure, we estimate the amount of extinction using the SDSS QSO template reddened by Small-Magellanic-Cloud-(SMC) like dust. It is possible to get a good match to the observed (rest-frame ultraviolet) spectra, but it is not possible to match the observed near-IR photometry from UKIDSS for nearly all the reddened QSOs. The most likely reasons are that the SDSS QSO template is too red at optical wavelengths due to contaminating host galaxy light and because the assumed SMC extinction curve is too shallow. Three of the compact galaxies display old stellar populations with ages of several Gyr and masses of about 1010 M ? (based on spectral energy distribution modeling). The inferred stellar densities in these galaxies exceed 1010 M ? kpc-2, which is among the highest measured for early-type galaxies. Our survey has demonstrated that selection of QSOs based on near-IR photometry is an efficient way to select QSOs, including reddened QSOs, with only small contamination from late-type stars and compact galaxies. This will be useful with ongoing and future wide-field near-IR surveys such as the VISTA and EUCLID surveys. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under program 088.A-0098, and on observations made with the Nordic Optical Telescope, jointly operated on the island of La Palma by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

Fynbo, J. P. U.; Krogager, J.-K.; Venemans, B.; Noterdaeme, P.; Vestergaard, M.; Møller, P.; Ledoux, C.; Geier, S.

2013-01-01

189

An object detection strategy for uncooled infrared imagery H. A. SCHMITT*, J. G. RIDDLE and T. M. BRUCKS  

E-print Network

differ significantly from cooled infrared sensors that employ photon-counting detectors. As such, UCIR & Hardware, 1020 Sherman Avenue, Hamden, CT 06514, USA (Received 15 February 2002; revision received 20 April imagery tends to be very low contrast, since the sensor operates over a broad spectral band; and blurry

Cohen, Israel

190

AGN with faint broad line regions: Some `True'-Seyfert 2s might be Narrow Line Seyfert 1s  

NASA Astrophysics Data System (ADS)

The intriguing existence of `True'-Seyfert 2s has opened a debate on the validity of the unified model of active galactic nuclei (AGN). These objects, also called `Naked'-AGN, seem to lack a broad line region. In some cases, their X-ray emission is unabsorbed, typical of Seyfert 1 galaxies, indicating a clear view toward the nucleus, but no broad lines are seen in the optical. In `True'-Seyfert 2s with higher column densities, observations of polarized light have failed to reveal the hidden broad emission. We performed high-resolution near-infrared integral-field observations of two `True'-Seyfert 2 candidates: IRAS 01072+4954 and NGC 7496. We found that the AGN in these sources might power very faint and narrow broad emission lines (FWHMbroad < 1500km s-1). Here, we discuss the properties of the broad components estimated from published X-ray and/or optical measurements and present their near-infrared candidate identification. Both galaxies host intermediate-mass black holes, with masses ~ 105-106 M?. Our results favor the unified model in the cases of high accretion rates, and stress the necessity of a multiwavelength approach to unveil the nature of `Naked'-AGN.

Valencia-S., Mónica; Busch, G.; Smaji?, S.; Fazeli, N.; Behroozian, S.; Zuther, J.; Fischer, S.; Eckart, A.

2014-07-01

191

MOVING OBJECTS IN THE HUBBLE ULTRA DEEP FIELD  

SciTech Connect

We identify proper motion objects in the Hubble Ultra Deep Field (UDF) using the optical data from the original UDF program in 2004 and the near-infrared data from the 128 orbit UDF 2012 campaign. There are 12 sources brighter than I = 27 mag that display >3{sigma} significant proper motions. We do not find any proper motion objects fainter than this magnitude limit. Combining optical and near-infrared photometry, we model the spectral energy distribution of each point-source using stellar templates and state-of-the-art white dwarf models. For I {<=} 27 mag, we identify 23 stars with K0-M6 spectral types and two faint blue objects that are clearly old, thick disk white dwarfs. We measure a thick disk white dwarf space density of 0.1-1.7 Multiplication-Sign 10{sup -3} pc{sup -3} from these two objects. There are no halo white dwarfs in the UDF down to I = 27 mag. Combining the Hubble Deep Field North, South, and the UDF data, we do not see any evidence for dark matter in the form of faint halo white dwarfs, and the observed population of white dwarfs can be explained with the standard Galactic models.

Kilic, Mukremin; Gianninas, Alexandros [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019 (United States); Von Hippel, Ted, E-mail: kilic@ou.edu, E-mail: alexg@nhn.ou.edu, E-mail: ted.vonhippel@erau.edu [Embry-Riddle Aeronautical University, 600 S. Clyde Morris Blvd., Daytona Beach, FL 32114 (United States)

2013-09-01

192

Development of a simultaneous two-color near-infrared multi-object spectrograph SWIMS for the TAO 6.5-m telescope  

NASA Astrophysics Data System (ADS)

Simultaneous Color Wide-?eld Infrared Multi-object Spectrograph, SWIMS, is one of the ?rst generation in- struments for the University of Tokyo Atacama Observatory (TAO) 6.5m Telescope now under construction. A dichroic mirror being inserted in the collimated beam, it is capable of two-color simultaneous imaging with FoV of 9:16? or R ˜ 1000 multi-object spectroscopy at 0.9-2.5?m wavelength range in one shot, and enables us to carry out e?cient NIR imaging/spectroscopic survey of objects such as distant galaxies and young stellar objects. All the major components have been fabricated and we will start integration and laboratory cool-down test in the summer of 2014. After the engineering and initial science observations at the Subaru telescope, SWIMS will be transported to TAO telescope and see the ?rst light in 2018.

Motohara, Kentaro; Konishi, Masahiro; Takahashi, Hidenori; Tateuchi, Ken; Kitagawa, Yutaro; Todo, Soya; Kato, Natsuko M.; Ohsawa, Ryou; Aoki, Tsutomu; Asano, Kentaro; Doi, Mamoru; Kamizuka, Takafumi; Kawara, Kimiaki; Kohno, Kotaro; Koshida, Shintaro; Minezaki, Takeo; Miyata, Takashi; Morokuma, Tomoki; Okada, Kazushi; Sako, Shigeyuki; Soyano, Takao; Tamura, Yoichi; Tanabe, Toshihiko; Tanaka, Masuo; Tarusawa, Ken'ichi; Uchiyama, Mizuho; Yoshii, Yuzuru

2014-07-01

193

Physical and Chemical Properties of Protocluster Clumps and Massive Young Stellar Objects Associated to Infrared Dark Clouds  

NASA Astrophysics Data System (ADS)

The study of high-mass stars is important not only because of the effects they produce in their environment through outflows, expanding HII regions, stellar winds, and eventually supernova shock waves, but also because they play a crucial role in estimating star formation rates in other galaxies. Although we have an accepted evolutionary scenario that explains (isolated) low-mass star formation, the processes that produce massive stars (M_star > 8 M_sol) and star clusters, especially their earliest stages, are not well understood. The newly discovered class of interstellar clouds now termed infrared dark clouds (IRDCs) represent excellent laboratories to study the earliest stages of high-mass star formation given that some of the clumps within them are known to have high masses (~100's M_sol), high densities (n > 10^5 cm^-3), and low temperatures (10-20K) as expected for the birthplaces of high-mass stars. Some questions remain unanswered: Do IRDCs harbor the very early stages of high-mass star formation, i.e., the pre-protocluster phase? If so, how do they compare with low-mass star formation sites? Is there chemical differentiation in IRDC clumps? What is the mass distribution of IRDCs? In this dissertation and for the first time, a catalog of 12529 IRDC candidates at 24 um has been created using archival data from the MIPSGAL/Spitzer survey, as a first step in searching for the massive pre-protocluster clumps. From this catalog, a sample of ~60 clumps has been selected in order to perform single-pointing observations with the IRAM 30m, Effelsberg 100m, and APEX 12m telescopes. One IRDC clump seems to be a promising candidate for being in the pre-protocluster phase. In addition, molecular line mapping observations have been performed on three clumps within IRDCs and a detailed chemical study of 10 molecular lines has been carried out. A larger difference in column densities and abundances has been found between these clumps and high-m! ass protostellar objects than between these clumps and low-mass pre-stellar cores and protostellar objects. A non-LTE Monte Carlo code was used to model the N_2H^+ (1-0) and (3-2) lines in order to constrain the physical properties of two clumps. Six IRDC complexes have been mapped in the 870 um dust continuum emission with the LABOCA instrument on the APEX 12m telescope. Line observations have been carried out in order to obtain temperature and kinematic distances of selected clumps. Physical properties such as masses, effective radii, and column densities have been obtained. The mass spectrum of these clumps has been fitted with a power-law whose best-fitting index is alpha =-1.60. This value is consistent with the CO clump mass function reported in the literature. A relation between the dust emission at 870 um and the degree of extinction (contrast) at 24 um has been obtained by combining dust emission observations and extinction studies. A study with the Plateau de Bure Interferometer of a core in an archetypal filamentary IRDC at few arcsecond resolution has been carried out to determine its physical and chemical structure. Extended 4.5 um emission, "wings" in the CH_3OH 2_k -> 1_k spectra, and a CH_3OH abundance enhancement provide evidence of an outflow in the East-West direction. In addition, a gradient of ~4 km/s in the same direction has been found, which is interpreted as being produced by an outflow(s)-cloud interaction. Finally, Very Large Array interferometric observations of the 7_0-6_1 A^+ (class I) methanol maser transition at 44 GHz toward three high-mass star-forming regions have been carried out in order to provide accurate maser positions and parameters. For all three sources, the masers were well-separated from the HII region, with projected distances ranging from 0.1 to 0.3 pc.

Gomez Gonzalez, Laura

2012-01-01

194

Unveiling the near-infrared structure of the massive-young stellar object NGC3603 IRS 9A with sparse aperture masking and spectroastrometry  

E-print Network

According to the current theories, massive stars gather mass during their initial phases via accreting disk-like structures. However, those disks have remained elusive for massive young objects. This is mainly because of the observational challenges due to the large distances at which they are located, their rareness, and the high interstellar extinction. Therefore, the study of each young massive stellar object matters. NGC 3603 IRS 9A is a young massive stellar object still surrounded by an envelope of molecular gas. Previous mid-infrared observations with long-baseline interferometry provided evidence for a disk of 50 mas diameter at its core. This work studies the IRS 9A physics and morphology at near-infrared wavelengths. This study analyzed new sparse aperture masking data taken with NACO/VLT at K s and Lp filters in addition to archive CRIRES spectra of the H2 and Br_gamma lines. The calibrated visibilities trends of the Ks and Lp bands suggest the presence of a partially resolved compact object of 30 ...

Sanchez-Bermudez, J; Tuthill, P; Alberdi, A; Schödel, R; Lacour, S

2014-01-01

195

Constraining the luminosity function of faint undetected i-dropout galaxies  

NASA Astrophysics Data System (ADS)

We present a new technique to quantify the light contribution coming from the faint high-redshift (z ˜ 6) galaxies below the detection threshold of imaging data, set conventionally at S/N = 4.5. We illustrate the technique with an application to Hubble Space Telescope Advanced Camera for Surveys images in the F775W and F850LP filters of the Ultra Deep Field parallel field NICP12. The aim of this analysis is to extend by a few magnitudes the faint end of the luminosity function at z ˜ 6. After masking all the detected sources in the field, we apply a fast Fourier transform to obtain the spatial power spectrum of the background signal. The power spectrum permits us to separate the background noise signal, the residuals due to the data reduction of the wide field and the overall signal produced by faint galaxies. The ratio of the signal in the i775 and z850 bands is used to estimate the contribution of the faint i-dropout objects. We rely on extensive Monte Carlo simulations to characterize various sources of uncertainty and quantify the number of faint i-dropout galaxies in the field. The analysis allows us to put constraints on the luminosity function at z ˜ 6 down to z850 = 30 mag, 2.5 mag fainter than with standard techniques on the same data. The data are consistent with a faint-end slope of the luminosity function of ? = -1.9. Assuming a specific set of values for the clumping factor, escape fraction and spectral energy distribution, we find that the z ˜ 6 undetected galaxies down to z850 = 30 mag could have driven cosmic reionization.

Calvi, V.; Pizzella, A.; Stiavelli, M.; Morelli, L.; Corsini, E. M.; Dalla Bontà, E.; Bradley, L.; Koekemoer, A. M.

2013-07-01

196

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

197

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.

198

Exploring the faint source population at 15.7 GHz  

NASA Astrophysics Data System (ADS)

A sample of 296 faint (> 0.5 mJy) radio sources is selected from an area of the Tenth Cambridge (10C) survey at 15.7 GHz in the Lockman Hole. The 10C survey is complete to 0.5 mJy at 15.7 GHz and has a resolution of 30 arcsec. By matching this catalogue to several lower frequency surveys (e.g. including a deep GMRT survey at 610 MHz, a WSRT survey at 1.4 GHz, NVSS, FIRST and WENSS) I have investigated the radio spectral properties of the sources in this sample; all but 30 of the 10C sources are matched to a source in one or more of these surveys. I have found a significant increase in the proportion of flat spectrum sources at flux densities below 1 mJy -- the median spectral index between 15.7 GHz and 610 MHz changes from 0.75 for flux densities greater than 1.5 mJy to 0.08 for flux densities less than 0.8 mJy. Thus a population of faint, flat spectrum sources is emerging at flux densities greater than approximately 1 mJy. The spectral index distribution of this sample of sources selected at 15.7 GHz is compared to those of two samples selected at 1.4 GHz from FIRST and NVSS. I find that there is a significant flat spectrum population present in the 10C sample which is missing from the samples selected at 1.4 GHz. The 10C sample is compared to a sample of sources selected from the SKADS Simulated Sky by Wilman et al.; this simulation fails to reproduce the observed spectral index distribution and significantly under predicts the number of sources in the faintest flux density bin. I conclude that it is likely that the observed faint, flat spectrum sources are a result of the cores of FRI sources becoming dominant at high frequencies, rather than the emergence of a new population of starforming galaxies. I have used recent Very Long Baseline Interferometry (VLBI) observations by Middleberg et al. with a resolution of 10 mas to investigate the properties of these faint 10C sources in the Lockman Hole and find that 33 out of the 51 10C sources in the VLBI field (65 percent) are detected by the VLBI observations. The high brightness temperature of these VLBI-detected sources rules out the possibility that this faint, high frequency population is dominated by starbursting or starforming sources and indicates that they must be Active Galactic Nuclei. The sources in the Lockman Hole 10C sample are matched to optical, infrared and Xray data available in the field. A complete sample of 96 sources with high-resolution radio information available is defined; multi-wavelength counterparts are identified for 80 out of the 96 sources in this sample, for which is it possible to derive photometric redshifts. The radio-to-optical ratios of these sources show that the 10C sample is almost completely dominated by radio galaxies. 59/80 sources have luminosities greater than the FRI/FRII dividing luminosity. The nature of these radio galaxies is investigated, using the multi-wavelength data to split the sources into high-excitation and low-excitation radio galaxies (HERGs and LERGs respectively). This shows that 34 sources are probably HERGs and 33 are probably LERGs, with 29 which could not be classified at this stage. The properties of these HERGs and LERGs are compared and I find that the HERGs tend to be found at higher redshifts, have flatter spectra, higher flux densities and smaller linear sizes. This study is extended to lower flux densities using new, very deep, observations made with the Arcminute Microkelvin Imager in two fields. I use these observations to extend the 15.7-GHz source count down to 0.1 mJy, a factor of five deeper than the 10C count. These new deeper counts are consistent with the extrapolation of the fit to the 10C count, and do not show any evidence for an upturn. There is therefore no evidence for a new population (e.g. of starforming sources) contributing to the 15.7 GHz source count above 0.1 mJy, and suggesting that the faint, high-frequency population continues to be dominated by radio galaxies. Recent models of the high-frequency source counts under-predict the number of sources observed by a factor of

Whittam, Imogen

2014-10-01

199

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

200

An HST Morphological Survey of Faint EROs  

E-print Network

We present the results from a survey for Extremely Red Objects (EROs) in deep, high resolution optical images taken from the Hubble Space Telescope (HST) Medium Deep Survey. We have surveyed 35 deep F814W HST/WFPC2 fields in the near-infrared to a typical depth of K~20. From a total area of 206 arcmin^2 and to a limit of K=20.0 we identify 224 EROs ((1.14+/-0.08) arcmin^-2) with (I_{814}-K)=>4.0 and 83 ((0.41+/-0.05) arcmin^-2) with (I_{814}-K)=>5.0. We find that the slope of the number counts of the (I_{814}-K)=>4.0 EROs flattens beyond K~19, in line with results from previous surveys, and the typical colours of the EROs become redder beyond the break magnitude. We morphologically classify our ERO sample using visual and quantitative schemes and find that 35% of our sample exhibit clear disk components, 15% are disturbed or irregular, a further 30% are either spheroidal or compact and the remaining 20% are unclassifiable. Using a quantitative measure of morphology, we find that the ERO morphological distribution evolves across the break in their counts, such that low concentration (disk-like) galaxies decline. We relate the morphological and colour information for our EROs and conclude that those EROs morphologically classified as bulges do indeed possess SEDs consistent with passive stellar populations; while EROs with dusty star-forming SEDs are mostly associated with disk-like and peculiar galaxies. However, ~30% of disk EROs reside in the passive region of I/J/K colour-colour space. These could be either genuinely passive systems, lower redshift contaminants to the high-z ERO population, or systems with composite star-forming and passive SEDs.

David G. Gilbank; Ian Smail; R. J. Ivison; C. Packham

2003-08-19

201

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

202

The Population of Tiny Near-Earth Objects Observed by NEOWISE  

NASA Astrophysics Data System (ADS)

Only a very small fraction of the asteroid population at size scales comparable to the object that exploded over Chelyabinsk, Russia has been discovered to date, and physical properties are poorly characterized. We present previously unreported detections of 105 close approaching near-Earth objects (NEOs) by the Wide-field Infrared Survey Explorer (WISE) mission's NEOWISE project. These infrared observations constrain physical properties such as diameter and albedo for these objects, many of which are found to be smaller than 100 m. Because these objects are intrinsically faint, they were detected by WISE during very close approaches to the Earth, often at large apparent on-sky velocities. We observe a trend of increasing albedo with decreasing size, but as this sample of NEOs was discovered by visible light surveys, it is likely that selection biases against finding small, dark NEOs influence this finding.

Mainzer, A.; Bauer, J.; Grav, T.; Masiero, J.; Cutri, R. M.; Wright, E.; Nugent, C. R.; Stevenson, R.; Clyne, E.; Cukrov, G.; Masci, F.

2014-04-01

203

Chemical evolution of classical and ultra-faint dwarf spheroidal galaxies  

NASA Astrophysics Data System (ADS)

We present updated chemical evolution models of two dwarf spheroidal galaxies (Sculptor and Carina) and the first detailed chemical evolution models of two ultra-faint dwarfs (Hercules and Boötes I). Our results suggest that the dwarf spheroidals evolve with a low efficiency of star formation, confirming previous results, and the ultra-faint dwarfs with an even lower one. Under these assumptions, we can reproduce the stellar metallicity distribution function, the [?/Fe] versus [Fe/H] abundance patterns and the total stellar and gas masses observed at the present time in these objects. In particular, for the ultra-faint dwarfs we assume a strong initial burst of star formation, with the mass of the system being already in place at early times. On the other hand, for the classical dwarf spheroidals the agreement with the data is found by assuming the star formation histories suggested by the colour-magnitude diagrams and a longer time-scale of formation via gas infall. We find that all these galaxies should experience galactic winds, starting in all cases before 1 Gyr from the beginning of their evolution. From comparison with Galaxy data, we conclude that it is unlikely that the ultra-faint dwarfs have been the building blocks of the whole Galactic halo, although more data are necessary before drawing firm conclusions.

Vincenzo, F.; Matteucci, F.; Vattakunnel, S.; Lanfranchi, G. A.

2014-07-01

204

The Contribution of Low Surface-Brightness Galaxies to Faint Galaxy Counts  

E-print Network

Low Surface-Brightness (LSB) galaxies are severely underrepresented in surveys used to define the local luminosity function (LF), but could it in principle be detected in deep surveys. To explore the possible contribution of such objects to faint galaxy counts, we construct catalogs of simulated non-evolving galaxies drawn from a multivariate distribution of galaxy luminosities, central surface brightnesses, bulge/disk ratios and spectral-energy distributions. We compare two models dominated by LSB galaxies to a standard non-evolving model. Model galaxies are convolved with seeing and selected in a manner that closely matches real surveys. For each model we compute the local LF, HI mass function, number counts, redshift and color distributions. We find it possible to include a large population of LSB galaxies and incorporate a steep faint-end slope of the LF in our simulations without violating the constraints on the local LF or HI mass function. For $q_0 = 0.5$, the most favorable model matches the counts to B=23, but falls short of the observations at fainter magnitudes. The colors and redshift distributions remain roughly consistent with observations to B=24. The most serious discrepancy with observations is in the distribution of $r_e$ at faint magnitudes, suggesting that the model contains too many LSB galaxies. Nevertheless, the results suggest that LSB galaxies could be a significant contributor to faint-galaxy counts, reducing the need for such extreme models of galaxy evolution as rapid merging or bursting dwarf galaxies.

Henry C. Ferguson; Stacy S. McGaugh

1994-09-27

205

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. PMID:17185734

2006-01-01

206

NEAR-INFRARED H{sub 2} AND CONTINUUM SURVEY OF EXTENDED GREEN OBJECTS. II. COMPLETE CENSUS FOR THE NORTHERN GALACTIC PLANE  

SciTech Connect

We discuss 94 Extended Green Objects (EGOs) in the northern Galactic plane cataloged by Cyganowski et al., based on near-infrared narrow H{sub 2} (2.122 ?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 H{sub 2} emission. Of our sample, only 28% of EGOs with H{sub 2} emission show similar morphologies between 4.5 ?m and H{sub 2} emission. These results suggest that the 4.5 ?m emission mainly comes from scattered continuum from the embedded young stellar objects, and partially from H{sub 2} emission. About half of EGOs are associated with H{sub 2} outflows, if the H{sub 2} outflow incompleteness is considered. The H{sub 2} outflow detection rate for EGOs with K-band detections (61%) is significantly higher than for those without K-band detections (36%). This difference may be due to the fact that both H{sub 2} and K-band emissions are associated with outflows, i.e., H{sub 2} emission and K-band continuum are associated with shocks and outflow cavities, respectively. We also compared the correlation between the H{sub 2} outflows and Class I 44 GHz methanol masers from the literature. The methanol masers can be located upstream or downstream of the H{sub 2} outflows and some bright H{sub 2} spots or outflows are not associated with methanol masers, suggesting that methanol masers and H{sub 2} emission trace different excitation conditions.

Lee, Hsu-Tai; Karr, Jennifer; Su, Yu-Nung; Liu, Sheng-Yuan; Takami, Michihiro [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Liao, Wei-Ting [Department of Mechanical Engineering, National Taiwan University, 1 Roosevelt Rd., Section 4, Taipei 10617, Taiwan (China); Froebrich, Dirk; Ioannidis, Georgios [Centre for Astrophysics and Planetary Science, University of Kent, Canterbury CT2 7NH (United Kingdom); Lee, Yong-Hyun [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Duan, Hao-Yuan, E-mail: htlee@illinois.edu [Institute of Astronomy and Department of Physics, National Tsing-Hua University, Hsinchu 30013, Taiwan (China)

2013-10-01

207

Detecting Moving Objects in Airborne Forward Looking InfraRed Sequences Alexander Strehl and J. K. Aggarwal \\Lambda  

E-print Network

on model­based approaches and multi­sensor fu­ sion [16, 18, 5]. While common ATR systems can track objects. Aggarwal \\Lambda Computer and Vision Research Center The University of Texas at Austin Department of Electrical and Computer Engineering Austin, TX 78712­1084, U.S.A. fstrehl

Strehl, Alexander

208

Target discrimination of man-made objects using passive polarimetric signatures acquired in the visible and infrared spectral bands  

Microsoft Academic Search

Surveillance operations and search and rescue missions regularly exploit electro-optic imaging systems to detect targets of interest in both the civilian and military communities. By incorporating the polarization of light as supplementary information to such electro-optic imaging systems, it is possible to increase their target discrimination capabilities, considering that man-made objects are known to depolarized light in different manner than

Daniel A. Lavigne; Mélanie Breton; Georges Fournier; Jean-François Charette; Mario Pichette; Vincent Rivet; Anne-Pier Bernier

2011-01-01

209

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 Å 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° to 270°) 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

210

Joint US-Japan Observations with the Infrared Space Observatory (ISO): Deep Surveys and Observations of High-Z Objects  

NASA Technical Reports Server (NTRS)

Several important milestones were passed during the past year of our ISO observing program: (1) Our first ISO data were successfully obtained. ISOCAM data were taken for our primary deep field target in the 'Lockman Hole'. Thirteen hours of integration (taken over 4 contiguous orbits) were obtained in the LW2 filter of a 3 ft x 3 ft region centered on the position of minimum HI column density in the Lockman Hole. The data were obtained in microscanning mode. This is the deepest integration attempted to date (by almost a factor of 4 in time) with ISOCAM. (2) The deep survey data obtained for the Lockman Hole were received by the Japanese P.I. (Yoshi Taniguchi) in early December, 1996 (following release of the improved pipeline formatted data from Vilspa), and a copy was forwarded to Hawaii shortly thereafter. These data were processed independently by the Japan and Hawaii groups during the latter part of December 1996, and early January, 1997. The Hawaii group made use of the U.S. ISO data center at IPAC/Caltech in Pasadena to carry out their data reduction, while the Japanese group used a copy of the ISOCAM data analysis package made available to them through an agreement with the head of the ISOCAM team, Catherine Cesarsky. (3) Results of our LW2 Deep Survey in the Lockman Hole were first reported at the ISO Workshop "Taking ISO to the Limits: Exploring the Faintest Sources in the Infrared" held at the ISO Science Operations Center in Villafranca, Spain (VILSPA) on 3-4 February, 1997. Yoshi Taniguchi gave an invited presentation summarizing the results of the U.S.-Japan team, and Dave Sanders gave an invited talk summarizing the results of the Workshop at the conclusion of the two day meeting. The text of the talks by Taniguchi and Sanders are included in the printed Workshop Proceedings, and are published in full on the Web. By several independent accounts, the U.S.-Japan Deep Survey results were one of the highlights of the Workshop; these data showed conclusively that the ISOCAM S/N continues to decrease as the square root of time for periods as long as 13 hours.

Sanders, David B.

1997-01-01

211

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

212

Studies of the association of faint blue and luminous galaxies using the Hitchhiker parallel camera  

Microsoft Academic Search

At B magnitudes >24 there is a well-known excess of galaxies (compared to standard models) which is probably due to an (evolving) population of sub-L^*^ galaxies at moderate redshifts (<~0.4). One particular hypothesis which is hard to test directly via number counts or even redshift surveys is the possibility that the faint blue galaxies are in fact sub-galactic objects destined

J. B. Jones; S. P. Driver; S. Phillipps; J. I. Davies; I. Morgan; M. J. Disney

1997-01-01

213

Star Formation and the Interstellar Medium in Nearby Tidal Streams (SAINTS): Spitzer Mid-infrared spectroscopy and Imaging of Intergalactic Star-forming Objects  

NASA Astrophysics Data System (ADS)

A spectroscopic analysis of 10 intergalactic star-forming objects (ISFOs) and a photometric analysis of 67 ISFOs in a sample of 14 interacting systems is presented. The majority of the ISFOs have relative polycyclic aromatic hydrocarbon (PAH) band strengths similar to those of nearby spiral and starburst galaxies. In contrast to what is observed in blue compact dwarfs (BCDs) and local giant H II regions in the Milky Way (NGC 3603) and the Magellanic Clouds (30 Doradus and N 66), the relative PAH band strengths in ISFOs correspond to models with a significant PAH ion fraction (<50%) and bright emission from large PAHs (~100 carbon atoms). The [Ne III]/[Ne II] and [S IV]/[S III] line flux ratios indicate moderate levels of excitation with an interstellar radiation field that is harder than the majority of the Spitzer Infrared Nearby Galaxies Survey and starburst galaxies, but softer than BCDs and local giant H II regions. The ISFO neon line flux ratios are consistent with a burst of star formation lsim6 million years ago. Most of the ISFOs have ~106 M ? of warm H2 with a likely origin in photo-dissociation regions (PDRs). Infrared Array Camera photometry shows the ISFOs to be bright at 8 ?m, with one-third having [4.5] - [8.0] > 3.7, i.e., enhanced non-stellar emission, most likely due to PAHs, relative to normal spirals, dwarf irregulars, and BCD galaxies. The relative strength of the 8 ?m emission compared to that at 3.6 ?m or 24 ?m separates ISFOs from dwarf galaxies in Spitzer two-color diagrams. The infrared power in two-thirds of the ISFOs is dominated by emission from grains in a diffuse interstellar medium. One in six ISFOs have significant emission from PDRs, contributing ~30%-60% of the total power. ISFOs are young knots of intense star formation.

Higdon, S. J. U.; Higdon, J. L.; Smith, B. J.; Hancock, M.

2014-06-01

214

Star formation in infrared bright and infrared faint starburst interacting galaxies  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

215

Water in star-forming regions with Herschel (WISH). III. Far-infrared cooling lines in low-mass young stellar objects  

NASA Astrophysics Data System (ADS)

Context. Understanding the physical phenomena involved in the earlierst stages of protostellar evolution requires knowledge of the heating and cooling processes that occur in the surroundings of a young stellar object. Spatially resolved information from its constituent gas and dust provides the necessary constraints to distinguish between different theories of accretion energy dissipation into the envelope. Aims. Our aims are to quantify the far-infrared line emission from low-mass protostars and the contribution of different atomic and molecular species to the gas cooling budget, to determine the spatial extent of the emission, and to investigate the underlying excitation conditions. Analysis of the line cooling will help us characterize the evolution of the relevant physical processes as the protostar ages. Methods. Far-infrared Herschel-PACS spectra of 18 low-mass protostars of various luminosities and evolutionary stages are studied in the context of the WISH key program. For most targets, the spectra include many wavelength intervals selected to cover specific CO, H2O, OH, and atomic lines. For four targets the spectra span the entire 55-200 ?m region. The PACS field-of-view covers ~47" with the resolution of 9.4". Results. Most of the protostars in our sample show strong atomic and molecular far-infrared emission. Water is detected in 17 out of 18 objects (except TMC1A), including 5 Class I sources. The high-excitation H2O 818-707 63.3 ?m line (Eu/kB = 1071 K) is detected in 7 sources. CO transitions from J = 14-13 up to J = 49 - 48 are found and show two distinct temperature components on Boltzmann diagrams with rotational temperatures of ~350 K and ~700 K. H2O has typical excitation temperatures of ~150 K. Emission from both Class 0 and I sources is usually spatially extended along the outflow direction but with a pattern that depends on the species and the transition. In the extended sources, emission is stronger off source and extended on &?10,000 AU scales; in the compact sample, more than half of the flux originates within 1000 AU of the protostar. The H2O line fluxes correlate strongly with those of the high-J CO lines, both for the full array and for the central position, as well as with the bolometric luminosity and envelope mass. They correlate less strongly with OH fluxes and not with [O I] fluxes. In contrast, [O I] and OH often peak together at the central position. Conclusions. The PACS data probe at least two physical components. The H2O and CO emission very likely arises in non-dissociative (irradiated) shocks along the outflow walls with a range of pre-shock densities. Some OH is also associated with this component, most likely resulting from H2O photodissociation. UV-heated gas contributes only a minor fraction to the CO emission observed by PACS, based on the strong correlation between the shock-dominated CO 24-23 line and the CO 14-13 line. [O I] and some of the OH emission probe dissociative shocks in the inner envelope. The total far-infrared cooling is dominated by H2O and CO, with the fraction contributed by [O I] increasing for Class I sources. Consistent with previous studies, the ratio of total far-infrared line emission over bolometric luminosity decreases with the evolutionary state. Appendices A-J are available in electronic form at http://www.aanda.org

Karska, A.; Herczeg, G. J.; van Dishoeck, E. F.; Wampfler, S. F.; Kristensen, L. E.; Goicoechea, J. R.; Visser, R.; Nisini, B.; San José-García, I.; Bruderer, S.; ?niady, P.; Doty, S.; Fedele, D.; Y?ld?z, U. A.; Benz, A. O.; Bergin, E.; Caselli, P.; Herpin, F.; Hogerheijde, M. R.; Johnstone, D.; Jørgensen, J. K.; Liseau, R.; Tafalla, M.; van der Tak, F.; Wyrowski, F.

2013-04-01

216

A search for T Tauri stars in high-latitude molecular clouds. 2: The IRAS Faint Source Survey catalog  

NASA Technical Reports Server (NTRS)

We present a catalog of infrared point sources from the IRAS Faint Source Survey at Galactic latitudes the absolute magnitude of b is greater than or equal to 30 deg. The aim of this paper is to provide a list of possible star-forming sites at high Galactic latitudes in order to address the question of whether or not the translucent molecular clouds (which are most easily identified at high latitudes) are capable of star formation. The primary list of sources has 12, 25, 60, and 100 micron fluxes within the range typical of pre-main-sequence or T Tauri stars. A secondary list has the same range of 12, 25, and 60 micron fluxes, but only upper limits at 100 microns. A total of 127 candidates from the first category and 65 candidates from the second category are identified and their positions and infrared spectral characteristics tabulated. Although the colors and fluxes of these sources are typical of T Tauri or pre-main-sequence stars and YSOs, extragalactic sources and planetary nebulae sometimes have similar colors. These lists provide a starting point for optical spectroscopy or other techniques to positively identify these objects. We can determine an upper limit to the star forming efficiency of high-latitude molecular clouds assuming all the candidates in our sample are pre-main sequence stars of one solar mass. The upper limit of a few tenths of 1% is less than the star-forming efficiency of local dark cloud complexes such as the Taurus-Auriga or rho Ophiuchus clouds.

Magnani, Loris; Caillault, Jean-Pierre; Buchalter, Ari; Beichman, C. A.

1995-01-01

217

High-Resolution Studies of Circumstellar Material around Intermediate-Mass Young Stellar Objects at Far-Infrared and Millimeter Wavelengths  

NASA Astrophysics Data System (ADS)

Clues to the physical conditions that favor the formation of a particular stellar mass are found in the surrounding environments of young stars. Dust particles within these regions, warmed by the young stars themselves, emit strongly at millimeter and far-infrared wavelengths. Therefore, observations at these wavelengths provide excellent probes of these environments. This dissertation combines two high-resolution studies at these wavelengths of the environments of several very young, intermediate-mass (i.e., 2-10 Msolar) stellar objects. First, millimeter wavelength emission was observed from 9 Herbig Ae/Be stars, the higher-mass counterparts to T Tauri stars. Interferometers were used to attain ~6'' resolution, so structure on small scales could be examined. Only 1-3 stars were detected at 2.7 mm. Two of these were also observed at 7 mm, 1.3 cm, and 3.6 cm; only 1 star (Elias 3-1) was detected in all three radio bands. The amount of detected radio emission suggested 10% of the 2.7 mm emission arises from free-free processes. The unresolved nature and strength of the thermal emission at 2.7 mm and 7 mm suggest the presence of an accretion disk with a mass of 0.12 Msolar. At 140 pc, Elias 3-1 is the closest source in our sample, so the low detection rate in our sample may be the result of their larger distance, if the Elias 3-1 disk can be considered typical. Second, far-infrared emission was observed from a sample of 10 highly-embedded IRAS point sources of intermediate-luminosity (i.e., 100-1000 Lsolar) and 10 Herbig Ae/Be stars. The Kuiper Airborne Observatory was used to obtain maps at 100 ?m at 30-40'' resolution or 50 ?m at 20-30'' resolution. Almost all sources observed were detected, with most 100 ?m flux densities not significantly different from those observed by IRAS. Almost all sources were resolved. Almost all IRAS sources were located within a half-beamwidth of their IRAS positions but only 7 sources near Herbig Ae/Be stars were found to peak within a half-beamwidth of stellar positions. The far-infrared data of the embedded source IRAS 22198 + 6336 and the Herbig Be star MWC 1080 were chosen to test the Terebey, Shu, & Cassen (TSC) model of protostellar collapse for low-mass sources. Using codes that simulate this model by Kenyon, Hartmann, & Calvet (1993), their spectral energy distributions, and far-infrared sizes and shapes, were approximately reproduced using some parameters consistent with independent observations. However, very long infall timescales were implied for both objects. With the high constant mass fluxes also implied for each object, these long infall timescales suggest central masses inconsistent with other estimates. This result suggests the TSC model does not apply for higher-mass stars, possibly due to the influence of turbulence or non-equilibrium pre-collapse conditions in the original cloud.

di Francesco, James

218

NASA Researches the 'FaINT' Side of Sonic Booms  

NASA Video Gallery

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

219

Spectroscopic Determination of the Faint End of the Luminosity Function in the Nearby Galaxy Clusters A2199 and Virgo  

E-print Network

We report a new determination of the faint end of the galaxy luminosity function in the nearby clusters Virgo and Abell 2199 using data from SDSS and the Hectospec multifiber spectrograph on the MMT. The luminosity function of A2199 is consistent with a single Schechter function to M_r=-15.6 + 5 log h_70 with a faint-end slope of alpha=-1.13+/-0.07. The LF in Virgo extends to M_r=-13.5= M^*+8 and has a slope of alpha=-1.28+/-0.06. The red sequence of cluster members is prominent in both clusters, and almost no cluster galaxies are redder than this sequence. We show that selecting objects on the red sequence and blueward produces a steeply rising faint-end. A large fraction of photometric red-sequence galaxies lie behind the cluster. We compare our results to previous estimates and find poor agreement with estimates based on statistical background subtraction but good agreement with estimates based on photometric membership classifications (e.g., colors, morphology, surface brightness). We conclude that spectroscopic data are critical for estimating the faint end of the luminosity function in clusters. The faint-end slope we find is consistent with values found for field galaxies, weakening any argument for environmental evolution in the relative abundance of dwarf galaxies. However, dwarf galaxies in clusters are significantly redder than field galaxies of similar luminosity or mass, indicating that star formation processes in dwarfs do depend on environment.

Kenneth Rines; Margaret J. Geller

2007-10-04

220

The morphology of faint galaxies in Medium Deep Survey images using WFPC2  

NASA Technical Reports Server (NTRS)

First results from Hubble Space Telescope (HST) Medium Deep Survey images taken with Wide Field/Planetary Camera-2 (WFPC2) demonstrate that galaxy classifications can be reliably performed to magnitudes I814 approximately less than 22.0 in the F815W band. Published spectroscopic surveys to this depth indicate a mean redshift of bar-z approximately 0.5. We have classified over 200 galaxies in nine WFPC2 fields according to a basic morphological scheme. The majority of these faint galaxies appear to be similar to regular Hubble-sequence examples observed at low redshift. To the precision of our classification scheme, the relative proportion of spheroidal and disk systems of normal appearance is as expected from nearby samples, indicating that the bulk of the local galaxy population was in place at half the Hubble time. However, the most intriguing result is the relatively high proportion (approximately 40%) of objects which are in some way anomalous, and which may be of relevance in understanding the origin of the familiar excess population of faint galaxies established by others. These diverse objects include apparently interacting pairs whose multiple structure is only revealed with HST's angular resolution, galaxies with superluminous star-forming regions, diffuse low surface brightness galaxies of various forms, and compact galaxies. These anomalous galaxies contribute a substantial fraction of the excess counts at our limiting magnitude, and may provide insights into the 'faint blue galaxy' problem.

Griffiths, R. E.; Casertano, S.; Ratnatunga, K. U.; Neuschaefer, L. W.; Ellis, R. S.; Gilmore, G. F.; Glazebrook, K.; Santiago, B.; Huchra, J. P.; Windhorst, R. A.

1994-01-01

221

Dust-Bounded Ultraluminous Infrared Galaxies: Model Predictions for Infrared Spectroscopic Surveys  

Microsoft Academic Search

The observed faintness of infrared fine-structure line emission along with the warm far-infrared (FIR) colors of ultraluminous infrared galaxies (ULIRGs) is a long-standing problem. In this work, we calculate the line and continuum properties of a cloud exposed to an active galactic nucleus (AGN) and starburst spectral energy distribution. We use an integrated modeling approach, predicting the spectrum of ionized,

N. P. Abel; C. Dudley; Jacqueline Fischer; S. Satyapal; P. A. M. van Hoof

2009-01-01

222

Near-infrared Spectroscopy of Low-mass X-ray Binaries: Accretion Disk Contamination and Compact Object Mass Determination in V404 Cyg and Cen X-4  

NASA Astrophysics Data System (ADS)

We present near-infrared (NIR) broadband (0.80-2.42 ?m) spectroscopy of two low-mass X-ray binaries: V404 Cyg and Cen X-4. One important parameter required in the determination of the mass of the compact objects in these systems is the binary inclination. We can determine the inclination by modeling the ellipsoidal modulations of the Roche-lobe filling donor star, but the contamination of the donor star light from other components of the binary, particularly the accretion disk, must be taken into account. To this end, we determined the donor star contribution to the infrared flux by comparing the spectra of V404 Cyg and Cen X-4 to those of various field K-stars of known spectral type. For V404 Cyg, we determined that the donor star has a spectral type of K3 III. We determined the fractional donor contribution to the NIR flux in the H and K bands as 0.98 ± 0.05 and 0.97 ± 0.09, respectively. We remodeled the H-band light curve from Sanwal et al. after correcting for the donor star contribution to obtain a new value for the binary inclination. From this, we determined the mass of the black hole in V404 Cyg to be M BH = 9.0+0.2 -0.6 M sun. We performed the same spectral analysis for Cen X-4 and found the spectral type of the donor star to be in the range K5-M1 V. The donor star contribution in Cen X-4 is 0.94 ± 0.14 in the H band while in the K band, the accretion disk can contribute up to 10% of the infrared flux. We remodeled the H-band light curve from Shahbaz et al., again correcting for the fractional contribution of the donor star to obtain the inclination. From this, we determined the mass of the neutron star as M NS = 1.5+0.1 -0.4 M sun. However, the masses obtained for both systems should be viewed with some caution since contemporaneous light curve and spectral data are required to obtain definitive masses.

Khargharia, Juthika; Froning, Cynthia S.; Robinson, Edward L.

2010-06-01

223

A peculiar faint satellite in the remote outer halo of M31  

E-print Network

We present Hubble Space Telescope imaging of a newly-discovered faint stellar system, PAndAS-48, in the outskirts of the M31 halo. Our photometry reveals this object to be comprised of an ancient and very metal-poor stellar population with age > 10 Gyr and [Fe/H] PAndAS-48 is most likely a remote M31 satellite with a 3D galactocentric radius of 149 (+19 -8) kpc. We observe an apparent spread in color on the upper red giant branch that is larger than the photometric uncertainties should allow, and briefly explore the implications of this. Structurally, PAndAS-48 is diffuse, faint, and moderately flattened, with a half-light radius rh = 26 (+4 -3) pc, integrated luminosity Mv = -4.8 +/- 0.5, and ellipticity = 0.30 (+0.08 -0.15). On the size-luminosity plane it falls between the extended globular clusters seen in several nearby galaxies, and the recently-discovered faint dwarf satellites of the Milky Way; however, its characteristics do not...

Mackey, Dougal; Martin, Nicolas; Ferguson, Annette; Dotter, Aaron; McConnachie, Alan; Ibata, Rodrigo; Irwin, Mike; Lewis, Geraint; Sakari, Charli; Tanvir, Nial; Venn, Kim

2013-01-01

224

Calibration of HST wide field camera for quantitative analysis of faint galaxy images  

NASA Technical Reports Server (NTRS)

We present the methods adopted to optimize the calibration of images obtained with the Hubble Space Telescope (HST) Wide Field Camera (WFC) (1991-1993). Our main goal is to improve quantitative measurement of faint images, with special emphasis on the faint (I approximately 20-24 mag) stars and galaxies observed as a part of the Medium-Deep Survey. Several modifications to the standard calibration procedures have been introduced, including improved bias and dark images, and a new supersky flatfield obtained by combining a large number of relatively object-free Medium-Deep Survey exposures of random fields. The supersky flat has a pixel-to-pixel rms error of about 2.0% in F555W and of 2.4% in F785LP; large-scale variations are smaller than 1% rms. Overall, our modifications improve the quality of faint images with respect to the standard calibration by about a factor of five in photometric accuracy and about 0.3 mag in sensitivity, corresponding to about a factor of two in observing time. The relevant calibration images have been made available to the scientific community.

Ratnatunga, Kavan U.; Griffiths, Richard E.; Casertano, Stefano; Neuschaefer, Lyman W.; Wyckoff, Eric W.

1994-01-01

225

Star Formation and the Interstellar Medium In Nearby Tidal Streams (SAINTS): Spitzer Mid-infrared Spectroscopy and Imaging of Intergalactic Star-forming Objects  

E-print Network

A spectroscopic analysis of 10 intergalactic star forming objects (ISFOs) and a photometric analysis of 67 ISFOs in a sample of 14 interacting systems is presented. The majority of the ISFOs have relative polycyclic aromatic hydrocarbon (PAH) band strengths similar to those of nearby spiral and starburst galaxies. In contrast to what is observed in blue compact dwarfs (BCDs) and local giant HII regions in the Milky Way (NGC 3603) and the Magellanic Clouds (30 Doradus and N 66), the relative PAH band strengths in ISFOs correspond to models with a significant PAH ion fraction ( 3.7, i.e., enhanced non-stellar emission, most likely due to PAHs, relative to normal spirals, dwarf irregulars and BCD galaxies. The relative strength of the 8 um emission compared to that at 3.6 um or 24 um separates ISFOs from dwarf galaxies in Spitzer two color diagrams. The infrared power in two thirds of the ISFOs is dominated by emission from grains in a diffuse interstellar medium. One in six ISFOs have significant emission from ...

Higdon, S J U; Smith, B J; Hancock, M

2014-01-01

226

CONSTRAINING MASS RATIO AND EXTINCTION IN THE FU ORIONIS BINARY SYSTEM WITH INFRARED INTEGRAL FIELD SPECTROSCOPY  

SciTech Connect

We report low-resolution near-infrared spectroscopic observations of the eruptive star FU Orionis using the Integral Field Spectrograph (IFS) Project 1640 installed at the Palomar Hale telescope. This work focuses on elucidating the nature of the faint source, located 0.''5 south of FU Ori, and identified in 2003 as FU Ori S. We first use our observations in conjunction with published data to demonstrate that the two stars are indeed physically associated and form a true binary pair. We then proceed to extract J- and H-band spectro-photometry using the damped LOCI algorithm, a reduction method tailored for high contrast science with IFS. This is the first communication reporting the high accuracy of this technique, pioneered by the Project 1640 team, on a faint astronomical source. We use our low-resolution near-infrared spectrum in conjunction with 10.2 {mu}m interferometric data to constrain the infrared excess of FU Ori S. We then focus on estimating the bulk physical properties of FU Ori S. Our models lead to estimates of an object heavily reddened, A{sub V} = 8-12, with an effective temperature of {approx}4000-6500 K. Finally, we put these results in the context of the FU Ori N-S system and argue that our analysis provides evidence that FU Ori S might be the more massive component of this binary system.

Pueyo, Laurent [Johns Hopkins University, Department of Physics and Astronomy, 366 Bloomberg Center 3400 N. Charles Street, Baltimore, MD 21218 (United States); Hillenbrand, Lynne; Hinkley, Sasha; Dekany, Richard; Roberts, Jenny [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Vasisht, Gautam; Roberts, Lewis C. Jr.; Shao, Mike; Burruss, Rick; Cady, Eric [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Oppenheimer, Ben R.; Brenner, Douglas; Zimmerman, Neil [American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Monnier, John D. [Department of Astronomy, University of Michigan, 941 Dennison Building, 500 Church Street, Ann Arbor, MI 48109-1090 (United States); Crepp, Justin [Department of Physics, 225 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556 (United States); Parry, Ian [University of Cambridge, Institute of Astronomy, Madingley Road, Cambridge, CB3, OHA (United Kingdom); Beichman, Charles [NASA Exoplanet Science Institute, 770 South Wilson Avenue, Pasadena, CA 91225 (United States); Soummer, Remi [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2012-09-20

227

The nature of faint emission-line galaxies  

NASA Technical Reports Server (NTRS)

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

Smetanka, John J.

1993-01-01

228

Bidirectional quantum key distribution protocol with practical faint laser pulses  

SciTech Connect

We present a two-way protocol for the quantum key distribution with practical faint laser pulses. It is secure when the faint laser pulses contain no more than two photons. The key distribution task is completed in two transmissions. Bob first sends the laser pulses to Alice, and Alice encodes the key message through certain unitary operations and returns the laser pulses to Bob. Security is achieved by placing eavesdropping check procedures in both transmissions. This protocol is secure and is close to practical conditions. In addition, it does not require the exchange of measuring basis information between Alice and Bob, hence saving a lot of storage space.

Deng Fuguo [Department of Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory for Quantum Information and Measurements, Beijing 100084 (China); Long Guilu [Department of Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory for Quantum Information and Measurements, Beijing 100084 (China); Center for Atomic and Molecular NanoSciences, Tsinghua University, Beijing 100084 (China); Center for Quantum Information, Tsinghua University, Beijing, 100084 (China)

2004-07-01

229

Flickering Faint Galaxies: Few and Far Between  

E-print Network

Optical variability in galaxies at high redshift is a tracer of evolution in AGN activity, and should provide a useful constraint on models of galaxy evolution, AGN structure, and cosmology. We studied optical variability in multiple deep CCD and photographic surveys of blank fields for galaxies with $B_j = 20 - 25$ mag. Weakly variable objects are far more common than strongly variable ones. For objects near $B_j = 22$, $0.74\\% \\pm 0.2 \\%$ vary by 0.026~mag RMS or more, over a decade. This is small compared with previous claims based on photographic surveys, and also small compared with the fraction of bright quasars ($\\approx 5\\%$ at $B_j = 20$~mag) or Seyferts ($\\approx 1-2\\%$ for $B_j < 18$). The fraction of objects that vary increases slowly with magnitude. Detection probabilities and error rates were checked by simulations and statistical analysis of fluctuations of sample sky spots.

Greg P. Kochanski; J. Anthony Tyson; Philippe Fischer

1996-01-30

230

A sensitive search for CO emission from faint blue galaxies at z~0.5  

E-print Network

We have obtained sensitive upper limits on the CO J=2-1 and CO J=3-2 emission lines for five faint blue galaxies with redshifts $z\\sim 0.5$ using the IRAM 30~m telescope. These observations would have been able to detect the luminous infrared galaxy IRAS F10214+4724 if it were located at this redshift and unlensed. However, they are not sensitive enough to detect the prototype starburst galaxy M82 or the HII galaxy UM448 if they were located at this redshift. Our upper limits for the CO emission are consistent with between 19% and 66% of the total galactic mass being in the form of molecular hydrogen, and thus shed little light on the ultimate fate of these galaxies.

C. D. Wilson; F. Combes

1997-10-06

231

Discovery of an Optically-Faint Quasar at z=5.70 and Implications for the Faint End of the Quasar Luminosity Function  

E-print Network

We present observations of an optically-faint quasar, RD J114816.2+525339, discovered from deep multi-color observations of the field around the z = 6.42 quasar SDSS J1148+5251. The two quasars have a projected separation of 109 arcsec and both are outliers in r-z versus z-J color-color space. Keck spectroscopy reveals RD J114816.2+525339 to be a broad-absorption line quasar at z = 5.70. With z_AB = 23.0, RD J114816.2+525339 is 3.3 mag fainter than SDSS J1148+5251, making it the faintest quasar known at z>5.5. This object was identified in a survey of ~2.5 square degrees. The implied surface density of quasars at these redshifts and luminosities is broadly consistent with previous extrapolations of the faint end of the quasar luminosity function and supports the idea that active galaxies provide only a minor component of the reionizing ultraviolet flux at these redshifts.

A. Mahabal; D. Stern; M. Bogosavljevic; S. G. Djorgovski; D. Thompson

2005-10-17

232

The nature of faint submm-selected galaxies  

E-print Network

We present the source catalogue for the SCUBA Lens Survey. We summarise the results of extensive multi-wavelength observations of the 15 submillimetre-selected galaxies in the catalogue, from X-rays to radio. We discuss the main observational characteristics of faint submillimetre galaxies as a population, and consider their interpretation within the framework of our understanding of galaxy formation and evolution.

Ian Smail; R. J. Ivison; A. W. Blain; J. -P. Kneib

2001-12-05

233

CONFIRMATION OF FAINT DWARF GALAXIES IN THE M81 GROUP  

SciTech Connect

We have followed up on the results of a 65 deg{sup 2} 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{sub r{sup '}}= -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 R{sub e} ? 100 pc and total magnitude estimates M{sub r{sup '}}= -6.8 and M{sub I} ? –9.1.

Chiboucas, Kristin [Gemini Observatory, 670 North A'ohoku Pl, Hilo, HI 96720 (United States); Jacobs, Bradley A.; Tully, R. Brent [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96821 (United States); Karachentsev, Igor D., E-mail: kchibouc@gemini.edu, E-mail: bjacobs@ifa.hawaii.edu, E-mail: tully@ifa.hawaii.edu, E-mail: ikar@luna.sao.ru [Special Astrophysical Observatory (SAO), Russian Academy of Sciences, Nizhnij Arkhyz, Karachai-Cherkessian Republic 369167 (Russian Federation)

2013-11-01

234

Dust-Bounded ULIRGs? Model Predictions for Infrared Spectroscopic Surveys  

Microsoft Academic Search

The observed faintness of infrared fine-structure line emission along with\\u000athe warm far-infrared (FIR) colors of ultraluminous infrared galaxies (ULIRGs)\\u000ais a long-standing problem. In this work, we calculate the line and continuum\\u000aproperties of a cloud exposed to an Active Galactic Nucleus (AGN) and starburst\\u000aspectral energy distribution (SED). We use an integrated modeling approach,\\u000apredicting the spectrum of

N. P. Abel; C. Dudley; Jacqueline Fischer; S. Satyapal; P. A. M. van Hoof

2009-01-01

235

Evidence of AGN-driven Outflows in Young Radio Quasars Selected from the Wide-field Infrared Survey Explorer  

NASA Astrophysics Data System (ADS)

We present near-infrared spectra of young radio quasars selected by cross-correlating the Wide-field Infrared Survey Explorer (WISE) all-sky survey catalog with the radio catalog [Faint Images of the Radio Sky at Twenty cm (FIRST) and NRAO VLA Sky Survey (NVSS)]. The objects have typical redshifts of z ~ 2 and [O III] luminosities of 107 erg s-1 comparable to those of luminous quasars. The observed flux ratios of narrow emission lines indicate that these objects appear to be powered by active galactic nuclei. The [O III] line is broad, with full width at half maximum ~1300 to 2100 km s-1, significantly larger than that of ordinary quasars. These large line widths might be explained by jet-induced outflows.

Kim, Minjin; Ho, Luis C.; Lonsdale, Carol J.; Lacy, Mark; Blain, Andrew W.; Kimball, Amy E.

2014-07-01

236

FIREBALL: The Faint Intergalactic medium Redshifted Emission Balloon --Overview and 1st Science Flight Results  

E-print Network

FIREBALL: The Faint Intergalactic medium Redshifted Emission Balloon -- Overview and 1st Science Emission Balloon) is a balloon-borne 1m telescope coupled to an ultraviolet fiber-fed spectrograph the Faint Intergalactic-medium Redshifted Emission Balloon (FIREBALL), designed to discover and map faint

Martin, Chris

237

On the Poisson Approximation to Photon Distribution for Faint Lasers Yucheng Hua  

E-print Network

On the Poisson Approximation to Photon Distribution for Faint Lasers Yucheng Hua , Xiang Pengb statistics for attenuated faint laser pulses is quantitatively studied. It confirms that, even for a non-Poissonian laser source, after being attenuated into faint laser with ultra-low mean photon number, the photon

Lu, Tiao

238

A normal abundance of faint satellites in the fossil group NGC 6482  

NASA Astrophysics Data System (ADS)

A fossil group is considered the end product in a galaxy group's evolution. It is a massive central galaxy that dominates the luminosity budget of the group, and is the outcome of efficient merging between intermediate-luminosity members. Little is known, however, about the faint satellite systems of fossil groups. Here we present a Subaru/Suprime-Cam wide-field, deep imaging study in the B - and R -bands of the nearest fossil group NGC 6482 (Mtot ~ 4 × 1012M?), covering the virial radius out to 310 kpc. We performed detailed completeness estimations and selected group member candidates by a combination of automated object detection and visual inspection. A fiducial sample of 48 member candidates down to MR ~ -10.5 mag is detected, making this study the deepest of a fossil group to now. We investigate the photometric scaling relations, the color-magnitude relation, and the luminosity function of our galaxy sample. We find evidence of recent and ongoing merger events among bright group galaxies. The color-magnitude relation is comparable to that of nearby galaxy clusters, and it exhibits significant scatter at the faintest luminosities. The completeness-corrected luminosity function is dominated by early-type dwarfs and is characterized by a faint end slope ? = -1.32 ± 0.05. We conclude that the NGC 6482 fossil group shows photometric properties consistent with those of regular galaxy clusters and groups, including a normal abundance of faint satellites. Appendix A is available in electronic form at http://www.aanda.orgThe reduced data are only 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/559/A76

Lieder, S.; Mieske, S.; Sánchez-Janssen, R.; Hilker, M.; Lisker, T.; Tanaka, M.

2013-11-01

239

Infrared microscope inspection apparatus  

DOEpatents

Apparatus and system for inspecting infrared transparents, such as an array of photovoltaic modules containing silicon solar cells, includes an infrared microscope, at least three sources of infrared light placed around and having their axes intersect the center of the object field and means for sending the reflected light through the microscope. The apparatus is adapted to be mounted on an X-Y translator positioned adjacent the object surface.

Forman, Steven E. (Framingham, MA); Caunt, James W. (Concord, MA)

1985-02-26

240

The Formation History of the Ultra-Faint Dwarf Galaxies  

NASA Astrophysics Data System (ADS)

We present early results from a Hubble Space Telescope survey of the ultra-faint dwarf galaxies. These Milky Way satellites were 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. We find that the six galaxies of our survey have very similar star-formation histories, and that each is dominated by stars older than 12 Gyr.

Brown, Thomas M.; Tumlinson, J.; Geha, M. C.; Kirby, E. N.; VandenBerg, D. A.; Kalirai, J. S.; Simon, J. D.; Avila, R. J.; Munoz, R.; Guhathakurta, P.; Renzini, A.; Ferguson, H. C.; Vargas, L. C.; Gennaro, M.

2014-01-01

241

The Luminosity Function Normalization and the Faint Galaxy Counts  

Microsoft Academic Search

We present a study of the B-band galaxy counts as a function of morphological type measured from publicly available images from three recent wide field ground-based surveys. These new data with B≲18 mag are then combined with the fainter HST surveys (19≲B≲27 mag) in an effort to more fully understand the faint blue galaxy excess and the distribution of Hubble

S. H. Cohen; R. A. Windhorst; S. C. Odewahn

2003-01-01

242

CCD time-resolved photometry of faint cataclysmic variables. IV  

NASA Technical Reports Server (NTRS)

Time-resolved CCD photometry in V, B, and the near-IR has been obtained, with average time-series length of 3 hours, for 15 certified or candidate cataclysmic-variable faint stars. Orbital periods are found in three of the stars, and nine others are noted to exhibit evidence leading toward confirmation of cataclysmic-variable status. The characteristics of PG 0917+342 and PG 2240+193 are as yet unclear.

Howell, Steve B.; Dobrzycka, Danuta; Szkody, Paula; Kreidl, Tobias J.

1991-01-01

243

The Munich Near-Infrared Cluster Survey - IV. Biases in the completeness of near-infrared imaging data  

NASA Astrophysics Data System (ADS)

We present the results of completeness simulations for the detection of point sources as well as redshifted elliptical and spiral galaxies in the K'-band images of the Munich Near-Infrared Cluster Survey (MUNICS). The main focus of this work is to quantify the selection effects introduced by threshold-based object detection algorithms used in deep imaging surveys. Therefore, we simulate objects obeying the well-known scaling relations between effective radius and central surface brightness, for both de Vaucouleurs and exponential profiles. The results of these simulations, while presented for the MUNICS project, are applicable in a much wider context to deep optical and near-infrared selected samples. We investigate the detection probability as well as the reliability for recovering the true total magnitude with Kron-like (adaptive) aperture photometry. The results are compared with the predictions of the visibility theory of Disney and Phillipps in terms of the detection rate and the lost-light fraction. Additionally, the effects attributable to seeing are explored. The results show a bias against detecting high-redshifted massive elliptical galaxies in comparison to disc galaxies with exponential profiles, and that the measurements of the total magnitudes for intrinsically bright elliptical galaxies are systematically too faint. Disc galaxies, in contrast, show no significant offset in the magnitude measurement of luminous objects. Finally, we present an analytic formula to predict the completeness of point sources using only basic image parameters.

Snigula, J.; Drory, N.; Bender, R.; Botzler, C. S.; Feulner, G.; Hopp, U.

2002-11-01

244

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

245

Objective assessment of skin tightening in Asians using a water-filtered near-infrared (1,000-1,800 nm) device with contact-cooling and freezer-stored gel  

PubMed Central

Background Near-infrared has been shown to penetrate deeper than optical light sources independent of skin color, allowing safer treatment for the Asian skin type. Many studies have indicated the efficacy of various types of devices, but have not included a sufficiently objective evaluation. In this study, we used three-dimensional imaging for objective evaluation of facial skin tightening using a water-filtered near-infrared device. Methods Twenty Japanese patients were treated with the water-filtered near-infrared (1,000–1,800 nm) device using a contact-cooling and nonfreezing gel stored in a freezer. Three-dimensional imaging was performed, and quantitative volume measurements were taken to evaluate the change in post-treatment volume. The patients then provided their subjective assessments. Results Objective assessments of the treated cheek volume evaluated by a three-dimensional color schematic representation with quantitative volume measurements showed significant improvement 3 months after treatment. The mean volume reduction at the last post-treatment visit was 2.554 ± 0.999 mL. The post-treatment volume was significantly reduced compared with the pretreatment volume in all patients (P < 0.0001). Eighty-five percent of patients reported satisfaction with the improvement of skin laxity, and 80% of patients reported satisfaction with improvement of rhytids, such as the nasolabial folds. Side effects, such as epidermal burns and scar formation, were not observed throughout the study. Conclusion The advantages of this water-filtered near-infrared treatment are its high efficacy for skin tightening, associated with a minimal level of discomfort and minimal side effects. Together, these characteristics facilitate our ability to administer repeated treatments and provide alternative or adjunctive treatment for patients, with improved results. This study provides a qualitative and quantitative volumetric assessment, establishing the ability of this technology to reduce volume through noninvasive skin tightening. PMID:23837000

Tanaka, Yohei; Tsunemi, Yuichiro; Kawashima, Makoto; Tatewaki, Naoto; Nishida, Hiroshi

2013-01-01

246

THE ABUNDANCE GRADIENT IN THE EXTREMELY FAINT OUTER DISK OF NGC 300  

SciTech Connect

In an earlier work, we showed for the first time that the resolved stellar disk of NGC 300 is very extended with no evidence for truncation, a phenomenon that has since been observed in other disk galaxies. We revisit the outer disk of NGC 300 in order to determine the metallicity of the faint stellar population. With the Gemini Multi Object Spectrograph camera at Gemini South, we reach 50% completeness at (g', i') = (26.8-27.4, 26.1-27.0) in photometric conditions and 0.''7 seeing. At these faint depths, careful consideration must be given to the background galaxy population. The mean colors of the outer disk stars fall within the spread of colors for the background galaxies, but the stellar density dominates the background galaxies by {approx}2:1. The predominantly old stellar population in the outer disk exhibits a negative abundance gradient-as expected from models of galaxy evolution-out to about 10 kpc where the abundance trend changes sign. We present two scenarios to explain the flattening, or upturn, in the metallicity gradient of NGC 300 and discuss the implication this has for the broader picture of galaxy formation.

Vlajic, M. [Astrophysics, Department of Physics, Keble Road, University of Oxford, Oxford OX1 3RH (United Kingdom); Bland-Hawthorn, J. [Institute of Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Freeman, K. C. [Mount Stromlo Observatory, Private Bag, Woden, ACT 2611 (Australia)], E-mail: vlajic@astro.ox.ac.uk

2009-05-20

247

A Possible Local Counterpart to the Excess Population of Faint Blue Galaxies  

E-print Network

OBSERVATIONS of galaxies to very faint magnitudes have revealed a population of blue galaxies at intermediate redshift$^{1-5}$. These galaxies represent a significant excess over the expectation of standard cosmological models for reasonable amounts of evolution of the locally observed galaxy population. However, the surveys which define the local galaxy population are strongly biased against objects of low surface brightness$^{6-9}$. Low surface brightness galaxies have properties very similar to those of the excess blue population$^{10,11}$, and recent work suggests that they are comparable in abundance to the more readily detected normal galaxies$^{9,12}$. I show that the very deep surveys which reveal the excess population can easily detect low surface brightness galaxies to large redshifts, but that local surveys will miss them because they are not comparably sensitive. This suggests that the excess faint galaxies {\\it are\\/} low surface brightness galaxies. No alteration of standard cosmology is required, but it is necessary to reconsider the way in which the galaxy distribution function is specified.

Stacy McGaugh

1993-12-12

248

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

NASA Technical Reports Server (NTRS)

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

249

Searching for Faint Companions to Nearby Stars with the Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

A search for faint companions (FC's) to selected stars within 5 pc of the Sun using the Hubble Space Telescope's Planetary Camera (PC) has been initiated. To assess the PC's ability to detect FCs, we have constructed both model and laboratory-simulated images and compared them to actual PC images. We find that the PC's point-spread function (PSF) is 3-4 times brighter over the angular range 2-5 sec than the PSF expected for a perfect optical system. Azimuthal variations of the PC's PSF are 10-20 times larger than expected for a perfect PSF. These variations suggest that light is scattered nonuniformly from the surface of the detector. Because the anomalies in the PC's PSF cannot be precisely simulated, subtracting a reference PSF from the PC image is problematic. We have developed a computer algorithm that identifies local brightness anomalies within the PSF as potential FCs. We find that this search algorithm will successfully locate FCs anywhere within the circumstellar field provided that the average pixel signal from the FC is at least 10 sigma above the local background. This detection limit suggests that a comprehensive search for extrasolar Jovian planets with the PC is impractical. However, the PC is useful for detecting other types of substellar objects. With a stellar signal of 10(exp 9) e(-), for example, we may detect brown dwarfs as faint as M(sub I) = 16.7 separated by 1 sec from alpha Cen A.

Schroeder, Daniel J.; Golimowski, David A.

1996-01-01

250

The Enigmatic Young Object: Walker 90/V590 Monocerotis  

E-print Network

We assess the evolutionary status of the intriguing object Walker 90/V590 Mon, which is located about 20 arcminutes 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 magnitudes 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 Halpha emission, Mg II emission, IR excess, UV continuum, and optical variability. 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. 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. 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 images secured in 2004, Walker 90 appears as a point source placing an upper limit of 0.1 arcsec for its diameter. We conclude that many observational features are explained if W90 is a flared disk system, surrounded by an inclined optically thick accretion disk.

Mario R. Perez; Bruce McCollum; Mario E. van den Ancker; Michael D. Joner

2008-04-08

251

DISCOVERIES FROM A NEAR-INFRARED PROPER MOTION SURVEY USING MULTI-EPOCH TWO MICRON ALL-SKY SURVEY DATA  

SciTech Connect

We have conducted a 4030 deg{sup 2} near-infrared proper motion survey using multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778 proper motion candidates, 647 of which are not listed in SIMBAD. After comparison to Digitized Sky Survey images, we find that 107 of our proper motion candidates lack counterparts at B, R, and I bands and are thus 2MASS-only detections. We present results of spectroscopic follow-up of 188 targets that include the infrared-only sources along with selected optical-counterpart sources with faint reduced proper motions or interesting colors. We also establish a set of near-infrared spectroscopic standards with which to anchor near-infrared classifications for our objects. Among the discoveries are six young field brown dwarfs, five 'red L' dwarfs, three L-type subdwarfs, twelve M-type subdwarfs, eight 'blue L' dwarfs, and several T dwarfs. We further refine the definitions of these exotic classes to aid future identification of similar objects. We examine their kinematics and find that both the 'blue L' and 'red L' dwarfs appear to be drawn from a relatively old population. This survey provides a glimpse of the kinds of research that will be possible through time-domain infrared projects such as the UKIDSS Large Area Survey, various VISTA surveys, and WISE, and also through z- or y-band enabled, multi-epoch surveys such as Pan-STARRS and LSST.

Kirkpatrick, J. Davy; Cutri, Roc M. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Looper, Dagny L. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Burgasser, Adam J. [Center for Astrophysics and Space Science, University of California, San Diego, CA 92093 (United States); Schurr, Steven D. [Planck Science Center, MS 220-6, California Institute of Technology, Pasadena, CA 91125 (United States); Cushing, Michael C. [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States); Cruz, Kelle L. [Department of Physics and Astronomy, Hunter College, New York, NY 10065 (United States); Sweet, Anne C. [British Consulate, San Francisco, CA 94104 (United States); Knapp, Gillian R. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Barman, Travis S. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Bochanski, John J. [Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building 37, Cambridge, MA 02139 (United States); Roellig, Thomas L. [NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000 (United States); McLean, Ian S. [Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1562 (United States); McGovern, Mark R. [Antelope Valley College, Lancaster, CA 93536 (United States); Rice, Emily L., E-mail: davy@ipac.caltech.ed [American Museum of Natural History, New York, NY 10024 (United States)

2010-09-15

252

Strong Near-Infrared Emission Interior to the Dust-Sublimation Radius of Young Stellar Objects MWC275 and AB Aur  

E-print Network

Using the longest optical-interferometeric baselines currently available, we have detected strong near-infrared (NIR) emission from inside the dust-destruction radius of Herbig Ae stars MWC275 and AB Aur. Our sub-milli-arcsecond resolution observations unambiguously place the emission between the dust-destruction radius and the magnetospheric co-rotation radius. We argue that this new component corresponds to hot gas inside the dust-sublimation radius, confirming recent claims based on spectrally-resolved interferometry and dust evaporation front modeling.

A. Tannirkulam; J. D. Monnier; R. Millan-Gabet; T. J. Harries; E. Pedretti; T. A. ten Brummelaar; H. McAlister; N. Turner; J. Sturmann; L. Sturmann

2008-03-10

253

A MERLIN and VLBI Survey of Faint Compact Radio Sources  

E-print Network

We have selected a field from the VLA FIRST Survey which is typical in all aspects except one: it contains a bright, but extremely compact VLBI calibrator - J1159+291. 127 unresolved FIRST sources with $S_{FIRST}\\ge 10$ mJy lie within $2.5^{\\circ}$ of this calibrator. $\\lambda 6$ cm MERLIN observations with a resolution $\\sim 60$ mas detect around half the sources. These detections form the basis of a sample of faint but compact radio sources which are ideally suited to follow-up VLBI observations.

M. A. Garrett; Simon T. Garrington

1997-09-25

254

GRB 051028: an intrinsically faint GRB at high redshift?  

Microsoft Academic Search

We present multiwavelength observations of the gamma-ray burst GRB 051028\\u000adetected by HETE-2 in order to derive its afterglow emission parameters and to\\u000adetermine the reason for its optical faintness when compared to other events.\\u000aObservations were taken in the optical (2.0m Himalayan Chandra Telescope, 1.34m\\u000aTautenburg, 4.2m William Herschel Telescope) and in X-rays (Swift\\/XRT) between\\u000a2.7 hours and 10

A. J. Castro-Tirado; M. Jel ´ inek; S. B. Pandey; S. McBreen; J. de Jong; D. K. Sahu; P. Ferrero; J. A. Caballero; J. Gorosabel; D. A. Kann; S. Klose; A. de Ugarte Postigo; G. C. Anupama; C. Gry; S. Guziy; S. Srividya; L. Valdivielso; S. Vanniarajan; A. A. Henden

2006-01-01

255

Two-photon processes in faint biphoton fields  

E-print Network

The goal of this research is to determine and study a physical system that will enable a fast and intrinsically two-photon detector, which would be of interest for quantum information and metrology applications. We consider two types of two-photon processes that can be observed using a very faint, but quantum-correlated biphoton field. These are optical up-conversion and an external photoelectric effect. We estimate the correlation enhancement factor for the biphoton light compared to coherent light, report and discuss the preliminary experimental results.

Strekalov, D V; Chekhova, M V; Dowling, J P; Strekalov, Dmitry V.; Stowe, Matt; Chekhova, Maria V.; Dowling, Jonathan P.

2002-01-01

256

On the Poisson Approximation to Photon Distribution for Faint Lasers  

E-print Network

It is proved, that for a certain kind of input distribution, the strongly binomially attenuated photon number distribution can well be approximated by a Poisson distribution. This explains why we can adopt poissonian distribution as the photon number statistics for faint lasers. The error of such an approximation is quantitatively estimated. Numerical tests are carried out, which coincide with our theoretical estimations. This work lays a sound mathematical foundation for the well-known intuitive idea which has been widely used in quantum cryptography.

Yucheng Hu; Xiang Peng; Tiejun Li; Hong Guo

2006-09-23

257

Object extraction Object extraction  

E-print Network

Object extraction #12;Object extraction · Extracting topographic objects from images · the main goal of aerial photogrammetry · object extraction consists of two steps · image interpretation extraction · Extracting topographic objects from images · identify all objects of a certain class · measure

Giger, Christine

258

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

259

Faint, Evolving Radio Active Galactic Nuclei in SDSS Luminous Red Galaxies  

NASA Astrophysics Data System (ADS)

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 ?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 opt) as L 1.4 GHz vprop L ? opt, where ? depends on the redshift being probed. Above z sime 0.4, ? appears to decrease from ? sime 1 at z = 0.4 to ? sime 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 1.4 GHz vprop (1 + z)3.15±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.; White, R. L.

2009-09-01

260

Spitzer Mid-Infrared Spectroscopy of 70um-Selected Distant Luminous Infrared Galaxies  

E-print Network

We present mid-infrared spectroscopy obtained with the Spitzer Space Telescope of a sample of 11 optically faint, infrared luminous galaxies selected from a Spitzer MIPS 70um imaging survey of the NDWFS Bootes field. These are the first Spitzer IRS spectra presented of distant 70um-selected sources. All the galaxies lie at redshifts 0.3infrared luminosities of L_IR~ 0.1-17 x 10^12 solar luminosities. Seven of the galaxies exhibit strong emission features attributed to polycyclic aromatic hydrocarbons (PAHs). The average IRS spectrum of these sources is characteristic of classical starburst galaxies, but with much larger infrared luminosities. The PAH luminosities of L(7.7) ~ 0.4 - 7 x 10^11 solar luminosities imply star formation rates of ~ 40 - 720 solar masses per year. Four of the galaxies show deep 9.7um silicate absorption features and no significant PAH emission features (6.2um equivalent widths < 0.03um). The large infrared luminosities and low f70/f24 flux density ratios suggests that these sources have AGN as the dominant origin of their large mid-infrared luminosities, although deeply embedded but luminous starbursts cannot be ruled out. If the absorbed sources are AGN-dominated, a significant fraction of all far-infrared bright, optically faint sources may be dominated by AGN.

Kate Brand; Dan W. Weedman; Vandana Desai; Emeric Le Floc'h; Lee Armus; Arjun Dey; Jim R. Houck; Buell T. Jannuzi; Howard A. Smith; B. T. Soifer

2007-09-20

261

MULTIPLE BEAM COMBINATION FOR FAINT OBJECTS E. Ribak ,G. Perrin, S. Lacour  

E-print Network

the central, white-light fringe. It is possible instead to use a chromatic corrector in order to match. Because of the pseudo-Michelson combination, white light fringes are formed naturally. Along the diagonal interferometry and single-mode fibers", SPIE 5491- 153 (this meeting). The order of the fibres is not related

Ribak, Erez

262

Guaranteed time observations support for Faint Object Spectrograph (FOS) on HST  

NASA Technical Reports Server (NTRS)

The goals of the GTO effort are for investigations defined in previous years by the IDT to be carried out as HST observations and for the results to be communicated to the scientific community and to the public. The search for possible black holes in the nuclei of both normal and active nucleus galaxies has had to be delayed to the post-servicing era. FOS spectropolarimetric observations of the nuclear region of the peculiar Seyfert galaxy Mrk 231 reveal that the continuum polarization peaks at 18% in the near UV and then declines rapidly toward shorter wavelengths. The papers on the absorption line analysis for our galactic halo address the spatial distribution of high and intermediate level ions in the halo and illustrate the patchy and heterogeneous nature of the halo. The papers on the scattering characteristics of the HST/FOS have provided us with data that shows that the HST mirror surfaces are quite smooth, even at the UV wavelengths. WF-PC and FOC images of the halo PN K648 have been fully analyzed.

Harms, Richard

1994-01-01

263

A faint discrete source origin for the highly ionized iron emission from the Galactic Centre region.  

PubMed

The origin of the X-ray emission for the central region of our Galaxy has remained a mystery. In particular, the relative spectral contributions of the diffuse emission and discrete sources, which are critical to understanding the high-energy phenomena in this environment, have been unclear because of the lack of sufficient spatial resolution. Here we report the results of a large-scale imaging survey of the Galactic Centre that resolves these components. We find that the Kalpha emission from iron that has been highly ionized (so that it has only two electrons left), which has previously been attributed to the diffuse component, actually arises mainly from discrete sources. This suggests that the presence of a large amount of hot gas (T approximately 108 K) is no longer required to explain the iron line emission. The spectra of the discrete sources indicate the presence of numerous accreting white dwarfs, neutron stars, and/or black holes in the region. The diffuse emission dominates over the contribution from the faint point sources, and is shown to be associated globally with interstellar features that have been observed at radio and mid-infrared wavelengths, suggesting that it is the product of recent massive star formation. PMID:11805827

Wang, Q D; Gotthelf, E V; Lang, C C

2002-01-10

264

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

265

Infrared Astronomy  

NSDL National Science Digital Library

This website from NASA's Infrared Astrophysics Data Center describes: the discovery of infrared waves; what infrared waves are and how they are used in astronomy; atmospheric windows; near, middle, and far infrared; the infrared universe; and infrared (IR) spectroscopy. It also provides an IR astronomy timeline; history and development of IR detector technology; information on projects, news and discoveries; an IR gallery; classroom activities; and links for getting involved in astronomy.

Hermans-Killam, Linda

266

Infrared Heaters  

NASA Technical Reports Server (NTRS)

The heating units shown in the accompanying photos are Panelbloc infrared heaters, energy savers which burn little fuel in relation to their effective heat output. Produced by Bettcher Manufacturing Corporation, Cleveland, Ohio, Panelblocs are applicable to industrial or other facilities which have ceilings more than 12 feet high, such as those pictured: at left the Bare Hills Tennis Club, Baltimore, Maryland and at right, CVA Lincoln- Mercury, Gaithersburg, Maryland. The heaters are mounted high above the floor and they radiate infrared energy downward. Panelblocs do not waste energy by warming the surrounding air. Instead, they beam invisible heat rays directly to objects which absorb the radiation- people, floors, machinery and other plant equipment. All these objects in turn re-radiate the energy to the air. A key element in the Panelbloc design is a coating applied to the aluminized steel outer surface of the heater. This coating must be corrosion resistant at high temperatures and it must have high "emissivity"-the ability of a surface to emit radiant energy. The Bettcher company formerly used a porcelain coating, but it caused a production problem. Bettcher did not have the capability to apply the material in its own plant, so the heaters had to be shipped out of state for porcelainizing, which entailed extra cost. Bettcher sought a coating which could meet the specifications yet be applied in its own facilities. The company asked The Knowledge Availability Systems Center, Pittsburgh, Pennsylvania, a NASA Industrial Applications Center (IAC), for a search of NASA's files

1979-01-01

267

Measuring the orbital history of the ultra-faint dwarf galaxy Hercules with GSAOI  

NASA Astrophysics Data System (ADS)

The Milky Way ultra-faint dwarf galaxies are the most dark matter dominated systems known to date. Their low masses, low luminosities, and extremely low metallicities offer a glimpse into galaxy formation at the earliest epochs, while their high inferred dark matter densities and proximity make them ideal candidates for indirect dark matter detection experiments. However, significant uncertainties remain in key observables such as the mass and infall history of these extreme objects. For example, without knowledge of their orbits, it is difficult to determine whether their masses are overestimated because their radial velocity dispersions have been inflated by past tidal encounters with the Milky Way. We propose to measure the proper motion of the Hercules ultra-faint dwarf galaxy using GSAOI to understand its orbital history. Hercules is a particularly intriguing target because structural and kinematic studies have motivated claims that it is tidally disrupting despite its relatively large present distance from the Milky Way and apparently high mass-to-light ratio. It also has a very old stellar population, making it a prime candidate for a "fossil galaxy" whose star formation was shut off by reionization. With observations in 2014A, 2015A, and 2017A in conjunction with HST data taken in 2011, we will be able to achieve 35 km/s proper motion precision, making it possible to reconstruct the orbit of Hercules. Knowledge of its perigalacticon will allow us to quantify the tidal effects of the Milky Way on its internal stellar dynamics, while its eccentricities and orbital energies will constrain the initial infall time into the Milky Way dark matter halo. This proposal aims to extend the technique developed of HST data to using background galaxies as absolute reference sources to ground based MCAO observations, which will be important for astrometry work after HST and for future extremely large telescopes.

Do, Tuan; Lu, Jessica; Simon, Josh; Peter, Annika; Boylan-Kolchin, Mike

2014-02-01

268

Physical Characteristics of Faint Meteors by Light Curve and High-resolution Observations  

NASA Astrophysics Data System (ADS)

The physical structure of a meteoroid may be inferred from optical observations, particularly the light curve, of a meteor. For example: a classically shaped (late peaked) light curve is seen as evidence of a solid single body, whereas a symmetric light curve may indicate a dustball structure. High-resolution optical observations show how the meteoroid fragments: continuously, leaving a long wake, or discretely, leaving several distinct pieces. Calculating the orbit of the meteoroid using two station data then allows the object to be associated with asteroidal or cometary parent bodies. Optical observations thus provide simultaneous information on meteoroid structure, fragmentation mode, and origin.CAMO (the Canadian Automated Meteor Observatory) has been continuously collecting faint (masses < 10-4 kg) two station optical meteors with image-intensified narrow field (with a resolution of up to 3 meters per pixel) and wide field (26 by 19 degrees) cameras since 2010. The narrow field, telescopic cameras allow the meteor fragmentation to be studied using a pair of mirrors to track the meteor. The wide-field cameras provide the light curve and trajectory solution.We present preliminary results from classifying light curves and high-resolution optical observations for 3000 faint meteors recorded since 2010. We find that most meteors (both asteroidal and cometary) show long trails, while meteors with short trails are the second most common morphology. It is expected that meteoroids that experience negligible fragmentation have the shortest trails, so our results imply that the majority of small meteoroids fragment during ablation. A surprising observation is that almost equal fractions of asteroidal and cometary meteors fragment (showing long trails), implying a similar structure for both types of meteoroids.

Subasinghe, Dilini; Campbell-Brown, Margaret D.; Stokan, Edward

2014-11-01

269

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

270

Comparison of fringe tracking algorithms for single-mode near-infrared long baseline interferometers  

E-print Network

To enable optical long baseline interferometry toward faint objects, long integrations are necessary despite atmospheric turbulence. Fringe trackers are needed to stabilize the fringes and thus increase the fringe visibility and phase signal-to-noise ratio (SNR), with efficient controllers robust to instrumental vibrations, and to subsequent path fluctuations and flux drop-outs. We report on simulations, analysis and comparison of the performances of a classical integrator controller and of a Kalman controller, both optimized to track fringes under realistic observing conditions for different source magnitudes, disturbance conditions, and sampling frequencies. The key parameters of our simulations (instrument photometric performance, detection noise, turbulence and vibrations statistics) are based on typical observing conditions at the Very Large Telescope observatory and on the design of the GRAVITY instrument, a 4-telescope single-mode long baseline interferometer in the near-infrared, next in line to be in...

Choquet, Élodie; Perrin, Guy; Cassaing, Frédéric; Lacour, Sylvestre; Eisenhauer, Frank

2014-01-01

271

Infrared Investigations  

NSDL National Science Digital Library

In this activity, learners explore how infrared technology is used by engineers to create equipment and systems for a variety of industries. Learners explore the application of infrared in remote controls, test materials that encourage or prevent infrared transmission, and develop systems that allow transmission of infrared in restricted environments.

Ieee

2013-08-30

272

The Location of the CO2, Fundamental in Clathrate Hydrates and its Application to Infrared Spectra of Icy Solar System Objects  

NASA Technical Reports Server (NTRS)

CO2 is present on the surface of many Solar System objects, but not always as a segregated, pure ice. In pure CO2-ice, the fundamental absorption is located near 4.268 micron (2343.3 wavenumbers). However, on several objects, the CO2 fundamental is shifted to higher frequency. This shift may be produced by CO2 gas trapped in another material, or adsorbed onto minerals. We have seen that a mixture of H2O, CH3OH4 and CO2 forms a type II clathrate when heated to 125 K and produces a CO2 fundamental near 4.26 micron. The exact location of the feature is strongly dependent on the initial ratio of the three components. We are currently exploring various starting ratios relevant to the Solar System to determine the minimum amount of CH3OH needed to convert all of the CO2 to the clathrate, i.e. eliminate the splitting of the CO2 fundamental. We are testing the stability of the clathrate to thermal processing and UV photolysis, and documenting the changes seen in the spectra in the wavelength range from 1-5 micron. We acknowledge financial support from the Origins of Solar Systems Program, the Planetary Geology and Geophysics and the NASA Postdoctoral Program.

Sandford, S. A.; Mastrapa, R. M. E.; Bernstein, M. P.; Cruikshank, D. P.

2006-01-01

273

Early-stage star-forming cloud cores in Galactic Legacy Infrared Mid-Plane Survey (GLIMPSE) extended green objects (EGOs) as traced by organic species  

NASA Astrophysics Data System (ADS)

In order to investigate the physical and chemical properties of massive star-forming cores in the early stages, we analyse the excitation and abundance of four organic species, CH3OH, CH3OCH3, HCOOCH3 and CH3CH2CN, towards 29 extended green object (EGO) cloud cores that were observed by our previous single-dish spectral line survey. The EGO cloud cores are found to have similar methanol J3-J2 rotation temperatures of ˜44 K, a typical linear size of ˜0.036 pc and a typical beam-averaged methanol abundance of several 10-9 (the beam-corrected value could reach several 10-7). The abundances of the latter three species, normalized by that of methanol, are also found to be correlated across a large variety of clouds such as EGO cloud cores, hot corinos, massive hot cores and Galactic Centre clouds. The chemical properties of the EGO cloud cores lie between those of hot cores and hot corinos. However, the abundances and abundance ratios of the four species cannot be explained satisfactorily by recent chemical models, either among EGO cloud cores or among the various types of cloud core from literature.

Ge, J. X.; He, J. H.; Chen, X.; Takahashi, S.

2014-12-01

274

Keck spectroscopy of faint 3 < z < 7 Lyman break galaxies - I. New constraints on cosmic reionization from the luminosity and redshift-dependent fraction of Lyman ? emission  

NASA Astrophysics Data System (ADS)

We present the first results of a new Keck spectroscopic survey of UV faint Lyman break galaxies in the redshift range 3 < z < 7. Combined with earlier Keck and published European Southern Observatory (ESO) VLT data, our spectroscopic sample contains more than 600 dropouts offering new insight into the nature of sub-L* sources typical of those likely to dominate the cosmic reionization process. In this first paper, in a series discussing these observations, we characterize the fraction of strong Ly? emitters within the continuum-selected dropout population. By quantifying how the `Ly? fraction', xLy?, varies with redshift, we seek to constrain changes in Ly? transmission associated with reionization. In order to distinguish the effects of reionization from other factors which affect the Ly? fraction [e.g. dust, interstellar medium (ISM) kinematics], we study the luminosity and redshift-dependence of the Ly? fraction over 3 <~ z <~ 6, when the intergalactic medium (IGM) is known to be ionized. These results reveal that low-luminosity galaxies show strong Ly? emission much more frequently (xLy? = 0.47 +/- 0.16 at MUV = -19) than luminous systems (xLy? = 0.08 +/- 0.02 at MUV = -21), and that at fixed luminosity, the prevalence of strong Lyman ? emission increases moderately with redshift over 3 < z < 6 (d xLy?/d z = 0.05 +/- 0.03). Based on the bluer mean UV slopes of the strong Ly? emitting galaxies in our data set (Ly? - noLy? = -0.33 +/- 0.09 at MUV = -20.5) we argue that the Ly? fraction trends are governed by redshift and luminosity-dependent variations in the dust obscuration, with likely additional contributions from trends in the kinematics and covering fraction of neutral hydrogen. Using the limited infrared spectroscopy of candidate z ~= 7 galaxies, we find a tentative decrease in the Ly? fraction by a factor of >1.9 with respect to the predicted z ~= 7 value, a result which, if confirmed with future surveys, would suggest an increase in the neutral fraction by this epoch. Given the abundant supply of z and Y drops now available from deep Hubble WFC3/IR surveys, we show it will soon be possible to significantly improve estimates of the Ly? fraction using optical and near-infrared multi-object spectrographs, thereby extending the study conducted in this paper to 7 <~ z <~ 8.

Stark, Daniel P.; Ellis, Richard S.; Chiu, Kuenley; Ouchi, Masami; Bunker, Andrew

2010-11-01

275

SUPERNOVA 2003ie WAS LIKELY A FAINT TYPE IIP EVENT  

SciTech Connect

We present new photometric observations of supernova (SN) 2003ie starting one month before discovery, obtained serendipitously while observing its host galaxy. With only a weak upper limit derived on the mass of its progenitor (<25 M{sub Sun }) from previous pre-explosion studies, this event could be a potential exception to the ''red supergiant (RSG) problem'' (the lack of high-mass RSGs exploding as Type IIP SNe). However, this is true only if SN2003ie was a Type IIP event, something which has never been determined. Using recently derived core-collapse SN light-curve templates, as well as by comparison to other known SNe, we find that SN2003ie was indeed a likely Type IIP event. However, with a plateau magnitude of {approx} - 15.5 mag, it is found to be a member of the faint Type IIP class. Previous members of this class have been shown to arise from relatively low-mass progenitors (<12 M{sub Sun }). It therefore seems unlikely that this SN had a massive RSG progenitor. The use of core-collapse SN light-curve templates is shown to be helpful in classifying SNe with sparse coverage. These templates are likely to become more robust as large homogeneous samples of core-collapse events are collected.

Arcavi, Iair; Gal-Yam, Avishay [Department of Particle Physics and Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Sergeev, Sergey G., E-mail: iair.arcavi@weizmann.ac.il [Crimean Astrophysical Observatory, P/O Nauchny, Crimea 98409 (Ukraine)

2013-04-15

276

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

277

Assessment of child neurology outpatients with headache, dizziness, and fainting.  

PubMed

Neurologic symptoms such as headache, vertigo, dizziness, and fainting can create a diagnostic problem in pediatric neurology practice because they are also the most common presenting symptoms of psychiatric disorders. Children, especially adolescents, who are often admitted with such autonomic symptoms, are frequently misdiagnosed. In this study, we aimed to investigate the psychiatric morbidity and comorbidity rate in children and adolescents presenting with neurologic symptoms such as headache, vertigo, and syncope. We investigated 31 children who presented with these symptoms. All children were evaluated for their medical history and had a physical and neurologic examination. We attempted to rule out a possible organic etiology. All patients received a complete laboratory examination (blood count, electroencephalography), pediatric cardiology and otorhinolaryngology consultations, and a caloric test. All patients were assessed according to Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) criteria. The majority of the patients (93.5%) received a psychiatric diagnosis according to the DSM-IV criteria. Most of these patients were adolescents and female. Psychosocial stressors such as academic problems, familial dysfunction, parental psychopathology, and child sexual abuse were associated with somatic symptoms. The results of this study demonstrated the importance of differential diagnosis and psychiatric comorbidity in a pediatric neurologic outpatient population. Treatment should be directed at biopsychosocial integrity, and a multidisciplinary treatment approach should be applied. PMID:15224706

Emiro?lu, Fatma Neslihan Inal; Kurul, Semra; Akay, Aynur; Miral, Süha; Dirik, Eray

2004-05-01

278

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

279

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

280

Carbon Dioxide Cycling, Climate, Impacts, and the Faint Young Sun  

NASA Technical Reports Server (NTRS)

Evidence for relatively mild climates on ancient Earth and Mars has been a puzzle in light of the faint early sun. The geologic evidence, although far from conclusive, would appear to indicate that the surfaces of both planets were, if anything, warmer ca. 3-4 Ga than they are now. The astrophysical argument that the sun ought to have brightened approx. 30% since it reached the main sequence is hard to refute. There results a paradox between the icehouse we expect and the greenhouse we think we see. The usual fix has been to posit massive CO2 atmospheres, although reduced gases (e.g., NH3 or CH4 ) have had their partisans. Evidence against siderite in paleosols dated 2.2-2.75 Ga sets a rough upper limit of 30 PAL (present atmospheric levels) on pCO2 at that time. This is an order of magnitude short of what is needed to defeat the fainter sun. We present here an independent argument against high pCO2 on early Earth that applies not only to the Archean but yet more forcefully to the Hadean era. Additional information is contained in the original extended abstract.

Zahnle, K. J.; Sleep, H. H.

1999-01-01

281

Mid-infrared imaging of the massive young star AFGL 2591: Probing the circumstellar environment of an outflow source  

E-print Network

Most, if not all, stars are now believed to produce energetic outflows during their formation. Yet, almost 20 years after the discovery of bipolar outflows from young stars, the origins of this violent phenomenon are not well understood. One of the difficulties of probing the outflow process, particularly in the case of massive embedded stars, is a deficit of high spatial resolution observations. Here, we present sub-arcsecond-resolution mid-infrared images of one massive young stellar object, AFGL 2591, and its immediate surroundings. Our images, at 11.7, 12.5 and 18.0 microns, reveal a knot of emission ~6'' SW of the star, which may be evidence for a recent ejection event or an embedded companion star. This knot is roughly coincident with a previously seen near-infrared reflection nebula and a radio source, and lies within the known large-scale CO outflow. We also find a new faint NW source which may be another embedded lower-luminosity star. The IRAS mid-infrared spectrum of AFGL 2591 shows a large silicate absorption feature at 10 microns, implying that the primary source is surrounded by an optically thick dusty envelope. We discuss the interrelationship of these phenomena and suggest that mid-infrared imaging and spectroscopy provide powerful tools for probing massive star birth.

Massimo Marengo; Ray Jayawardhana; Giovanni G. Fazio; William F. Hoffmann; Joseph L. Hora; Aditya Dayal; Lynne K. Deutsch

2000-08-02

282

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.

2013-12-01

283

Signs of a faint disc population at polluted white dwarfs  

NASA Astrophysics Data System (ADS)

Observations of atmospheric metals and dust discs around white dwarfs provide important clues to the fate of terrestrial planetary systems around intermediate-mass stars. We present Spitzer Infrared Array Camera observations of 15 metal polluted white dwarfs to investigate the occurrence and physical properties of circumstellar dust created by the disruption of planetary bodies. We find subtle infrared excess emission consistent with warm dust around KUV 15519+1730 and HS 2132+0941, and weaker excess around the DZ white dwarf G245-58, which, if real, makes it the coolest white dwarf known to exhibit a 3.6 ?m excess and the first DZ star with a bright disc. All together our data corroborate a picture where (1) discs at metal-enriched white dwarfs are commonplace and most escape detection in the infrared (possibly as narrow rings), (2) the discs are long lived, having lifetimes on the order of 106 yr or longer and (3) the frequency of bright, infrared detectable discs decreases with age, on a time-scale of roughly 500 Myr, suggesting large planetesimal disruptions decline on this same time-scale.

Bergfors, C.; Farihi, J.; Dufour, P.; Rocchetto, M.

2014-11-01

284

The Portia group satellites as sources for faint rings  

NASA Astrophysics Data System (ADS)

The Portia group is a set of nine small satellites densely packed within 2 and 3 radii of Uranus, and some of these moons are related to faint rings: the nu ring orbits between Portia and Rosalind, while the mu ring peak is aligned with the orbit of Mab. Sfair & Giuliatti Winter (2012) showed that the alignment and the triangular radial profile of the mu ring may be explained by a combination of the dust ejection caused by the bombardment of micrometeoroids onto the surface of Mab, and the subsequent effects of the planetary oblateness and the solar radiation force acting upon the grains. In spite of all members of the Portia family are subject to a similar flux of impactors and forces, so far there is no evidence of other ring paired with a satellite. We found that a possible exception is Bianca, the innermost member of the family, and therefore less sensitive to observations. With an appropriate size for a ringThe Portia group is a set of nine small satellites densely packed within 2 and 3 radii of Uranus, and some of these moons are related to faint rings: the nu ring orbits between Portia and Rosalind, while the mu ring peak is aligned with the orbit of Mab. Sfair & Giuliatti Winter (2012) showed that the alignment and the triangular radial profile of the mu ring may be explained by a combination of the dust ejection caused by the bombardment of micrometeoroids onto the surface of Mab, and the subsequent effects of the planetary oblateness and the solar radiation force acting upon the grains. In spite of all members of the Portia family are subject to a similar flux of impactors and forces, so far there is no evidence of other ring paired with a satellite. We found that a possible exception is Bianca, the innermost member of the family, and therefore less sensitive to observations. With an appropriate size for a ring-producing moon, our calculations suggests that the bombardment may provide material to the surroundings at a rate of 40 g/s. The solar radiation force effects can be noticed in an asymmetrical triangular distribution of the ejected grains, and in the slight offset between the density peak of the resulting ring and Bianca's orbit. In our numerical simulations the dust grains can survive in the region up to 8000 years, when all dust particles are removed by collisions with the source body. This survival time allows us to estimate an upper limit of tau=10(-4) for the optical depth of this hypothetical ring, but a more accurate model is necessary to place better constrains for future observations. -producing moon, our calculations suggests that the bombardment may provide material to the surroundings at a rate of 40 g/s. The solar radiation force effects can be noticed in an asymmetrical triangular distribution of the ejected grains, and in the slight offset between the density peak of the resulting ring and Bianca's orbit. In our numerical simulations the dust grains can survive in the region up to 8000 years, when all dust particles are removed by collisions with the source body. This survival time allows us to estimate an upper limit of tau=10(-4) for the optical depth of this hypothetical ring, but a more accurate model is necessary to place better constrains for future observations.

Sfair, Rafael; Giuliatti Winter, Silvia Maria; Horn, Jason

285

The Nature of the Faint Chandra X-ray Sources in the Galactic Centre  

E-print Network

Recent Chandra observations have revealed a large population of faint X-ray point sources in the Galactic Centre. The observed population consists of about 2000 faint sources in the luminosity range ~10^31-10^33 erg/s. The majority of these sources (70%) are described by hard spectra, while the rest are rather soft. The nature of these sources still remains unknown. Belczynski & Taam (2004) demonstrated that X-ray binaries with neutron star or black hole accretors may account for most of the soft sources, but are not numerous enough to account for the observed number and X-ray properties of the faint hard sources. A population synthesis calculation of the Galactic Centre region has been carried out. Our results indicate that the numbers and X-ray luminosities of intermediate polars are consistent with the observed faint hard Galactic Centre population.

A. J. Ruiter; K. Belczynski; T. E. Harrison

2005-11-30

286

Deep spectroscopic luminosity function of Abell 85: no evidence for a steep upturn of the faint-end slope  

NASA Astrophysics Data System (ADS)

We present a new deep determination of the spectroscopic luminosity function (LF) within the virial radius of the nearby and massive Abell 85 (A85) cluster down to the dwarf regime (M* + 6) using Very Large Telescope/Visible Multi-Object Spectrograph (VLT/VIMOS) spectra for ˜2000 galaxies with mr ? 21 mag and ? 24 mag arcsec-2. The resulting LF from 438 cluster members is best modelled by a double Schechter function due to the presence of a statistically significant upturn at the faint end. The amplitude of this upturn (? f = -1.58^{+0.19}_{-0.15}), however, is much smaller than that of the Sloan Digital Sky Survey (SDSS) composite photometric cluster LF by Popesso et al., ?f ˜ -2. The faint-end slope of the LF in A85 is consistent, within the uncertainties, with that of the field. The red galaxy population dominates the LF at low luminosities, and is the main factor responsible for the upturn. The fact that the slopes of the spectroscopic LFs in the field and in a cluster as massive as A85 are similar suggests that the cluster environment does not play a major role in determining the abundance of low-mass galaxies.

Agulli, I.; Aguerri, J. A. L.; Sánchez-Janssen, R.; Barrena, R.; Diaferio, A.; Serra, A. L.; Méndez-Abreu, J.

2014-10-01

287

The Quenching of the Ultra-Faint Dwarf Galaxies in the Reionization Era  

E-print Network

We present new constraints on the star formation histories of six ultra-faint dwarf galaxies: Bootes I, Canes Venatici II, Coma Berenices, Hercules, Leo IV, and Ursa Major I. Our analysis employs a combination of high-precision photometry obtained with the Advanced Camera for Surveys on the Hubble Space Telescope, medium-resolution spectroscopy obtained with the DEep Imaging Multi-Object Spectrograph on the W.M. Keck Observatory, and updated Victoria-Regina isochrones tailored to the abundance patterns appropriate for these galaxies. The data for five of these Milky Way satellites are best fit by a star formation history where at least 75% of the stars formed by z~10 (13.3 Gyr ago). All of the galaxies are consistent with 80% of the stars forming by z~6 (12.8 Gyr ago) and 100% of the stars forming by z~3 (11.6 Gyr ago). The similarly ancient populations of these galaxies support the hypothesis that star formation in the smallest dark matter sub-halos was suppressed by a global outside influence, such as the r...

Brown, Thomas M; Geha, Marla; Simon, Joshua D; Vargas, Luis C; VandenBerg, Don A; Kirby, Evan N; Kalirai, Jason S; Avila, Roberto J; Gennaro, Mario; Ferguson, Henry C; Munoz, Ricardo R; Guhathakurta, Puragra; Renzini, Alvio

2014-01-01

288

The Quenching of the Ultra-faint Dwarf Galaxies in the Reionization Era  

NASA Astrophysics Data System (ADS)

We present new constraints on the star formation histories of six ultra-faint dwarf galaxies: Bootes I, Canes Venatici II, Coma Berenices, Hercules, Leo IV, and Ursa Major I. Our analysis employs a combination of high-precision photometry obtained with the Advanced Camera for Surveys on the Hubble Space Telescope, medium-resolution spectroscopy obtained with the DEep Imaging Multi-Object Spectrograph on the W. M. Keck Observatory, and updated Victoria-Regina isochrones tailored to the abundance patterns appropriate for these galaxies. The data for five of these Milky Way satellites are best fit by a star formation history where at least 75% of the stars formed by z ~ 10 (13.3 Gyr ago). All of the galaxies are consistent with 80% of the stars forming by z ~ 6 (12.8 Gyr ago) and 100% of the stars forming by z ~ 3 (11.6 Gyr ago). The similarly ancient populations of these galaxies support the hypothesis that star formation in the smallest dark-matter sub-halos was suppressed by a global outside influence, such as the reionization of the universe. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-12549.

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

2014-12-01

289

The Search for Faint Radio Supernova Remnants in the Outer Galaxy: Five New Discoveries  

E-print Network

High resolution and sensitivity large-scale radio surveys of the Milky Way are critical in the discovery of very low surface brightness supernova remnants (SNRs), which may constitute a significant portion of the Galactic SNRs still unaccounted for (ostensibly the Missing SNR problem). The overall purpose here is to present the results of a systematic, deep data-mining of the Canadian Galactic Plane Survey (CGPS) for faint, extended non-thermal and polarized emission structures that are likely the shells of uncatalogued supernova remnants. We examine 5$\\times$5 degree mosaics from the entire 1420 MHz continuum and polarization dataset of the CGPS after removing unresolved point sources and subsequently smoothing them. Newly revealed extended emission objects are compared to similarly-prepared CGPS 408 MHz continuum mosaics, as well as to source-removed mosaics from various existing radio surveys at 4.8 GHz, 2.7 GHz, and 327 MHz, to identify candidates with non-thermal emission characteristics. We integrate fl...

Gerbrandt, Stephanie; Kothes, Roland; Geisbuesch, Joern; Tung, Albert

2014-01-01

290

Star Formation Rate and Extinction in Faint z~4 Lyman-Break Galaxies  

E-print Network

We present a statistical detection of 1.5 GHz radio continuum emission from a sample of faint z~4 Lyman-break galaxies (LBGs). LBGs are key tracers of the high-redshift star formation history and important sources of UV photons that ionized the intergalactic medium in the early universe. In order to better constrain the extinction and intrinsic star formation rate (SFR) of high-redshift LBGs, we combine the latest ultradeep Karl G. Jansky Very Large Array 1.5 GHz radio image and the Hubble Space Telescope Advance Camera for Surveys (ACS) optical images in the Great Observatories Origins Deep Survey-North. We select a large sample of 1771 z~4 LBGs from the ACS catalogue using $\\bband$-dropout color criteria. Our LBG samples have $\\iband$~25-28 (AB), ~0-3 magnitudes fainter than M*_UV at z~4. In our stacked radio images, we find the LBGs to be point-like under our 2" angular resolution. We measure their mean 1.5 GHz flux by stacking the measurements on the individual objects. We achieve a statistical detection ...

To, Chun-Hao; Owen, Frazer N

2014-01-01

291

Classifying Discoveries from a Large-area Near-infrared Proper Motion Survey  

NASA Astrophysics Data System (ADS)

Using multi-epoch 2MASS data, we have conducted a very large area (~6000 square degrees) near-infrared proper motion survey. The goal of this survey is to search for nearby, optically faint/invisible sources that would have been missed by previous optical motion surveys. Earlier near-infrared searches for nearby stars have relied solely on photometric criteria that are heavily biased toward solar-age, solar- metallicity stars and brown dwarfs. Such color-based surveys lead to an incomplete and biased census of the Solar Neighborhood. On the other hand, dwarfs that are nearby or have halo kinematics are generally distinguished by high proper motions. Using our new survey we have amassed a list of 159 proper motion stars ((mu) ? 0.2 arcsec/yr, J ? 16.5) that are invisible on optical blue and red sky survey plates. We wish to obtain classification spectra of a subset of these (27 objects) to provide ample statistics on the makeup of this sample. Knowledge of heretofore missed classes of objects can lead to better photometric selections in the future. The only known halo brown dwarf (2MASS 0532+82) was discovered serendipitously; our discovery of a few more halo brown dwarfs would provide much greater insight into this population.

Kirkpatrick, J. Davy; Looper, Dagny L.; Cutri, Roc M.; Burgasser, Adam J.

2006-02-01

292

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

E-print Network

We present near-infrared (nIR) and optical observations of the afterglow of GRB 030115. Discovered in an infrared search at Kitt Peak 5 hours after the burst trigger, this afterglow is amongst the faintest observed in the R-band at an early epoch, and exhibits very red colors, with $R-K\\approx 6$. The magnitude of the optical afterglow of GRB 030115 is fainter than many upper limits for other bursts, suggesting that without early nIR observations it would have been classified as a ``dark'' burst. Both the color and optical magnitude of the afterglow are likely due to dust extinction and indicate that at least some optical afterglows are very faint due to dust along the line of sight. Multicolor {\\it Hubble Space Telescope} observations were also taken of the host galaxy and the surrounding field. Photometric redshifts imply that the host, and a substantial number of faint galaxies in the field are at $z \\sim 2.5$. The overdensity of galaxies is sufficiently great that GRB 030115 may have occurred in a rich high-redshift cluster. The host galaxy shows extremely red colors (R-K=5) and is the first GRB host to be classified as an Extremely Red Object (ERO). Some of the galaxies surrounding the host also show very red colors, while the majority of the cluster are much bluer, indicating ongoing unobscured star formation. As it is thought that much of high redshift star formation occurs in highly obscured environments it may be that GRB 030115 represent a transition object, between the relatively unobscured afterglows seen to date and a population which are very heavily extinguished, even in the nIR.

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

2006-08-08

293

Ultraluminous infrared galaxies  

NASA Technical Reports Server (NTRS)

One of the major discoveries of the the IRAS all-sky survey was a population of sources having the bolometric luminosities of quasars, but where more than 90 percent of the luminosity emerges in the infrared. These objects, more numerous than quasars, are found exclusivly in interacting/merging galaxies that are extremely rich in interstellar gas. We have accumulated evidence that suggests that these systems are indeed quasars, obscured by many tens of magnitudes of extinction. We suggest that these Ultraluminous Infrared Galaxies are the formation stage of quasars, and that colliding galaxies, ultraluminous infrared galaxies, and quasars might be linked through an evolutionary sequence where the infrared bright phase is one in which the quasar is formed in the nucleus of a merger system, and is enshrouded in gas and dust, while the UV excess quasars are at the end state of quasar evolution where most of the enveloping dust cloud has been dissipated, and the quasar is visible directly.

Soifer, B. T.

1991-01-01

294

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

295

The Aromatic Features in Very Faint Dwarf Galaxies  

NASA Astrophysics Data System (ADS)

We present optical and mid-infrared photometry of a statistically complete sample of 29 dwarf galaxies (Mr > - 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 lsim0.005) 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

2011-04-01

296

Searching for Faint Exozodiacal Disks: Keck Results and LBTI Status  

NASA Astrophysics Data System (ADS)

The possible presence of dust in the habitable zone around nearby main-sequence stars is considered as a major hurdle toward the direct imaging of Earth-like extrasolar planets with future dedicated space-based telescopes (e.g., Roberge et al. 2012). In this context, NASA has funded two ground-based mid-infrared nulling interferometers to combine the large apertures available at the Keck Observatory and the Large Binocular Telescope (LBT). In this poster, we present the preliminary results of the extended survey carried out with the Keck Interferometer Nuller (KIN) between 2008 and 2011 and describe the forthcoming LBTI survey.

Defrère, D.; Hinz, P.; Mennesson, B.; Millan-Gabet, R.; Skemer, A.; Bailey, V.; Rodigas, T. J.

2014-01-01

297

Discoveries from a Near-infrared Proper Motion Survey Using Multi-epoch Two Micron All-Sky Survey Data  

NASA Astrophysics Data System (ADS)

We have conducted a 4030 deg2 near-infrared proper motion survey using multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778 proper motion candidates, 647 of which are not listed in SIMBAD. After comparison to Digitized Sky Survey images, we find that 107 of our proper motion candidates lack counterparts at B, R, and I bands and are thus 2MASS-only detections. We present results of spectroscopic follow-up of 188 targets that include the infrared-only sources along with selected optical-counterpart sources with faint reduced proper motions or interesting colors. We also establish a set of near-infrared spectroscopic standards with which to anchor near-infrared classifications for our objects. Among the discoveries are six young field brown dwarfs, five "red L" dwarfs, three L-type subdwarfs, twelve M-type subdwarfs, eight "blue L" dwarfs, and several T dwarfs. We further refine the definitions of these exotic classes to aid future identification of similar objects. We examine their kinematics and find that both the "blue L" and "red L" dwarfs appear to be drawn from a relatively old population. This survey provides a glimpse of the kinds of research that will be possible through time-domain infrared projects such as the UKIDSS Large Area Survey, various VISTA surveys, and WISE, and also through z- or y-band enabled, multi-epoch surveys such as Pan-STARRS and LSST. Some of the spectroscopic data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Other spectroscopic data were collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Kirkpatrick, J. Davy; Looper, Dagny L.; Burgasser, Adam J.; Schurr, Steven D.; Cutri, Roc M.; Cushing, Michael C.; Cruz, Kelle L.; Sweet, Anne C.; Knapp, Gillian R.; Barman, Travis S.; Bochanski, John J.; Roellig, Thomas L.; McLean, Ian S.; McGovern, Mark R.; Rice, Emily L.

2010-09-01

298

Scientific objectives of IRAS  

Microsoft Academic Search

The need for the IRAS mission is discussed, the objects and phenomena which the mission is particularly suited to investigate are described, the discoveries which may be made are speculated on. The main reasons for the lack of a far infrared survey up to now are summarized, including atmospheric absorption, telescope noise, and the excessive amount of time such a

P. E. Clegg

1983-01-01

299

MEASURING X-RAY VARIABILITY IN FAINT/SPARSELY SAMPLED ACTIVE GALACTIC NUCLEI  

SciTech Connect

We study the statistical properties of the normalized excess variance of variability process characterized by a ''red-noise'' power spectral density (PSD), as in the case of active galactic nuclei (AGNs). We perform Monte Carlo simulations of light curves, assuming both a continuous and a sparse sampling pattern and various signal-to-noise ratios (S/Ns). We show that the normalized excess variance is a biased estimate of the variance even in the case of continuously sampled light curves. The bias depends on the PSD slope and on the sampling pattern, but not on the S/N. We provide a simple formula to account for the bias, which yields unbiased estimates with an accuracy better than 15%. We show that the normalized excess variance estimates based on single light curves (especially for sparse sampling and S/N < 3) are highly uncertain (even if corrected for bias) and we propose instead the use of an ''ensemble estimate'', based on multiple light curves of the same object, or on the use of light curves of many objects. These estimates have symmetric distributions, known errors, and can also be corrected for biases. We use our results to estimate the ability to measure the intrinsic source variability in current data, and show that they could also be useful in the planning of the observing strategy of future surveys such as those provided by X-ray missions studying distant and/or faint AGN populations and, more in general, in the estimation of the variability amplitude of sources that will result from future surveys such as Pan-STARRS and LSST.

Allevato, V. [Department of Physics, University of Helsinki, Gustaf Haellstroemin katu 2a, FI-00014 Helsinki (Finland); Paolillo, M. [Department of Physical Sciences, University Federico II, via Cinthia 6, I-80126 Naples (Italy); Papadakis, I. [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, 71003 Heraklion (Greece); Pinto, C. [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584-CA Utrecht (Netherlands)

2013-07-01

300

The First Hyper-Luminous Infrared Galaxy Discovered by WISE  

E-print Network

We report the discovery by the Wide-field Infrared Survey Explorer of the z = 2.452 source WISE J181417.29+341224.9, the first hyperluminous source found in the WISE survey. WISE 1814+3412 is also the prototype for an all-sky sample of ~1000 extremely luminous "W1W2-dropouts" (sources faint or undetected by WISE at 3.4 and 4.6 microns and well detected at 12 or 22 microns). The WISE data and a 350 micron detection give a minimum bolometric luminosity of 3.7 x 10^13 Lsun, with ~10^14 Lsun plausible. Followup images reveal four nearby sources: a QSO and two Lyman Break Galaxies (LBGs) at z = 2.45, and an M dwarf star. The brighter LBG dominates the bolometric emission. Gravitational lensing is unlikely given the source locations and their different spectra and colors. The dominant LBG spectrum indicates a star formation rate ~300 Msun/yr, accounting for ~4. WISE 1814+3412 may be a heavily obscured object where the peak AGN activity occurred prior to the peak era of star formation.

Eisenhardt, Peter R M; Tsai, Chao-Wei; Assef, Roberto; Benford, Dominic; Blain, Andrew; Bridge, Carrie; Condon, J J; Cushing, Michael C; Cutri, Roc; Evans, Neal J; Gelino, Chris; Griffith, Roger L; Grillmair, Carl J; Jarrett, Tom; Lonsdale, Carol J; Masci, Frank J; Mason, Brian S; Petty, Sara; Sayers, Jack; Stanford, S Adam; Stern, Daniel; Wright, Edward L; Yan, Lin; 10.1088/0004-637X/755/2/173

2012-01-01

301

Retinex enhancement of infrared images  

Microsoft Academic Search

With the ability of imaging the temperature distribution of body, infrared imaging is promising in diagnostication and prognostication of diseases. However the poor quality of the raw original infrared images prevented applications and one of the essential problems is the low contrast appearance of the imagined object. In this paper, the image enhancement technique based on the Retinex theory is

Ying Li; Renjie He; Guizhi Xu; Changzhi Hou; Yunyan Sun; Lei Guo; Liyun Rao; Weili Yan

2008-01-01

302

Adaptive optics for high-contrast imaging of faint substellar companions  

NASA Astrophysics Data System (ADS)

Direct imaging of faint objects around bright stars is challenging because the primary star's diffracted light can overwhelm low-mass companions. Nevertheless, advances in adaptive optics (AO) and high-contrast imaging have revealed the first pictures of extrasolar planets. In this dissertation I employ today's high-contrast AO techniques to image brown dwarfs around stars in the nearby Hyades cluster. Furthermore, I prepare for the next generation of high-contrast AO instrumentation, by qualifying MEMS deformable mirrors for wavefront control in the Gemini Planet Imager. In Part I, I present discovery of 3 new brown dwarfs and 36 low-mass stellar companions to 85 stars in the Hyades, imaged with AO at Keck and Lick Observatories. The "locally-optimized combination of images" (LOCI) image-diversity technique filters out the primary star to reveal faint companions. This survey is complete to the hydrogen-burning limit at separations beyond 20 AU. In the complete sample, multiplicity increases as primary star mass decreases. Additionally, the brown dwarfs are at wide >150 AU separations. Finding this preference for low binding-energy systems is an unexpected result, as the Hyades is 625 Myr old and dynamically relaxed. Future work will continue to explore this trend to understand the dynamical and star formation history of the Hyades. The brown dwarfs are near interesting transition regimes for low-mass objects; therefore, characterizing their atmospheres with spectrophotometry will serve as an important benchmark for our understanding of these cool objects. In Part II, I demonstrate micro-electro-mechanical systems (MEMS) deformable mirrors for high-order wavefront control in the Gemini Planet Imager (GPI). MEMS micromirrors have thousands of degrees of freedom and represent a significant cost efficiency over conventional glass deformable mirrors, making them ideal for high-contrast AO. In Chapter 7, I present experimental evidence that MEMS actuators function well and are stable and repeatable at the sub-nm level over the course of an hour. In Chapter 8, I prove MEMS ability to correct high-order Kolmogorov turbulence and maintain the high-contrast "dark hole" in the GPI woofer-tweeter architecture. Finally, in Chapter 9, I analyze MEMS performance on sky with Villages, a telescope testbed for MEMS technology, visible-light AO, and open-loop control. The MEMS remains repeatably flat and controllable over ˜4 years and ˜800 hours of operation. Open loop control of the hysteresis-free MEMS produces a diffraction-limited core in I-band, while internal static errors dominate the on-sky error budget. This work establishes MEMS deformable mirrors as excellent wavefront correctors for high-order AO. The MEMS in GPI will produce a deeper, broader dark hole, allowing for detection and characterization of directly-imaged planets in a fainter, wider search space.

Morzinski, Katie M.

303

Infrared rainbow.  

PubMed

Radition in the near-infrared spectral region should produce a rainbow that is not visible to the human eye. An infrared photograph is shown which displays the primary bow, the secondary bow, and two supernumerary bows in side the primary bow. PMID:17775214

Greenler, R G

1971-09-24

304

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.

305

The Wide-Field Infrared Explorer  

NASA Astrophysics Data System (ADS)

We propose to build a Wide Field Infrared Explorer (WIRE) in response to NASA's 1992 Announcement of Opportunity for Small Explorers. WIRE will be capable of detecting typical starburst galaxies at a redshift of 0.5, ultraluminous infrared galaxies beyond a redshift of 2, and luminous protogalaxies beyond a redshift of 5. This instrument will survey about 100 deg(2) of high Galactic latitude sky at 12 and 25 microns, in passbands where 20% of the luminosity from local starbursts is radiated. WIRE will measure the 12--25 microns color of the starburst galaxies, which is a powerful statistical luminosity indicator. The distribution of starburst galaxy 12--25 microns colors as a function of flux density will reveal their evolutionary history and perhaps the presence of protogalaxies at high redshifts. Follow-up observations of a subset of the WIRE survey will provide a test of our assumptions in using the flux-color distribution to determine the evolution of starburst galaxies. The objective of the WIRE mission is to answer the following questions: (1) What fraction of the luminosity of the Universe at a redshift of 0.5 and beyond is due to starburst galaxies? (2) How fast and in what ways are starburst galaxies evolving? (3) Are luminous protogalaxies common at redshifts less than 3? During its four-month mission lifetime, WIRE will gather ample data to answer these questions and amass a catalog exceeding the size of the IRAS Point Source Catalog. If starburst galaxies are evolving at a modest pace, then a three-hour exposure will reach flux densities below 0.4 mJy, 5sigma , and will be dominated by confusion noise. WIRE is specifically designed to detect the maximum number of high-redshift starburst galaxies using the smallest, simplest instrument possible. The 28cm aperture Cassegrain telescope has no moving parts and a wide 34 times 34 arcminute field of view. It capitalizes on the 128 times 128 Si:As IBC detector arrays now available. The optics and detectors are cooled during the mission using only 3 kg of solid H_2. The WIRE instrument requires only a single stare-type observing mode, fixed solar panel, 35 watts of power, and a low data rate (7 kbits/sec average). The WIRE survey will be over 500 times fainter than the IRAS Faint Source Survey at 12 and 25 microns. This revolutionary gain in sensitivity over a significant part of the sky permits breakthroughs in all areas of astronomy.

Hacking, P.; Schember, H.

1993-05-01

306

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

307

The First Hyper-Luminous Infrared Galaxy Discovered by WISE  

NASA Technical Reports Server (NTRS)

We report the discovery by the Wide-field Infrared Survey Explorer of the z = 2.452 source WISEJ181417.29+341224.9, the first hyperluminous source found in the WISE survey. WISE 1814+3412 is also the prototype for an all-sky sample of approximately 1000 extremely luminous "W1W2-dropouts" (sources faint or undetected by WISE at 3.4 and 4.6 micrometers and well detected at 12 or 22 micrometers). The WISE data and a 350 micrometers detection give a minimum bolometric luminosity of 3.7 x 10(exp 13) solar luminosity, with approximately 10(exp 14) solar luminosity plausible. Followup images reveal four nearby sources: a QSO and two Lyman Break Galaxies (LBGs) at z = 2.45, and an M dwarf star. The brighter LBG dominates the bolometric emission. Gravitational lensing is unlikely given the source locations and their different spectra and colors. The dominant LBG spectrum indicates a star formation rate approximately 300 solar mass yr(exp -1), accounting for less than or equal to 10 percent of the bolometric luminosity. Strong 22 micrometer emission relative to 350 micrometer implies that warm dust contributes significantly to the luminosity, while cooler dust normally associated with starbursts is constrained by an upper limit at 1.1 mm. Radio emission is approximately 10? above the far-infrared/radio correlation, indicating an active galactic nucleus is present. An obscured AGN combined with starburst and evolved stellar components can account for the observations. If the black hole mass follows the local MBH-bulge mass relation, the implied Eddington ratio is approximately greater than 4. WISE 1814+3412 may be a heavily obscured object where the peak AGN activity occurred prior to the peak era of star formation.

Eisenhardt, Peter R.; Wu, Jingwen; Tsai, Chao-Wei; Assef, Roberto; Benford, Dominic; Blain, Andrew; Bridge, Carrie; Condon, J. J.; Cushing, Michael C.; Cutri, Roc; Evans, Neal J., III; Gelino, Chris; Griffith, Roger L.; Grillmair, Carl J.; Jarrett, Tom; Lonsdale, Carol J.; Masci, Frank J.; Mason, Brian S.; Petty, Sara; Sayers, Jack; Stanford, S. Adam; Stern, Daniel; Wright, Edward L.; Yan, Lin

2012-01-01

308

The First Hyper-luminous Infrared Galaxy Discovered by WISE  

NASA Astrophysics Data System (ADS)

We report the discovery by the Wide-field Infrared Survey Explorer (WISE) of the z = 2.452 source WISE J181417.29+341224.9, the first hyperluminous source found in the WISE survey. WISE 1814+3412 is also the prototype for an all-sky sample of ~1000 extremely luminous "W1W2-dropouts" (sources faint or undetected by WISE at 3.4 and 4.6 ?m and well detected at 12 or 22 ?m). The WISE data and a 350 ?m detection give a minimum bolometric luminosity of 3.7 × 1013 L ?, with ~1014 L ? plausible. Follow-up images reveal four nearby sources: a QSO and two Lyman break galaxies (LBGs) at z = 2.45, and an M dwarf star. The brighter LBG dominates the bolometric emission. Gravitational lensing is unlikely given the source locations and their different spectra and colors. The dominant LBG spectrum indicates a star formation rate ~300 M ? yr-1, accounting for <~ 10% of the bolometric luminosity. Strong 22 ?m emission relative to 350 ?m implies that warm dust contributes significantly to the luminosity, while cooler dust normally associated with starbursts is constrained by an upper limit at 1.1 mm. Radio emission is ~10 times above the far-infrared/radio correlation, indicating an active galactic nucleus (AGN) is present. An obscured AGN combined with starburst and evolved stellar components can account for the observations. If the black hole mass follows the local M BH-bulge mass relation, the implied Eddington ratio is >~ 4. WISE 1814+3412 may be a heavily obscured object where the peak AGN activity occurred prior to the peak era of star formation.

Eisenhardt, Peter R. M.; Wu, Jingwen; Tsai, Chao-Wei; Assef, Roberto; Benford, Dominic; Blain, Andrew; Bridge, Carrie; Condon, J. J.; Cushing, Michael C.; Cutri, Roc; Evans, Neal J., II; Gelino, Chris; Griffith, Roger L.; Grillmair, Carl J.; Jarrett, Tom; Lonsdale, Carol J.; Masci, Frank J.; Mason, Brian S.; Petty, Sara; Sayers, Jack; Stanford, S. A.; Stern, Daniel; Wright, Edward L.; Yan, Lin

2012-08-01

309

Beyond the Hubble Deep Field Limiting Magnitude: Faint Galaxy Number Counts from Surface-Brightness Fluctuations  

E-print Network

The faint end of the differential galaxy number counts, n(m), in the Hubble Deep Field (HDF) North has been determined for the F450W, F606W, and F814W filters by means of surface-brightness fluctuation (SBF) measurements. This technique allows us to explore n(m) beyond the limiting magnitude of the HDF, providing new, stronger constraints on the faint end of n(m). This has allowed us to test the validity of previous number count studies and to produce a new determination of the faint end of n(m) for magnitudes fainter than 28.8 in the AB system and to extend this estimate down to 31. This value represents an extension of more than two magnitudes beyond the limits of previous photometric studies. The obtained n(m) slopes are \\gamma=0.27, 0.21, and 0.26 in B_{450}, V_{606}, and I_{814}, respectively.

A. Marin-Franch; A. Aparicio

2003-05-16

310

HAWAII QUASAR AND T DWARF SURVEY. I. METHOD AND DISCOVERY OF FAINT FIELD ULTRACOOL DWARFS ,  

SciTech Connect

The Hawaii Quasar and T dwarf survey (HQT Survey) is a wide-field, red optical survey carried out with the Suprime-Cam mosaic CCD camera on the 8.2 m Subaru telescope. The HQT survey is designed to search for low-luminosity (M{sub AB1450} < -23) quasars at high redshift (z>5.7) as well as T dwarfs, both of which are selected by their very red I - z' colors. We use an optical narrowband filter NB816 to break a well-known I - z' color degeneracy between high-z quasars and foreground M and L dwarfs, which are more numerous than quasars. This paper is the first in a series of papers from the HQT survey and we report on the discovery of six faint (19 {<=} J {<=} 20) ultracool dwarfs found over a {approx}9.3 deg{sup 2} area with a limiting magnitude of z'{sub AB} {<=} 23.3. These dwarfs were confirmed by near-IR imaging and/or spectroscopy conducted at various facilities on Mauna Kea. With estimated distances of 60-170 pc, these are among the most distant spectroscopically confirmed field brown dwarfs to date. Limits on the proper motions of these ultracool dwarfs suggest that they are old members of the Galactic disk, though future follow-up observations are necessary to minimize errors. Our finding rate of ultracool dwarfs is within model predictions of Liu et al. However, the large brightening amplitude ({approx}1 mag) previously reported for the L/T transition objects appears to overpredict the numbers. We also examine how the survey field latitude affects the survey sensitivity to the vertical scale height of ultracool dwarfs.

Kakazu, Yuko; Capak, Peter L. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Hu, Esther M.; Liu, Michael C.; Wainscoat, Richard J. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Wang Weihao, E-mail: kakazu@astro.caltech.ed [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China)

2010-11-01

311

Near-Infrared Photometric Variability of Stars Toward the Chamaeleon I Molecular Cloud  

E-print Network

We present the results of a J, H, and K_s photometric monitoring campaign of a 0.72 x 6 sq deg. area centered on the Chamaeleon I star forming region. Data were obtained on 15 separate nights over a 4 month time interval using the 2MASS South telescope. Out of a total of 34,539 sources brighter than the photometric completeness limits (J=16.0, H=15.2, K_s=14.8), 95 exhibit near-infrared variability in one or more bands. The variables can be grouped into a population of bright, red objects that are associated with the Chamaeleon I association, and a population of faint, blue variables that are dispersed over the full 6 deg of the survey and are likely field stars or older pre-main-sequence stars unrelated to the present-day Chamaeleon I molecular cloud. Ten new candidate members of Chamaeleon I, including 8 brown dwarf candidates, have been identified based on variability and/or near-infrared excess emission in the J-H vs. H-K_s color-color-diagram. We also provide a compendium of astrometry and J, H, and K_s photometry for previously identified members and candidate members of Chamaeleon I.

John M. Carpenter; Lynne A. Hillenbrand; M. F. Skrutskie; Michael R. Meyer

2002-04-25

312

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

313

A New Strategy for the Routine Detection & Imaging of Faint Radio Sources with VLBI  

E-print Network

In this paper I outline a new strategy for the routine detection and imaging of faint (sub-mJy and microJy) radio sources with VLBI and SVLBI. The strategy relies on a combination of in-beam phase-referencing, wide-field VLBI imaging and simultaneous correlation of multiple field centres. A combination of these techniques, together with the steeply rising radio source counts observed at cm wavelengths, permit routine high resolution observations of radio sources previously considered too faint for conventional VLBI.

M. A. Garrett

2000-03-06

314

Modeling Stars to Improve the Faint Flux Calibration of WISE  

NASA Astrophysics Data System (ADS)

The all sky survey done by the Widefield Infrared Survey Explorer (WISE) at 3.4, 4.6, 12, and 22 microns (W1 -- W4, respectively) provides an invaluable data set for all branches of astronomy. As stated in the "Cautionary Notes" section of its "Explanatory Supplement," however, the All Sky Release Source Catalog systematically underestimates fluxes for sources with W1 > 14.0 and W2 > 13.5 Vega magnitudes. Here we show that for unconfused point-like sources this bias is consistent with a constant flux offset of 7 +/- 2 microJy in W1 and 11 +/- 2 microJy in W2. This result comes from modeling star-like sources from the Sloan Digital Sky Survey Data Release 9 (SDSSdr9), augmented with 2 Micron All Sky Survey (2MASS) photometry where available, using the Kurucz (1993) grid of ATLAS9 stellar atmosphere models and the stellar dust extinction models of Cardelli et al. (1989). While this correction will be unneeded for the upcoming AllWISE analysis of the data, the matched catalog should prove useful for tests of more current stellar models and flux calibration standards in the future.

Lake, Sean E.; Wright, E. L.; Cutri, R. M.; Eisenhardt, P. R.

2013-01-01

315

Performance of the HgCdTe Detector for MOSFIRE, an Imager and Multi-Object Spectrometer for Keck Observatory  

E-print Network

MOSFIRE is a new multi-object near-infrared spectrometer for the Keck 1 telescope with a spectral resolving power of R 3500 for a 0.7" slit (2.9 pixels). The detector is a substrate-removed 2K x 2K HAWAII 2-RG HgCdTe array from Teledyne Imaging Sensors with a cut-off wavelength of 2.5 {\\mu}m and an operational temperature of 77K. Spectroscopy of faint objects sets the requirement for low dark current and low noise. MOSFIRE is also an infrared camera with a 6.9' field of view projected onto the detector with 0.18" pixel sampling. Broad-band imaging drives the requirement for 32-channel readout and MOSFIREs fast camera optics implies the need for a very flat detector. In this paper we report the final performance of the detector selected for MOSFIRE. The array is operated using the SIDECAR ASIC chip inside the MOSFIRE dewar and v2.3 of the HxRG software. Dark current plus instrument background is measured at <0.008 e- s-1 pixel-1 on average. Multiple Correlated Double Sampling (MCDS) and Up-The-Ramp (UTR) sa...

Kulas, Kristin R; Steidel, Charles C

2012-01-01

316

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

317

Preliminary analysis on faint luminous lightning events recorded by multiple high speed cameras  

NASA Astrophysics Data System (ADS)

The objective of this work is the study of some faint luminous events produced by lightning flashes that were recorded simultaneously by multiple high-speed cameras during the previous RAMMER (Automated Multi-camera Network for Monitoring and Study of Lightning) campaigns. The RAMMER network is composed by three fixed cameras and one mobile color camera separated by, in average, distances of 13 kilometers. They were located in the Paraiba Valley (in the cities of São José dos Campos and Caçapava), SP, Brazil, arranged in a quadrilateral shape, centered in São José dos Campos region. This configuration allowed RAMMER to see a thunderstorm from different angles, registering the same lightning flashes simultaneously by multiple cameras. Each RAMMER sensor is composed by a triggering system and a Phantom high-speed camera version 9.1, which is set to operate at a frame rate of 2,500 frames per second with a lens Nikkor (model AF-S DX 18-55 mm 1:3.5 - 5.6 G in the stationary sensors, and a lens model AF-S ED 24 mm - 1:1.4 in the mobile sensor). All videos were GPS (Global Positioning System) time stamped. For this work we used a data set collected in four RAMMER manual operation days in the campaign of 2012 and 2013. On Feb. 18th the data set is composed by 15 flashes recorded by two cameras and 4 flashes recorded by three cameras. On Feb. 19th a total of 5 flashes was registered by two cameras and 1 flash registered by three cameras. On Feb. 22th we obtained 4 flashes registered by two cameras. Finally, in March 6th two cameras recorded 2 flashes. The analysis in this study proposes an evaluation methodology for faint luminous lightning events, such as continuing current. Problems in the temporal measurement of the continuing current can generate some imprecisions during the optical analysis, therefore this work aim to evaluate the effects of distance in this parameter with this preliminary data set. In the cases that include the color camera we analyzed the RGB mode (red, green, blue) and compared them with the data provided by the black and white cameras for the same event and the influence of these parameters with the luminosity intensity of the flashes. Two peculiar cases presented, from the data obtained at one site, a stroke, some continuing current during the interval between the strokes and, then, a subsequent stroke; however, the other site showed that the subsequent stroke was in fact an M-component, since the continuing current had not vanished after its parent stroke. These events generated a dubious classification for the same event that was based only in a visual analysis with high-speed cameras and they were analyzed in this work.

Alves, J.; Saraiva, A. V.; Pinto, O.; Campos, L. Z.; Antunes, L.; Luz, E. S.; Medeiros, C.; Buzato, T. S.

2013-12-01

318

In infrared search for very low mass stars: The luminosity function  

SciTech Connect

Infrared photometry can reveal cool companions to hot sub-main-sequence stars to very faint limtis of luminosity. We have surveyed approx.100 white dwarfs at 2.2 ..mu..m for very low mass red dwarf companions in a search complete to M/sub v/approx.21. Very few new companions were found, none with M/sub v/>15. This does not appear due to either selection effects or evolutionary effects on precursor systems. The cumulative body of evidence suggests termination of the hydrogen-burning main sequence at M/sub v/roughly-equal17.5, M/sub bol/roughly-equal12.8. Our survey and other results indicate the luminosity function declines for >13, with a resulting decline in the mass function. The mass density in objects of M<0.2 M unaccounted for in the Luyten luminosity function is < or approx. =0.005 M pc/sup -3/ in the solar neighborhood. It is suggested that a massive Galactic halo is not composed of substellar-mass objects; however, if it is, such a population could be identified with the Space Telescope without confusion with similar dish population objects.

Probst, R.G.

1983-11-01

319

Polymer infrared proximity sensor  

NASA Astrophysics Data System (ADS)

A proximity sensor that combines a polymer light-emitting diode and a polymer photodiode is presented. The operation wavelength is in the near infrared from 700to850nm. The infrared emission is obtained by adding a color conversion film of polyvinylpyrrolidone polymer matrix blended with infrared dye 1,1-diethyl-2,2-dicarbocyanine iodide to a red polymer light-emitting diode. The photodetector relies on the direct charge-transfer exciton generation in a donor-acceptor polymer blend of poly(3-hexylthiophene) and (6,6)-phenyl-C61-butyric acid methyl ester. The detection distance is up to 19cm for objects with various colors and roughness under ambient indoor lighting.

Chen, En-Chen; Tseng, Shin-Rong; Ju, Jia-Hong; Yang, Chia-Ming; Meng, Hsin-Fei; Horng, Sheng-Fu; Shu, Ching-Fong

2008-08-01

320

An All-Sky Catalog of Faint Extreme Ultraviolet Sources  

Microsoft Academic Search

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

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

1997-01-01

321

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

NASA Astrophysics Data System (ADS)

A comprehensive set of optical and near-infrared (NIR) photometry and spectroscopy is presented for the faint and fast 2008ha-like supernova (SN) 2010ae. Contingent on the adopted value of host extinction, SN 2010ae reached a peak brightness of -13.8 > MV > -15.3 mag, while modeling of the UVOIR light curve suggests it produced 0.003-0.007 M? of 56Ni, ejected 0.30-0.60 M? of material, and had an explosion energy of 0.04-0.30 × 1051 erg. The values of these explosion parameters are similar to the peculiar SN 2008ha -for which we also present previously unpublished early phase optical and NIR light curves - and places these two transients at the faint end of the 2002cx-like SN population. Detailed inspection of the post-maximum NIR spectroscopic sequence indicates the presence of a multitude of spectral features, which are identified through SYNAPPS modeling to be mainly attributed to Co ii. Comparison with a collection of published and unpublished NIR spectra of other 2002cx-like SNe, reveals that a Co ii footprint is ubiquitous to this subclass of transients, providing a link to Type Ia SNe. A visual-wavelength spectrum of SN 2010ae obtained at +252 days past maximum shows a striking resemblance to a similar epoch spectrum of SN 2002cx. However, subtle differences in the strength and ratio of calcium emission features, as well as diversity among similar epoch spectra of other 2002cx-like SNe indicates a range of physical conditions of the ejecta, highlighting the heterogeneous nature of thispeculiar class of transients. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile (ESO Programs 082.A-0526, 084.D-0719, 088.D-0222, 184.D-1140, and 386.D-0966); the Gemini Observatory, Cerro Pachon, Chile (Gemini Programs GS-2010A-Q-14 and GS-2010A-Q-38); the Magellan 6.5 m telescopes at Las Campanas Observatory; and the SOAR telescope.Tables 1-5 and Appendix A are available in electronic form at http://www.aanda.orgReduced spectra are available as FITS files 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/561/A146

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

2014-01-01

322

The Faint Young Sun Piet Martens Harvard-Smithsonian Center for  

E-print Network

(Ice age) First shelly fossils (Cambrian explosion) Snowball Earth ice ages Warm Ice age (?) #12 developed on Earth, yet geological and biological evidence points to a warm young Earth, 60 to 70 C #12;A Faint Young Sun Leaves the Earth Frozen Solid Kasting et al, Scientific American, 1988 #12;Where to look

Martens, Petrus C.

323

The FSVS Cluster Catalogue: galaxy clusters and groups in the Faint Sky Variability Survey  

Microsoft Academic Search

We describe a large sample of 598 galaxy clusters and rich groups discovered in the data of the Faint Sky Variability Survey (FSVS). The clusters have been identified using a fully automated, semiparametric technique based on a maximum likelihood approach applied to Voronoi tessellation, and enhanced by colour discrimination. The sample covers a wide range of richness, has a density

Ilona K. Söchting; Mark E. Huber; Roger G. Clowes; Steve B. Howell

2006-01-01

324

Circumventing the Vasovagal Fainting ResponseA Novel Method of In Vivo Exposure for Injection Phobia  

Microsoft Academic Search

A novel method of in vivo exposure therapy was administered to a 26-year-old female with injection phobia. She had a history of fainting at the sight of syringes, needles, and other medical devices and went to great lengths to avoid physicians and optometrists, putting off receiving necessary examinations and vaccinations. The patient was treated in one long session. The session

Richard W. Seim; Matthew S. Willerick; Scott T. Gaynor; C. Richard Spates

2008-01-01

325

Vulnerability to simple faints is predicted by regional differences in brain anatomy  

Microsoft Academic Search

Neurocardiogenic syncope (NCS, simple fainting) is a common and typically benign familial condition, which rarely may result in traumatic injury or hypoxic convulsions. NCS is associated with emotional triggers, anxiety states and stress. However, the etiology of NCS, as a psychophysiological process, is poorly understood. We therefore investigated the relationship between NCS and brain anatomy. We studied a non-clinical sample

Felix D. C. C. Beacher; Marcus A. Gray; Christopher J. Mathias; Hugo D. Critchley

2009-01-01

326

Compulsive Gambling "With what trembling, with what faintness of heart do I  

E-print Network

the gambling hall, two rooms away, as soon as I begin to hear the clinking of money being poured out, I almost. Thus, gambling is motivated by both wins and losses, and it is easy to see why it is so hardCompulsive Gambling "With what trembling, with what faintness of heart do I hear the croupier's cry

Squire, Larry R.

327

Imaging Faint Sources within a Speckle Halo with Synchronous Interferometric Speckle Subtraction  

Microsoft Academic Search

The performance of high-contrast imaging systems is very often limited by the presence of speckles in the point-spread function (PSF) of the central source. Since this unwanted light is coherent with the central source, it is possible to make it interfere with light extracted from the center of the PSF. The light of a faint companion, however, will not interfere

Olivier Guyon

2004-01-01

328

A VIRUS-P Survey of Galaxy Clusters to Find Faint Ly?-emitting Galaxies  

NASA Astrophysics Data System (ADS)

The VIRUS-P instrument on the 2.7m telescope at the McDonald Observatory was originally built as a prototype of the larger VIRUS instrument that will be used for HETDEX. We demonstrate that this multi-fiber, optical integral field unit spectrograph can be efficiently used to detect faint Ly?-emitting galaxies (LAEs) at intermediate redshift (z = 2-3) with the aid of gravitational lensing from galaxy clusters. The bulk z=2-3 LAEs to date have been discovered with narrowband imaging campaigns, which are highly efficient only at selecting L > L_star galaxies and only over a narrow redshift slice. By making use of gravitational lensing, however, we are able to observe intrinsically very faint galaxies that only appear to have brightnesses ? L_star. Gravitationally lensed faint LAEs, such as our sample from VIRUS-P, allow us to go fainter than existing narrowband surveys and therefore allow for better constraints at the faint end of the Ly? luminosity function at these intermediate redshifts.

McLinden, Emily; Finkelstein, S. L.; Siana, B. D.; Alavi, A.

2014-01-01

329

Color Infrared, Terra Sirenum  

NASA Technical Reports Server (NTRS)

This is the first high-resolution color infrared image taken of Mars. The image was constructed using three of the ten infrared filters on the thermal emission imaging system of NASA's 2001 Mars Odyssey spacecraft. Color infrared images reveal differences in the surface materials' composition, and three different compositional units can be detected in this region, which is known as Terra Sirenum.

One of the imaging system's major objectives will be using color infrared images to make global mineral maps. This image was processed to enhance the infrared color differences and contains many artifacts that will be removed with further processing. This image covers an area about 32 by 66 kilometers (20 by 40 miles) in size. It is centered near 35.5 degrees south, 141.5 degrees west, and was taken on February 19, 2002 at about 3:15 p.m. local Martian time. North is to the left.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The thermal emission imaging system was provided by Arizona State University, Tempe. Lockheed Martin Astronautics, Denver, is the prime contractor for the project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2002-01-01

330

Exploring the faint source population at 15.7 GHz  

E-print Network

frequencies or in dense regions, syn- chrotron self-absorption takes place. This causes a very different spectral shape, with a spec- trum which rises with frequency and a spectral index of around -5/2. The synchrotron spectra in these two different regimes... in clouds of gas moving rapidly located close to the central black hole, and narrow emission lines produced in more slowly moving gas clouds further from the accretion disc (this is shown in Figure 1.3). The anisotropic structure of these objects means...

Whittam, Imogen Helen

2014-10-07

331

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

332

Infrared Thermometer  

NASA Technical Reports Server (NTRS)

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

333

Infrared Spectroscopy  

NSDL National Science Digital Library

This 38-page PDF document is a chapter from the Handbook of Instrumental Techniques for Analytical Chemistry. The chapter explains how infrared spectroscopy works (no comma) along with its general uses, common applications, range and limitations. Also included are spectrometer designs, information about sample preparation, analytical methods, related methods such as gas chromotography and diffuse reflectance, and costs and instrument vendors.

Hsu, C. P.; Hall, Prentice

334

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

335

Faint Emission Lines and Temperature Fluctuations in M8  

NASA Astrophysics Data System (ADS)

We present echelle spectroscopy in the 3500-10300 Å range of the Hourglass Nebula, which is embedded in the Galactic H II region M8. The data were obtained using the 2.1 m telescope at Observatorio Astronómico Nacional in San Pedro Mártir, Baja California. We have measured the intensities of 274 emission lines, in particular 88 permitted lines of C+, N0, N+, O0, O+, Ne0, S0, S+, Si0, Si+, and Si++, some of them produced by recombination only and others mainly by fluorescence. We have determined electron temperatures and densities using different line intensity ratios. We derive the He+, C++, O+, and O++ ionic abundances as well as--for the first time in a nebular object--the total O abundance from recombination lines; these nebular values are independent of the temperature structure of the nebula. We have also derived abundances from collisionally excited lines for a large number of ions and elements; these abundances do depend on the temperature structure. Accurate t2 values have been derived by comparing the C++, O+, and O++ ionic abundances obtained making use of both collisionally excited lines and recombination lines. A comparison of the solar, Orion Nebula, and M8 chemical abundances is made.

Esteban, César; Peimbert, Manuel; Torres-Peimbert, Silvia; García-Rojas, Jorge; Rodríguez, Mónica

1999-01-01

336

Faint Emission Lines and Temperature Fluctuations in M8  

NASA Astrophysics Data System (ADS)

We present echelle spectroscopy in the 3500 to 10300AA range of the Hourglass Nebula which is embedded in the galactic HII region M8. The data were obtained using the 2.1 m telescope at Observatorio Astronomico Nacional in San Pedro Martir, Baja California. We have measured the intensities of 274 emission lines, in particular 88 permitted lines of C+, N0, N+, O0, O+, Ne0, S0, S+, Si0, Si+ and Si++, some of them produced by recombination only and others mainly by fluorescence. We have determined electron temperatures and densities using different line intensity ratios. We derive the He^+, C++, O+ and O++ ionic abundances as well as --for the first time in a nebular object-- the total O abundance from recombination lines, these nebular values are independent of the temperature structure of the nebula. We have derived also abundances from collisionally excited lines for a large number of ions and elements, these abundances do depend on the temperature structure. Accurate t^2 values have been derived by comparing the C++, O+ and O++ ionic abundances obtained making use of both, collisionally excited lines and recombination lines. A comparison of the solar, Orion nebula and M8 chemical abundances is made.

Torres-Peimbert, S.; Peimbert, M.; Esteban, C.; Garcia Rojas, J.; Rodriguez, M.

1998-11-01

337

Light curves and colours of the faint Uranian irregular satellites Sycorax, Prospero, Stephano, Setebos, and Trinculo  

NASA Astrophysics Data System (ADS)

Context: After the work of Gladman et al. (1998, Nature, 392, 897), it is now assessed that many irregular satellites are orbiting around Uranus. Aims: Despite many studies performed in past years, very little is know about the light-curves of these objects and inconsistencies are present between colours derived by different authors. This situation motivated our effort to improve both the knowledge of colours and light curves. Methods: We present and discuss, the time series observations of Sycorax, Prospero, Stephano, Setebos, and Trinculo, five faint, irregular satellites of Uranus, which were carried out at VLT, ESO Paranal (Chile) on the nights between 29 and 30 July, 2005 and 25 and 30 November, 2005. Results: We derive light curves for Sycorax and Prospero and colours for all of these these bodies. Conclusions: For Sycorax we obtain colours B-V = 0.839 ± 0.014, V-R = 0.531 ± 0.005, and a light-curve which is suggestive of a periodical variation with period ?3.6 h and amplitude ?0.067 ± 0.004 mag. The periods and colours we derive also for Sycorax are in agreement with our previous determination in 1999 using NTT. We also derive a light-curve for Prospero which suggests an amplitude of about 0.2 mag and a periodicity of about 4 h. However, the sparseness of our data, prevents a more precise characterization of the light-curves, and we can not determine whether they are one-peaked or two-peaked. Hence, these periods and amplitudes have to be considered preliminary estimates. As for Setebos, Stephano, and Trinculo the present data do not allow us to derive any unambiguous periodicity, despite the fact that Setebos displays a significant variability with amplitude about as large as that of Prospero. Colours for Prospero, Setebos, Stephano, and Trinculo are in marginal agreement with the literature. Based on observations with the ESO Very Large Telescope + FORS2 at the Paranal Observatory, Chile, under program 075.C-0023. Table [see full text] is only available in electronic form at http://www.aanda.org

Maris, M.; Carraro, G.; Parisi, M. G.

2007-09-01

338

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

339

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

340

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

341

GRIS: The grating infrared spectrometer  

Microsoft Academic Search

The grating infrared spectrometer (GRIS) is an echelle grating, prism cross-dispersed, spectrometer designed for the 2.3-m Steward Observatory telescope. The cross-dispersed format utilizes a Near Infrared Camera and Multi-Object Spectrometer 3 (NICMOS 3) HgCdTe detector array for observations in the 0.86-2.5 micrometer spectral region. An echelle grating, ruled on both sides, provides resolutions of 3449 and 9439 per slit width,

Rodger I. Thompson; Harland W. Epps; Greg Winters; William Womack; Eric Mentzell

1994-01-01

342

Writing Objectives.  

ERIC Educational Resources Information Center

The general procedures used to develop educational objectives for the National Assessment of Educational Progress are outlined, as are the procedures used to develop writing objectives. Four objectives related to writing skills are stated: "write to communicate adequately in a social situation"; "write to communicate adequately in a business or…

Norris, Eleanor L.

343

Hubble Provides Infrared View of Jupiter's Moon, Ring, and Clouds  

NASA Technical Reports Server (NTRS)

Probing Jupiter's atmosphere for the first time, the Hubble Space Telescope's new Near Infrared Camera and Multi-Object Spectrometer (NICMOS) provides a sharp glimpse of the planet's ring, moon, and high-altitude clouds.

The presence of methane in Jupiter's hydrogen- and helium-rich atmosphere has allowed NICMOS to plumb Jupiter's atmosphere, revealing bands of high-altitude clouds. Visible light observations cannot provide a clear view of these high clouds because the underlying clouds reflect so much visible light that the higher level clouds are indistinguishable from the lower layer. The methane gas between the main cloud deck and the high clouds absorbs the reflected infrared light, allowing those clouds that are above most of the atmosphere to appear bright. Scientists will use NICMOS to study the high altitude portion of Jupiter's atmosphere to study clouds at lower levels. They will then analyze those images along with visible light information to compile a clearer picture of the planet's weather. Clouds at different levels tell unique stories. On Earth, for example, ice crystal (cirrus) clouds are found at high altitudes while water (cumulus) clouds are at lower levels.

Besides showing details of the planet's high-altitude clouds, NICMOS also provides a clear view of the ring and the moon, Metis. Jupiter's ring plane, seen nearly edge-on, is visible as a faint line on the upper right portion of the NICMOS image. Metis can be seen in the ring plane (the bright circle on the ring's outer edge). The moon is 25 miles wide and about 80,000 miles from Jupiter.

Because of the near-infrared camera's narrow field of view, this image is a mosaic constructed from three individual images taken Sept. 17, 1997. The color intensity was adjusted to accentuate the high-altitude clouds. The dark circle on the disk of Jupiter (center of image) is an artifact of the imaging system.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

1997-01-01

344

The Faint End of the Quasar Luminosity Function at z ~ 4: Implications for Ionization of the Intergalactic Medium and Cosmic Downsizing  

NASA Astrophysics Data System (ADS)

We present an updated determination of the z ~ 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 deg2. We study the effect of using K-corrections to compute the rest-frame absolute magnitude at 1450 Å compared with measuring M 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 1450 for all the quasars, we fit a double power law to the binned QLF. Our best fit has a bright-end slope, ? = 3.3 ± 0.2, and faint-end slope, ? = 1.6+0.8 -0.6. Our new data revise the faint-end slope of the QLF down to flatter values similar to those measured at z ~ 3. The break luminosity, though poorly constrained, is at M* = -24.1+0.7 -1.9, approximately 1-1.5 mag fainter than at z ~ 3. This QLF implies that QSOs account for about half the radiation needed to ionize the intergalactic medium at these redshifts. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Glikman, Eilat; Djorgovski, S. G.; Stern, Daniel; Dey, Arjun; Jannuzi, Buell T.; Lee, Kyoung-Soo

2011-02-01

345

Emission lines in the Near-infrared Spectra of the IR Quintuplet Stars in the Galactic Center  

NASA Astrophysics Data System (ADS)

The natures of the five infrared stars for which the Galactic center’s “Quintuplet Cluster” were named have long been a mystery, although the pinwheel morphologies of two of them suggest that those two are Wolf-Rayet colliding wind binaries. Not only does each of the five IR stars suffer the same large interstellar extinction that obscures all objects in the Galactic center, but also each is embedded within its own warm and dusty cocoon. Until recently near-infrared spectra of them have revealed only dust continua steeply rising to long wavelengths. In the J and H bands the Quintuplet stars are very faint due to the high extinction, but the continuum emission from their warm cocoons is much less than at longer wavelengths and lines arising within their dust shells should be relatively more prominent. Here we report the detection of a number of emission lines characteristic of hot and massive stars in 1.0-1.8?m spectra of four of the IR Quintuplet stars. The lines that have been detected to date allow initial classifications of most of these stars.

Geballe, Thomas R.; Najarro, F.; de la Fuente, D.; Figer, D. F.

2014-01-01

346

Reference-less detection, astrometry, and photometry of faint companions with adaptive optics  

E-print Network

We propose a complete framework for the detection, astrometry, and photometry of faint companions from a sequence of adaptive optics corrected short exposures. The algorithms exploit the difference in statistics between the on-axis and off-axis intensity. Using moderate-Strehl ratio data obtained with the natural guide star adaptive optics system on the Lick Observatory's 3-m Shane Telescope, we compare these methods to the standard approach of PSF fitting. We give detection limits for the Lick system, as well as a first guide to expected accuracy of differential photometry and astrometry with the new techniques. The proposed approach to detection offers a new way of determining dynamic range, while the new algorithms for differential photometry and astrometry yield accurate results for very faint and close-in companions where PSF fitting fails. All three proposed algorithms are self-calibrating, i.e. they do not require observation of a calibration star thus improving the observing efficiency.

Szymon Gladysz; Julian C. Christou

2008-05-13

347

The FSVS Cluster Catalogue: Galaxy Clusters and Groups in the Faint Sky Variability Survey  

Microsoft Academic Search

We describe a large sample of 598 galaxy clusters and rich groups discovered\\u000ain the data of the Faint Sky Variability Survey. The clusters have been\\u000aidentified using a fully automated, semi-parametric technique based on a\\u000amaximum likelihood approach applied to Voronoi tessellation, and enhanced by\\u000acolour discrimination. The sample covers a wide range of richness, has a\\u000adensity of

Ilona K. Sochting; Mark E. Huber; Roger G. Clowes; Steve B. Howell

2006-01-01

348

Studies of the association of faint blue and luminous galaxies using the Hitchhiker parallel camera  

Microsoft Academic Search

At B magnitudes >~ 24 there is a well-known excess of galaxies (compared to\\u000astandard models) which is probably due to an (evolving) population of sub-L*\\u000agalaxies at moderate redshifts (<~ 0.4). One particular hypothesis which is\\u000ahard to test directly via number counts or even redshift surveys is the\\u000apossibility that the faint blue galaxies are in fact sub-galactic

J. B. Jones; S. P. Driver; S. Phillipps; J. I. Davies; I. Morgan; M. J. Disney

1996-01-01

349

The faint source population at 15.7 GHz - I. The radio properties  

NASA Astrophysics Data System (ADS)

We have studied a sample of 296 faint (>0.5 mJy) radio sources selected from an area of the Tenth Cambridge (10C) survey at 15.7 GHz in the Lockman Hole. By matching this catalogue to several lower frequency surveys (e.g. including a deep GMRT survey at 610 MHz, a WSRT survey at 1.4 GHz, NVSS, FIRST and WENSS) we have investigated the radio spectral properties of the sources in this sample; all but 30 of the 10C sources are matched to one or more of these surveys. We have found a significant increase in the proportion of flat-spectrum sources at flux densities below ?1 mJy - the median spectral index between 15.7 GHz and 610 MHz changes from 0.75 for flux densities greater than 1.5 mJy to 0.08 for flux densities less than 0.8 mJy. This suggests that a population of faint, flat-spectrum sources are emerging at flux densities ?1 mJy. The spectral index distribution of this sample of sources selected at 15.7 GHz is compared to those of two samples selected at 1.4 GHz from FIRST and NVSS. We find that there is a significant flat-spectrum population present in the 10C sample which is missing from the samples selected at 1.4 GHz. The 10C sample is compared to a sample of sources selected from the SKADS Simulated Sky by Wilman et al. and we find that this simulation fails to reproduce the observed spectral index distribution and significantly underpredicts the number of sources in the faintest flux density bin. It is likely that the observed faint, flat-spectrum sources are a result of the cores of Fanaroff-Riley type I sources becoming dominant at high frequencies. These results highlight the importance of studying this faint, high-frequency population.

Whittam, I. H.; Riley, J. M.; Green, D. A.; Jarvis, M. J.; Prandoni, I.; Guglielmino, G.; Morganti, R.; Röttgering, H. J. A.; Garrett, M. A.

2013-03-01

350

The Spectral Energy Distribution of a Very Faint X-ray Transient  

NASA Astrophysics Data System (ADS)

Very faint X-ray transient accretion states {peak L X < 10^36 ergs/s} are hard to explain with standard theories of disk instabilities. The unusual globular cluster transient M15 X-3 has only been seen at Lx 6e33 and at 2-6e31 ergs/s. We aim to determine the nature of the companion star through near-simultaneous Chandra and HST imaging, measuring its X-ray spectrum and optical colors.

Heinke, Craig

2011-10-01

351

The Spectral Energy Distribution of a Very Faint X-ray Transient  

NASA Astrophysics Data System (ADS)

Very faint X-ray transient accretion states (peak L_X < 10^36 ergs/s) are hard to explain with standard theories of disk instabilities. The unusual globular cluster transient M15 X-3 has only been seen at Lx~6e33 and at 2-6e31 ergs/s. We aim to determine the nature of the companion star through near-simultaneous Chandra and HST imaging, measuring its X-ray spectrum and optical colors.

Heinke, Craig

2011-09-01

352

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

353

Discovery of a new faint dwarf galaxy associated with NGC 253  

E-print Network

We report the discovery of a new faint dwarf galaxy, which we dub Scl-MM-Dw1, at a projected distance of $\\sim$65 kpc from the spiral galaxy NGC 253. The discovery results from the Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), a program with the Magellan/Megacam imager to study faint substructure in resolved stellar light around massive galaxies outside of the Local Group. We measure a tip of the red giant branch distance to Scl-MM-Dw1 of $D$=3.9$\\pm$0.5 Mpc, consistent with that of NGC 253, making their association likely. The new dwarf's stellar population is complex, with an old, metal poor red giant branch ($\\gtrsim$10 Gyr, [Fe/H]$\\sim$$-$2), and an asymptotic giant branch with an age of $\\sim$500 Myr. Scl-MM-Dw1 has a half-light radius of $r_{h}$=340$\\pm$50 pc and an absolute magnitude of $M_{V}$=$-$10.3$\\pm$0.6 mag, comparable to the Milky Way's satellites at the same luminosity. Once complete, our imaging survey of NGC 253 and other nearby massive galaxies will provide a census of faint ...

Sand, D J; Strader, J; Toloba, E; Simon, J D; Caldwell, N; Guhathakurta, P; McLeod, B; Seth, A C

2014-01-01

354

The Subaru high-z quasar survey: discovery of faint z~6 quasars  

E-print Network

We present the discovery of one or two extremely faint z~6 quasars in 6.5 deg^2 utilizing a unique capability of the wide-field imaging of the Subaru/Suprime-Cam. The quasar selection was made in (i'-z_B) and (z_B-z_R) colors, where z_B and z_R are bandpasses with central wavelengths of 8842A and 9841A, respectively. The color selection can effectively isolate quasars at z~6 from M/L/T dwarfs without the J-band photometry down to z_Rquasar candidates. The follow-up spectroscopy for seven targets identified one apparent quasar at z=6.156 with M_1450=-23.10. We also identified one possible quasar at z=6.041 with a faint continuum of M_1450=-22.58 and a narrow Lyman-alpha emission with HWHM=427 km/s, which cannot be distinguished from Lyman-alpha emitters. We derive the quasar luminosity function at z~6 by combining our faint quasar sample with the bright quasar samples by SDSS and CFHQS. Including our data points invokes a higher number...

Kashikawa, Nobunari; Willott, Chris J; Onoue, Masafusa; Im, Myungshin; Furusawa, Hisanori; Toshikawa, Jun; Ishikawa, Shogo; Niino, Yuu; Shimasaku, Kazuhiro; Ouchi, Masami; Hibon, Pascale

2014-01-01

355

Infrared backscattering  

NASA Technical Reports Server (NTRS)

All particles in the atmosphere are not spherical. Moreover, the scattering properties of randomly oriented nonspherical particles are not equivalent to those of spherical particles no matter how the term equivalent is defined. This is especially true for scattering in the backward direction and at the infrared wavelengths at which some atmospheric particles have strong absorption bands. Thus calculations based on Mie theory of infrared backscattering by dry or insoluble atmospheric particles are suspect. To support this assertion, it was noted that peaks in laboratory-measured infrared backscattering spectra show appreciable shifts compared with those calculated using Mie theory. One example is ammonium sulfate. Some success was had in modeling backscattering spectra of ammonium sulfate particles using a simple statistical theory called the continuous distribution of ellipsoids (CDE) theory. In this theory, the scattering properties of an ensemble are calculated. Recently a modified version of this theory was applied to measured spectra of scattering by kaolin particles. The particles were platelike, so the probability distribution of ellipsoidal shapes was chosen to reflect this. As with ammonium sulfate, the wavelength of measured peak backscattering is shifted longward of that predicted by Mie theory.

Bohren, Craig F.; Nevitt, Timothy J.; Singham, Shermila Brito

1989-01-01

356

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

357

An Update on the X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007: Swift observations of UV variability and persistence of X-ray faintness  

E-print Network

We report on the detection of UV variability and the persistence of X-ray faintness of the X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007 based on the first year of monitoring this AGN with Swift between 2005 October and 2007 January. WPVS 007 has been an unusual source. While being X-ray bright during the ROSAT All-Sky Survey it has been extremely faint in all following X-ray observations. Swift also finds this NLS1 to be X-ray faint and not detected in the Swift X-Ray Telescope at an 3$\\sigma$ upper limit of $2.6\\times 10^{-17}$ W m$^{-2}$ in the 0.3-10.0 keV band and confirms that the AGN is still in a low state. During the 2006 July and December observations with \\swift's UV-Optical Telescope (UVOT) the AGN became fainter by about 0.2 mag in the UV filters and by about 0.1 mag in V, B, and U compared with the 2005 October to 2006 January and 2006 September/October observations followed by a rebrightening in the 2007 January observation. This variability can be caused either by a change in the absorption column density and therefore the reddening in the UV, or by flux variations of the central engine. We also noticed that the flux in the UVOT filters agree with earlier measurements by the International Ultraviolet Explorer taken between 1993-1995, but spectra taken by the Hubble Space Telescope Faint Object Spectrograph show that WPVS 007 was fainter in the UV by a factor of at least 2 in 1996. The flat optical/UV spectrum suggests that some UV extinction is present in the spectrum, but that alone cannot at all account for the dramatic fading in the X-ray flux. Most likely we see a partial covering absorber in X-rays. Alternatively, the current X-ray emission seen from WPVS 007 may also be the emission from the host galaxy.

Dirk Grupe; Patricia Schady; Karen M. Leighly; Stefanie Komossa; Paul O'Brien; John A. Nousek

2007-01-19

358

The Stratospheric Observatory for Infrared Astronomy - A New Tool for Planetary Science  

NASA Astrophysics Data System (ADS)

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a joint US/German effort to fly a 2.5 meter telescope on a modified Boeing 747SP aircraft at stratospheric altitudes where the atmosphere is largely transparent at infrared wavelengths. Key goals of the observatory include understanding the formation of stars and planets; the origin and evolution of the interstellar medium; the star formation history of galaxies; and planetary science. SOFIA offers the convenient accessibility of a ground-based observatory coupled with performance advantages of a space-based telescope. SOFIA’s scientific instruments can be exchanged regularly for repairs, to accommodate changing scientific requirements, and to incorporate new technologies. SOFIA’s portability will enable specialized observations of transient and location-specific events such as stellar occultations of Trans-Neptunian Objects. Unlike many spaceborne observatories, SOFIA can observe bright planets and moons directly, and can observe objects closer to the sun than Earth, e.g. comets in their most active phase, and the planet Venus. SOFIA’s first generation instruments cover the spectral range of .3 to 240 microns and have been designed with planetary science in mind. The High-speed Imaging Photometer for Occultations (HIPO) is designed to measure occultations of stars by Kuiper Belt Objects, with SOFIA flying into the predicted shadows and timing the occultation ingress and egress to determine the size of the occulting body. HIPO will also enable transit observations of extrasolar planets. The Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) and the High-resolution Airborne Wideband Camera (HAWC) will enable mid-infrared and far-infrared (respectively) imaging with a wide range of filters for comets and giant planets, and colorimetric observations of small, unresolved bodies to measure the spectral energy distribution of their thermal emission. The German Receiver for Astronomy at Terahertz Frequencies (GREAT) will measure far-infrared and microwave spectral lines at km/s resolution to search for molecular species and achieve a significant improvement over current knowledge of abundance and distribution of water in planetary bodies. The Echelon Cross Echelle Spectrograph (EXES) and the Field Imaging Far Infrared Line Spectrometer (FIFI LS) will provide high-resolution spectral data between 5 and 210 microns to support mineralogical analysis of solar system and extrasolar debris disk dust and observe spectral features in planetary atmospheres. The First Light Infrared Test Experiment Camera (FLITECAM) will offer imaging and moderate resolution spectroscopy at wavelengths between 1 and 5 microns for observations of comets and asteroids, and can be used simultaneously with HIPO to characterize the atmosphere of transiting exoplanets. SOFIA’s first light flight occurred in May, 2010 and the first short science observing program is scheduled to begin in November, 2010. The Program will issue a call for new instrumentation proposals in the summer of 2011, as well as regular calls for observing proposals beginning in late summer 2011. SOFIA is expected to make ~120 science mission flights each year when fully operational in 2014.

Ruzek, M. J.; Becklin, E.; Burgdorf, M. J.; Reach, W.

2010-12-01

359

Solutions to the faint young Sun paradox simulated by a general circulation model  

NASA Astrophysics Data System (ADS)

The faint young Sun paradox has dominated our thinking regarding early climate. Geological evidence abounds for warm, possibly hot, seawater temperatures and the proliferation of early life during the Archean period of Earth's history (3.8-2.5 Ga). However the standard solar model indicates that the Sun was only 75 to 82 percent as bright as today, implying an apparent contradiction between warm surface temperatures and weak solar irradiance. Geological evidence also places constraints on the amount of atmospheric carbon dioxide present early in Earth's history. Over the past four decades there has been much debate amongst geological, planetary, and climate science communities regarding how to properly resolve the issue of the faint young Sun. Up until very recently, 1-dimensional radiative convective models were the standard tool for deep paleoclimate modeling studies. These studies have notably lacked the ability to treat clouds, surface ice, and meridional energy transport. However, advancements in computing technology now allow us to tackle the faint young Sun paradox using a three-dimensional climate model. Here we use a modified version of the Community Atmosphere Model version 3 from the National Center for Atmospheric Research to study early climate. We find that resolving the faint young Sun paradox becomes less problematic when viewing a full representation of the climate system. Modest amounts of carbon dioxide and methane can provide adequate warming for the Archean within given constraints. Cooler climates with large ice caps but temperate tropical regions can be supported with even less carbon dioxide. The incorporation of systematic climate system differences expected during the Archean, such as fewer cloud condensation nuclei, reduced land albedos, and increased atmospheric nitrogen, can provide additional non-greenhouse means of warming the early Earth. A warm Archean no longer appears at odds with a faint young Sun. Here, we will also discuss the consequences of the oft-suggested Titan-like photochemical haze that may have enshrouded the early Earth if methane was a significant constituent of the atmosphere. Finally, we briefly consider the inverse problem. What fate may be in store for the Earth as the Sun continues to brighten far past its present level?

Wolf, Eric Theodore

360

Symbiotic Miras vs. Planetary Nebulae in the Near Infrared  

E-print Network

While symbiotic Miras and planetary nebulae are hard to distinguish by optical spectroscopy, their near infrared colors differ. We propose the near infrared two-color diagram to be an excellent tool to easily distinguish these two classes of objects.

S. Schmeja; S. Kimeswenger

2002-08-06

361

MODULATION DOMAIN FEATURES FOR DISCRIMINATING INFRARED TARGETS AND BACKGROUNDS  

E-print Network

tracking, object recognition 1. INTRODUCTION The problem of detecting military targets in forwardMODULATION DOMAIN FEATURES FOR DISCRIMINATING INFRARED TARGETS AND BACKGROUNDS Chuong T Nguyen USA ABSTRACT For the first time, we compute modulation domain features for infrared targets

Havlicek, Joebob

362

Objective lens  

NASA Technical Reports Server (NTRS)

An objective lens and a method for using same. The objective lens has a first end, a second end, and a plurality of optical elements. The optical elements are positioned between the first end and the second end and are at least substantially symmetric about a plane centered between the first end and the second end.

Olczak, Eugene G. (Inventor)

2011-01-01

363

Infrared cosmology from space  

NASA Technical Reports Server (NTRS)

The potential scientific impact of the Space Infrared Telescope Facility (SIRTF) on studies of high-redshift phenomena and the evolution of the universe is discussed. Several observational programs are described: (1) studies of very high redshift objects and their absorption spectra, and what they reveal about pregalactic gas and galaxy formation; (2) a large high-redshift galaxy survey for studying the evolution of galaxy clustering at z about 1 to 2; (3) generating a statistically complete catalog of several hundred gravitational lens systems; and (4) studies of the spectrum and anisotropy of the far-infrared background and what it reveals about the nature and distribution of pregalactic stars, gas, and dust.

Hogan, Craig J.

1988-01-01

364

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

NASA Astrophysics Data System (ADS)

We present near-infrared (NIR) and optical observations of the afterglow of GRB 030115. Discovered in an infrared search at Kitt Peak 5 hr after the burst trigger, this afterglow is the faintest ever observed in the R band at such an early epoch and exhibits very red colors, with R-K~6. The optical magnitude of the afterglow of GRB 030115 is fainter than many upper limits for other bursts, suggesting that without early NIR observations it would have been classified as a ``dark'' burst. Both the color and optical magnitude of the afterglow are likely due to dust extinction at moderate redshift z>2 and indicate that at least some optical afterglows are very faint due to dust along the line of sight. Multicolor Hubble Space Telescope observations were also taken of the host galaxy and the surrounding field. Photometric redshifts imply that the host and a substantial number of faint galaxies in the field are at z~2.5. The overdensity of galaxies is sufficiently great that GRB 030115 may have occurred in a rich high-redshift cluster. The host galaxy shows extremely red colors (R-K=5) and is the first GRB host to be classified as an extremely red object (ERO). Some of the galaxies surrounding the host also show very red colors, while the majority of the cluster are much bluer, indicating ongoing unobscured star formation. As it is thought that much of high-redshift star formation occurs in highly obscured environments, it may well be that GRB 030115 represents a transition object, between the relatively unobscured afterglows seen to date and a population of objects that are very heavily extinguished, even in the NIR. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 9074 and 9405. Also based in part on observations obtained at Kitt Peak National Observatory under program 03A-0470 at the European Southern Observatory (ESO) under program 70.D-0701 at the WHT, 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; and at NOT/Asaigo.

Levan, Andrew; Fruchter, Andrew; Rhoads, James; Mobasher, Bahram; Tanvir, Nial; Gorosabel, Javier; Rol, Evert; Kouveliotou, Chryssa; Dell'Antonio, Ian; Merrill, Michael; Bergeron, Eddie; Castro Cerón, José María; 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

2006-08-01

365

Adaptive Optics Photometry and Astrometry of Binary Stars. III. a Faint Companion Search of O-Star Systems  

NASA Astrophysics Data System (ADS)

We present the results of an adaptive optics survey for faint companions among Galactic O-type star systems (with V lsim 8) using the Advanced Electro-Optical System (AEOS) 3.6 m telescope on Haleakala. We surveyed these O-star systems in the I-band, typically being able to detect a companion with a magnitude difference of utrimI lsim 6 in the projected separation range 0farcs5 < ? < 1farcs0, and utrimI lsim 9.5 in the range 1farcs0 < ? < 5farcs0. In the course of the survey, we discovered 40 new companions among 31 of the 116 objects examined and made astrometric and differential magnitude measurements of 24 additional known pairs, several of them being confirmation detections. We present new astrometric orbits for two binaries, BU 1032AB (WDS 05387-0236 ? Ori AB) and SEE 322 (WDS 17158-3344 HD 155889AB). We lack magnitude differences for other filter bands, so it is difficult to determine physical from line-of-sight companions, but we present empirical arguments for the limiting magnitude difference where field contamination is significant. Based on observations made at the Maui Space Surveillance System operated by Detachment 15 of the US Air Force Research Laboratory's Directed Energy Directorate.

Turner, Nils H.; ten Brummelaar, Theo A.; Roberts, Lewis C.; Mason, Brian D.; Hartkopf, William I.; Gies, Douglas R.

2008-08-01

366

Adaptive optics point spread function reconstruction project at W. M. Keck Observatory: first results with faint natural guide stars  

NASA Astrophysics Data System (ADS)

We discuss in this paper the last results of our adaptive optics point spread function reconstruction (PSF-R) project at theW. M. Keck Observatory. Objective of the project are recalled, followed by a short reintroduction of the basis of the method. Amongst the novelties, a method for a drastic reduction of the number of the so-called Ui,j functions for any pupil shape and an arbitrary number of actuators is presented, making the current PSF-R technique easily applicable to extremely large telescopes AO systems. Our success at reconstructing the PSF in bright natural guide star (NGS) conditions is revisited in details and confirmed. First results on PSF-R with faint NGS are presented and it is shown that our reconstructed PSF Strehl ratio drops with the NGS magnitude basically like the measured sky performance. These preliminary but encouraging results, in real conditions, can be considered as a validation of our PSF-R approach. Plans for the next steps of the project are discussed at the end of this progress report.

Jolissaint, Laurent; Neyman, Chris; Christou, Julian; Wizinowich, Peter

2012-07-01

367

Far infrared supplement: Catalog of infrared observations  

NASA Technical Reports Server (NTRS)

The Far Infrared Supplement: catalog of infrared observations summarizes all infrared astronomical observations at far infrared wavelengths published in the scientific literature between 1965 and 1982. The Supplement list contains 25% of the observations in the full catalog of infrared observations (C10), and essentially eliminates most visible stars from the listings. The Supplement is more compact than the main Catalog (it does not contain the bibliography and position index of the C10), and is intended for easy reference during astronomical observations.

Gezari, D. Y.; Schmitz, M.; Mead, J. M.

1984-01-01

368

Syncope (Fainting)  

MedlinePLUS

... physician, including blood pressure and heart rate measured lying and standing, is generally the only evaluation required. ... pressure and heart rate will be measured while lying down on a board and after the board ...

369

In infrared search for very low mass stars: The luminosity function  

Microsoft Academic Search

Infrared photometry can reveal cool companions to hot sub-main-sequence stars to very faint limtis of luminosity. We have surveyed approx.100 white dwarfs at 2.2 ..mu..m for very low mass red dwarf companions in a search complete to M\\/sub v\\/approx.21. Very few new companions were found, none with M\\/sub v\\/>15. This does not appear due to either selection effects or evolutionary

R. G. Probst

1983-01-01

370

Swallowed Object  

MedlinePLUS

... coins, safety pins, buttons, bones, wood, glass, magnets, batteries or other foreign objects. Problems may arise when ... are sharp, or contain corrosive materials (such as batteries). 187008 InteliHealth 2011-12-12 t InteliHealth Medical ...

371

Vague objects  

E-print Network

Peter Unger's puzzle, the problem of the many, is an argument for the conclusion that we are grossly mistaken about what kinds of objects are in our immediate surroundings. But it is not clear what we should make of Unger's ...

Ólafur Páll Jónsson

2001-01-01

372

Trusted Objects  

SciTech Connect

In the world of computers a trusted object is a collection of possibly-sensitive data and programs that can be allowed to reside and execute on a computer, even on an adversary's machine. Beyond the scope of one computer we believe that network-based agents in high-consequence and highly reliable applications will depend on this approach, and that the basis for such objects is what we call ''faithful execution.''

CAMPBELL,PHILIP L.; PIERSON,LYNDON G.; WITZKE,EDWARD L.

1999-10-27

373

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

374

High spatial resolution mid-infrared observations of the low-mass young star TW Hya  

E-print Network

We want to improve knowledge of the structure of the inner few AU of the circumstellar disk around the nearby T Tauri star TW Hya. Earlier studies have suggested the existence of a large inner hole, possibly caused by interactions with a growing protoplanet. We used interferometric observations in the N-band obtained with the MIDI instrument on the Very Large Telescope Interferometer, together with 10 micron spectra recorded by the infrared satellite Spitzer. The fact that we were able to determine N-band correlated fluxes and visibilities for this comparatively faint source shows that MIR interferometry can be applied to a large number of low-mass young stellar objects. The MIR spectra obtained with Spitzer reveal emission lines from HI (6-5), HI (7-6), and [Ne II] and show that over 90% of the dust we see in this wavelength regime is amorphous. According to the correlated flux measured with MIDI, most of the crystalline material is in the inner, unresolved part of the disk, about 1 AU in radius. The visibil...

Ratzka, T; Henning, T; Bouwman, J; Dullemond, C P; Jaffe, W

2007-01-01

375

Infrared Variation of Blazars  

E-print Network

In this paper, the historical infrared (JHK) data compiled from the published literature are presented here for 30 blazars. Maximum near-IR variations are found and compared with the optical ones. For the color-magnitude relation, some objects show that the color index increases with magnitude while 1253-055 shows complex behaviour, which perhaps suggests that the emission mechanism consists of, at least, two parts. The spectral indexes are in the range of $\\alpha_{IR}$ = 0.77 to 2.37.

J. H. Fan

1999-10-14

376

Gravitational Lensing of Distant Field Galaxies by Rich Clusters: I. -- Faint Galaxy Redshift Distributions  

E-print Network

{}From deep optical images of three clusters selected by virtue of their X-ray luminosity and/or optical richness (1455+22; $z=0.26$, 0016+16; $z=0.55$ and 1603+43; $z=0.89$), we construct statistically-complete samples of faint field galaxies ($I \\leq 25$) suitable for probing the effects of gravitational lensing. By selecting clusters across a wide redshift range we separate the effects of the mean redshift distribution of the faint field population well beyond spectroscopic limits and the distribution of dark matter in the lensing clusters. A significant lensing signature is seen in the two lower redshift clusters whose X-ray properties are well-constrained. Based on these and dynamical data, it is straightforward to rule out field redshift distributions for $I \\leq 25$ which have a significant low redshift excess compared to the no evolution prediction, such as would be expected if the number counts at faint limits were dominated by low-$z$ dwarf systems. The degree to which we can constrain any high redshift tail to the no evolution redshift distribution depends on the distribution of dark matter in the most distant lensing cluster. In the second paper in this series, we use the lensing signal to reconstruct the full two-dimensional mass distribution in the clusters and, together with high resolution X-ray images, demonstrate that their structural properties are well-understood. The principal result is therefore the absence of a dominant low-$z$ dwarf population to $I \\leq25$.

Ian Smail; Richard S. Ellis; Michael J. Fitchett

1994-02-21

377

Resolving the faint end of the satellite luminosity function for the nearest elliptical Centaurus A  

NASA Astrophysics Data System (ADS)

We request HST/ACS imaging to follow up 15 new faint candidate dwarfs around the nearest elliptical Centaurus A (3.8 Mpc). The dwarfs were found via a systematic ground-based (Magellan/Megacam) survey out to ~150 kpc, designed to directly confront the "missing satellites" problem in a wholly new environment. Current Cold Dark Matter models for structure formation fail to reproduce the shallow slope of the satellite luminosity function in spiral-dominated groups for which dwarfs fainter than M_V<-14 have been surveyed (the Local Group and the nearby, interacting M81 group). Clusters of galaxies show a better agreement with cosmological predictions, suggesting an environmental dependence of the (poorly-understood) physical processes acting on the evolution of low mass galaxies (e.g., reionization). However, the luminosity function completeness for these rich environments quickly drops due to the faintness of the satellites and to the difficult cluster membership determination. We target a yet unexplored "intermediate" environment, a nearby group dominated by an elliptical galaxy, ideal due to its proximity: accurate (10%) distance determinations for its members can be derived from resolved stellar populations. The proposed observations of the candidate dwarfs will confirm their nature, group membership, and constrain their luminosities, metallicities, and star formation histories. We will obtain the first complete census of dwarf satellites of an elliptical down to an unprecedented M_V<-9. Our results will crucially constrain cosmological predictions for the faint end of the satellite luminosity function to achieve a more complete picture of the galaxy formation process.

Crnojevic, Denija

2014-10-01

378

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

379

Faint Submillimeter Galaxies Revealed by Multifield Deep ALMA Observations: Number Counts, Spatial Clustering, and a Dark Submillimeter Line Emitter  

NASA Astrophysics Data System (ADS)

We present the statistics of faint submillimeter/millimeter galaxies (SMGs) and serendipitous detections of a submillimeter/millimeter line emitter (SLE) with no multi-wavelength continuum counterpart revealed by the deep ALMA observations. We identify faint SMGs with flux densities of 0.1-1.0 mJy in the deep Band-6 and Band-7 maps of 10 independent fields that reduce cosmic variance effects. The differential number counts at 1.2 mm are found to increase with decreasing flux density down to 0.1 mJy. Our number counts indicate that the faint (0.1-1.0 mJy, or SFRIR ~ 30-300 M ? yr–1) SMGs contribute nearly a half of the extragalactic background light (EBL), while the remaining half of the EBL is mostly contributed by very faint sources with flux densities of <0.1 mJy (SFRIR <~ 30 M ? yr–1). We conduct counts-in-cells analysis with multifield ALMA data for the faint SMGs, and obtain a coarse estimate of galaxy bias, b g < 4. The galaxy bias suggests that the dark halo masses of the faint SMGs are <~ 7 × 1012 M ?, which is smaller than those of bright (>1 mJy) SMGs, but consistent with abundant high-z star-forming populations, such as sBzKs, LBGs, and LAEs. Finally, we report the serendipitous detection of SLE-1, which has no continuum counterparts in our 1.2 mm-band or multi-wavelength images, including ultra deep HST/WFC3 and Spitzer data. The SLE has a significant line at 249.9 GHz with a signal-to-noise ratio of 7.1. If the SLE is not a spurious source made by the unknown systematic noise of ALMA, the strong upper limits of our multi-wavelength data suggest that the SLE would be a faint galaxy at z >~ 6.

Ono, Yoshiaki; Ouchi, Masami; Kurono, Yasutaka; Momose, Rieko

2014-11-01

380

Studying the diverse nature of faint galaxies in nearby clusters of the WINGS sample  

NASA Astrophysics Data System (ADS)

We present the first results of our X-shooter observations for a sample of dwarf (-17 faint early-type galaxies.

Bettoni, D.; Kjærgaard, P.; Milvang-Jensen, B.; D'Onofrio, M.; Moretti, A.; Poggianti, B. M.; Fasano, G.; Moles, M.

2011-03-01

381

Digital image profilers for detecting faint sources which have bright companions  

NASA Technical Reports Server (NTRS)

For this program, an image profiling system was developed which offers the potential for detecting extremely faint optical sources that are located in close proximity to bright companions. The approach employed is novel in three respects. First, it does not require an optical system wherein extraordinary measures must be taken to minimize diffraction and scatter. Second, it does not require detectors possessing either extreme uniformity in sensitivity or extreme temporal stability. Finally, the system can readily be calibrated, or nulled, in space by testing against an unresolved singular stellar source.

Morris, Elena; Flint, Graham; Slavey, Robert

1992-01-01

382

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

NASA Technical Reports Server (NTRS)

Atmospheric mixing ratios of approximately 10(-5 +/- 1) for ammonia on the early Earth would have been sufficient, through the resulting greenhouse warming, to counteract the temperature effects of the faint early sun. One argument against such model atmospheres has been the short time scale for ammonia photodissociation by solar ultraviolet light. Here it is shown that ultraviolet absorption by steady-state amounts of high-altitude organic solids produced from methane photolysis may have shielded ammonia sufficiently that ammonia resupply rates were able to maintain surface temperatures above freezing.

Sagan, C.; Chyba, C.

1997-01-01

383

The faint young sun problem. [in regulating surface temperature of early earth  

NASA Technical Reports Server (NTRS)

It is shown that the faint young sun problem was most likely solved by an increase in atmospheric CO2 concentration in the earth's atmosphere brought about by the CO2 geochemical cycle. Because the loss process for atmospheric CO2 requires liquid water, and because the earth is continually resupplying atmospheric CO2 by carbonate metamorphism, the surface temperature should never have fallen below the point at which the ocean would freeze. Indeed, the early earth may have been quite warm if carbonate metamorphism was faster and if the continents were originally smaller, so that silicate weathering was inhibited.

Kasting, James F.; Grinspoon, David H.

1991-01-01

384

Balloon-borne telescopes for far-infrared astronomy  

Microsoft Academic Search

Earlier and current efforts and developments in balloon-borne IR astronomy are surveyed. Astronomical objectives of balloon-borne IR research are discussed: sky surveys, high-resolution mapping, photometry and spectroscopy of faint sources, studies of the cosmic background flux\\/isotropy\\/spectra, mapping of diffuse low surface brightness, and solar system measurements. Attention is given to the behavior of atmospheric absorption by triatomic and diatomic molecules

W. F. Hoffmann

1977-01-01

385

Mean-shift tracking of moving objects using multidimensional histograms  

Microsoft Academic Search

In this paper, a moving object tracking algorithm for infrared image sequences is presented. The tracking algorithm is based on the mean-shift tracking method which is based on comparing the histograms of moving objects in consecutive image frames. In video obtained after visible light, the color histogram of the object is used for tracking. In forward looking infrared image sequences,

Halil I. Cuce; Ahmet E. Cetin

2004-01-01

386

Intimate objects  

Microsoft Academic Search

We present a preliminary and ongoing study into intimate objects: technological devices for maintaining intimacy at a distance. We use the notion of critical technical practice to provide a theoretical framework on which to base our designs, building devices that differ from mass communication devices in three ways: they are for couples in a relationship to communicate with each other,

Joseph'Jofish' Kaye; Liz Goulding

2004-01-01

387

Rapid infrared heating of a surface  

DOEpatents

High energy flux infrared heaters are used to treat an object having a surface section and a base section such that a desired characteristic of the surface section is physically, chemically, or phasically changed while the base section remains unchanged.

Sikka, Vinod K. (Oak Ridge, TN); Blue, Craig A. (Concord, TN); Ohriner, Evan Keith (Knoxville, TN)

2002-01-01

388

Rapid infrared heating of a surface  

DOEpatents

High energy flux infrared heaters are used to treat an object having a surface section and a base section such that a desired characteristic of the surface section is physically, chemically, or phasically changed while the base section remains unchanged.

Sikka, Vinod K. (Oak Ridge, TN); Blue, Craig A. (Concord, TN); Ohriner, Evan Keith (Knoxville, TN)

2001-01-01

389

The Very Faint End of the UV Luminosity Function over Cosmic Time: Constraints from the Local Group Fossil Record  

NASA Astrophysics Data System (ADS)

We present a new technique to estimate the evolution of the very faint end of the UV luminosity function (LF) out to z ~ 5. Measured star formation histories (SFHs) from the fossil record of Local Group (LG) galaxies are used to reconstruct the LF down to M UV ~-5 at z ~ 5 and M UV ~-1.5 at z < 1. Such faint limits are well beyond the current observational limits and are likely to remain beyond the limits of next-generation facilities. The reconstructed LFs, when combined with direct measurements of the LFs at higher luminosity, are well-fit by a standard Schechter function with no evidence of a break to the faintest limits probed by this technique. The derived faint-end slope, ?, steepens from ? - 1.2 at z < 1 to ? - 1.6 at 4 < z < 5. We test the effects of burstiness in the SFHs and find the recovered LFs to be only modestly affected. Incompleteness corrections for the faintest LG galaxies and the (unlikely) possibility of significant luminosity-dependent destruction of dwarf galaxies between high redshift and the present epoch are important uncertainties. These and other uncertainties can be mitigated with more detailed modeling and future observations. The reconstructed faint end LF from the fossil record can therefore be a powerful and complementary probe of the high-redshift faint galaxies believed to play a key role in the reionization of the universe.

Weisz, Daniel R.; Johnson, Benjamin D.; Conroy, Charlie

2014-10-01

390

THE DISCOVERY OF AN ULTRA-FAINT STAR CLUSTER IN THE CONSTELLATION OF URSA MINOR  

SciTech Connect

We report the discovery of a new ultra-faint globular cluster in the constellation of Ursa Minor, based on stellar photometry from the MegaCam imager at the Canada-France-Hawaii Telescope. We find that this cluster, Munoz 1, is located at a distance of 45 {+-} 5 kpc and at a projected distance of only 45' from the center of the Ursa Minor dwarf spheroidal galaxy. Using a maximum-likelihood technique we measure a half-light radius of 0.'5, or equivalently 7 pc, and an ellipticity consistent with being zero. We estimate its absolute magnitude to be M{sub V} -0.4 {+-} 0.9, which corresponds to L{sub V} = 120{sup +160}{sub -65} L{sub Sun} and we measure a heliocentric radial velocity of -137 {+-} 4 km s{sup -1} based on Keck/DEIMOS spectroscopy. This new satellite is separate from Ursa Minor by {approx}30 kpc and 110 km s{sup -1} suggesting the cluster is not obviously associated with the dSph, despite the very close angular separation. Based on its photometric properties and structural parameters we conclude that Munoz 1 is a new ultra-faint stellar cluster. Along with Segue 3 this is one of the faintest stellar clusters known to date.

Munoz, R. R.; Geha, M.; Vargas, L. C. [Astronomy Department, Yale University, New Haven, CT 06520 (United States); Cote, P.; Stetson, P. [Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria, BC V9E 2E7 (Canada); Santana, F. A. [Departamento de Astronomia, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago (Chile); Simon, J. D. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Djorgovski, S. G., E-mail: rmunoz@das.uchile.cl [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States)

2012-07-01

391

A Morphological and Multicolor Survey for Faint QSOs in the Groth-Westphal Strip  

E-print Network

Quasars representative of the populous faint end of the luminosity function are frustratingly dim with m~24 at intermediate redshift; moreover groundbased surveys for such faint QSOs suffer substantial morphological contamination by compact galaxies having similar colors. In order to establish a more reliable ultrafaint QSO sample, we used the APO 3.5-m telescope to take deep groundbased U-band CCD images in fields previously imaged in V,I with WFPC2/HST. Our approach hence combines multicolor photometry with the 0.1" spatial resolution of HST, to establish a morphological and multicolor survey for QSOs extending about 2 magnitudes fainter than most extant groundbased surveys. We present results for the "Groth-Westphal Strip", in which we identify 10 high likelihood UV-excess candidates having stellar or stellar-nucleus+galaxy morphology in WFPC2. For m(606)<24.0 (roughly B<24.5) the surface density of such QSO candidates is 420 (+180,-130) per square degree, or a surface density of 290 (+160,-110) per square degree with an additional V-I cut that may further exclude compact emission line galaxies. Even pending confirming spectroscopy, the observed surface density of QSO candidates is already low enough to yield interesting comparisons: our measures agree extremely well with the predictions of several recent luminosity function models.

Bernhard Beck-Winchatz; Scott F. Anderson

1999-01-15

392

Linking Burst-Only X-Ray Binary Sources to Faint X-Ray Transients  

NASA Astrophysics Data System (ADS)

Burst-only sources are X-ray sources discovered thanks to their bursting activity with no associated emission (at least with the monitoring instrument that led to their discovery). This bursting activity consists in one single short (tens of seconds to minutes) burst of X-ray emission, with spectral and timing properties consistent with thermonuclear (type I) bursts usually occurring on the surface of a neutron star. This likely provides a tight link between burst-only sources and neutron star X-ray binary transients. We carried out a series of snapshot observations of the entire sample of burst-only sources with the Swift satellite. We found a few sources in outburst and detected faint candidates, likely representing their quiescent counterparts. To provide a more comprehensive view, we analyzed data for three quasi-persistent faint X-ray binary transients, another sub-class closely related to burst-only sources. We discuss burst-only sources and quasi-persistent sources in the framework of neutron star transients, providing clues on their nature.

Campana, S.

2009-07-01

393

Stellar Archaeology in the Galactic halo with Ultra-Faint Dwarfs: VII. Hercules  

E-print Network

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 6 fundamental-mode (ab-type) and 3 first overtone (c-type) RR Lyrae stars, and one Anomalous Cepheid. The average period of the ab-type RR Lyrae stars, = 0.68 d (sigma = 0.03 d), 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)o = 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...

Musella, Ilaria; 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

2012-01-01

394

Gamma-Ray Bright BL Lac Object RX J1211+2242.  

National Technical Information Service (NTIS)

RX J1211+2242 is an optically faint (B approximately equal to 19.2mag) but X-ray bright (f2-10kev = 5 x l0(exp -12)erg per square centimeter per second) AGN, which has been shown to be a BL Lac object at redshift z = 0.455. The ROSAT X-ray, Calar Alto opt...

V. Beckmann, P. Favre, F. Tavecchio, T. Bussien, J. Fliri, A. Wolter

2004-01-01

395

Object Oriented Classes, Objects, Inheritance,  

E-print Network

simplifyPoly() {} public polynomial subPoly(polynomial px) {} } #12;Properties of an Object · The big 3, but does not guarantee, information hiding. ­ i.e. In Java you can have encapsulated data (Ruby, C++, Java) · Private variables are only visible from within the same class as they are created

Carette, Jacques

396

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

397

Ultraviolet polarimetry and spectroscopy of the BL Lacertae object PKS 2155-304  

NASA Technical Reports Server (NTRS)

HST and Faint Object Spectrograph spectropolarimetry is presented for the BL Lac object PKS 2155-304; attention is given to the wavelength dependence of the UV linear polarization in a BL Lac object. The UV polarimetry yields evidence that the UV polarized flux is generated by the synchrotron mechanism responsible for optical polarization. Both the UV and optical emission are produced in the same region of the source.

Allen, Richard G.; Smith, Paul S.; Angel, J. R. P.; Miller, Bryan W.; Anderson, Scott F.; Margon, Bruce

1993-01-01

398

RESEARCH Open Access Human tracking with an infrared camera using  

E-print Network

are repeated in the target trajectory. Keywords: object tracking, far-infrared imaging, human target, curveRESEARCH Open Access Human tracking with an infrared camera using curve matching framework Suk Jin includes a human-tracking mobile robot used in an indoor environment, fitted with an infrared camera

Motai, Yuichi

399

A far-infrared view of the Lockman hole from ISO 95-?m observations - II. Optical identifications and insights into the nature of the far-infrared sources  

NASA Astrophysics Data System (ADS)

We present the optical identifications of a 95-?m ISOPHOT sample in the Lockman hole over an area of approximately half a deg2. The Rodighiero et al. catalogue includes 36 sources, making up a complete flux-limited sample for S95?m>= 100 mJy. Reliable sources were detected, with decreasing but well-controlled completeness, down to S95?m~= 20 mJy. We have combined mid-infrared (IR) and radio catalogues in this area to identify the potential optical counterparts of the far-IR sources. We found 14 radio and 13 15-?m associations, 10 of which have both associations. For the 11 sources with spectroscopic redshift, we have performed a spectrophotometric analysis of the observed spectral energy distributions (SEDs). Four of these 95-?m sources have been classified as faint IR (FIR) galaxies (LFIR < 1.e11 Lsolar), six as luminous IR galaxies (LIRGs) and only one as an ultraluminous IR galaxy (ULIRG). We have discussed the redshift distribution of these objects, comparing our results with evolutionary model predictions 95 and 175 ?m. Given their moderate distances (the bulk of the closest spectroscopically identified objects lying at z < 0.2), their luminosities and star formation rates (SFR; median value ~ 10 Msolar yr-1), the sources unveiled by ISOPHOT at 95 ?m seem to correspond to the low redshift (z < 0.3) FIRBACK 175-?m population, composed of dusty, star-forming galaxies with moderate SFRs. We computed and compared different SFR estimators, and found that the SF derived from the bolometric IR luminosity is well correlated with that computed from the radio and mid-IR fluxes.

Rodighiero, G.; Fadda, D.; Franceschini, A.; Lari, C.

2005-02-01

400

The Cassini mission: Infrared and microwave spectroscopic measurements  

NASA Technical Reports Server (NTRS)

The Cassini Orbiter and Titan Probe model payloads include a number of infrared and microwave instruments. This document describes: (1) the fundamental scientific objectives for Saturn and Titan which can be addressed by infrared and microwave instrumentation, (2) the instrument requirements and the accompanying instruments, and (3) the synergism resulting from the comprehensive coverage of the total infrared and microwave spectrum by the complement of individual instruments. The baseline consists of four instruments on the orbiter and two on the Titan probe. The orbiter infrared instruments are: (1) a microwave spectrometer and radiometer; (2) a far to mid-infrared spectrometer; (3) a pressure modulation gas correlation spectrometer, and (4) a near-infrared grating spectrometer. The two Titan probe infrared instruments are: (1) a near-infrared instrument, and (2) a tunable diode laser infrared absorption spectrometer and nephelometer.

Kunde, V. G.

1989-01-01