Spitzer Space Telescope Observations of Low Mass X-ray Binaries
Stefanie Wachter
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6 pages, updated and expanded version of article to appear in Proceedings of "A Population Explosion: The Nature and Evolution of X-ray Binaries in Diverse Environments", 28 Oct - 2 Nov, St. Pete Beach, FL; eds. R.M. Bandyopadhyay, S. Wachter, D. Gelino, C.R. Gelino; AIP Conference Proceedings Series
We present preliminary results from our archival Spitzer Space Telescope program aimed at characterizing the mid-IR properties of compact objects, both isolated and in binary systems, i.e. white dwarfs, X-ray binaries, cataclysmic variables, and magnetars. Most of these sources are too faint at mid-IR wavelengths to be observable from the ground, so this study provides the very first comprehensive look at the mid-IR emission of these objects. Here we present our results for the low mass X-ray binaries. We considered all of the systems listed in the most recent catalog of Liu et al. (2007) that have known optical counterparts. The particular goals of our projects encompass: to establish the mid-IR spectral energy distribution, to search for the signatures of jets, circumbinary disks, low mass or planetary companions and debris disks, and to study the local environment of these sources.
A summary of JENAM 2008 Symposium 9 "Star Formation from Spitzer (Lyman) to Spitzer (Space Telescope) and Beyond", held in Vienna, 10-12 September 2008.
We present the results of Spitzer mid-infrared spectroscopic observations of two highly-obscured massive X-ray binaries: IGR J16318-4848 and GX301-2. Our observations reveal for the first time the extremely rich mid-infrared environments of this type of source, including multiple continuum emission components (a hot component with T > 700 K and a warm component with T ~ 180 K) with apparent silicate absorption features, numerous HI recombination lines, many forbidden ionic lines of low ionization potentials, and pure rotational H2 lines. This indicates that both sources have hot and warm circu…
The Spitzer Space Telescope, born as the Shuttle Infrared Telescope Facility (SIRTF) and later the Space Infrared Telescope Facility (still SIRTF), was under discussion and development within NASA and the scientific community for more than 30 years prior to its launch in 2003. This brief history chronicles a few of the highlights and the lowlights of those 30 years from the authors personal perspective. A much more comprehensive history of SIRTF/Spitzer has been written by George Rieke (2006).
This article provides a brief overview of the Spitzer Space Telescope and discusses its initial scientific results on galactic and solar system science.
We present an infrared adaptation of the Cluster Red-Sequence method. We modify the two filter technique of Gladders & Yee (2000) to identify clusters based on their R-[3.6] color. We apply the technique to the 4 degree^2 Spitzer First Look Survey and detect 123 clusters spanning the redshift range 0.09 < z < 1.4. Our results demonstrate that the Spitzer Space Telescope will play an important role in the discovery of large samples of high redshift galaxy clusters.
The Infrared Array Camera (IRAC) is one of three focal plane instruments on board the Spitzer Space Telescope. IRAC is a four-channel camera that obtains simultaneous broad-band images at 3.6, 4.5, 5.8, and 8.0 microns in two nearly adjacent fields of view. We summarize here the in-flight scientific, technical, and operational performance of IRAC.
We have carried out photometry of the microlensing event MACHO-LMC-5 with Spitzer's IRAC ten years after the magnification of the LMC source star was recorded. This event is unique in the annals of gravitational microlensing: the lensing star itself has been observed using HST (once with WFPC2 and twice with ACS/HRC). Since the separation between the source and lens at the epoch of the Spitzer observations was $\sim0.24''$, the two stars cannot be resolved in the Spitzer images. However, the IRAC photometry clearly establishes that the lens is a M5 dwarf star from its infrared excess, which in…
The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescope. The IRS comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38micron with spectral resolutions, R \~90 and 600, and it was optimized to take full advantage of the very low background in the space environment. The IRS is performing at or better than the pre-launch predictions. An autonomous target acquisition capability enables the IRS to locate the mid-infrared centroid of a source, providing the information so that the spacecraft can accurately offset that cen…
The Spitzer Space Telescope, NASA's Great Observatory for infrared astronomy, was launched 2003 August 25 and is returning excellent scientific data from its Earth-trailing solar orbit. Spitzer combines the intrinsic sensitivity achievable with a cryogenic telescope in space with the great imaging and spectroscopic power of modern detector arrays to provide the user community with huge gains in capability for exploration of the cosmos in the infrared. The observatory systems are largely performing as expected and the projected cryogenic lifetime is in excess of 5 years. This paper summarizes t…
Simultaneous multiwavelength studies of X-ray binaries have been remarkably successful and resulted in improved physical constraints, a new understanding of the dependence of mass accretion rate on X-ray state, as well as insights on the time-dependent relationship between disk structure and mass-transfer rate. I will give some examples of the tremendous gains we have obtained in our understanding of XRBs by using multiwavelength observations. I will end with an appeal that while Spitzer cryogens are still available a special effort be put forth to obtaining coordinated observations including …
We present several corrections for point source photometry to be applied to data from the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. These corrections are necessary because of characteristics of the IRAC arrays and optics and the way the instrument is calibrated in-flight. When these corrections are applied, it is possible to achieve a ~2% relative photometric accuracy for sources of adequate signal to noise in an IRAC image.
We explore the stellar population of M31 in a Spitzer Space Telescope survey utilizing IRAC and MIPS observations. Red supergiants are the brightest objects seen in the infrared; they are a prominent evolutionary phase. Due to their circumstellar envelopes, many of these radiate the bulk of their luminosity at IRAC wavelengths and do not stand out in the near infrared or optically. Going fainter, we see large numbers of luminous asymptotic giant branch (AGB) stars, many of which are known long period variables. Relative to M33, the AGB carbon star population of M31 appears sparse, but this nee…
We use archival Spitzer Space Telescope photometry of the old, super-solar metallicity massive open cluster NGC 6791 to look for evidence of enhanced mass loss, which has been postulated to explain the optical luminosity function and low white dwarf masses in this benchmark cluster. We find a conspicuous lack of evidence for prolificacy of circumstellar dust production that would have been expected to accompany such mass loss. We also construct the optical and infrared luminosity functions, and demonstrate that these fully agree with theoretical expectations. We thus conclude that there is no …
(Abridged) Among the various issues that remain open in the field of accretion onto black hole X-ray binaries (BHBs) is the way the gas accretes at very low Eddington ratios, in the so-called quiescent regime. While there is general agreement that the X-rays are produced by a population of high-energy electrons near to the BH, the controversy comes about in modeling the contribution from inflowing vs. outflowing particles, and their relative energy budget. Recent Spitzer observations of three quiescent BHBs have shown evidence for excess emission with respect to the tail of the companion star …
We present a new planetary nebula, first identified in images from the Australia Telescope Compact Array, although not recognized at that time. Recent observations with the Spitzer Space Telescope during the GLIMPSE Legacy program have rediscovered the object. The high-resolution radio and infrared images enable the identification of the central star or its wind, the recognition of the radio emission as thermal, and the probable presence of polycylic aromatic hydrocarbons in and around the source. These lead to the conclusion that G313.3+00.3 is a planetary nebula. This object is of particular…
We present infrared observations of the young, oxygen-rich supernova remnant 1E 0102.2-7219 (E0102) in the Small Magellanic Cloud, obtained with the Spitzer Space Telescope. The remnant is detected at 24 um but not at 8 or 70 um and has a filled morphology with two prominent filaments. We find evidence for the existence of up to 8x10^-4 Msolar of hot dust (T~120 K) associated with the remnant. Most of the hot dust is located in the central region of E0102 which appears significantly enhanced in infrared and radio continuum emission relative to the X--ray emission. Even if all of the hot dust w…
We present the first mid-infrared (5.5-14.5 micron) spectrum of a highly magnetic cataclysmic variable, EF Eridani, obtained with the Infrared Spectrograph on the Spitzer Space Telescope. The spectrum displays a relatively flat, featureless continuum. A spectral energy distribution model consisting of a 9500 K white dwarf, L5 secondary star, cyclotron emission corresponding to a B~13 MG white dwarf magnetic field, and an optically thin circumbinary dust disk is in reasonable agreement with the extant 2MASS, IRAC, and IRS observations of EF Eri. Cyclotron emission is ruled out as a dominant con…
The Infrared Array Camera (IRAC) is one of three focal plane instruments in the Spitzer Space Telescope. IRAC is a four-channel camera that obtains simultaneous broad-band images at 3.6, 4.5, 5.8, and 8.0 microns. Two nearly adjacent 5.2x5.2 arcmin fields of view in the focal plane are viewed by the four channels in pairs (3.6 and 5.8 microns; 4.5 and 8 microns). All four detector arrays in the camera are 256x256 pixels in size, with the two shorter wavelength channels using InSb and the two longer wavelength channels using Si:As IBC detectors. IRAC is a powerful survey instrument because of i…
(Abridged) We present R-band images covering more than 11 square degrees of sky obtained with the KPNO 4-m telescope in preparation for the Spitzer Space Telescope First Look Survey. The FLS was designed to characterize the mid-infrared sky at depths 2 orders of magnitude deeper than previous surveys. The extragalactic component is the first cosmological survey done with Spitzer. Two relatively large regions of the sky were observed: the main FLS extra galactic field (17h18m+59d30m) and ELAIS-N1 field (16h10m+54d30m). The overall quality of the images is high. The relative astrometric accuracy…
Infrared-Faint Radio Sources (IFRSs) are a class of source which are bright at radio frequencies, but do not appear in deep infrared images. We report the detection of 14 IFRSs within the Spitzer extragalactic First Look Survey field, eight of which are detected near to the limiting magnitude of a deep R-band image of the region, at R ~ 24.5. Sensitive Spitzer Space Telescope images are stacked in order to place upper limits on their mid-infrared flux densities, and using recent 610-MHz and 1.4-GHz observations we find that they have spectral indices which vary between alpha = 0.05 and 1.38, w…
Precision infrared photometry from Spitzer has enabled the first direct studies of light from extrasolar planets, via observations at secondary eclipse in transiting systems. Current Spitzer results include the first longitudinal temperature map of an extrasolar planet, and the first spectra of their atmospheres. Spitzer has also measured a temperature and precise radius for the first transiting Neptune-sized exoplanet, and is beginning to make precise transit timing measurements to infer the existence of unseen low mass planets. The lack of stellar limb darkening in the infrared facilitates p…
SMART is a software package written in IDL to reduce and analyze Spitzer data from all four modules of the Infrared Spectrograph, including the peak-up arrays. The software is designed to make full use of the ancillary files generated in the Spitzer Science Center pipeline so that it can either remove or flag artifacts and corrupted data and maximize the signal-to-noise in the extraction routines. It may be run in both interactive and batch mode. The software and Users Guide will be available for public release in December 2004. We briefly describe some of the main features of SMART including:…
We present observations of L1014, a dense core in the Cygnus region previously thought to be starless, but data from the Spitzer Space Telescope shows the presence of an embedded source. We propose a model for this source that includes a cold core, heated by the interstellar radiation field, and a low-luminosity internal source. The low luminosity of the internal source suggests a substellar object. If L1014 is representative, other "starless" cores may turn out to harbor central sources.
We review the available near- and mid-infrared photometry for white dwarfs obtained from the Two Micron All-Sky Survey (2MASS) and by the Spitzer Space Telescope. Both data sets have recently been used to seek white dwarfs with infrared excesses due to the presence of unresolved companions or circumstellar disks, and also to derive the atmospheric parameters of cool white dwarfs. We first attempt to evaluate the reliability of the 2MASS photometry by comparing it with an independent set of published JHK CIT magnitudes for 160 cool white dwarf stars, and also by comparing the data with the pred…
We present the first observations of magnetic cataclysmic variables with the Spitzer Space Telescope. We used the Infrared Array Camera to obtain photometry of the polars EF Eri, GG Leo, V347 Pav, and RX J0154.0-5947 at 3.6, 4.5, 5.8, and 8.0 $μ$m. In all of our targets, we detect excess mid-infrared emission over that expected from the component stars alone. We explore the origin of this IR excess by examining bremsstrahlung, cyclotron emission, circumbinary dust, and L/T brown dwarf secondary stars. Bremsstrahlung and cyclotron emission appear unlikely to be significant contributors to the o…
The unprecedented sensitivity of the Infrared Spectrograph on the Spitzer Space Telescope allows for the first time the measurement of mid-infrared spectra from 14 to 38 microns of faint high-z galaxies. This unique capability is demonstrated with observations of sources having 16 micron fluxes of 3.6 mJy (CFRS 14.1157) and 0.35 mJy (CFRS 14.9025). A spectral-fitting technique is illustrated which determines the redshift by fitting emission and absorption features characteristic of nearby galaxies to the spectrum of an unknown source. For CFRS 14.1157, the measured redshift is z = 1.00+/-0.20 …
We present Spitzer high-resolution spectra of off-nuclear regions in the central cluster galaxies NGC 1275 and NGC 4696 in the Perseus and Centaurus clusters, respectively. Both objects are surrounded by extensive optical emission-line filamentary nebulae, bright outer parts of which are the targets of our observations. The 10-37um spectra show strong pure rotational lines from molecular hydrogen revealing a molecular component to the filaments which has an excitation temperature of ~300-400K. The flux in the 0-0S(1) molecular hydrogen line correlates well with the strength of the optical line…
The First Look Survey (FLS) is the first scientific product to emerge from the Spitzer Space Telescope. A small region of this field (the verification strip) has been imaged very deeply, permitting the detection of cosmologically distant sources. We present Westerbork Synthesis Radio Telescope (WSRT) observations of this region, encompassing a ~1 sq. deg field, centred on the verification strip (J2000 RA=17:17:00.00, DEC=59:45:00.000). The radio images reach a noise level of ~ 8.5 microJy/beam - the deepest WSRT image made to date. We summarise here the first results from the project, and pres…
We identify 17 possible 8.0 micron-selected counterparts to the submillimeter galaxies in the CUDSS 14-hour field, derived from deep imaging carried out with the IRAC and MIPS instruments aboard the Spitzer Space Telescope. Ten of the 17 counterparts are not the same as those previously identified at shorter wavelengths. We argue that 8.0 micron selection offers a better means for identifying counterparts to submillimeter galaxies than near-infrared or optical selection. Based on the panchromatic SEDs, most counterparts appear to be powered by ongoing star formation. Power-law fits to the SEDs…
Detecting heat from minor planets in the outer solar system is challenging, yet it is the most efficient means for constraining the albedos and sizes of Kuiper Belt Objects (KBOs) and their progeny, the Centaur objects. These physical parameters are critical, e.g., for interpreting spectroscopic data, deriving densities from the masses of binary systems, and predicting occultation tracks. Here we summarize Spitzer Space Telescope observations of 47 KBOs and Centaurs at wavelengths near 24 and 70 microns. We interpret the measurements using a variation of the Standard Thermal Model (STM) to der…
We present new stellar population models that include the contribution of the Thermally Pulsing Asymptotic Giant Branch (TP-AGB) phase also in the synthetic spectral energy distribution (SED). The TP-AGB phase is essential for a correct modeling of intermediate-age (0.2 < t/Gyr < 1-2) stellar populations, because it provides ~40% of the bolometric contribution, and up to ~80% of that in the K-band. These models are obtained by coupling the energetic of the TP-AGB phase as calibrated with data of Magellanic Clouds star clusters (Maraston 1998), with empirical spectra of TP-AGB stars (Lancon & M…
The magnetic cataclysmic variable AE Aquarii hosts a rapidly rotating white dwarf which is thought to expel most of the material streaming onto it. Observations of AE Aqr have been obtained in the wavelength range of 5 - 70 microns with the IRS, IRAC, and MIPS instruments on board the Spitzer Space Telescope. The spectral energy distribution reveals a significant excess above the K4V spectrum of the donor star with the flux increasing with wavelength above 12.5 microns. Superposed on the energy distribution are several hydrogen emission lines, identified as Pf alpha and Hu alpha, beta, gamma. …
In an earlier study of the spiral galaxy M33, we photometrically identified arcs or outer spiral arms of intermediate age (0.6 Gyr - 2 Gyr) carbon stars precisely at the commencement of the HI-warp. Stars in the arcs were unresolved, but were likely thermally-pulsing asymptotic giant branch carbon stars. Here we present Keck I spectroscopy of seven intrinsically bright and red target stars in the outer, northern arc in M33. The target stars have estimated visual magnitudes as faint as V \sim 25 mag. Absorption bands of CN are seen in all seven spectra reported here, confirming their carbon sta…
I analyze several catalogs of known visual and spectroscopic binaries and conclude that a large number of binaries is missing in current catalogs. Samples of the best studied (nearby and bright) stars indicate that the true binary fraction may be as high as 95%. A preliminary analysis indicates that these binaries can a ect the astrometry signicantly.
We present sub-millimeter statistical detections of galaxies discovered in the 5'x5' Spitzer Early Release Observations (to 4-15 microJy 5 sigma at 3.6-8 microns, 170 microJy at 24 microns) through a stacking analysis of our reanalysed SCUBA 8mJy survey maps, and a Spitzer identification of a new sub-millimeter point source in the 8mJy survey region. For sources detected at 5.8 or 8 microns (154 and 111 sources respectively), we detect positive skews in the sub-millimeter flux distributions at 99.2-99.8% confidence using Kolmogorov-Smirnov tests, at both 850 microns and 450 microns. We also ma…
We present spectra taken with the Infrared Spectrograph on Spitzer covering the 5-38micron region of three Ultraluminous Infrared Galaxies (ULIRGs): Mrk 1014 (z=0.163), and Mrk 463 (z=0.051), and UGC 5101 (z=0.039). The continua of UGC 5101 and Mrk 463 show strong silicate absorption suggesting significant optical depths to the nuclei at 10microns. UGC 5101 also shows the clear presence of water ice in absorption. PAH emission features are seen in both Mrk 1014 and UGC 5101, including the 16.4micron line in UGC 5101. The fine structure lines are consistent with dominant AGN power sources in bo…
We present the ultraviolet-optical-infrared spectral energy distribution of the low inclination novalike cataclysmic variable V592 Cassiopeiae, including new mid-infrared observations from 3.5-24 microns obtained with the Spitzer Space Telescope. At wavelengths shortward of 8 microns, the spectral energy distribution of V592 Cas is dominated by the steady state accretion disk, but there is flux density in excess of the summed stellar components and accretion disk at longer wavelengths. Reproducing the observed spectral energy distribution from ultraviolet to mid-infrared wavelengths can be acc…
Spectra have been obtained with the low-resolution modules of the Infrared Spectrograph (IRS) on the Spitzer Space Telescope (Spitzer) for 58 sources having f$_ν$(24 micron) > 0.75 mJy. Sources were chosen from a survey of 8.2 deg$^{2}$ within the NOAO Deep Wide-Field Survey region in Bootes (NDWFS) using the Multiband Imaging Photometer (MIPS) on the Spitzer Space Telescope. Most sources are optically very faint (I > 24mag). Redshifts have previously been determined for 34 sources, based primarily on the presence of a deep 9.7 micron silicate absorption feature, with a median z of 2.2. Spectr…
Observations using the Spitzer Space Telescope provided the first detections of photons from extrasolar planets. Spitzer observations are allowing us to infer the temperature structure, composition, and dynamics of exoplanet atmospheres. The Spitzer studies extend from many hot Jupiters, to the hot Neptune orbiting GJ436. Here I review the current status of Spitzer secondary eclipse observations, and summarize the results from the viewpoint of what is robust, what needs more work, and what the observations are telling us about the physical nature of exoplanet atmospheres.
We compare the history of the galaxy mass build-up, as inferred from near-IR observations, and the Star Formation Rate of massive stars in the comoving volume traced by deep extensive far-IR surveys, both possible now with the Spitzer Space Telescope. These two independent and complementary approaches to the history of galaxy formation consistently indicate that a wide interval of cosmic epochs between z~0.7 to z~2 brackets the main evolutionary phases. The rate of the integrated galaxy mass growth indicated by the IR-based comoving SFR appears consistent with the observed decrease of the stel…
Sensitive 5-38 um Spitzer Space Telescope (SST) and ground based 3-5 um spectra of the embedded low mass protostars B5 IRS1 and HH46 IRS show deep ice absorption bands superposed on steeply rising mid-infrared continua. The ices likely originate in the circumstellar envelopes. The CO2 bending mode at 15 um is a particularly powerful tracer of the ice composition and processing history. Toward these protostars, this band shows little evidence for thermal processing at temperatures above 50 K. Signatures of lower temperature processing are present in the CO and OCN- bands, however. The observed …
The Spitzer Space Telescope (formerly SIRTF) extragalactic First-Look Survey covered about 5 square degrees centered on J2000 17:18 +59:30 in order to characterize the infrared sky with high sensitivity. We used the 100-m Green Bank Telescope to image the 21cm Galactic HI emission over a 3x3 degree field covering this position with an effective angular resolution of 9.8 arcmin and a velocity resolution of 0.62 km/s. In the central square degree of the image the average column density is N(HI) = 2.5 x 10^{20} cm-2 with an rms fluctuation of 0.3 x 10^{20}. The Galactic HI in this region has a ve…
We have surveyed a field covering 9.0 degrees^2 within the NOAO Deep Wide-Field Survey region in Bootes with the Multiband Imaging Photometer on the Spitzer Space Telescope (SST) to a limiting 24 um flux density of 0.3 mJy. Thirty one sources from this survey with F(24um) > 0.75 mJy which are optically very faint (R > 24.5 mag) have been observed with the low-resolution modules of the Infrared Spectrograph on SST. Redshifts derived primarily from strong silicate absorption features are reported here for 17 of these sources; 10 of these are optically invisible (R > 26 mag), with no counterpart …
We report on mid- and far-IR Spitzer observations of 7 nearby dusty elliptical galaxies by using the Multiband Imaging Photometer (MIPS) and Infrared Spectrograph (IRS). Our sample galaxies are known to contain an excessive amount of interstellar dust against sputtering destruction in hot plasma filling the interstellar space of elliptical galaxies. In order to study the origin and the properties of the excess dust in the hot plasma, we selected galaxies with a wide range of X-ray luminosities but similar optical luminos ities for our Spitzer Guest Observers (GO1) program. The 7 galaxies are d…
Full low resolution (65<R<130) and high resolution (R~600) spectra between 5 microns and 37 microns obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope are presented for eight classical active galactic nuclei (AGN) which have been extensively studied previously. Spectra of these AGN are presented as comparison standards for the many objects, including sources at high redshift, which are being observed spectroscopically in the mid-infrared for the first time using the IRS. The AGN are NGC4151, Markarian 3, I Zwicky 1, NGC 1275, Centaurus A, NGC 7469, Markarian 231, and …
The advent of the large effective apertures of the Keck telescopes has resulted in the determination with unprecedented accuracy of the mass functions and mass ratios of faint (R ~ 21 mag) X-ray transients (GS 2000+25, GRO J0422+32, Nova Oph 1977, Nova Vel 1993), as well as constraining the main-sequence companion star parameters and producing images of the accretion disks around the black holes.
Mid-infrared (23-35 micron) emission from the deeply embedded "Class 0" protostar IRAS16293-2422 is detected with the Spitzer Space Telescope infrared spectrograph. A detailed radiative transfer model reproducing the full spectral energy distribution (SED) from 23 micron to 1.3 mm requires a large inner cavity of radius 600 AU in the envelope to avoid quenching the emission from the central sources. This is consistent with a previous suggestion based on high angular resolution millimeter interferometric data. An alternative interpretation using a 2D model of the envelope with an outflow cavity…
The Infrared Array Camera (IRAC) on the Spitzer Space Telescope is absolutely calibrated by comparing photometry on a set of A stars near the north ecliptic pole to predictions based on ground-based observations and a stellar atmosphere model. The brightness of point sources is calibrated to an accuracy of 3%, relative to models for A star stellar atmospheres, for observations performed and analyzed in the same manner as the calibration stars. This includes corrections for location of the star in the array and the location if the centroid within the peak pixel. Long-term stability of the IRAC …
We have performed infrared imaging of the jet of the quasar 3C 273 at wavelengths 3.6 and 5.8 microns with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. When combined with the radio, optical and X-ray measurements, the IRAC photometry clearly shows that the optical emission is dominated by the high-energy component of the jet, not by the radio synchrotron component, as had been assumed to date. The high-energy component may be due to a second synchrotron component or to IC scattering of ambient photons. In the former case, we argue that the acceleration of protons exceeding …
We present the results of a search for new members of the Taurus star-forming region using the Infrared Array Camera (IRAC) aboard the Spitzer Space Telescope}. With IRAC images of 29.7 deg^2 of Taurus at 3.6, 4.5, 5.8, and 8.0 um, we have identified sources with red mid-infrared colors indicative of disk-bearing objects and have obtained optical and infrared spectra of 23 of these candidate members. Through this work, we have discovered 13 new members of Taurus, two of which have spectral types later than M6 and thus are likely to be brown dwarfs according to the theoretical evolutionary mode…
We present mid-infrared photometry of 124 white dwarf stars with Spitzer Space Telescope. Objects were observed simultaneously at 4.5 and 8.0um with sensitivities better than 1 mJy. This data can be used to test models of white dwarf atmospheres in a new wavelength regime, as well as to search for planetary companions and debris disks.
(abridged:) The Taurus Molecular Cloud (TMC) contains numerous prototypical examples of deeply embedded protostars with massive disks and outflows, classical and weak-lined T Tauri stars, jets and Herbig-Haro objects, and a growing number of confirmed brown dwarfs. Star formation is ongoing, and the cloud covers all stages of pre-main sequence stellar evolution. We have initiated comprehensive surveys of the TMC, in particular including: (i) a deep X-ray survey of about 5 sq. degrees with XMM-Newton; (ii) a near-to-mid-infrared photometric survey of ~30 sq. degrees with the Spitzer Space Teles…
The spectral energy distributions (SEDs) of dust-enshrouded galaxies with powerful restframe far-infrared emission have been constrained by a range of ground-based and space-borne surveys. The IRAS catalog provides a reasonably complete picture of the dust emission from nearby galaxies (at redshifts of order 0.1) that are typically less luminous than about 10 to the 12 solar luminosities. However, at higher redshifts, the observational coverage from all existing far-IR and submillimeter surveys is much less complete. Here we investigate the SEDs of a new sample of high-redshift submillimeter-s…
Data from the Spitzer Space Telescope (the First Look Survey - FLS) have recently been made public. We have compared the 24 micron images with very deep WSRT 1.4 GHz observations, centred on the FLS verification strip (FLSv). Approximately 75% of the radio sources have corresponding 24 micron identifications. Such a close correspondence is expected, especially at the fainter radio flux density levels, where star forming galaxies are thought to dominate both the radio and mid-IR source counts. However, a significant fraction of radio sources detected by WSRT (25%) have no mid-IR detection in th…
We present deep u*-, and g-band images taken with the MegaCam on the 3.6 m Canada-France-Hawaii Telescope (CFHT) to support the extragalactic component of the Spitzer First Look Survey (hereafter, FLS). In this paper we outline the observations, present source catalogs and characterize the completeness, reliability, astrometric accuracy and number counts of this dataset. In the central 1 deg2 region of the FLS, we reach depths of g~26.5 mag, and u*~26.2 mag (AB magnitude, 5$σ$ detection over a 3" aperture) with ~4 hours of exposure time for each filter. For the entire FLS region (~5 deg2 cover…
We present Spitzer Space Telescope photometry of six short-period polars, EF Eri, V347 Pav, VV Pup, V834 Cen, GG Leo, and MR Ser. We have combined the Spitzer Infrared Array Camera (3.6 -8.0 microns) data with the 2MASS J, H, K_s photometry to construct the spectral energy distributions of these systems from the near- to mid-IR (1.235 - 8 microns). We find that five out of the six polars have flux densities in the mid-IR that are substantially in excess of the values expected from the stellar components alone. We have modeled the observed SEDs with a combination of contributions from the white…
We present a Spitzer Space Telescope imaging survey of the most massive Galactic globular cluster, omega Centauri, and investigate stellar mass loss at low metallicity and the intracluster medium (ICM). The survey covers approximately 3.2x the cluster half-mass radius at 3.6, 4.5, 5.8, 8, and 24 microns, resulting in a catalog of over 40,000 point-sources in the cluster. Approximately 140 cluster members ranging 1.5 dex in metallicity show a red excess at 24 microns, indicative of circumstellar dust. If all of the dusty sources are experiencing mass loss, the cumulative rate of loss is estimat…
We present Infrared Array Camera (IRAC) data and source catalogs from the Spitzer Space Telescope Extragalactic First Look Survey. The data were taken in four broad bands centered at nominal wavelengths of 3.6, 4.5, 5.8 and 8.0 microns. A set of mosaics and catalogs have been produced which are ~80% complete and ~99% reliable to their chosen flux density limits. The main field survey covers 3.8 deg^2, and has flux density limits of 20muJy, 25muJy, 100muJy and 100muJy at wavelengths of 3.6, 4.5, 5.8 and 8.0 microns,respectively. The deeper ``verification'' survey covers 0.25 deg^2 with limits o…
We present limits on transit timing variations and secondary eclipse depth variations at 8 microns with the Spitzer Space Telescope IRAC camera. Due to the weak limb darkening in the infrared and uninterrupted observing, Spitzer provides the highest accuracy transit times for this bright system, in principle providing sensitivity to secondary planets of Mars mass in resonant orbits. Finally, the transit data provides tighter constraints on the wavelength- dependent atmospheric absorption by the planet.
We report the results of the mid-infrared spectroscopy of 14 Galactic star-forming regions with the high-resolution modules of the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. We detected [SiII] 35um, [FeII] 26um, and [FeIII] 23um as well as [SIII] 33um and H2 S(0) 28um emission lines. Using the intensity of [NII] 122um or 205um and [OI] 146um or 63um reported by previous observations in four regions, we derived the ionic abundance Si+/N+ and Fe+/N+ in the ionized gas and Si+/O0 and Fe+/O0 in the photodissociation gas. For all the targets, we derived the ionic abundance of…
