Showing papers by "Michael W. Werner published in 2004"
TL;DR: 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 as mentioned in this paper.
Abstract: 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 the on-orbit scientific, technical, and operational performance of Spitzer. Subsequent papers in this special issue describe the Spitzer instruments in detail and highlight many of the exciting scientific results obtained during the first 6 months of the Spitzer mission.
3,177 citations
TL;DR: The Multiband Imaging Photometer for Spitzer (MIPS) as discussed by the authors provides long-wavelength capability for the mission in imaging bands at 24, 70, and 160?m and measurements of spectral energy distributions between 52 and 100?m at a spectral resolution of about 7%.
Abstract: The Multiband Imaging Photometer for Spitzer (MIPS) provides long-wavelength capability for the mission in imaging bands at 24, 70, and 160 ?m and measurements of spectral energy distributions between 52 and 100 ?m at a spectral resolution of about 7%. By using true detector arrays in each band, it provides both critical sampling of the Spitzer point-spread function and relatively large imaging fields of view, allowing for substantial advances in sensitivity, angular resolution, and efficiency of areal coverage compared with previous space far-infrared capabilities. The 24 ?m array has excellent photometric properties, and measurements with rms relative errors of about 1% can be obtained. The two longer-wavelength arrays use detectors with poor photometric stability, but a system of onboard stimulators used for relative calibration, combined with a unique data pipeline, produce good photometry with rms relative errors of less than 10%.
2,370 citations
TL;DR: In this article, an overview of the survey design, reduction, calibration, star-galaxy separation, and initial results is provided, as well as initial results of the NOAO Deep Wide-Field Survey in Bootes with three or more 30 s exposures per position.
Abstract: The Infrared Array Camera (IRAC) shallow survey covers 8.5 deg2 in the NOAO Deep Wide-Field Survey in Bootes with three or more 30 s exposures per position. An overview of the survey design, reduction, calibration, star-galaxy separation, and initial results is provided. The survey includes ≈370,000, 280,000, 38,000, and 34,000 sources brighter than the 5 σ limits of 6.4, 8.8, 51, and 50 μJy at 3.6, 4.5, 5.8, and 8 μm, respectively, including some with unusual spectral energy distributions.
244 citations
TL;DR: 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 as discussed by the authors.
Abstract: 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 the on-orbit scientific, technical and operational performance of Spitzer. Subsequent papers in this special issue describe the Spitzer instruments in detail and highlight many of the exciting scientific results obtained during the first six months of the Spitzer mission.
174 citations
TL;DR: In this paper, the authors presented Spitzer Space Telescope early release observations of Fomalhaut, a nearby A-type star with dusty circumstellar debris, spatially resolved at 24, 70, and 160 m using the Multiband Imaging Photometer for Spitzer (MIPS).
Abstract: We present Spitzer Space Telescope early release observations of Fomalhaut, a nearby A-type star with dusty circumstellar debris. The disk is spatially resolved at 24, 70, and 160 � m using the Multiband Imaging Photometer for Spitzer (MIPS). While the disk orientation and outer radius are comparable to values measured in the submillimeter, the disk inner radius cannot be precisely defined: the central hole in the submillimeter ring is at least partially filled with emission from warm dust, seen inSpitzerInfrared Spectrograph (IRS) 17.5‐34 � m spectra and MIPS 24 � m images. The disk surface brightness becomes increasingly asymmetric toward shorter wavelengths, with the south-southeast ansa always brighter than the north-northwest one. This asymmetry may reflect perturbations on the disk by an unseen interior planet. Subject headingg circumstellar matter — infrared: stars — planetary systems — stars: individual (Fomalhaut)
164 citations
TL;DR: This paper observed the reflection nebula NGC 7023 with the Short-High module and the long-slit Short-Low and Long-Low modules of the Infrared Spectrograph on the Spitzer Space Telescope.
Abstract: We observed the reflection nebula NGC 7023, with the Short-High module and the long-slit Short-Low and Long-Low modules of the Infrared Spectrograph on the Spitzer Space Telescope. We also present Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS) images of NGC 7023 at 3.6, 4.5, 8.0, and 24 m. We observe the aromatic emission features (AEFs) at 6.2, 7.7, 8.6, 11.3, and 12.7 m, plus a wealth of weaker features. We find new unidentified interstellar emission features at 6.7, 10.1, 15.8, 17.4, and 19.0 m. Possible identifications include aromatic hydrocarbons or nanoparticles of unknown mineralogy. We see variations in relative feature strengths, central wavelengths, and feature widths, in the AEFs and weaker emission features, depending on both distance from the star and nebular position (southeast vs. northwest).
156 citations
TL;DR: In this article, the authors obtained thermal images and spectra of 29P/Schwassmann-Wachmann 1 in late 2003 November and revealed an extensive coma with an estimated dust production rate of 50 kg s-1.
Abstract: We obtained thermal images and spectra of comet and Centaur object 29P/Schwassmann-Wachmann 1 in late 2003 November. Images at 8, 24, and 70 ?m reveal an extensive coma. At 24 ?m the coma extends at least 8' from the nucleus and exhibits a single jet. The dust production rate is estimated as 50 kg s-1. The 24 to 70 ?m color temperature of the coma is 160 K. The debris trail is also detected at 24 ?m and has an optical depth of ~(7 ? 3) ? 10-9. Thermal models fitted to photometry at 8, 24, and 70??m indicate a nuclear radius of 27 ? 5 km, larger than all previous size estimates, and a geometric albedo of 0.025 ? 0.01, lower than any other Centaur object, but consistent with other comets. Analysis of the jet morphology indicates a rotation period in excess of 60 days. The spectra reveal features at 11.3 and 34 ?m, which are tentatively identified as emission from olivine, including forsterite. This is the first identification of the minerology of the dust emitted by a Centaur object.
103 citations
TL;DR: In this article, the authors presented new images of the supernova remnant (SNR) Cas A observed in the 24 and 70 μm bands of the Spitzer Space Telescope (Spitzer).
Abstract: We present new images of the supernova remnant (SNR) Cas A observed in the 24 and 70 μm bands of the Spitzer Space Telescope (Spitzer). The IR emission correlates well with the Si X-ray and optical [S II] emission but poorly with either the synchrotron-dominated radio structure or the continuum X-ray emission. The IR is therefore dominated by thermal emission from dust within the SNR and associated with emission-line gas inside the reverse shock region, confirming earlier IRAS and Infrared Space Observatory results. Supplemented by new photometric measurements from archived Midcourse Space Experiment images, we suggest stochastic heating to model the overall mid- to far-IR spectral energy distribution. The 24 and 70 μm images also reveal a counterjet to the well-known northeast jet feature imaged previously at X-ray, optical, and radio wavelengths. This IR counterjet corresponds well with (optical) fast-moving knots confirming its outflow nature. The opposing jetlike features define a symmetry axis that bisects the SNR and suggest that the supernova explosion was axisymmetric. The IR images also show a region in which the SNR forward shock appears to be propagating into a ~650 M⊙ molecular cloud. The new images also show other details of the surrounding ISM structure, including two groups of knots extending ~6'-12' on either side of the SNR.
95 citations
TL;DR: In this paper, Chandra observations were taken with the ACIS-I camera with an exposure time of 48.1 ks, and the authors presented a catalog of 263 sources, including X-ray luminosity, optical and infrared photometry, and Xray variability information, with most of these objects being pre-main-sequence stars with ages younger than 3 Myr.
Abstract: We present results of a Chandra observation of a field in NGC 2264. The observations were taken with the ACIS-I camera with an exposure time of 48.1 ks. We present a catalog of 263 sources, which includes X-ray luminosity, optical and infrared photometry, and X-ray variability information. We found 41 variable sources, 14 of which have a flarelike light curve, and two of which have a pattern of a steady increase or decrease over a 10 hr period. The optical and infrared photometry for the stars identified as X-ray sources are consistent with most of these objects being pre–main-sequence stars with ages younger than 3 Myr.
62 citations
TL;DR: In this article, the authors present results of a Chandra observation of a field in NGC 2264 with an exposure time of 48.1 ks and a catalog of 263 sources, which includes X-ray luminosity, optical and infrared photometry and Xray variability information, with most of these objects being pre-main sequence stars with ages younger than 3 Myr.
Abstract: We present results of a Chandra observation of a field in NGC 2264. The observations were taken with the ACIS-I camera with an exposure time of 48.1 ks. We present a catalog of 263 sources, which includes X-ray luminosity, optical and infrared photometry and X-ray variability information. We found 41 variable sources, 14 of which have a flare-like light curve, and 2 of which have a pattern of a steady increase or decrease over a 10 hour period. The optical and infrared photometry for the stars identified as X-ray sources are consistent with most of these objects being pre-main sequence stars with ages younger than 3 Myr.
51 citations
TL;DR: In this paper, small-aperature photometry and new high-resolution images at 10 mu (N band) for 87 Seyfert galaxies from the Extended 12 mu Sample drawn from the IRASX database were presented.
Abstract: We present small-aperature(15) photometry and new high-resolution images at 10 mu (N band) for 87 Seyfert galaxies from the Extended 12 mu Sample drawn from the IRASX database.
TL;DR: In this article, optical/infrared spectral energy distributions (SEDs) for 45 X-ray/24 mum sources in the Lockman Hole (LH) and the extended Groth strip (EGS) detected at 24 mum using the Multiband Imaging Photometer (MIPS) and also with the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope.
Abstract: We investigate the luminous X-ray sources in the Lockman Hole (LH) and the extended Groth strip (EGS) detected at 24 mum using the Multiband Imaging Photometer (MIPS) and also with the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope. We assemble optical/infrared spectral energy distributions (SEDs) for 45 X-ray/24 mum sources in the EGS and LH. Only about one-quarter of the hard X-ray/24 mum sources show pure type 1 active galactic nucleus (AGN) SEDs. More than half of the X-ray/24 mum sources have stellar emission-dominated or obscured SEDs, similar to those of local type 2 AGN and spiral/starburst galaxies. One-third of the sources detected in hard X-rays do not have a 24 mum counterpart. Two such sources in the LH have SEDs resembling those of S0/elliptical galaxies. The broad variety of SEDs in the optical-to-Spitzer bands of X-ray-selected AGNs means that AGNs selected according to the behavior in the optical/infrared will have to be supplemented by other kinds of data (e.g., X-ray) to produce unbiased samples of AGNs.
TL;DR: In this paper, the authors used infrared images and optical images of Henize 206 to explore the complex structure of the Large Magellanic Cloud (LMC) and showed that the radiation from young stars has excited strong polycyclic aromatic hydrocarbon (PAH) emission throughout Henize206.
Abstract: Henize 206 is a region of star formation in the Large Magellanic Cloud of the approximate scale of the Orion belt and sword. Our Spitzer Space Telescope infrared images and Cerro Tololo Inter-American Observatory (CTIO) optical images show that the region is experiencing very energetic star formation. The radiation from young stars has excited strong polycyclic aromatic hydrocarbon (PAH) emission throughout Henize 206, except on the side of the nebula with the prominent young supernova remnant. As is also seen in early Spitzer observations of M81, star formation rates calculated from Hα for Henize 206 may miss the deeply embedded young stars, compared with star formation rates calculated from far infrared emission. For one of the highest surface brightness regions of Henize 206, we obtained snapshot exposures with the Thermal-Region Camera Spectrograph on Gemini South to explore the complex structure. A few percent of the total flux from this brightest region in Henize 206 emanates from infrared peaks of subparsec scale.
TL;DR: The Space Infrared Telescope Facility (SIRTF) as mentioned in this paper is an observatory for infrared astronomy from space with an 85 cm aperture telescope operating at 5.5 K and a 2.5-5 years cryogenic lifetime.
TL;DR: In this article, the authors carried out photometry of the microlensing event MACHO-LMC-5 with Spitzer Infrared Array Camera (IRAC) 10 years after the magnification of the LMC source star was recorded.
Abstract: We have carried out photometry of the microlensing event MACHO-LMC-5 with Spitzer Infrared Array Camera (IRAC) 10 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 the Hubble Space Telescope (once with WFPC2 and twice with ACS/HRC). Since the separation between the source and lens at the epoch of the Spitzer observations was ~024, the two stars cannot be resolved in the Spitzer images. However, the IRAC photometry clearly establishes that the lens is an M5 dwarf star from its infrared excess, which in turn yields a mass of ~0.2 M⊙. This demonstrates the potential of Spitzer to detect the lenses in other gravitational microlensing events.
TL;DR: The Spitzer Space Telescope (SIRTF) was successfully launched on August 25, 2003, and has completed its initial in-orbit checkout and science validation and calibration period as discussed by the authors.
Abstract: The Spitzer Space Telescope (formally known as SIRTF) was successfully launched on August 25, 2003, and has completed its initial in-orbit checkout and science validation and calibration period. The measured performance of the observatory has met or exceeded all of its high-level requirements, it has entered normal operations, and is beginning to return high-quality science data. A superfluid-helium cooled 85 cm diameter telescope provides extremely low infrared backgrounds and feeds three science instruments covering wavelengths ranging from 3.2 to 180 microns. The telescope optical quality is excellent, providing diffraction-limited performance down to wavelengths below 6.5 microns. Based on the first helium mass and boil-off rate measurements, a cryogenic lifetime in excess of 5 years is expected. This presentation will provide a summary of the overall performance of the observatory, with an emphasis on those performance parameters that have the greatest impact on its ultimate science return.
01 Apr 2004
TL;DR: The Single Aperture Far Infrared Observatory (SAFIR) as discussed by the authors was proposed to study the birth and evolution of stars and planetary systems so young that they are invisible to optical and near-infrared telescopes such as NGST.
Abstract: The Single Aperture Far Infrared Observatory (SAFIR) will study the birth and evolution of stars and planetary systems so young that they are invisible to optical and near-infrared telescopes such as NGST Not only does the far-infrared radiation penetrate the obscuring dust clouds that surround these systems, but the protoplanetary disks also emit much of their radiation in the far infrared Furthermore, the dust reprocesses much of the optical emission from the newly forming stars into this wavelength band Similarly, the obscured central regions of galaxies, which harbor massive black holes and huge bursts of star formation, can be seen and analyzed in the far infrared SAFIR will have the sensitivity to see the first dusty galaxies in the universe For studies of both star-forming regions in our galaxy and dusty galaxies at high redshifts, SAFIR will be essential in tying together information that NGST will obtain on these systems at shorter wavelengths and that ALMA will obtain at longer wavelengths
TL;DR: The adaptive system design and evolution, implementation, and lessons learned from IOC/SV operations are described, showing how it was used in flight both to cover activity redesign and growth due to continually improving spacecraft and instrument knowledge, and to recover from anomalies.
Abstract: The Spitzer Space Telescope is an 85-cm telescope with three cryogenically cooled instruments. Following launch, the observatory was initialized and commissioned for science operations during the in-orbit checkout (IOC) and science verification (SV) phases, carried out over a total of 98.3 days. The execution of the IOC/SV mission plan progressively established Spitzer capabilities taking into consideration thermal, cryogenic, optical, pointing, communications, and operational designs and constraints. The plan was carried out with high efficiency, making effective use of cryogen-limited flight time. One key component to the success of the plan was the pre-launch allocation of schedule reserve in the timeline of IOC/SV activities, and how it was used in flight both to cover activity redesign and growth due to continually improving spacecraft and instrument knowledge, and to recover from anomalies. This paper describes the adaptive system design and evolution, implementation, and lessons learned from IOC/SV operations. It is hoped that this information will provide guidance to future missions with similar engineering challenges
TL;DR: An overview of the SIRTF mission, telescope, cryostat, instruments, spacecraft, orbit, operations and project management approach is given in this article, along with an introduction to the accompanying set of detailed papers about specific aspects of specific aspects.
Abstract: This paper provides an overview of the SIRTF mission, telescope, cryostat, instruments, spacecraft, orbit, operations and project management approach; and this paper serves as an introduction to the accompanying set of detailed papers about specific aspects of SIRTF.
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01 Jun 2004TL;DR: In this article, the authors 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.
Abstract: 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 turn yields a mass of $\sim0.2 M_{\odot}$. This demonstrates the potential of Spitzer to detect the lenses in other gravitational microlensing events.
TL;DR: In this article, high-dynamic-range images of circumstellar dust around HR 4796A were obtained with MIRLIN at the Keck II telescope at lambda = 7.9, 10.3, 12.5, 20.8, and 24.5 um with PSF FWHM's of 0.37" and 0.55", respectively, and confirmed the presence of an outer ring centered at 70 AU.
Abstract: We present high-dynamic-range images of circumstellar dust around HR 4796A that were obtained with MIRLIN at the Keck II telescope at lambda = 7.9, 10.3, 12.5 and 24.5 um. We also present a new continuum measurement at 350 um obtained at the Caltech Submillimeter Observatory. Emission is resolved in Keck images at 12.5 and 24.5 um with PSF FWHM's of 0.37" and 0.55", respectively, and confirms the presence of an outer ring centered at 70 AU. Unresolved excess infrared emission is also detected at the stellar position and must originate well within 13 AU of the star. A model of dust emission fit to flux densities at 12.5, 20.8, and 24.5 um indicates dust grains are located 4(+3/-2) AU from the star with effective size, 28+/-6 um, and an associated temperature of 260+/-40 K.
We simulate all extant data with a simple model of exozodiacal dust and an outer exo-Kuiper ring. A two-component outer ring is necessary to fit both Keck thermal infrared and HST scattered-light images. Bayesian parameter estimates yield a total cross-sectional area of 0.055 AU^2 for grains roughly 4 AU from the star and an outer-dust disk composed of a narrow large-grain ring embedded within a wider ring of smaller grains. The narrow ring is 14+/-1 AU wide with inner radius 66+/-1 AU and total cross-sectional area 245 AU^2. The outer ring is 80+/-15 AU wide with inner radius 45+/-5 AU and total cross-sectional area 90 AU^2. Dust grains in the narrow ring are about 10 times larger and have lower albedos than those in the wider ring. These properties are consistent with a picture in which radiation pressure dominates the dispersal of an exo-Kuiper belt.
01 Apr 2004
TL;DR: The contents include the following: 1. Submillimeter polarimetry. 2. Variation of Polarization With Wavelength. 3. SIRTF. 4. Extragalactic Science. 5. Galaxy Discovery Rates for Future Missions as mentioned in this paper.
Abstract: The contents include the following: 1. SIRTF. Long wavelength surveys planned for SIRTF. Galaxy Discovery Rates for Future Missions. Impact of SIRTF s Improved Resolution at 160um: Resolving the Background. 2. Polarimetry. Submillimeter Polarimetry - The State of Play. Magnetic Vectors Across the Orion Molecular Cloud Core. Neutral and Ionized Molecular Spectral Lines. Variation of Polarization With Wavelength. The Polarization Spectrum. Submillimeter Polarimetry - Looking Ahead. 3.Confusion. Confusion at 500, 600 micron. 4. Extragalactic Science. Do Massive Black Holes and Galaxy Bulges form Together? 5. Galactic Science. Can We See the First Generations of Stars and Metal Formation? The Birth of Planets and the Origins of Life. Spatial Resolution at 100 microns. Far-ir/Sub-mm Transitions of Linear Carbon Clusters. Predicted Spectra of Glycine.