Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Spitzer”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Science with the James Webb Space Telescope

The James Webb Space Telescope is the scientific successor to the Hubble and Spitzer Space Telescopes. It will be a large (6.6m) cold (50K) telescope launched into orbit around the second Earth-Sun lagrange point. It is a partnership of NASA with the European and Canadian Space Agencies. The science goals for JWST include the formation of the first stars and galaxies in the early universe; the chemical, morphological and dynamical buildup of galaxies and the formation of stars and planetary systems. Recently, the goals have expanded to include studies of dark energy, dark matter, active galactic nuclei, exoplanets and Solar System objects. Webb will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Near-Infrared Imager and Slitiess Spectrograph will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. The observatory is confirmed for launch in 2018; the design is complete and it is in its construction phase. Recent progress includes the completion of the mirrors, the delivery of the first flight instrument(s) and the start of the integration and test phase.

Gardner, Jonathan P.↗
NASA NTRS2012

Constructing a WISE High Resolution Galaxy Atlas

After eight months of continuous observations, the Wide-field Infrared Survey Explorer (WISE) mapped the entire sky at 3.4 micron, 4.6 micron, 12 micron, and 22 micron. We have begun a dedicated WISE High Resolution Galaxy Atlas project to fully characterize large, nearby galaxies and produce a legacy image atlas and source catalog. Here we summarize the deconvolution techniques used to significantly improve the spatial resolution of WISE imaging, specifically designed to study the internal anatomy of nearby galaxies. As a case study, we present results for the galaxy NGC 1566, comparing the WISE enhanced-resolution image processing to that of Spitzer, Galaxy Evolution Explorer, and ground-based imaging. This is the first paper in a two-part series; results for a larger sample of nearby galaxies are presented in the second paper.

Jarrett, T. H.↗
NASA NTRS2012

Space Telescopes

Space telescopes have been a dominant force in astrophysics and astronomy over the last two decades. As Lyman Spitzer predicted in 1946, space telescopes have opened up much of the electromagnetic spectrum to astronomers, and provided the opportunity to exploit the optical performance of telescopes uncompromised by the turbulent atmosphere. This special section of Optical Engineering is devoted to space telescopes. It focuses on the design and implementation of major space observatories from the gamma-ray to far-infrared, and highlights the scientific and technical breakthroughs enabled by these telescopes. The papers accepted for publication include reviews of major space telescopes spanning the last two decades, in-depth discussions of the design considerations for visible and x-ray telescopes, and papers discussing concepts and technical challenges for future space telescopes.

Clampin, Mark↗
NASA NTRS2009

Infrared and X-Ray Spectroscopy of the KES 75 Supernova Remnant Shell: Characterizing the Dust and Gas Properties

We present deep Chandra observations and Spitzer Space Telescope infrared (IR) spectroscopy of the shell in the composite supernova remnant (SNR) Kes 75 (G29.7-0.3). The remnant is composed of a central pulsar wind nebula and a bright partial shell in the south that is visible at radio, IR, and X-ray wavelengths. The X-ray emission can be modeled by either a single thermal component with a temperature of ~ 1.5 keV, or with two thermal components with temperatures of 1.5 and 0.2 keV. Previous studies suggest that the hot component may originate from reverse-shocked SN ejecta. However, our new analysis shows no definitive evidence for enhanced abundances of Si, S, Ar, Mg, and Fe, as expected from supernova (SN) ejecta, or for the IR spectral signatures characteristic of confirmed SN condensed dust, thus favoring a circumstellar or interstellar origin for the X-ray and IR emission. The X-ray and ill emission in the shell are spatially correlated, suggesting that the dust particles are collisionally heated by the X-ray emitting gas. The IR spectrum of the shell is dominated by continuum emission from dust with little, or no line emission. Modeling the IR spectrum shows that the dust is heated to a temperature of ~ 140 K by a relatively dense, hot plasma, that also gives rise to the hot X-ray emission component. The density inferred from the IR emission is significantly higher than the density inferred from the X-ray models, suggesting a low filling factor for this X-ray emitting gas. The total mass of the warm dust component is at least 1.3 x 10(exp -2) solar mass, assuming no significant dust destruction has occurred in the shell. The IR data also reveal the presence of an additional plasma component with a cooler temperature, consistent with the 0.2 keV gas component. Our IR analysis therefore provides an independent verification of the cooler component of the X-ray emission. The complementary analyses of the X-ray and IR emission provide quantitative estimates of density and filling factors of the clumpy medium swept up by the SNR.

Temim, Tea↗
NASA NTRS2012

The Path to Far-IR Interferometry in Space: Recent Developments, Plans, and Prospects

The far-IR astrophysics community is eager to follow up Spitzer and Herschel observations with sensitive, highresolution imaging and spectroscopy, for such measurements are needed to understand merger-driven star formation and chemical enrichment in galaxies, star and planetary system formation, and the development and prevalence of waterbearing planets. The community is united in its support for a space-based interferometry mission. Through concerted efforts worldwide, the key enabling technologies are maturing. Two balloon-borne far-IR interferometers are presently under development. This paper reviews recent technological and programmatic developments, summarizes plans, and offers a vision for space-based far-IR interferometry involving international collaboration.

Leisawitz, David T.↗
NASA NTRS2012

The James Webb Space Telescope

The James Webb Space Telescope is the scientific successor to the Hubble and Spitzer Space Telescopes. It will be a large (6.6m) cold (SDK) telescope launched into orbit around the second Earth-Sun Lagrange point. It is a partnership of NASA with the European and Canadian Space Agencies. The science goals for JWST include the formation of the first stars and galaxies in the early universe; the chemical, morphological and dynamical buildup of galaxies and the formation of stars and planetary systems. Recently, the goals have expanded to include studies of dark energy, dark matter, active galactic nuclei, exoplanets and Solar System objects. Webb will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Near-Infrared Imager and Slitless Spectrograph will cover the wavelength range 0.6 to S microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. The observatory is confirmed for launch in 2018; the design is complete and it is in its construction phase. Recent progress includes the completion of the mirrors, the delivery of the first flight instruments and the start of the integration and test phase.

Gardner, Jonathan P.↗
NASA NTRS2012

Coronagraphic Imaging of Debris Disks from a High Altitude Balloon Platform

Debris disks around nearby stars are tracers of the planet formation process, and they are a key element of our understanding of the formation and evolution of extrasolar planetary systems. With multi-color images of a significant number of disks, we can probe important questions: can we learn about planetary system evolution; what materials are the disks made of; and can they reveal the presence of planets? Most disks are known to exist only through their infrared flux excesses as measured by the Spitzer Space Telescope, and through images measaured by Herschel. The brightest, most extended disks have been imaged with HST, and a few, such as Fomalhaut, can be observed using ground-based telescopes. But the number of good images is still very small, and there are none of disks with densities as low as the disk associated with the asteroid belt and Edgeworth-Kuiper belt in our own Solar System. Direct imaging of disks is major observational challenge, demanding high angular resolution and extremely high dynamic range close to the parent star. The ultimate experiment requires a space-based platform, but demonstrating much of the needed technology, mitigating the technical risks of a space-based coronagraph, and performing valuable measurements of circumstellar debris disks, can be done from a high-altitude balloon platform. In this paper we present a balloon-borne telescope concept based on the Zodiac II design that could undertake compelling studies of a sample of debris disks.

Unwin, Stephen↗
NASA NTRS2012

Debris Disks as Tracers of Nearby Planetary Systems

Many main-sequence stars possess tenuous circumstellar dust clouds believed to trace extrasolar analogs of the Sun's asteroid and Kuiper Belts. While most of these "debris disks" are known only from far-infrared photometry, dozens are now spatially resolved. In this talk, I'll review the observed structural properties of debris disks as revealed by imaging with the Hubble, Spitzer, and Herschel Space Telescopes. I will show how modeling of the far-infrared spectral energy distributions of resolved disks can be used to constrain their dust particle sizes and albedos. I will review cases of disks whose substructures suggest planetary perturbations, including a newly-discovered eccentric ring system. I'll conclude with thoughts on the potential of upcoming and proposed facilities to resolve similar structures around a greatly expanded sample of nearby debris systems.

Stapelfeldt, Karl↗
NASA NTRS2012

The Structure and Emission Model of the Relativistic Jet in the Quasar 3C 279 Inferred From Radio To High-Energy Gamma-Ray Observations in 2008-2010

We present time-resolved broad-band observations of the quasar 3C 279 obtained from multiwavelength campaigns conducted during the first two years of the Fermi Gamma-ray Space Telescope mission. While investigating the previously reported gamma-ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appears delayed with respect to the gamma-ray emission by about 10 days. X-ray observations reveal a pair of 'isolated' flares separated. by approx. 90 days, with only weak gamma-ray/optical counterparts. The spectral structure measured by Spitzer reveals a synchrotron component peaking in the mid-infrared band with a sharp break at the far-infrared band during the gamma-ray flare, while the peak appears in the mm/sub-mm band in the low state. Selected spectral energy distributions are fitted with leptonic models including Comptonization of external radiation produced in a dusty torus or the broad-line region. Adopting the interpretation of the polarization swing involving propagation of the emitting region along a curved trajectory, we can explain the evolution of the broad-band spectra during the gamma-ray flaring event by a shift of its location from approx. 1 pc to approx. 4 pc from the central black hole. On the other hand, if the gamma-ray flare is generated instead at sub-pc distance from the central black hole, the far-infrared break can be explained by synchrotron self-absorption. We also model the low spectral state, dominated by the mm/sub-mm peaking synchrotron component, and suggest that the corresponding inverse-Compton component explains the steady X-ray emission.

Source record↗
NASA NTRS2012

New Measurements of the Cosmic Infrared Background Fluctuations in Deep SpitzerllRAC Survey Data and their Cosmological Implications

We extend the previous measurements of CIB fluctuations to angular scales of less than or equal to 1 degree new data obtained in the course of the 2,000+ hour Spitzer Extended Deep Survey. Two fields with completed observations of approximately equal to 12 hr/pixel are analyzed for source-subtracted CIB fluctuations at 3.6 and 4.5 micrometers. The fields, EGS and UDS, cover a total area of approximately 0.25 deg and lie at high Galactic and Ecliptic latitudes, thus minimizing cirrus and zodiacal light contributions to the fluctuations. The observations have been conducted at 3 distinct epochs separated by about 6 months. As in our previous studies, the fields were assembled using the self-calibration method which is uniquely suitable for probing faint diffuse backgrounds. The assembled fields were cleaned off the bright sources down to the low shot noise levels corresponding to AB mag approximately equal to 25, Fourier-transformed and their power spectra evaluated. The noise was estimated from the time-differenced data and subtracted from the signal isolating the fluctuations remaining above the noise levels. The power spectra of the source-subtracted fields remain identical (within the observational uncertainties) for the three epochs of observations indicating that zodiacal light contributes negligibly to the fluctuations. By comparing to the measurements for the same regions at 8 micrometers we demonstrate that Galactic cirrus cannot account for the levels of the fluctuations either. The signal appears isotropically distributed on the sky as required by its origin in the CIB fluctuations. This measurement thus extends our earlier results to the important range of sub-degree scales. We find that the CIB fluctuations continue to diverge to more than 10 times those of known galaxy populations on angular scales out to less than or equal to 1 degree. The low shot noise levels remaining in the diffuse maps indicate that the large scale fluctuations arise from spatial clustering of faint sources well within the confusion noise. The spatial spectrum of these fluctuations is in reasonable agreement with simple fitting assuming that they originate in early populations spatially distributed according to the standard cosmological model (ACDM) at epochs coinciding with the first stars era. The alternative to this identification would require a new population never observed before, nor expected on theoretical grounds, but if true this would represent an important discovery in its own right.

Kashlinsky, A.↗
NASA NTRS2012

Black Holes in Bulgeless Galaxies: An XMM-Newton Investigation of NGC 3367 AND NGC 4536

The vast majority of optically identified active galactic nuclei (AGNs) in the local Universe reside in host galaxies with prominent bulges, supporting the hypothesis that black hole formation and growth is fundamentally connected to the build-up of galaxy bulges. However, recent mid-infrared spectroscopic studies with Spitzer of a sample of optically "normal" late-type galaxies reveal remarkably the presence of high-ionization [NeV] lines in several sources, providing strong evidence for AGNs in these galaxies. We present follow-up X-ray observations recently obtained with XMM-Newton of two such sources, the late-type optically normal galaxies NGC 3367 and NGC 4536. Both sources are detected in our observations. Detailed spectral analysis reveals that for both galaxies, the 2-10 keV emission is dominated by a power law with an X-ray luminosity in the L(sub 2- 10 keV) approximates 10(exp 39) - 10(exp 40) ergs/s range, consistent with low luminosity AGNs. While there is a possibility that X-ray binaries account for some fraction of the observed X-ray luminosity, we argue that this fraction is negligible. These observations therefore add to the growing evidence that the fraction of late-type galaxies hosting AGNs is significantly underestimated using optical observations alone. A comparison of the midinfrared [NeV] luminosity and the X-ray luminosities suggests the presence of an additional highly absorbed X-ray source in both galaxies, and that the black hole masses are in the range of 10(exp 5) - 10(exp 7) solar M for NGC 3367 and 10(exp 4) - (exp 10) solar M for NGC 4536

McAlpine, W.↗
NASA NTRS2011

Investigating the Nuclear Activity of Barred Spiral Galaxies: The Case of NGC 1672

We have performed an X-ray study of the nearby barred spiral galaxy NGC 1672, primarily to ascertain the effect of the bar on its nuclear activity. We use both Chandra and XMM-Newton observations to investigate its X-ray properties, together with supporting high-resolution optical imaging data from the Hubble Space Telescope (HST) infrared imaging from the Spitzer Space Telescope, and Australia Telescope Compact Array ground-based radio data. We detect 28 X-ray sources within the D25 area of the galaxy; many are spatially correlated with star formation in the bar and spiral arms, and two are identified as background galaxies in the HST images. Nine of the X-ray sources are ultraluminous X-ray sources, with the three brightest (LX 5 * 10(exp 39) erg s(exp -1)) located at the ends of the bar. With the spatial resolution of Chandra, we are able to show for the first time that NGC 1672 possesses a hard (1.5) nuclear X-ray source with a 2-10 keV luminosity of 4 * 10(exp 38) erg s(exp -1). This is surrounded by an X-ray-bright circumnuclear star-forming ring, comprised of point sources and hot gas, which dominates the 2-10 keV emission in the central region of the galaxy. The spatially resolved multiwavelength photometry indicates that the nuclear source is a low-luminosity active galactic nucleus (LLAGN), but with star formation activity close to the central black hole. A high-resolution multiwavelength survey is required to fully assess the impact of both large-scale bars and smaller-scale phenomena such as nuclear bars, rings, and nuclear spirals on the fueling of LLAGN.

COLOR FIGURES↗
NASA NTRS2012

The Keys to Successful Extended Missions

Many of NASA's successful missions of robotic exploration have gone on to highly productive mission extensions, from Voyager, Magellan, Ulysses, and Galileo, to the Mars Exploration Rovers Spirit and Opportunity, a variety of Mars orbiters, Spitzer, Deep Impact / EPOXI, and Cassini. These missions delivered not only a high science return during their prime science phase, but a wealth of opportunities during their extensions at a low incremental cost to the program. The success of such mission extensions can be traced to demonstration of new and unique science achievable during the extension; reduction in cost without significant increase in risk to spacecraft health; close inclusion of the science community and approval authorities in planning; intelligent design during the development and prime operations phase; and well crafted and conveyed extension proposals. This paper discusses lessons learned collected from a variety of project leaders which can be applied by current and future missions to maximize their chances of approval and success.

mission lifetime↗
NASA NTRS2012

Coronagraphic Imaging of Debris Disks from a High Altitude Balloon Platform

Debris disks around nearby stars are tracers of the planet formation process, and they are a key element of our understanding of the formation and evolution of extrasolar planetary systems. With multi-color images of a significant number of disks, we can probe important questions: can we learn about planetary system evolution; what materials are the disks made of; and can they reveal the presence of planets? Most disks are known to exist only through their infrared flux excesses as measured by the Spitzer Space Telescope, and through images measured by Herschel. The brightest, most extended disks have been imaged with HST, and a few, such as Fomalhaut, can be observed using ground-based telescopes. But the number of good images is still very small, and there are none of disks with densities as low as the disk associated with the asteroid belt and Edgeworth-Kuiper belt in our own Solar System. Direct imaging of disks is a major observational challenge, demanding high angular resolution and extremely high dynamic range close to the parent star. The ultimate experiment requires a space-based platform, but demonstrating much of the needed technology, mitigating the technical risks of a space-based coronagrap, and performing valuable measurements of circumstellar debris disks, can be done from a high-altitude balloon platform. In this paper we present a balloon-borne telescope experiment based on the Zodiac II design that would undertake compelling studies of a sample of debris disks.

debris disk↗
NASA NTRS2013

The Carnegie Hubble Program: The Infrared Leavitt Law in IC 1613

We have observed the dwarf galaxy IC 1613 at multiple epochs in the midinfrared using Spitzer and the in the near-infrared using the new FourStar near-IR camera on Magellan. We have constructed Cepheid period luminosity relations in the J, H, Ks, [3.6] and [4.5] bands and have used the run of their apparent distance moduli as a function of wavelength to derive the line of sight reddening and distance to IC 1613. Using a nineband fit, we find E(BV ) = 0.050.01 mag and an extinction corrected distance modulus of 0 = 24.29 0.03statistical 0.03systematic mag. By comparing our multiband and [3.6] distance moduli to results from the tip of the red giant branch and red clump distance indicators, we find that metallicity has no measurable effect on Cepheid distances at 3.6 m in the metallicity range 1.0 [Fe/H] 0.2, hence derivations of the Hubble constant at this wavelength require no correction for metallicity.

Scowcroft, Victoria↗
NASA NTRS2012

Hubble Space Telescope Observations of the HD 202628 Debris Disk

A ring-shaped debris disk around the G2V star HD 202628 (d = 24.4 pc) was imaged in scattered light at visible wavelengths using the coronagraphic mode of the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The ring is inclined by approx.64deg from face-on, based on the apparent major/minor axis ratio, with the major axis aligned along PA = 130deg. It has inner and outer radii (> 50% maximum surface brightness) of 139 AU and 193 AU in the northwest ansae and 161 AU and 223 AU in the southeast ((Delta)r/r approx. = 0.4). The maximum visible radial extent is approx. 254 AU. With a mean surface brightnesses of V approx. = 24 mag arcsec.(sup -2), this is the faintest debris disk observed to date in reflected light. The center of the ring appears offset from the star by approx.28 AU (deprojected). An ellipse fit to the inner edge has an eccentricity of 0.18 and a = 158 AU. This offset, along with the relatively sharp inner edge of the ring, suggests the influence of a planetary-mass companion. There is a strong similarity with the debris ring around Fomalhaut, though HD 202628 is a more mature star with an estimated age of about 2 Gyr. We also provide surface brightness limits for nine other stars in our study with strong Spitzer excesses around which no debris disks were detected in scattered light (HD 377, HD 7590, HD 38858, HD 45184, HD 73350, HD 135599, HD 145229, HD 187897, and HD 201219).

Krist, John E.↗
NASA NTRS2012

WISE Detections of Dust in the Habitable Zones of Planet-Bearing Stars

We use data from the Wide-field Infrared Survey Explorer (WISE) all-sky release to explore the incidence of warm dust in the habitable zones around exoplanet-host stars. Dust emission at 12 and/or 22 microns (T(sub dust) approx.300 and/or approx.150 K) traces events in the terrestrial planet zones; its existence implies replenishment by evaporation of comets or collisions of asteroids, possibly stirred by larger planets. Of the 591 planetary systems (728 extrasolar planets) in the Exoplanet Encyclopedia as of 2012 January 31, 350 are robustly detected by WISE at > or = 5(sigma) level. We perform detailed photosphere subtraction using tools developed for Spitzer data and visually inspect all the WISE images to confirm bona fide point sources. We find nine planet-bearing stars show dust excess emission at 12 and/or 22 microns at > or = 3(sigma) level around young, main-sequence, or evolved giant stars. Overall, our results yield an excess incidence of approx.2.6% for stars of all evolutionary stages, but approx.1% for planetary debris disks around main-sequence stars. Besides recovering previously known warm systems, we identify one new excess candidate around the young star UScoCTIO 108.

Morales, Farisa Y.↗
NASA NTRS2012

Exploring the Connection Between Star Formation and AGN Activity in the Local Universe

We study a combined sample of 264 star-forming, 51 composite, and 73 active galaxies using optical spectra from SDSS and mid-infrared (mid-IR) spectra from the Spitzer Infrared Spectrograph. We examine optical and mid-IR spectroscopic diagnostics that probe the amount of star formation and relative energetic con- tributions from star formation and an active galactic nucleus (AGN). Overall we find good agreement between optical and mid-IR diagnostics. Misclassifications of galaxies based on the SDSS spectra are rare despite the presence of dust obscuration. The luminosity of the [NeII] 12.8 micron emission-line is well correlated with the star formation rate (SFR) measured from the SDSS spectra, and this holds for the star forming, composite, and AGN-dominated systems. AGN show a clear excess of [NeIII] 15.6 micron emission relative to star forming and composite systems. We find good qualitative agreement between various parameters that probe the relative contributions of the AGN and star formation, including: the mid-IR spectral slope, the ratio of the [NeV] 14.3 micron to [NeII] micron 12.8 fluxes, the equivalent widths of the 7.7, 11.3, and 17 micron PAH features, and the optical "D" parameter which measures the distance a source lies from the locus of star forming galaxies in the optical BPT emission-line diagnostic diagram. We also consider the behavior of the three individual PAH features by examining how their flux ratios depend upon the degree of AGN-dominance. We find that the PAH 11.3 micron feature is significantly suppressed in the most AGN-dominated systems.

LaMassa, Stephanie M.↗