SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 11 - MAY 30, 2006
89 ASTRONOMY
Includes observations of celestial bodies; astronomical instruments and techniques; radio, gamma-ray, x-ray, ultraviolet, and infrared astronomy; and astrometry.
20060013178 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Elemental and Molecular Relative Abundances in the Ejecta of Eta Carinae
Kober, G. V.; Gull, T. R.; Nielsen, K.; Bruhweiler, F.; Verner, K.; Stahl, O.; Weis, K.; Bomans, D.; Bulletin of the American Astronomical Society; [2006]; Volume 37, No. 4; 1 pp.; In English; American Astronautical Society 207th Meeting, 8-12 Jan. 2006, Washington, DC, USA; Copyright; Avail.: Other Sources; Abstract Only
We are measuring relative elemental abundances for the ejecta in the line of sight from Eta Carinae using high dispersion spectroscopy with the HST/STIS and the VLT/UVES. While multiple velocity components have been identified, we focus on the -513 and -146 km/s components originating from the Homunculus and the Little Homunculus. Complicating factors are the complex nebular structures in the immediate vicinity of the bright, massive star: the very bright emission structures, Weigelt blobs B, C and D, the broad, clumpy structures of the extended wind apparently not photoionized by Eta Car B, and general scattered starlight from the extended wind and the dusty core of the circumstellar material. We have used the 3050 to 3160A region of overlap between STIS and UVES to intercompare equivalent widths of absorption lines to estimate the 'contributing factor', namely the amount of light originating from the star compared to nebular structures. While the extracted STIS spectra are from 0.1' wide aperture, the UVES spectra are limited by the 1' seeing conditions. Curiously we find that the scattering contribution in the UVES spectra changes with time, apparently with orbital phase of the 5.54-year period. This indicates that the dust may be modified by changes in the central source with phase. The noticeable drop in scattered light appears to occur about 1.7 years (phase 0.35) after the spectroscopic minimum. Relative abundances of iron peak elements and some molecules will be estimated. Observations in this study were accomplished with HST through STSci and with VLT through ESO and funded under STIS GTO resources. Author
Ejecta; Abundance; Massive Stars; Binary Stars; Molecules
20060013181 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Normal and Starburst Galaxies in Deep X-ray Surveys
Cardiff, A. Hornschemeier; [2006]; 1 pp.; In English; No Copyright; Avail.: Other Sources; Abstract Only
This talk will cover progress of the last several years in unraveling the nature of normal and starburst galaxies in deep X-ray surveys. This includes discussion of the normal galaxy X-ray Luminosity Function in deep field and cluster surveys and what it tells us about the binary populations in galaxies. The utility of broad band X-ray emission, especially as compared to other multiwavelength measurements of current/recent star formation, will be reviewed. These broad band X-ray measurements of star formation are based upon X-ray/Star Formation Rate correlations that span the currently available redshift range (0 \h z \h 1). I will also discuss new efforts underway to systematically characterize the X-ray emission from galaxies in group and cluster environments, including a new effort underway in the Coma cluster of galaxies. Author
Star Formation; Galactic Clusters; Correlation; Starburst Galaxies; X Rays; Galactic Radiation; Emission
20060013187 NASA Goddard Space Flight Center, Greenbelt, MD, USA
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The Observed Galactic Annihilation Line: Possible Signature of Accreting Small Mass Black Holes in the Galactic Center
Titarchuk, Lev; Chardonnet, Pascal; Astrophysical Journal 10; [2006]; Volume 639, Issue 2; 23 pp.; In English; Original contains black and white illustrations Contract(s)/Grant(s): SSHN2004-413077D; Copyright; Avail.: CASI: A03, Hardcopy
Various balloon and satellite observatories have revealed what appears to be an extended source of 0.511 MeV annihilation radiation with flux of approx. 10(exp -3) photons/sq cm/s centered on the Galactic Center. Positrons from radioactive products of stellar explosions can account for a significant fraction of the emission.We discuss an additional source for this emission: namely e(+)e(-) pairs produced when X-rays generated from the approx. 2.6 x 10(exp 6) solar mass Galactic Center Black Hole interact with approx. 10 MeV temperature blackbody emission from 10(exp 17) g black holes within 10(exp14-l5) cm of the center. The number of such Small Mass Black Holes (SMMBHs) can account for the production of the 10(exp42) e(+)/s that produces the observed annihilation in the inner Galaxy when transport effects are taken into account. We consider the possibility for confirming the presence of these SMMBHs in the Galactic Center region with future generations of gamma-ray instruments if a blackbody like emission of approx. 10 MeV temperature would be detected by them. Small Mass Black Hole can be a potential candidate for dark (invisible) matter hal Author
Black Holes (Astronomy); Dark Matter; Stellar Mass; Radiation Dosage; Annihilation Reactions; Black Body Radiation; Gamma Rays
20060013192 NASA Goddard Space Flight Center, Greenbelt, MD, USA
MEASURING the MASS OF 4UO900-40 DYNAMICALLY
Dolan, J. F.; Etzel, Paul B.; Boyd, Patricia T.; January 2006; 24 pp.; In English; Copyright; Avail.: CASI: A03, Hardcopy
Accurate measurements of neutron star masses are needed to constrain the equation of state of neutron star matter - of importance to both particle physics and the astrophysics of neutron stars - and to identify the evolutionary track of the progenitor stars that form neutron stars. The best measured values of the mass of 4UO900-40 (= Vela XR-l), 1.86 +/- 0.16 Msun (Barziv et al. 2001) and 1.93 +/- 0.20 Msun (Abubekerov et al. 2004), make it a leading candidate for the most massive neutron star known. The direct relationship between the maximum mass of neutron stars and the equation of state of ultra-dense matter makes 4UO900-40 an important neutron star mass to determine accurately. The confidence interval on previous mass estimates, obtained from observations that include parameters determined by non-dynamical methods, are not small enough to significantly restrict possible equations of state.We describe here a purely dynamical method for determining the mass of 4UO900-40, an X-ray pulsar, using the reprocessed UV pulses emitted by its BO.5Ib companion. One can derive the instantaneous radial velocity of each component by simultaneous X-ray and UV observations at the two quadratures of the system. The Doppler shift caused by the primary's rotational velocity and the illumination pattern of the X-rays on the primary, two of the three principal contributors to the uncertainty on the derived mass of the neutron star, almost exactly cancel by symmetry in this method. A heuristic measurement of the mass of 4UO900-40 using observations obtained previously with the High Speed Photometer on HST is given in Appendix A. Author
Stellar Mass; Neutron Stars; Matter (Physics); Massive Stars; Astrophysics
20060013205 NASA Goddard Space Flight Center, Greenbelt, MD, USA
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'Short, Hard Gamma-Ray Bursts - Mystery Solved?????'
Parsons, A.; [2006]; 1 pp.; In English; High Energy Physics/Astrophysics Seminar Society of Women in Physics, 6-7 Mar. 2006, Ann Arbor, MI, USA; No Copyright; Avail.: Other Sources; Abstract Only
After over a decade of speculation about the nature of short-duration hard-spectrum gamma-ray bursts (GRBs), the recent detection of afterglow emission from a small number of short bursts has provided the first physical constraints on possible progenitor models. While the discovery of afterglow emission from long GRBs was a real breakthrough linking their origin to star forming galaxies, and hence the death of massive stars, the progenitors, energetics, and environments for short gamma-ray burst events remain elusive despite a few recent localizations. Thus far, the nature of the host galaxies measured indicates that short GRBs arise from an old (\g 1 Gyr) stellar population, strengthening earlier suggestions and providing support for coalescing compact object binaries as the progenitors. On the other hand, some of the short burst afterglow observations cannot be easily explained in the coalescence scenario. These observations raise the possibility that short GRBs may have different or multiple progenitors systems. The study of the short-hard GRB afterglows has been made possible by the Swift Gamma-ray Burst Explorer, launched in November of 2004. Swift is equipped with a coded aperture gamma-ray telescope that can observe up to 2 steradians of the sky and can compute the position of a gamma-ray burst to within 2-3 arcmin in less than 10 seconds. The Swift spacecraft can slew on to this burst position without human intervention, allowing its on-board x ray and optical telescopes to study the afterglow within 2 minutes of the original GRB trigger. More Swift short burst detections and afterglow measurements are needed before we can declare that the mystery of short gamma-ray burst is solved. Author
Gamma Ray Bursts; Afterglows; Swift Observatory; Coalescing; Gamma Ray Telescopes; Actuators
20060013208 NASA Goddard Space Flight Center, Greenbelt, MD, USA
The Swift Gamma-ray Burst Explorer: Early views into Black-hole Creation
Hill, Joe; January 2006; 56 pp.; In English; Original contains black and white illustrations Contract(s)/Grant(s): NCC5-637; No Copyright; Avail.: CASI: A04, Hardcopy
Swift has exceeded every pre-launch predicted advance in GRB science. It has discovered the farthest GRB ever seen and identified new GRBs at a rate of 100/year. It has also explored a brand new time interval in GRB light curves by revealing unpredicted phenomena of GRB flares and rapid x-ray afterglow declines. Swift has conducted 20,00o successful slews to sources and is predicted to stay in orbit until 2022. Derived from text
Gamma Ray Bursts; Black Holes (Astronomy); Afterglows
20060013212 NASA Goddard Space Flight Center, Greenbelt, MD, USA
FE K EMISSION and ABSORPTION FEATURES IN the XMM-EPIC SPECTRUM of THE SEYFERT GALAXY IC 4329A
Markowitz, A.; Reeves, J. N.; Braito, V.; [2001]; 27 pp.; In English; Original contains black and white illustrations Contract(s)/Grant(s): NCC5-640; No Copyright; Avail.: CASI: A03, Hardcopy
We present a re-analysis of the XMM-Newton long-look of the X-ray bright Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two peaks, consistent with emission from neutral or near-neutral Fe Ka and KP. A relativistic diskline model whereby both peaks are the result of one doubly-peaked diskline profile is found to be a poor description of the data. Models using two relativistic disklines are found to describe the emission profile well. A low-inclination, moderately-relativistic dual-diskline model is possible if the contribution from narrow components, due to distant material, is small or absent. A high-inclination, moderately relativistic profile for each peak is possible if there are roughly equal contributions from both the broad and narrow components. Upper limits on Fe XXV and Fe XXVI emission and absorption at the systemic velocity of IC 4329a are obtained. We also present the results of RXTE monitoring of this source obtained so far; the combined XMM-Newton and RXTE data sets allow us to explore the time-resolved spectral behavior of this source on time scales ranging from hours to 2 years. We find no strong evidence for variability of the Fe Ka emission line on any time scale probed, likely due to the minimal level of continuum variability. We detect a narrow absorption line, at a energy of 7.68 keV in the rest frame of the source; its significance has been confirmed using Monte Carlo simulations. This feature is most likely due to absorption from Fe XXVI blueshifted to approximately 0.1c relative to the systemic velocity, making IC 4329a the lowest-redshiftAGN known with a high-velocity, highly-ionized outflow component. As is often the case with similar outflows seen in high-luminosity quasars, the estimated mass outflow rate is larger than the inflow accretion rate, signaling that the outflow represents a substantial portion of the total energy budget of the AGN. The outflow could arise from a radiatively-driven disk wind, or it may be in the form of a discrete, transient blob of ejected material. Author
Seyfert Galaxies; XMM-Newton Telescope; Active Galactic Nuclei; K Lines
20060013214 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Swift: Results from the first year of the mission
Krimm, H. A.; [2006]; 1 pp.; In English; No Copyright; Avail.: Other Sources; Abstract Only
The Swift gamma-ray burst explorer was launched on Nov. 20,2004 from Cape Canaveral, Florida. The first instrument onboard became fully operational less than a month later. Since that time the Burst Alert Telescope (BAT) on Swift has detected more than one hundred gamma-ray bursts (GRBs), most of which have also been observed within two minutes by the Swift narrow-field instruments: the X-Ray Telescope (XRT) and the Ultra-Violet and Optical Telescope (UVOT). Swift trigger notices are distributed worldwide within seconds of the trigger through the Gamma-ray burst Coordinates Network (GCN) and a substantial fraction of GRBs have been followed up by ground and space-based telescopes, ranging in wavelength from radio to TeV. Results have included the first rapid localization of a short GRB and further validation of the theory that short and long bursts have different origins; detailed observations of the short-term power-law decay of burst afterglows leading to an improved understanding of the fireball model; and detection of the most distant GRB ever found. Swift is also a sensitive X-ray observatory with capabilities to monitor galactic and extragalactic transients on a daily basis, carry out the first all-sky hard X-ray survey since HEAO-1, and study in detail the spectra of X-ray transients. significant results, both in GRB science and in the search for and study of hard X-ray sources. In this talk I will provide a broad overview of the Swift mission and its most significant results, both in GRB science and in the search for and study of hard X-ray sources. Author
Gamma Ray Bursts; X Ray Telescopes; Swift Observatory; Afterglows
20060013216 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Gamma Ray Bursts
Gehrels, Neil; [2006]; 1 pp.; In English; No Copyright; Avail.: Other Sources; Abstract Only
Gamma-ray bursts are among the most fascinating occurrences in the cosmos. They are thought to be the birth cries of black holes throughout the universe. There has been tremendous recent progress in our understanding of bursts with the new data from the Swift mission. Swift was launched in November 2004 and is a multiwave length observatory designed to determine the origin of bursts and use them to probe the early Universe. It was developed and is being operated by an international team of scientists from the US, UK and Italian. The first year of findings from the mission will be presented. A large step forward has been made in our understanding of the mysterious short GRBs. High redshift bursts have been detected leading to a better understanding of star formation rates and distant galaxy environments. GRBs have been found with giant X-ray flares occurring in their afterglow. These, and other topics, will be discussed. Author
Gamma Ray Bursts; Black Holes (Astronomy); X Rays; Observatories
20060013218 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Correlative Analysis of GRBs detected by Swift, Konus and HETE
Krimm, Hans A.; Barthelmy, S. D.; Gehrels, N.; Hullinger, D.; Sakamoto, T.; Donaghy, T.; Lamb, D. Q.; Pal'shin, V.; Golenetskii, S.; Ricker, G. R., et al.; [2005]; 4 pp.; In English; Original contains black and white illustrations; Copyright; Avail.: CASI: A01, Hardcopy
Swift has now detected a large enough sample of gamma-ray bursts (GRBs) to allow correlation studies of burst parameters. Such studies of earlier data sets have yielded important results leading to further understanding of burst parameters and classifications. This work focuses on seventeen Swift bursts that have also been detected either by Konus-Wind or HETE-II, providing high energy spectra and fits to E(sub peak). Eight of these bursts have spectroscopic redshifts and for others we can estimate redshifts using the variability/luminosity relationship. We can also compare E(sub peak) with E(subiso), and for those bursts for which a jet break was observed in the afterglow we can derive E(sub g) and test the relationship between E(peak) and E(sub gamma). For all bursts we can derive durations and hardness ratios from the prompt emission. Author
Gamma Ray Bursts; Energy Spectra; Red Shift; Classifications; Spectroscopy
20060013219 NASA Goddard Space Flight Center, Greenbelt, MD, USA
The Wide-Field Imaging Interferometry Testbed: Recent Results
Rinehart, Stephen; [2006]; 1 pp.; In English; Society of Photo-Optical Instrumentation Engineers, 24-31 May 2006, Orlando, FL, USA; No Copyright; Avail.: Other Sources; Abstract Only
We present recent results from the Wide-Field Imaging Interferometry Testbed (WIIT). The data acquired with the WIIT is 'double Fourier' data, including both spatial and spectral information within each data cube. We have been working with this data, and starting to develop algorithms, implementations, and techniques for reducing this data. Such algorithms and tools are of great importance for a number of proposed future missions, including the Space Infrared Interferometric Telescope (SPIRIT), the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS), and the Terrestrial Planet Finder Interferometer (TPF-I)/Darwin. Recent results are discussed and future study directions are described. Author
Interferometers; Infrared Telescopes; Algorithms; Submillimeter Waves; Interferometry
20060013221 NASA Goddard Space Flight Center, Greenbelt, MD, USA
The Hard X-ray 20-40 keV AGN Luminosity Function
Beckmann, V.; Soldi, S.; Shrader, C. R.; Gehrels, N.; Produit, N.; January 2006; 14 pp.; In English; Original contains black and white illustrations Contract(s)/Grant(s): NAG5-7385; NAG5-7067; Copyright; Avail.: CASI: A03, Hardcopy
We have compiled a complete, significance limited extragalactic sample based on approximately 25,000 deg(sup 2) to a limiting flux of 3 x 10(exp -11) ergs per square centimeter per second. (approximately 7,000 deg(sup 2)) to a flux limit of 10(exp -11) ergs per square centimeter per second)) in the 20 - 40 keV band with INTEGRAL.We have constructed a detailed exposure map to compensate for effects of non-uniform exposure. The flux-number relation is best described by a power-law with a slope of alpha = 1.66 plus or minus 0.11. The integration of the cumulative flux per unit area leads to f(sub 20-40 keV) = 2.6 x 10(exp -10) ergs per square centimeter per second per sr(sup -1) which is about 1% of the known 20-40 keV X-ray background.We present the first luminosity function of AGN in the 20-40 keV energy range, based on 68 extragalactic objects detected by the imager IBIS/ISGRI on-board INTEGRAL. The luminosity function shows a smoothly connected two power-law form, with an index of gamma (sub 1) = 0.9 below, and gamma (sub 2) = 2.2 above the turn-over luminosity of L(sub *), = 4.6 x 10(sup 43) ergs per second. The emissivity of all INTEGRAL AGNs per unit volume is W(sub 20-40keV)(greater than 10(sup 41) ergs per second) = 2.8 x 10(sup 38) ergs per second h(sup 3)(sub 70) Mpc(sup -3). These results are consistent with those derived in the 2-20keV energy band and do not show a significant contribution by Compton-thick objects. Because the sample used in this study is truly local (z(raised bar) = 0.022)), only limited conclusions can be drawn for the evolution of AGNs in this energy band. But the objects explaining the peak in the cosmic X-ray background are likely to be either low luminosity AGN (L(sub x) less than 10(sup 41) ergs per second) or of other type, such as intermediate mass black holes, clusters, and star forming regions. Author
Active Galactic Nuclei; Luminosity; X Ray Astronomy; Gamma Ray Astronomy; Energy Bands
20060013224 NASA Goddard Space Flight Center, Greenbelt, MD, USA
GLAST Observations of Pulsars and their Environments
Thompson, David J.; [2006]; 1 pp.; In English; No Copyright; Avail.: Other Sources; Abstract Only
Pulsars and pulsar wind nebulae seen at gamma-ray energies offer insight into particle acceleration to very high energies. Pulsed emission provides information about the geometry and interaction processes in the magnetospheres of these rotating neutron stars, while the pulsar wind nebulae yield information high-energy particles interacting with their surroundings. During the next decade, a number of new and expanded gamma-ray facilities will become available for pulsar studies. In particular, the GLAST Large Area Telescope, a successor to EGRET on the Compton Observatory, will provide an excellent complement to H.E.S.S. for the study of the highest-energy emissions powered by neutron stars. Author Gamma Ray Observatory; Gamma Ray Telescopes; Particle Acceleration; Nebulae; Gamma Rays
20060013225 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Swift and GRB's: Unveiling the Relativistic Universe
Marshall, Francis E.; [2006]; 1 pp.; In English; Swift and GRBs Unveiling the Relativistic Universe Conference, 5-9 Jun. 2006, Venice, Italy; No Copyright; Avail.: Other Sources; Abstract Only
We report Swift observations of GRB 051109A, a bright, long burst detected with BAT. A bright afterglow was quickly detected with the X-Ray Telescope and Ultraviolet and Optical Telescope, and observations continued for more than 10 days. The X-ray light is complex with a rapid initial decay followed by a more gradual decay. There is evidence for a jet break with an indicated opening angle of a few degrees. UVOT observations with the V filter are consistent with a power-law day for the first 10 ks. We discuss the observations in light of current models. Author
Universe; Swift Observatory; Gamma Ray Bursts
20060013226 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Ejecta of Eta Carinae: What We Learn about N-Rich Chemistry
Gull, Theodore; [2006]; 1 pp.; In English; Astonomical Institute Ultrecht Conference, 28 May - 1 Jun. 2006, Lunteren, Netherlands; No Copyright; Avail.: Other Sources; Abstract Only
At least one member of the binary system, Eta Carinae, is in the late stages of CNO-cycle. At least ten solar masses of ejecta make up the Homunculus, a neutral bi-polar shell ejected in the 1840s and the Little Homunculus, an internal, ionized bi-polar shell ejected in the 1890s. HST/STIS and VLTAJVES high dispersion spectroscopy revealed absorptions of multiple elements and diatomic molecules in these shells, some, such as V II and Sr II have not been seen previously in the ISM. The skirt region between the bi-lobes includes the very bright Weigelt blobs, within 0.1 to 0.3' of the central source, and the more distant, unusual Strontium Filament, a neutral emission nebula photoexcited by Balmer continuum, but shielded by Fe II from Lyman radiation. The 600+ emission lines are due to metals usually tied up in dust, but underabundances of C and O prevent precipitation as oxides onto the dust grains. Indications are that Ti/Ni is 100X solar, likely due not to nuclear processing, but the very different photo-excitation environments coupled with N-rich, C-, O-poor chemistry. In the Homunculus, level populations of the molecules indicate 60K gas; the metal absorption lines, 760K; that of the Little Homunculus 6400K during the broad spectroscopic maximum, relaxing to 5000K for the few month long minimum. Lyman radiation, including both continuum and Lyman lines, is trapped across periastron. leading to temporary relaxation of the ejecta. These ejecta are a treasure trove of information on material thrown out of massive stars in the CNO-cycle, well before the helium burning phase. Curiously, spectra of three very recent SWIFT GRBs indicate the presence of warm, photoexcited ejecta in the vicinity of the protoGRBs, but obviously of very different abundances. However, the ejecta of Eta Carinae promise to be a nearby example of massive ejecta, the study of which should lead to increased insight of earlier, very distant massive stars. Author
Ejecta; Binary Stars; Nitrogen
20060013256 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Swift-BAT: The First Year of Gamma-Ray Burst Detections
Krimm, Hans A.; [2006]; 1 pp.; In English; Amerian Astronomical Society Meeting, 9-12 Jan. 2006, Washington, DC, USA; Copyright; Avail.: Other Sources; Abstract Only
The Burst Alert Telescope (BAT) on the Swift has been detecting gamma-ray bursts (GRBs) since Dec. 17,2004 and automated burst alerts have been distributed since Feb. 14,2005. Since commissioning the BAT has triggered on more than 100 GRBs, nearly all of which have been followed up by the narrow-field instruments on Swift through automatic repointing, and by ground and other satellite telescopes after rapid notification. Within seconds of a trigger the BAT produces and relays to the ground a position good to three arc minutes and a four channel light curve. A full ten minutes of event data follows on subsequent ground station passes. The burst archive has allowed us to determine ensemble burst parameters such as fluence, peak flux and duration. An overview of the properties of BAT bursts and BAT'S performance as a burst monitor will be presented in this talk. BAT is a coded aperture imaging system with a wide (approx.2 sr) field of view consisting of a large coded mask located 1 m above a 5200 cm2 array of 32.768 CdZnTe detectors. All electronics and other hardware systems on the BAT have been operating well since commissioning and there is no sign of any degradation on orbit. The flight and ground software have proven similarly robust and allow the real time localization of all bursts and the rapid derivation of burst light curves, spectra and spectral fits on the ground. Author
Gamma Ray Bursts; Telescopes; Apertures; Field of View; Imaging Techniques; Real Time Operation; Degradation
20060013257 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes
Gardner, Jonathan F.; Barbier, L. M.; Barthelmy, S. D.; Cummings, J. R.; Fenimore, E. E.; Gehrels, N.; Hullinger, D. D.; Markwardt, C. B.; Palmer, D. M.; Parsons, A. M.; Sakamoto, T., et al.; [2006]; 1 pp.; In English; JPL Colloquium for the Astrophysics Group: Studying Galaxy Formation with Hubble, Spitzer, and James Webb Space Telescope, 29 Jan. - 3 Feb. 2006, Pasadena, CA, USA; No Copyright; Avail.: Other Sources; Abstract Only
The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts 2-6, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z\g10, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASAis planning the James Webb Space Telescope (JWST), a large (6.5m), cold (50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth- Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 27 microns. In addition to JWST s ability to study the formation and evolution of galaxies, I will also briefly review its expected contributions to studies of the formation of stars and planetary systems. Author
Galactic Evolution; Galaxies; James Webb Space Telescope; Hubble Space Telescope; Infrared Astronomy; Red Shift; Spaceborne Telescopes; Space Infrared Telescope Facility
20060013338 NASA Goddard Space Flight Center, Greenbelt, MD, USA
The Gamma-ray Large Area Space Telescope and Gamma-Ray Bursts
McEnery, Julie; Ritz, Steve; [2006]; 4 pp.; In English; Swift Conference Proceedings, 25 Nov. - 1 Dec. 2005, Washington, DC, USA; Original contains black and white illustrations; No Copyright; Avail.: CASI: A01, Hardcopy
The Gamma-ray Large Area Telescope (GLAST) is a satellite-based observatory to study the high energy gamma-ray sky. The main instrument on GLAST, the Large Area Telescope (LAT) is a pair-conversion telescope that will survey the sky from 20 MeV to greater than 300 GeV.With the GLAST launch in 2007, the LAT will open a new and important window on a wide variety of high energy phenomena, including supermassive black holes and active galactic nuclei, gamma-ray bursts, supernova remnants and cosmic ray acceleration and dark matter. A second instrument, the GLAST Burst Monitor (GBM), greatly enhances GLAST s capability to study GRB by providing important spectral and timing information in the 10 keV to 30 MeV range. We describe how the instruments, spacecraft and ground system work together to provide observations of gamma-ray bursts from 8 keV - 300 GeV and to provide rapid notification of bursts to the wider gamma-ray burst community. Author
Gamma Ray Telescopes; Gamma Rays; Active Galactic Nuclei; Supernova Remnants; Cosmic Rays; Black Holes (Astronomy); Gamma Ray Bursts; Dark Matter
20060013373 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Uses of the ICRF and implications for future VLBI
Ma, Chopo; [2006]; 1 pp.; In English; Fourth IVS General Meeting, 9-13 Jan. 2006, Concepcion, Chile; No Copyright; Avail.: Other Sources; Abstract Only
Since its inception on 1 Jan 1998, the fundamental ICRF has been set by the VLBI positions of 212 'defining' extragalactic radio sources. In all there are approx.3000 sources with usefully accurate (\h few mas) positions consistent with the ICRF. The uses of the ICRF include fundamental astrometry, monitoring of Earth orientation, and spacecraft navigation. For fundamental astrometry, stability and accuracy are most important, and realizations at different frequencies must be in proper registration. However, there is no preferred frequency, and the GAIA mission has the potential for an optical ICRF with 500,000 objects at the 50 microarcsec level some time after the planned 2011 launch. The radio ICRF should be properly prepared for a transition to assure long term stability and consistency. Earth orientation monitoring requires objects attached to the solid Earth, and VLBI will continue to be the fundamental technique. For this purpose it is essential that the new VLBI stations contemplated in the VLBI20l0 report be capable of observing a sufficiently large and well-distributed set of stable sources, and identifying these sources is an on-going effort. Spacecraft navigation by differential VLBI is planned using the Ka-band telemetry signal, and work has begun towards an ICRF realization suitable for this purpose. The balancing of different needs related to the VLBI ICRF will be discussed. Author
Extragalactic Radio Sources; Very Long Base Interferometry; Astrometry; Earth Orientation; Space Navigation; Stability; Accuracy
20060013397 NASA Goddard Space Flight Center, Greenbelt, MD, USA
GRB 050117: Simultaneous Gamma-ray and X-ray Observations with the Swift Satellite
Hill, J. E.; Morris, D. C.; Sakamoto, T.; Sato, G.; Burrows, D. N.; Angelini, L.; Pagani, C.; Moretti, A.; Abbey, A. F.; Barthelmy, S., et al.; [2005]; 4 pp.; In English; SWIFT Maryland Conference, 29 Nov. - 2 Dec. 2005, Washington, DC, USA; Original contains black and white illustrations Contract(s)/Grant(s): NAS5-00136; NCC5-637; PPA/Z/S/2003/00507; I/R/039/; Copyright; Avail.: CASI: A01, Hardcopy
The Swift Gamma-Ray Burst Explorer performed its first autonomous, X-ray follow-up to a newly detected GRB on 2005 January 17, within 193 seconds of the burst trigger by the Swift Burst Alert Telescope. While the burst was still in progress, the X-ray Telescope obtained a position and an image for an un-catalogued X-ray source; simultaneous with the gamma-ray observation. The XRT observed flux during the prompt emission was 1.1 x 10(exp -8) ergs/sq cm/s in the 0.5-10 keV energy band. The emission in the X-ray band decreased by three orders of magnitude within 700 seconds, following the prompt emission. This is found to be consistent with the gamma-ray decay when extrapolated into the XRT energy band. During the following 6.3 hours, the XRT observed the afterglow in an automated sequence for an additional 947 seconds, until the burst became fully obscured by the Earth limb. A faint, extremely slowly decaying afterglow, alpha=-0.21, was detected. Finally, a break in the lightcurve occurred and the flux decayed with alpha\h-1.2. The X-ray position triggered many follow-up observations: no optical afterglow could be confirmed, although a candidate was identified 3 arcsecs from the XRT position. Author
Gamma Ray Bursts; Gamma Rays; Swift Observatory; Afterglows; Energy Bands; X Ray Telescopes; X Ray Sources
20060013399 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Science with the James Webb Space Telescope
Gardner, Jonathan P.; [2006]; 1 pp.; In English; Visions of Infrared Astronomy, 20-22 Mar. 2006, Paris, France; No Copyright; Avail.: Other Sources; Abstract Only
The scientific capabilities of the James Webb Space Telescope (JWST) fall into four themes. The End of the Dark Ages: First Light and Reionization theme seeks to identify the first luminous sources to form and to determine the ionization history of the universe. The Assembly of Galaxies theme seeks to determine how galaxies and the dark matter, gas, stars, metals, morphological structures, and active nuclei within them evolved from the epoch of reionization to the present. The Birth of Stars and Protoplanetary Systems theme seeks to unravel the birth and early evolution of stars, from infall onto dust-enshrouded protostars, to the genesis of planetary systems. The Planetary Systems and the Origins of Life theme seeks to determine the physical and chemical properties of planetary systems around nearby stars and of our own, and investigate the potential for life in those systems. To enable these for science themes, JWST will be a large (6.5m) cold (50K) telescope launched to the second Earth-Sun Lagrange point early in the next decade. It is the successor to the Hubble Space Telescope, and is a partnership of NASA, ESA and CSA. JWST will have three instruments: The Near-Infrared Camera, and the Near-Infrared multi-object 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 27 microns. I review the status and capabilities of the observatory and instruments in the context of the major scientific goals. Author
James Webb Space Telescope; Dark Matter; Galaxies; Ionization; Protostars; Morphology; Stellar Evolution; Planetary Systems
Source: NASA
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