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  • Other Sources  (1,358)
  • Astrophysics  (790)
  • Instrumentation and Photography  (568)
  • 2020-2024
  • 2005-2009  (1,358)
  • 1
    Publication Date: 2011-08-24
    Description: We present the discovery of a 70 kpc X-ray tail behind the small late-type galaxy ESO 137-001, in the nearby, hot (T=6.5 keV) merging cluster A3627, from both Chandra and XMM-Newton observations. The tail has a length-to-width ratio of approx. 10. It is luminous (L(0.5-2keV) approx 1041 ergs/s), with a temperature of approx. 0.7 keV and an X-ray gas mass of approx 10(exp 9) solar masses (approx 10% of the galaxy's stellar mass). We interpret this tail as the stripped interstellar medium of ESO 137-001 mixed with the hot cluster medium, with this blue galaxy being converted into a gas-poor galaxy. Three X-ray point sources are detected in the axis of the tail, which may imply active star formation there. The straightness and narrowness of the tail also imply that the turbulence in the intracluster medium is not strong on scales of 20-70 kpc.
    Keywords: Astrophysics
    Type: Astrophysical Journal; Volume 637; Part 2; L81-L85
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  • 2
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    In:  CASI
    Publication Date: 2005-04-25
    Description: The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) is an integral component of the Mars Express mission. A low-frequency sounding radar was carried on the Russian Mars 96 spacecraft, and in keeping with the concept of re-flying the science experiments lost on that mission, a call for a radar sounder was part of the Announcement of Opportunity for the 2003 ESA Mars Express mission. MARSIS is the only totally new instrument on Mars Express. The instrument was developed, delivered and operated as a joint effort between the Italian Space Agency and the U.S space agency NASA. The MARSIS science mission has been delayed due to concerns about the safety of the antenna deployment. As a testament to the importance placed on the
    Keywords: Instrumentation and Photography
    Type: Workshop on Radar Investigations of Planetary and Terrestrial Environments; 68; LPI-Contrib-1231
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  • 3
    Publication Date: 2018-06-11
    Description: Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.
    Keywords: Astrophysics
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  • 4
    Publication Date: 2018-06-11
    Description: A method for measuring the acoustic velocity in a thin sheet of a graphite epoxy composite (GEC) material was investigated. This method uses two identical acoustic-emission (AE) sensors, one to transmit and one to receive. The delay time as a function of distance between sensors determines a bulk velocity. A lightweight fixture (balsa wood in the current implementation) provides a consistent method of positioning the sensors, thus providing multiple measurements of the time delay between sensors at different known distances. A linear fit to separation, x, versus delay time, t, will yield an estimate of the velocity from the slope of the line.
    Keywords: Instrumentation and Photography
    Type: John F. Kennedy Space Center's Technology Development and Application 2006-2007 Report; 48-49/50; NASA/TM-2008-214740
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  • 5
    Publication Date: 2018-06-11
    Description: SIM PlanetQuest (hereafter, just SIM) is a NASA mission to measure the angular positions of stars with unprecedented accuracy. We outline the main astrophysical science programs planned for SIM, and related opportunities for community participation. We focus especially on SIM's ability to detect exoplanets as small as the Earth around nearby stars. The planned synergy between SIM and other planet-finding missions including Kepler and GAIA, and planet-characterizing missions including the James Webb Space Telescope (JWST), Terrestrial Planet Finder--Coronagraph (TPF-C), and Terrestrial Planet Finder--Interferometer (TPF-I), is a key element in NASA's Navigator Program to find Earth-like planets, determine their habitability, and search for signs of life in the universe. SIM's technology development is now complete and the project is proceeding towards a launch in the next decade.
    Keywords: Astrophysics
    Type: Acta Astronautica; Volume 61; 52-62
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  • 6
    Publication Date: 2018-06-11
    Description: We present the design of a compact, wide-angle pushbroom imaging spectrometer suitable for exploration of solar system bodies from low orbit. The spectrometer is based on a single detector array with a broadband response that covers the range 400 to 3000 nm and provides a spectral sampling of 10 nm. The telescope has a 24-deg field of view with 600 spatially resolved elements (detector pixels). A specially designed convex diffraction grating permits optimization of the signal-to-noise ratio through the entire spectral band. Tolerances and design parameters permit the achievement of high uniformity of response through field and wavelength. The spectrometer performance is evaluated in terms of predicted spectral and spatial response functions and from the point of view of minimizing their variation through field and wavelength. The design serves as an example for illustrating the design principles specific to this type of system.
    Keywords: Instrumentation and Photography
    Type: Optical Engineering; Volume 46; No. 6
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  • 7
    Publication Date: 2018-06-11
    Description: We have updated the orbits of the small inner Saturnian satellites using additional Cassini imaging observations through 2007 March. Statistically significant changes from previously published values appear in the eccentricities and inclinations of Pan and Daphnis, but only small changes have been found in the estimated orbits of the other satellites. We have also improved our knowledge of the masses of Janus and Epimetheus as a result of their close encounter observed in early 2006.
    Keywords: Astrophysics
    Type: The Astronomical Journal; Volume 135; 261
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  • 8
    Publication Date: 2018-06-11
    Description: With a dynamic atmosphere and a large supply of particulate material, the surface of Mars is heavily influenced by wind-driven, or aeolian, processes. The High Resolution Imaging Science Experiment (HiRISE) camera on the Mars Reconnaissance Orbiter (MRO) provides a new view of Martian geology, with the ability to see decimeter-size features. Current sand movement, and evidence for recent bedform development, is observed. Dunes and ripples generally exhibit complex surfaces down to the limits of resolution. Yardangs have diverse textures, with some being massive at HiRISE scale, others having horizontal and cross-cutting layers of variable character, and some exhibiting blocky and polygonal morphologies. 'Reticulate' (fine polygonal texture) bedforms are ubiquitous in the thick mantle at the highest elevations.
    Keywords: Instrumentation and Photography
    Type: Geophysical Research Letters; Volume 34
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  • 9
    Publication Date: 2018-06-11
    Description: HEALPix the Hierarchical Equal Area isoLatitude Pixelization is a versatile structure for the pixelization of data on the sphere. An associated library of computational algorithms and visualization software supports fast scientific applications executable directly on discretized spherical maps generated from very large volumes of astronomical data. Originally developed to address the data processing and analysis needs of the present generation of cosmic microwave background experiments (e.g., BOOMERANG, WMAP), HEALPix can be expanded to meet many of the profound challenges that will arise in confrontation with the observational output of future missions and experiments, including, e.g., Planck, Herschel, SAFIR, and the Beyond Einstein inflation probe. In this paper we consider the requirements and implementation constraints on a framework that simultaneously enables an efficient discretization with associated hierarchical indexation and fast analysis/synthesis of functions defined on the sphere. We demonstrate how these are explicitly satisfied by HEALPix.
    Keywords: Astrophysics
    Type: The Astrophysical Journal; Volume 622; Issue 2; 759-771
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  • 10
    Publication Date: 2018-06-11
    Description: We report the discovery that impacts in the Stardust cometary collector are not distributed randomly in the collecting media, but appear to be clustered on scales smaller than 10 cm. We also report the discovery of at least two populations of oblique tracks. We evaluated several hypotheses that could explain the observations. No hypothesis was consistent with all the observations, but the preponderance of evidence points toward at least one impact on the central Whipple shield of the spacecraft as the origin of both clustering and low-angle oblique tracks. High-angle oblique tracks unambiguously originate from a non-cometary impact on the spacecraft bus just forward of the collector.
    Keywords: Astrophysics
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  • 11
    Publication Date: 2018-06-11
    Description: We report interferometric observations of the semiregular variable star RS CrB, a red giant with strong silicate emission features. The data were among the first long-baseline mid-infrared stellar fringes obtained between the Keck telescopes, using parts of the new nulling beam combiner.
    Keywords: Astrophysics
    Type: The Astrophysical Journal; Volume 634; L169-L172.
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  • 12
    Publication Date: 2018-06-11
    Description: We have analyzed the high-resolution ultraviolet (UV) emission spectrum of molecular deuterium hydride (HD) excited by electron impact at 100 eV under optically thin, single-scattering experimental conditions. The high-resolution spectrum (FWHM=160 mA) spans the wavelength range from 900 to 1650 A and contains the two Rydberg series of HD: (sup 1)Sigma(sub u)(sup +)1s(sigma), np(si n=2, 3, 4) --〉 X(sup 1)Sigma(sub g)(sup +) and (sup 1)Pi(sub u)(sup +)1s(sigma), np(pi)(C,D,D',D'', n=2, 3, 4, 5) --〉X(sup 1)Sigma(sub g)(sup +). A model spectrum of HD, based on newly calculated tra rovibrational coupling for the strongest band systems, B (sup 1)Sigma(sub u)(sup +)-X(sup 1)Sigma(sub g)(sup +),B'(sup 1)Sigma(sub g)(sup +)-X(sup 1)Sigma(sub g)(sup +),C(sup 1)Pi(sub u)-X(sup 1)Sigm sections for direct excitation at 100 eV of the B (sup 1)Sigma(sub u)(sup +), B' (sup 1)Sigma(sub u)(sup +), C(sup 1)Pi(sub u), and D(sup 1)Pi(sub u) states were derived from a model analysis of the state. The absolute cross section values for excitation to the B (sup 1)Sigma(sub u)(sup +), B' (sup 1)Sigma(sub u)(sup +), C(sup 1)Pi(sub u), and D(sup 1)Pi(sub u) states were found to be (2.57+/-0. and (0.17+/-0.04)x10(exp -17) sq cm, respectively. We have also determined the dissociative excitation cross sections at 100 eV for the emission of Ly(alpha) at 1216 A and Ly(Beta) at 1025 A lines, which are (7.98+/-1.12)x10(exp -18) and (0.40+/-0.10)x10(exp -18) sq cm, respectively. The summed excitation function of the closely spaced pair of lines, H Ly(alpha) and D Ly(Beta), resulting from excitation of HD, has been measured from the threshold to 800 eV and is analytically modeled with a semiempirical relation. The model cross sections are in good agreement with the corrected Ly(alpha) cross sections of Mohlmann et al. up to 2 keV. Based on measurements of H, D (2s) production cross section values by Mohlmann et al., the H, D (n=2) cross section is estimated to be 1.6 x 10(exp -17) sq cm at 100 eV.
    Keywords: Astrophysics
    Type: The Astrophysical Journal Supplement Series; Volume 159; 314-330
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  • 13
    Publication Date: 2018-06-11
    Description: In a recent paper, Kuchner, Crepp, and Ge describe new image-plane coronagraph mask designs that reject to eighth order the leakage of starlight caused by image motion at the mask, resulting in a substantial relaxation of image centroiding requirements compared to previous fourth-order and second-order masks. They also suggest that the new masks are effective at rejecting leakage caused by low-order aberrations (e.g., focus, coma, and astigmatism). In this paper, we derive the sensitivity of eighth-order masks to aberrations of any order and provide simulations of coronagraph behavior in the presence of optical aberrations.We find that the masks leak light as the fourth power of focus, astigmatism, coma, and trefoil. This has tremendous performance advantages for the Terrestrial Planet Finder Coronagraph.
    Keywords: Astrophysics
    Type: The Astrophysical Journal; Volume 628; 474-477
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  • 14
    Publication Date: 2018-06-11
    Description: Of the three major groups of comets approaching the Sun to between 6 and 12 solar radii and discovered with the coronagraphs on board SOHO, we investigate the Marsden and Kracht groups.We call these comets ''sunskirters'' to distinguish them from the Kreutz system sungrazers. Our objective is to understand the origin, history, and orbital evolution of the two groups.
    Keywords: Astrophysics
    Type: The Astrophysical Journal Supplement Series; Volume 161; 551-586
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  • 15
    Publication Date: 2018-06-11
    Description: The Stellar Planet Survey is an ongoing astrometric search for giant planets and brown dwarfs around a sample of ~30 M dwarfs. We have discovered several low-mass companions by measuring the motion of our target stars relative to their reference frames. The lowest mass discovery thus far is GJ 802b, a companion to the M5 dwarf GJ 802A. The orbital period is 3.14 +/-0:03 yr, the system mass is 0:214 +/- 0:045 M(circled dot operator), and the semimajor axis is 1:28+/- 0:10 AU or 81 + 6 mas. Imaging observations indicate that GJ 802b is likely to be a brow with the astrometrically determined mass 0:058 +/- 0:021 M(circled dot operator) (1 (sigma) limits). The remaining uncertainty in the orbit is the eccentricity that is now loosely constrained. We dis the system age limits the mass and the prospects of further narrowing the mass range when e is more precisely determined.
    Keywords: Astrophysics
    Type: The Astrophysical Journal
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  • 16
    Publication Date: 2018-06-11
    Description: Viewgraph topics include: optical image of Taurus; dust extinction in IR has provided a new tool for probing cloud morphology; observations of the gas can contribute critical information on gas temperature, gas column density and distribution, mass, and kinematics; the Taurus molecular cloud complex; average spectra in each mask region; mas 2 data; dealing with mask 1 data; behavior of mask 1 pixels; distribution of CO column densities; conversion to H2 column density; variable CO/H2 ratio with values much less than 10(exp -4) at low N indicated by UV results; histogram of N(H2) distribution; H2 column density distribution in Taurus; cumulative distribution of mass and area; lower CO fractional abundance in mask 0 and 1 regions greatly increases mass determined in the analysis; masses determined with variable X(CO) and including diffuse regions agrees well with the found from L(CO); distribution of young stars as a function of molecular column density; star formation efficiency; star formation rate and gas depletion; and enlarged images of some of the regions with numerous young stars. Additional slides examine the origin of the Taurus molecular cloud, evolution from HI gas, kinematics as a clue to its origin, and its relationship to star formation.
    Keywords: Astrophysics
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  • 17
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    In:  Other Sources
    Publication Date: 2018-06-11
    Description: SIM-PlanetQuest is a NASA astrophysics mission that is implementing the National Research Counsel's recommended Astrometric Interferometry Mission (AIM) to develop the first, in-space, optical, long-baseline Michelson Stellar Interferometer for performing micro-arcsecond-level astrometry. This level of astrometric precision will enable characterization of planetary systems around nearby stars and enable a number of key investigations in astrophysics including calibration of the cosmological distance scale, stellar and galactic structure and evolution, and dark matter/energy distribution. This paper provides an update on the SIM-PlanetQuest Mission covering the results of the 2005 mission redesign and the recent completion of the last in a series of technology "gates." The SIM-PlanetQuest mission redesign was directed by NASA to recover eroded mass and power margins and to meet specific implementation cost targets. The resulting mission redesign met all redesign objectives with minimal impact to mission science performance. This paper provides the mission redesign objectives and describes the resulting mission and system design including changes in science capability. SIM-PlanetQuest also completed the last of eight major technology development gates that were established in 2001 by NASA, completing the enabling technology development. The technology development program, the last gate, and its significance to the project's flight verification and validation (V&V) approach are briefly described (covered in more detail in a separate paper at this conference). An update on project programmatic status and plans is also provided.
    Keywords: Astrophysics
    Type: Proceedings SPIE, Space Missions and Technology; Volume 6268
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  • 18
    Publication Date: 2018-06-12
    Description: We analyze the effect of a highly dispersive element placed inside a modulated optical cavity on the frequency and amplitude of the output modulation to determine the conditions for enhanced gyroscopic sensitivities. The element is treated as both a phase and amplitude filter, and the time-dependence of the cavity field is considered. Both atomic gases (two-level and multi-level) and optical resonators (single and coupled) are considered and compared as dispersive elements. We find that it is possible to simultaneously enhance the gyro scale factor sensitivity and suppress the dead band by using an element with anomalous dispersion that has greater loss at the carrier frequency than at the side-band frequencies, i.e., an element that simultaneously pushes and intensifies the perturbed cavity modes, e.g. a two-level absorber or an under-coupled optical resonator. The sensitivity enhancement is inversely proportional to the effective group index, becoming infinite at a group index of zero. However, the number of round trips required to reach a steady-state also becomes infinite when the group index is zero (or two). For even larger dispersions a steady-state cannot be achieved, and nonlinear dynamic effects such as bistability and periodic oscillations are predicted in the gyro response.
    Keywords: Instrumentation and Photography
    Type: Physical Review A; Volume 78; Issue 5
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  • 19
    Publication Date: 2018-06-12
    Description: We investigate here the effects of plasma instabilities driven by rapid e(sup +/-) pair cascades, which arise in the environment of GRB sources as a result of back-scattering of a seed fraction of their original spectrum. The injection of e(sup +/-) pairs induces strong streaming motions in the ambient medium. One therefore expects the pair-enriched medium ahead of the forward shock to be strongly sheared on length scales comparable to the radiation front thickness. Using three-dimensional particle-in-cell simulations, we show that plasma instabilities driven by these streaming e(sup +/-) pairs are responsible for the excitation of near-equipartition, turbulent magnetic fields. Our results reveal the importance of the electromagnetic filamentation instability in ensuring an effective coupling between e(sup +/-) pairs and ions, and may help explain the origin of large upstream fields in GRB shocks.
    Keywords: Astrophysics
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  • 20
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    In:  Other Sources
    Publication Date: 2018-06-11
    Description: This slide presentation reviews theoretical considerations of the formation of massive stars. It addresses the questions that assuming a gravitationally unstable massive clump, how does enough material become concentrated into a sufficiently small volume within a sufficiently short time? and how does the forming massive star influence its immediate surroundings to limit its mass?
    Keywords: Astrophysics
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  • 21
    Publication Date: 2018-06-12
    Description: This viewgraph presentation reviews the use Automatic Fusion of Image Data System (AFIDS) for Automatic Co-Registration of QuickBird Data to ascertain if changes have occurred in images. The process is outlined, and views from Iraq and Los Angelels are shown to illustrate the process.
    Keywords: Instrumentation and Photography
    Type: Proceedings of the 2004 High Spatial Resolution Commercial Imagery Workshop; SSTI-2220-0039
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  • 22
    Publication Date: 2018-06-12
    Description: In this report, we summarize recent findings regarding the use spherical microcavities in the amplification of light that is inelastically scattered by either fluorescent or Raman-active molecules. This discussion will focus on Raman scattering, with the understanding that analogous processes apply to fluorescence. Raman spectra can be generated through the use of a very strong light source that stimulates inelastic light scattering by molecules, with the scattering occurring at wavelengths shifted from that of the source and being most prominent at shifts associated with the molecules natural vibrational frequencies. The Raman signal can be greatly enhanced by exposing a molecule to the intense electric fields that arise near surfaces (typically of gold or silver) exhibiting nanoscale roughness. This is known as surface-enhanced Raman scattering (SERS). SERS typically produces gain factors of 103 - 106, but under special conditions, factors of 1010 - 1014 have been achieved.
    Keywords: Instrumentation and Photography
    Type: The 2004 NASA Faculty Fellowship Program Research Reports; XVI-1 - XVI-6; NASA/CR-2005-213847
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  • 23
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    In:  CASI
    Publication Date: 2018-06-12
    Description: Cryogenic fluids play an important role in space transportation. Liquid oxygen and hydrogen are vital fuel components for liquid rocket engines. It is also difficult to accurately measure the liquid level in the cryogenic tanks containing the liquids. The current methods use thermocouple rakes, floats, or sonic meters to measure tank level. Thermocouples have problems examining the boundary between the boiling liquid and the gas inside the tanks. They are also slow to respond to temperature changes. Sonic meters need to be mounted inside the tank, but still above the liquid level. This causes problems for full tanks, or tanks that are being rotated to lie on their side.
    Keywords: Instrumentation and Photography
    Type: The 2004 NASA Faculty Fellowship Program Research Reports; XIV-1 - XIV-6; NASA/CR-2005-213847
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  • 24
    Publication Date: 2018-06-12
    Description: EXO 2030+375, a 42 s transient X-ray pulsar with a Be star companion, has been observed to undergo an outburst at nearly every periastron passage for the last 13.5 years. From 1994 through 2002, the global trend in the pulsar spin frequency was spin-down. Using Rossi X-Ray Timing Explorer (RXTE) data from 2003 September, we have observed a transition to global spin-up in EXO 2030+375. Although the spin-frequency observations are sparse, the relative spin-up between 2002 June and 2003 September observations, along with an overall brightening of the outbursts since mid-2002 observed with the RXTE All-Sky Monitor, accompanied by an increase in density of the Be disk, indicated by infrared magnitudes, suggest that the pattern observed with BATSE of a roughly constant spin frequency, followed by spin-up, followed by spin-down is repeating. If so, this pattern has approximately an 11 yr period, similar to the 15 +/- 3 yr period derived by Wilson et al. for the precession period of a one-armed oscillation in the Be disk. If this pattern is indeed repeating, we predict a transition from spin-up to spin-down in 2005.
    Keywords: Astrophysics
    Type: Astrophysical Journal; Volume 620; No. 2; L99-L102
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  • 25
    Publication Date: 2018-06-11
    Description: The following sections describe Ares V performance and its payoff to a wide array of potential solar system exploration missions. Application to potential Astrophysics missions is addressed in Reference 3.
    Keywords: Astrophysics
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  • 26
    Publication Date: 2018-06-11
    Description: In situ probing of a very few cometary comae has shown that dust particles present a low albedo and a low density, and that they consist of both rocky material and refractory organics. Remote observations of solar light scattered by cometary dust provide information on the properties of dust particles in the coma of a larger set of comets. The observations of the linear polarization in the coma indicate that the dust particles are irregular, with a size greater (on the average) than about one micron. Besides, they suggest, through numerical and experimental simulations, that both compact grains and fluffy aggregates (with a power law of the size distribution in the -2.6 to -3 range), and both rather transparent silicates and absorbing organics are present in the coma. Recent analysis of the cometary dust samples collected by the Stardust mission provide a unique ground truth and confirm, for comet 81P/Wild 2, the results from remote sensing observations. Future space missions to comets should, in the next decade, lead to a more precise characterization of the structure and composition of cometary dust particles.
    Keywords: Astrophysics
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  • 27
    Publication Date: 2018-06-11
    Description: Every day, ISS astronauts photograph designated sites and dynamic events on the Earth's surface using digital cameras equipped with a variety of lenses. Depending on observation parameters, astronauts can collect high resolution (4-6 m pixel size) or synoptic views (lower resolution but covering very large areas) digital data in 3 (red-green-blue) color bands. ISS crews have daily opportunities to document a variety of high-latitude phenomena. Although lighting conditions, ground track and other viewing parameters change with orbital precessions and season, the 51.6o orbital inclination and 400 km altitude of the ISS provide the crew an unique vantage point for collecting image-based data of polar phenomena, including surface observations to roughly 65o latitude, and upper atmospheric observations that reach nearly to the poles. During the 2007-2009 timeframe of the IPY, polar observations will become a scientific focus for the CEO experiment; the experiment is designated ISS-IPY. We solicit requests from scientists for observations from the ISS that are coordinated with or complement ground-based polar studies. The CEO imagery website for ISS-IPY provides an on-line form that allows IPY investigators to interact with CEO scientists and define their imagery requests. This information is integrated into daily communications with the ISS astronauts about their Earth Observations targets. All data collected are cataloged and posted on the website for downloading and assimilation into IPY projects. Examples of imagery and detailed information about scientific observations from the ISS can also be downloaded from the ISS-IPY web site.
    Keywords: Instrumentation and Photography
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  • 28
    Publication Date: 2018-06-11
    Description: Characteristic X-ray emission lines are detected from simulants of comet surfaces as they undergo collisions with highly charged ions (HCIs). The HCI projectiles are O+2-O+7. Ion energies are varied in the range (2-7)q keV, where q is the ion charge state. The targets are the insulator minerals olivine, augite, and quartz. It is found that the emission of characteristic K-L, K-M X-rays appears to proceed during positive charging of the surface by the HCI beam. When one uses low-energy, flood-gun electrons to neutralize the surface charge, the X-ray emission is eliminated or greatly reduced, depending on the flood-gun current. Acceleration of background electrons onto the charged surface results in excitation of elemental transitions, including the K-L2 and K-L3 target X-ray emission lines of Mg and Si located spectroscopically at 1253.6 and 1739.4 eV, respectively. Also observed are emission lines from O, Na, Ca, Al, and Fe atoms in the target and charge-exchange lines via surface extraction of electrons by the O+q electric field. Good agreement is found in the ratio of the measured X-ray yields for Mg and Si relative to the ratio of their electron-impact K-shell ionization cross sections. The present study may serve as a guide to astronomers as to specific observing X-ray energies indicative of solar/stellar wind or magnetospheric ion interactions with a comet, planetary surface, or circumstellar dust.
    Keywords: Astrophysics
    Type: The Astrophysical Journal
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  • 29
    Publication Date: 2018-06-11
    Description: Filamentary structures following magnetic field lines pervade the Sun's atmosphere and offer us insight into the solar magnetic field. Radio propagation measurements have shown that the smallest filamentary structures in the solar corona are more than 2 orders of magnitude finer than those seen in solar imaging. Here we use radio Doppler measurements to characterize their transverse density gradient and determine their finest scale in the outer corona at 20-30 R(circled dot operator), where open magnetic fields prevail. Filamentary structures overly active regions have the steepest gradient and finest scale, while those overlying coronal holes have the shallowest gradient and least finest scale. Their organization by the underlying corona implies that these subresolution structures extend radially from the entire Sun, confirming that they trace the coronal magnetic field responsible for the radial expansion of the solar wind. That they are rooted all over the Sun elucidates the association between the magnetic field of the photosphere and that of the corona, as revealed by the similarity between the power spectra of the photospheric field and the coronal density fluctuations. This association along with the persistence of filamentary structures far from the Sun demonstrate that subresolution magnetic fields must play an important role not only in magnetic coupling of the photosphere and corona, but also in coronal heating and solar wind acceleration through the process of small-scale magnetic reconnection. They also explain why current widely used theoretical models that extrapolate photospheric magnetic fields into the corona do not predict the correct source of the solar wind.
    Keywords: Astrophysics
    Type: The Astrophysical Journal; Volume 639; L95-L98
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  • 30
    Publication Date: 2018-06-11
    Description: Experimental cross sections are reported for the 1s(2)2s(2) S-1 -〉 1s(2)2s2p P-1(o) transition in O+4 located at 19.689 eV. Use is made of the electron energy-loss method, using a merged electron-ion beam geometry. The center-of-mass interaction energies for the measurements in the S-1 -〉 P-1(o) transition are in the range 18 eV ( below the threshold) to 30 eV. Data are compared with other previous electron energy-loss measurements and with results of a 26 term R-matrix calculation that includes fine structure explicitly via the Breit-Pauli Hamiltonian. Clear resonance enhancement is observed in all experimental and theoretical results near the threshold for this S-1 -〉 P-1(o) transition.
    Keywords: Astrophysics
    Type: The Astrophysical Journal
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  • 31
    Publication Date: 2018-06-12
    Description: 'SIM PlanetQuest will exploit the classical measuring tool of astrometry (interferometry) with unprecedented precision to make dramatic advances in many areas of astronomy and astrophysics'(1). In order to obtain interferometric data two large steerable mirrors, or Siderostats, are used to direct starlight into the interferometer. A gimbaled mechanism actuated by linear actuators is chosen to meet the unprecedented pointing and angle tracking requirements of SIM. A group of JPL engineers designed, built, and tested a linear ballscrew actuator capable of performing submicron incremental steps for 10 years of continuous operation. Precise, zero backlash, closed loop pointing control requirements, lead the team to implement a ballscrew actuator with a direct drive DC motor and a precision piezo brake. Motor control commutation using feedback from a precision linear encoder on the ballscrew output produced an unexpected incremental step size of 20 nm over a range of 120 mm, yielding a dynamic range of 6,000,000:1. The results prove linear nanometer positioning requires no gears, levers, or hydraulic converters. Along the way many lessons have been learned and will subsequently be shared.
    Keywords: Instrumentation and Photography
    Type: 39th Aerospace Mechanisms Symposium; 373-386; NASA/CP-2008-215252
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  • 32
    Publication Date: 2018-06-12
    Description: This viewgraph presentation reviews the carbon atmospheric exchange with Arctic tundra. In the Arctic the ecosystem has been a net carbon sink. The project investigates the question of how might climate warming effect high latitude ecosystems and the Earth ecosystems and how to measure the changes.
    Keywords: Instrumentation and Photography
    Type: Proceedings of the 2004 High Spatial Resolution Commercial Imagery Workshop; SSTI-2220-0039
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  • 33
    Publication Date: 2018-06-12
    Description: This viewgraph presentation reviews the principles of establishing and verifying the traceability of remote sensing measurements to national and international scales. Doing this allows comparisons to be made independent of time or locale, and improves understanding of instrument performance, provides confidence in the accuracy of the measurements, improves measurement accuracy and helps contractors understand and meet agency requirements, protecting contractor and customer.
    Keywords: Instrumentation and Photography
    Type: Proceedings of the 2004 High Spatial Resolution Commercial Imagery Workshop; SSTI-2220-0039
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  • 34
    Publication Date: 2018-06-12
    Description: We report on follow-up observations of the gamma-ray burst GRB 060927 using the robotic ROTSE-IIIa telescope and a suite of larger aperture groundbased telescopes. An optical afterglow was detected 20 s after the burst, the earliest rest-frame detection of optical emission from any GRB. Spectroscopy performed with the VLT about 13 hours after the trigger shows a continuum break at lambda approx. equals 8070 A, produced by neutral hydrogen absorption at zeta = 5.6. We also detect an absorption line at 8158 A which we interpret as Si II lambda 1260 at zeta = 5.467. Hence, GRB 060927 is the second most distant GRB with a spectroscopically measured redshift. The shape of the red wing of the spectral break can be fitted by a damped Ly(alpha) profile with a column density with log(N(sub HI)/sq cm) = 22.50 +/- 0.15. We discuss the implications of this work for the use of GRBs as probes of the end of the dark ages and draw three main conclusions: i) GRB afterglows originating from zeta greater than or approx. equal to 6 should be relatively easy to detect from the ground, but rapid near-infrared monitoring is necessary to ensure that they are found; ii) The presence of large H I column densities in some GRBs host galaxies at zeta 〉 5 makes the use of GRBs to probe the reionization epoch via spectroscopy of the red damping wing challenging; iii) GRBs appear crucial to locate typical star-forming galaxies at zeta 〉 5 and therefore the type of galaxies responsible for the reionization of the universe.
    Keywords: Astrophysics
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  • 35
    Publication Date: 2018-06-12
    Description: We present a systematic spectral analysis of 350 bright Gamma-Ray Bursts (GRBs) observed by the Burst and Transient Source Experiment (BATSE; approx. 30 keV - 2 MeV; including 17 short GRBs) with high energy and time resolution. Our sample was selected from the complete set of 2704 BATSE GRBs based on their energy fluence or peak photon flux values to assure good statistics. To obtain well-constrained, model-unbiased spectral parameters, a set of various photon models is used to fit each spectrum, and internal characteristics of each model are also investigated. A thorough analysis has been performed on 342 time-integrated and 8459 time-resolved burst spectra, and the effects of integration times in determining the spectral parameters are explored. The analysis results presented here provide the most detailed perspective of spectral aspects of the GRB prompt emission to date. Using the results, we study correlations among spectral parameters and spectral evolutions. The results of all spectral fits are available electronically in FITS format, from the High-Energy Astrophysics Science Archive Research Center (HEASARC).
    Keywords: Astrophysics
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  • 36
    Publication Date: 2018-06-06
    Description: The broad-line radio galaxy 3C 111 has been suggested as the counterpart of the y-ray source 3EG J0416+3650. While 3C 111 meets most of the criteria for a high-probability identification, like a bright flat-spectrum radio core and a blazar-like broadband SED, in the Third EGRET Catalog, the large positional offset of about 1.5' put 3C 111 outside the 99% probability region for 3EG J0416+3650, making this association questionable. We present a re-analysis of all available archival data for 3C 111 from the EGRET archives, resulting in detection of variable hard-spectrum high-energy gamma-ray emission above 1000 MeV from a position close to the nominal position of 3C 111, in three separate viewing periods (VPs), at a 3sigma level in each. A second variable hard-spectrum source is present nearby. At 〉100 MeV, one variable soft-spectrum source seems to account for most of the EGRET-detected emission of 3EG J0416+3650. A follow-up Swift UVOT/XRT observation reveals one moderately bright X-ray source in the error box of 3EG J0416+3650, but because of the large EGRET position uncertainty, it is not certain that the X-ray and gamma-ray sources are associated. Another Swift observation near the second (unidentified) hard gamma-ray source detected no X-ray source nearby.
    Keywords: Astrophysics
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  • 37
    Publication Date: 2018-06-06
    Description: I review photo-polarimetric and spectropolarimetric observations of V838 Mon, which revealed that it had an asymmetrical inner circumstellar envelope following its 2nd photometric outburst. Electron scattering, modified by pre- or post-scattering H absorption, is the polarizing mechanism in V838 Mon's envelope. The simplest geometry implied by these observations is that of a spheroidal shell, flattened by at least 10% and having a projected position angle on the sky of approx.37deg. Analysis of V838 Mon's polarized flux reveals that this electron scattering shell lies interior to the envelope region in which Ha and Ca I1 triplet emission originates. To date, none of the theoretical models proposed for V838 Mon have demonstrated that they can reproduce the evolution of V838 Mon's inner circumstellar environment, as probed by spectropolarimetry.
    Keywords: Astrophysics
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  • 38
    Publication Date: 2018-06-06
    Description: This viewgraph presentation reviews the Laser Interferometer Space Antenna (LISA). LISA os a joint ESA-NASA project to design, build and operate a space-based gravitational wave detector. The 5 million Kilometer long detector will consist of three spacecraft orbiting the Sun in a triangular formation. Space-Time strains induced by gravitational waves are detected by measuring changes in the separation of fiducial masses with laser interferometry. LISA is expected to detect signals from merging massive black holes, compact stellar objects spiraling into super massive black holes in galactic nuclei, thousands of close binaries of compact objects in the Milky way and possible backgrounds of cosmological origin.
    Keywords: Astrophysics
    Type: LISA meeting held on 9 Apr. 2008 at the Columbia University, New York, NY
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  • 39
    Publication Date: 2018-06-06
    Description: We report the detection with the Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) of 530 Hz burst oscillations in a thermonuclear (Type I) burst from the transient X-ray source A1744-361. This is only the second burst ever observed from this source, and the first to be seen in any detail. Our results confirm that A1744-361 is a low mass X-ray binary (LMXB) system harboring a rapidly rotating neutron star. The oscillations are first detected along the rising edge of the burst, and show evidence for frequency evolution of a magnitude similar to that seen in other burst sources. The modulation amplitude and its increase with photon energy are also typical of burst oscillations. The lack of any strong indication of photospheric radius expansion during the burst suggests a 9 kpc upper limit of the source distance. We also find energy dependent dips, establishing A1744-361 as a high inclination, dipping LMXB. The timescale between the two episodes of observed dips suggests an orbital period of approx. 97 min. We have also detected a 2 - 4 Hz quasi-periodic-oscillation (QPO) for the first time from this source. This QPO appears consistent with approx. 1 Hz QPOs seen from other high inclination systems. We searched for kilohertz QPOs, and found a suggestive 2.3 sigma feature at 800 Hz in one observation. The frequency, strength and quality factor are consistent with that of a lower frequency kilohertz QPO, but the relatively low significance argues for caution, so we consider this a tentative detection requiring confirmation.
    Keywords: Astrophysics
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  • 40
    Publication Date: 2018-06-06
    Description: Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-spectrum blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.
    Keywords: Astrophysics
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  • 41
    Publication Date: 2018-06-06
    Description: We studied extended X-ray emission from the Carina Nebula taken with the Suzaku CCD camera XIS on 2005 Aug. 29. The X-ray morphology, plasma temperature and absorption to the plasma are consistent with the earlier Einstein results. The Suzaku spectra newly revealed emission lines from various spices including oxygen, but not from nitrogen. This result restricts the N/O ratio significantly low, compared with evolved massive stellar winds, suggesting that the diffuse emission is originated in an old supernova remnant or a super shell produced by multiple supernova remnants. The X-ray spectra from the north and south of eta Car showed distinct differences between 0.3-2 keV. The south spectrum shows strong L-shell lines of iron ions and K-shell lines of silicon ions, while the north spectrum shows them weak in intensity. This means that silicon and iron abundances are a factor of 2-4 higher in the south region than in the north region. The abundance variation may be produced by an SNR ejecta, or relate to the dust formation around the star forming core.
    Keywords: Astrophysics
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  • 42
    Publication Date: 2018-06-06
    Description: We analyze Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) data of the transient low mass X-ray binary (LMXB) system A1744-361. We explore the X-ray intensity and spectral evolution of the source, perform timing analysis, and find that A1744-361 is a weak LMXB, that shows atoll behavior at high intensity states. The color-color diagram indicates that this LMXB was observed in a low intensity spectrally hard (low-hard) state and in a high intensity banana state. The low-hard state shows a horizontal pattern in the color-color diagram, and the previously reported dipper QPO appears only during this state. We also perform energy spectral analyses, and report the first detection of broad iron emission line and iron absorption edge from A1744-361.
    Keywords: Astrophysics
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  • 43
    Publication Date: 2018-06-06
    Description: We have developed and investigated the use of holographic optical elements (HOEs) and holographic transmission gratings for scanning lidar telescopes. For example, rotating a flat HOE in its own plane with the focal spot on the rotation axis makes a very simple and compact conical scanning telescope. We developed and tested transmission and reflection HOEs for use at the first three harmonic wavelengths of Nd:YAG lasers. The diffraction efficiency, diffraction angle, focal length, focal spot size and optical losses were measured for several HOEs and holographic gratings, and found to be suitable for use as lidar receiver telescopes, and in many cases could also serve as the final collimating and beam steering optic for the laser transmitter. Two lidar systems based on this technology have been designed, built, and successfully tested in atmospheric science applications. This technology will enable future spaceborne lidar missions by significantly lowering the size, weight, power requirement and cost of a large aperture, narrow field of view scanning telescope.
    Keywords: Instrumentation and Photography
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  • 44
    Publication Date: 2018-06-06
    Description: Far-infrared bolometric detectors are used extensively in ground-based and space-borne astronomy, and thus it is important to understand their optical behaviour precisely. We have studied the intensity and polarisation response of free-space bolometers, and shown that when the size of the absorber is reduced below a wavelength, the response changes from being that of a classical optical detector to that of a few-mode antenna. We have calculated the modal content of the reception patterns, and found that for any volumetric detector having a side length of less than a wavelength, three magnetic and three electric dipoles characterize the behaviour. The size of the absorber merely determines the relative strengths of the contributions. The same formalism can be applied to thin-film absorbers, where the induced current is forced to flow in a plane. In this case, one magnetic and two electric dipoles characterize the behaviour. The ability to model easily the intensity, polarisation, and straylight characteristics of electrically-small detectors will be of great value when designing high-performance polarimetric imaging arrays.
    Keywords: Instrumentation and Photography
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  • 45
    Publication Date: 2018-06-06
    Description: We quantify the rapid variations in X-ray brightness ("flares") from the extremely massive colliding wind binary Eta Carinae seen during the past three orbital cycles by RXTE. The observed flares tend to be shorter in duration and more frequent as periastron is approached, although the largest ones tend to be roughly constant in strength at all phases. Plausible scenarios include (1) the largest of multi-scale stochastic wind clumps from the LBV component entering and compressing the hard X-ray emitting wind-wind collision (WWC) zone, (2) large-scale corotating interacting regions in the LBV wind sweeping across the WWC zone, or (3) instabilities intrinsic to the WWC zone. The first one appears to be most consistent with the observations, requiring homologously expanding clumps as they propagate outward in the LBV wind and a turbulence-like powerlaw distribution of clumps, decreasing in number towards larger sizes, as seen in Wolf-Rayet winds.
    Keywords: Astrophysics
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  • 46
    Publication Date: 2018-06-06
    Description: We present a study of the correlations between spectral, timing properties and mass accretion rate observed in X-rays from the Galactic Black Hole (BH) binary GRS 1915+105 during the transition between hard and soft states. We analyze all transition episodes from this source observed with Rossi X-ray Timing Explorer (RXTE), coordinated with Ryle Radio Telescope (RT) observations. We show that broad-band energy spectra of GRS 1915+105 during all these spectral states can be adequately presented by two Bulk Motion Comptonization (BMC) components: a hard component (BMC1, photon index Gamma(sub 1) = 1.7 -- 3.0) with turnover at high energies and soft thermal component (BMC2, Gamma(sub 2) = 2.7 -- 4.2) with characteristic color temperature 〈 or = 1 keV, and the red-skewed iron line (LAOR) component. We also present observable correlations between the index and the normalization of the disk "seed" component. The use of "seed" disk normalization, which is presumably proportional to mass accretion rate in the disk, is crucial to establish the index saturation effect during the transition to the soft state. We discovered the photon index saturation of the soft and hard spectral components at values of 〈 or approximately equal 4.2 and 3 respectively. We present a physical model which explains the index-seed photon normalization correlations. We argue that the index saturation effect of the hard component (BMC1) is due to the soft photon Comptonization in the converging inflow close to 1311 and that of soft component is due to matter accumulation in the transition layer when mass accretion rate increases. Furthermore we demonstrate a strong correlation between equivalent width of the iron line and radio flux in GRS 1915+105. In addition to our spectral model components we also find a strong feature of "blackbody-like" bump which color temperature is about 4.5 keV in eight observations of the intermediate and soft states. We discuss a possible origin of this "blackbody-like" emission.
    Keywords: Astrophysics
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  • 47
    Publication Date: 2018-06-06
    Description: We report the detection of a 115 day periodicity in SWIFT/XRT monitoring data from the ultraluminous X-ray source (ULX) NGC 5408 X-1. Our o ngoing campaign samples its X-ray flux approximately twice weekly and has now achieved a temporal baseline of ti 485 days. Periodogram ana lysis reveals a significant periodicity with a period of 115.5 +/- 4 days. The modulation is detected with a significance of 3.2 x 10(exp -4) . The fractional modulation amplitude decreases with increasing e nergy, ranging from 0.13 +/- 0.02 above 1 keV to 0.24 +/- 0.02 below 1 keV. The shape of the profile evolves as well, becoming less sharply peaked at higher energies. The periodogram analysis is consistent wi th a periodic process, however, continued monitoring is required to c onfirm the coherent nature of the modulation. Spectral analysis indic ates that NGC 5408 X-1 can reach 0.3 - 10 keV luminosities of approxi mately 2 x 10 40 ergs/s . We suggest that, like the 62 day period of the ULX in M82 (X41.4-1-60), the periodicity detected in NGC 5408 X-1 represents the orbital period of the black hole binary containing the ULX. If this is true then the secondary can only be a giant or super giant star.
    Keywords: Astrophysics
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  • 48
    Publication Date: 2018-06-06
    Description: We present unambiguous evidence for a parsec scale wind in the Broad-Line Radio Galaxy (BLRG) 3C 382, the first radio-loud AGN whereby an outflow has been measured with X-ray grating spectroscopy. A 118 ks Chandra grating (HETG) observation of 3C 382 has revealed the presence of several high ionization absorption lines in the soft X-ray band, from Fe, Ne, Mg and Si. The absorption lines are blue-shifted with respect to the systemic velocity of 3C 382 by -840+/-60 km/s and are resolved by Chandra with a velocity width of sigma = 340+/-70 km/s. The outflow appears to originate from a single zone of gas of column density N(sub H) = 1.3 x 10(exp 21)/sq cm and ionization parameter log(E/erg/cm/s) = 2.45. From the above measurements we calculate that the outflow is observed on parsec scales, within the likely range from 10-1000 pc, i.e., consistent with an origin in the Narrow Line Region. Finally we also discuss the possibility of a much faster (0.1c) outflow component, based on a blue-shifted iron K(alpha) emission line in the Suzaku observation of 3C 382, which could have an origin in an accretion disk wind.
    Keywords: Astrophysics
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  • 49
    Publication Date: 2018-06-06
    Description: Ultrahigh energy cosmic rays that produce giant extensive showers of charged particles and photons when they interact in the Earth's atmosphere provide a unique tool to search for new physics. Of particular interest is the possibility of detecting a very small violation of Lorentz invariance such as may be related to the structure of space-time near the Planck scale of approximately 10 (exp -35) m. We discuss here the possible signature of Lorentz invariance violation on the spectrum of ultrahigh energy cosmic rays as compared with present observations of giant air showers. We also discuss the possibilities of using more sensitive detection techniques to improve searches for Lorentz invariance violation in the future. Using the latest data from the Pierre Auger Observatory, we derive a best fit to the LIV parameter of 3 .0 + 1.5 - 3:0 x 10 (exp -23) ,corresponding to an upper limit of 4.5 x 10-23 at a proton Lorentz factor of approximately 2 x 10(exp 11) . This result has fundamental implications for quantum gravity models.
    Keywords: Astrophysics
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  • 50
    Publication Date: 2018-06-06
    Description: We present a new way of looking at the very long term evolution of GRBs in which the disk of material surrounding the putative black hole powering the GRB jet modulates the mass flow, and hence the efficacy of the process that extracts rotational energy from the black hole and inner accretion disk. The pre-Swift paradigm of achromatic, shallow-to-steep "breaks" in the long term GRB light curves has not been borne out by detailed Swift data amassed in the past several years. We argue that, given the initial existence of a fall-back disk near the progenitor, an unavoidable consequence will be the formation of an "external disk" whose outer edge continually moves to larger radii due to angular momentum transport and lack of a confining torque. The mass reservoir at large radii moves outward with time and gives a natural power law decay to the GRB light curves. In this model, the different canonical power law decay segments in the GRB identified by Zhang et al. and Nousek et al. represent different physical states of the accretion disk. We identify a physical disk state with each power law segment.
    Keywords: Astrophysics
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  • 51
    Publication Date: 2018-06-06
    Description: We describe the scientific motivations, the mission concept and the instrumentation of SPACE, a class-M mission proposed for concept study at the first call of the ESA Cosmic-Vision 2015-2025 planning cycle. SPACE aims at producing the largest three-dimensional evolutionary map of the Universe over the past 10 billion years by taking near-IR spectra and measuring redshifts of more than half a billion galaxies at 0 〈 z 〈 2 down to AB approximately 23 over 37r sr of the sky. In addition, SPACE will also target a smaller sky field, performing a deep spectroscopic survey of millions of galaxies to AB approximately 26 and at 2 〈 z 〈 l0+. Owing to the depth, redshift range, volume coverage and quality of its spectra, SPACE will reveal with unique sensitivity most of the fundamental cosmological signatures, including the power spectrum of density fluctuations and its turnover, the baryonic acoustic oscillations imprinted when matter and radiation decoupled, the distance-luminosity relation of cosmological supernovae, the evolution of the cosmic expansion rate, the growth rate of cosmic large-scale structure, the large scale distribution of galaxies. The datasets from the SPACE mission will represent a long lasting legacy that will be data mined for many years to come.
    Keywords: Astrophysics
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  • 52
    Publication Date: 2018-06-06
    Description: Since launch in December 1999, Terra MODIS has been making continuous Earth observations for more than seven years. It has produced a broad range of land, ocean, and atmospheric science data products for improvements in studies of global climate and environmental change. Among its 36 spectral bands, there are 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB). MODIS thermal emissive bands cover the mid-wave infrared (MWIR) and long-wave infrared (LWIR) spectral regions with wavelengths from 3.7 to 14.4pm. They are calibrated on-orbit using an on-board blackbody (BB) with its temperature measured by a set of thermistors on a scan-by-scan basis. This paper will provide a brief overview of MODIS TEB calibration and characterization methodologies and illustrate on-board BB functions and TEB performance over more than seven years of on-orbit operation and calibration. Discussions will be focused on TEB detector short-term stability and noise characterization, and changes in long-term response (or system gain). Results show that Terra MODIS BB operation has been extremely stable since launch. When operated at its nominal controlled temperature of 290K, the BB temperature variation is typically less than +0.30mK on a scan-by-scan basis and there has been no time-dependent temperature drift. In addition to excellent short-term stability, most TEB detectors continue to meet or exceed their specified noise characterization requirements, thus enabling calibration accuracy and science data product quality to be maintained. Excluding the noisy detectors identified pre-launch and those that occurred post-launch, the changes in TEB responses have been less than 0.7% on an annual basis. The optical leak corrections applied to bands 32-36 have been effective and stable over the entire mission
    Keywords: Instrumentation and Photography
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  • 53
    Publication Date: 2018-06-06
    Description: We present measurements of high fill-factor arrays of superconducting transition-edge x-ray microcalorimeters designed to provide rapid thermalization of the x-ray energy. We designed an x-ray absorber that is cantilevered over the sensitive part of the thermometer itself, making contact only at normal metal-features. With absorbers made of electroplated gold, we have demonstrated an energy resolution between 2.4 and 3.1 eV at 5.9 keV on 13 separate pixels. We have determined the thermal and electrical parameters of the devices throughout the superconducting transition, and, using these parameters, have modeled all aspects of the detector performance.
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  • 54
    Publication Date: 2018-06-06
    Description: We have made comparative studies of ion anisotropy and high-energy variability of solar energetic particle (SEP) events previously examined by the Solar, Heliospheric, and Interplanetary Environment (SHINE) Workshop campaign. We have found distinctly different characteristics of SEPs between two large "gradual" events having very similar solar progenitors (the 2002 April 21 and August 24 events). Since the scattering centers of SEPs are approximately frozen in the solar wind, we emphasize work in the solar-wind frame where SEPs tend to be isotropized, and small anisotropies are easier to detect. While in the August event no streaming reversal occurred, in the April event the field-aligned anisotropy of all heavy ions showed sign of streaming reversal. The difference in streaming reversal was consistent with the difference in the presence of the outer reflecting boundary. In the April event the magnetic mirror, which was located behind the interplanetary shock driven by the preceding coronal mass ejection (CME), could block the stream of SEPs, while in the August event SEPs escaped freely because of the absence of nearby boundary. The magnetic mirror was formed at the bottleneck of magnetic field lines draped around a flank of the preceding CME. In the previous SHINE event analysis the contrasting event durations and Fe/O ratios of the both events were explained as the interplay between shock geometry and seed population. Our new findings, however, indicate that event duration and time as well as spectral variation are also affected by the presence of a nearby reflecting boundary.
    Keywords: Astrophysics
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  • 55
    Publication Date: 2018-06-06
    Description: We report the results of more than seven years of monitoring of PSR J0537-6910, the 16 ms pulsar in the Large Magellanic Cloud, using data acquired with the Rossi X-ray Timing Explorer. During this campaign the pulsar experienced 22 sudden increases in frequency ("glitches" - 21 with increases of at least eight microHz) amounting to a total gain of over six parts per million of rotation frequency superposed on its gradual spindown of nu-dot = -2 x 10(exp -l0) Hz /s. The time interval from one glitch to the next obeys a strong linear correlation to the amplitude of the first glitch, with a mean slope of about 400 days per part per million (6.5 days per micro Hz), such that these intervals can be predicted to within a few days, an accuracy which has never before been seen in any other pulsar. There appears to be an upper limit of approximately 40 micro Hz for the size of glitches in all pulsars, with the 1999 April glitch of PSR J0537-6910 as the largest so far. The change of its spindown across the glitches, delta (nu-dot), appears to have the same hard lower limit of -1.5 x 10 (exp -13) Hz/s, as, again, that observed in all other pulsars. The spindown continues to increase in the long term, nu-dot = -10(exp -21) Hz / s(exp 2), and thus the timing age of PSR 505374910 (-0.5 nu nu-dot (exp -1) continues to decrease at a rate of nearly one year every year, consistent with movement of its magnetic moment away from its rotational axis by one radian every 10,000 years, or about one meter per year. PSR J0537-6910 was likely to have been born as a nearly-aligned rotator spinning at 75-80 Hz, with a absolute value of nu considerably smaller than its current value of 2x 10(exp -10) Hz per second. Its pulse profile consists of a single pulse which is found to be flat at its peak for at least 0.02 cycles. Glitch activity may grow exponentially with a timescale of 170 years nu nu-dot ((nu nu-dot)(sub crab))exp -l in all young pulsars.
    Keywords: Astrophysics
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  • 56
    Publication Date: 2018-06-06
    Description: The ultra-sharp images of the Stellar Imager (SI) will revolutionize our view of many dynamic astrophysical processes: The 0.1 milliarcsec resolution of this deep-space telescope will transform point sources into extended sources, and simple snapshots into spellbinding evolving views. SI s science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI s prime goal is to enable long-term forecasting of solar activity and the space weather that it drives in support of the Living With a Star program in the Exploration Era by imaging a sample of magnetically active stars with enough resolution to map their evolving dynamo patterns and their internal flows. By exploring the Universe at ultra-high resolution, SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magnetohydrodynamically controlled structures and processes in the Universe.
    Keywords: Astrophysics
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  • 57
    Publication Date: 2018-06-06
    Description: Table 1 in our paper had erroneous numbers for the coefficients fitting the parametric form for the optical depth of the universe to gamma-rays; tau. The correct values for these parameters as described in the original text are given in the table for various redshifts for the baseline model (upper row) and fast evolution (lower row) for each individual redshift.
    Keywords: Astrophysics
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  • 58
    Publication Date: 2018-06-06
    Description: The GLAST Large Area Telescope (LAT) science objectives and capabilities in the detection of high energy electrons in the energy range from 20 GeV to approx. 1 TeV are presented. LAT simulations are used to establish the event selections. It is found that maintaining the efficiency of electron detection at the level of 30% the residual hadron contamination does not exceed 2-3% of the electron flux. LAT should collect approx. ten million of electrons with the energy above 20 GeV for each year of observation. Precise spectral reconstruction with high statistics presents us with a unique opportunity to investigate several important problems such as studying galactic models of IC radiation, revealing the signatures of nearby sources such as high energy cutoff in the electron spectrum, testing the propagation model, and searching for KKDM particles decay through their contribution to the electron spectrum.
    Keywords: Astrophysics
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  • 59
    Publication Date: 2018-06-06
    Description: Non-photospheric-radius-expansion(non-PRE) double-peaked bursts may be explained in terms of spreading (and temporary stalling) of thermonuclear flames on the neutron star surface, as we argued in a previous study of a burst assuming polar ignition. Here we analyze Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) data of such a burst (but with a considerably different intensity profile from the previous one) from the low mass X-ray binary (LMXB) system 4U 1636-536, and show that this model can qualitatively explain the observed burst profile and spectral evolution, if we assume an off-polar, but high-latitude ignition, and burning front stalling at a higher latitude compared to that for the previous burst. The off-polar ignition can account for the millisecond period brightness oscillations detected from this burst. This is the first time oscillations have been seen from such a burst. Our model can qualitatively explain the oscillation amplitude measured during the first (weaker) peak, and the absence of oscillations during the second peak. The higher latitude front stalling facilitates the first clear detection of a signature of this stalling, which is the primary result of this work, and may be useful for understanding thermonuclear flame spreading on neutron stars.
    Keywords: Astrophysics
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  • 60
    Publication Date: 2018-06-06
    Description: We report an analysis of the archival Rossi X-ray Timing Explorer (RXTE) data from the December 2004 hyperflare from SGR 1806-20. In addition to the approx. equal to 90 Hz QPO first discovered by Israel et al., we report the detection of higher frequency oscillations at approx. equal to 150, 625, and 1,835 Hz. In addition to these frequencies there are indications of oscillations at approx. equal to 720, and 2,384 Hz, but with lower significances. The 150 Hz QPO has a width (FWHM) of about 17 Hz, an average amplitude (rms) of 6.5%, and is detected in average power spectra centered on the rotational phase of the strongest peak in the pulse profile. This is approximately half a rotational cycle from the phase at which the 90 Hz QPO is strongly detected. The 625 Hz oscillation was first detected in an average power spectrum from nine successive cycles beginning approximately 180 s after the initial hard spike. It has a width (FWHM) of approx. equal to 2 Hz and an average amplitude (rms) during this interval of 9%. We find a strong detection of the 625 Hz oscillation in a pair of successive rotation cycles beginning about 230 s after the start of the flare. In these cycles we also detect the 1,835 Hz QPO with the 625 Hz oscillation. The rotational phase in which the 625 Hz &PO is detected is similar to that for the 90 Hz QPO, indeed, this feature is seen in the same average power spectrum. During the time the 625 Hz QPO is detected we also confirm the simultaneous presence of 30 and 92 Hz QPOs, first reported by Israel et al. The centroid frequency of the 625 Hz QPO detected with RXTE is within 1 Hz of the M 626 Hz oscillation recently found in RHESSI data from this hyperflare by Watts & Strohmayer, however, the two detections were made in different phase and energy intervals. Nevertheless, we argue that the two results likely represent detections of the same oscillation frequency intrinsic to the source, but we comment on some of the difficulties in making direct comparisons between the RXTE and RHESSI measurements
    Keywords: Astrophysics
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  • 61
    Publication Date: 2018-06-06
    Description: As part of the automated response to a new gamma-ray burst (GRB), the Ultraviolet and Optical Telescope (UVOT) instrument on Swift starts a 200-second exposure with the V filter within approximately 100 seconds of the BAT burst trigger. The instrument searches for sources in a 8' x 8' region, and sends the list of sources and a 160" x 160" sub-image centered on the burst position to the ground via Tracking and Data Relay Satellite System (TDRSS). These raw products and additional products calculated on the ground are then distributed through the GCN within a few minutes of the trigger. We describe the sensitivity of these data for detecting afterglows, summarize current results, and outline plans for rapidly distributing future detections.
    Keywords: Astrophysics
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  • 62
    Publication Date: 2018-06-06
    Description: We have obtained Fourier-resolved spectra of the black-hole binary 4U 1543-47 in the canonical states (high/soft, very high, intermediate and low/hard) observed in this source during the decay of an outburst that took place in 2002. Our objective is to investigate the variability of the spectral components generally used to describe the energy spectra of black-hole systems, namely a disk component, a power-law component attributed to Comptonization by a hot corona and the contribution of the iron line due to reprocessing of the high energy (E greater than or approx, equal to 7 keV) radiation. We find that i) the disk component is not variable on time scales shorter than approx. 100 seconds, ii) the reprocessing emission as manifest by the variability of the Fe K(alpha) line responds to the primary radiation variations down to time scales of approx. 70 ms in the high and very-high states, but longer than 2 s in the low state, iii) the low-frequency QPOs are associated with variations of the X-ray power law spectral component and not to the disk component and iv) the spectra corresponding to the highest Fourier frequency are the hardest (show the flatter spectra) at a given spectral state. These results questions the models that explain the observed power spectra as due to modulations of the accretion rate only.
    Keywords: Astrophysics
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  • 63
    Publication Date: 2018-06-06
    Description: Contents include the following: 1. Funded instruments in development. Advanced technology microwave sounder (ATMS) on NPOESS preperatory mission (NPP). Aquarius microwave radiometer. Global precipitation measurement (GPM) microwave imager (GMI). Hydros microwave radiometer. 2. Proposed/notional instruments. Cirrus clouds submmw radiometer. Cold-lends microwave radiometer. Geostationary millimeterwave radiometer (GeoSTAR). Geostationary soil moisture and salinity radiometer.
    Keywords: Instrumentation and Photography
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  • 64
    Publication Date: 2018-06-06
    Description: The dependence of Swift#s detection sensitivity on a burst#s temporal and spectral properties shapes the detected burst population. Using s implified models of the detector hardware and the burst trigger syste m I find that Swift is more sensitive to long, soft bursts than CGRO# s BATSE, a reference mission because of its large burst database. Thu s Swift has increased sensitivity in the parameter space region into which time dilation and spectral redshifting shift high redshift burs ts.
    Keywords: Astrophysics
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  • 65
    Publication Date: 2018-06-06
    Description: This paper describes the development of a Framework for benchmarking and comparing signal-extraction and noise-interference-removal methods that are applicable to interferometric Gravitational Wave detector systems. The primary use is towards comparing signal and noise extraction techniques at LISA frequencies from multiple (possibly confused) ,gravitational wave sources. The Framework includes extensive hybrid learning/classification algorithms, as well as post-processing regularization methods, and is based on a unique plug-and-play (component) architecture. Published methods for signal extraction and interference removal at LISA Frequencies are being encoded, as well as multiple source noise models, so that the stiffness of GW Sensitivity Space can be explored under each combination of methods. Furthermore, synthetic datasets and source models can be created and imported into the Framework, and specific degraded numerical experiments can be run to test the flexibility of the analysis methods. The Framework also supports use of full current LISA Testbeds, Synthetic data systems, and Simulators already in existence through plug-ins and wrappers, thus preserving those legacy codes and systems in tact. Because of the component-based architecture, all selected procedures can be registered or de-registered at run-time, and are completely reusable, reconfigurable, and modular.
    Keywords: Astrophysics
    Type: LISA Science Analysis
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  • 66
    Publication Date: 2018-06-06
    Description: A great deal of work has been devoted to the accumulation of accurate quantities describing atomic processes for use in analysis of astrophysical spectra. But in many situations of interest the interpretation of a quantity which is observed, such as a line flux, depends on the results of a modeling- or spectrum synthesis code. The results of such a code depends in turn on many atomic rates or cross sections, and the sensitivity of the observable quantity on the various rates and cross sections may be non-linear and if so cannot easily be derived analytically. This paper describes simple numerical experiments designed to examine some of these issues. Similar studies have been carried out previously in the context of solar UV lines by Gianetti et al. (2000); Savin & Laming (2002) and in the context of the iron M shell UTA in NGC 3783 by Netzer (2004).
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 124-128; NASA/CP-2006-214549
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  • 67
    Publication Date: 2018-06-06
    Description: Molecule specific astronomical observations rely on precisely determined laboratory molecular data for interpretation. The Herschel Heterodyne Instrument for Far Infrared, a suite of SOFIA instruments, and ALMA are each well placed to expose the limitations of available molecular physics data and spectral line catalogs. Herschel and SOFIA will observe in high spectral resolution over the entire far infrared range. Accurate data to previously unimagined frequencies including infrared ro-vibrational and ro-torsional bands will be required for interpretation of the observations. Planned ALMA observations with a very small beam will reveal weaker emission features requiring accurate knowledge of higher quantum numbers and additional vibrational states. Historically, laboratory spectroscopy has been at the front of submillimeter technology development, but now astronomical receivers have an enormous capability advantage. Additionally, rotational spectroscopy is a relatively mature field attracting little interest from students and funding agencies. Molecular data base maintenance is tedious and difficult to justify as research. This severely limits funding opportunities even though data bases require the same level of expertise as research. We report the application of some relatively new receiver technology into a simple solid state THz spectrometer that has the performance required to collect the laboratory data required by astronomical observations. Further detail on the lack of preparation for upcoming missions by the JPL spectral line catalog is given.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 233-238; NASA/CP-2006-214549
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  • 68
    Publication Date: 2018-06-06
    Description: A simple exponential-potential model of molecular collisions leads to a two-parameter analytic expression for rates of collisionally induced vibrational-translation (VT) energy exchange that has been shown to be accurate over variations of orders of magnitude as a function of temperature in a variety of systems. This includes excellent agreement with reported experimental and theoretical results for the fundamental self-relaxation rate of molecular hydrogen H2(v = 1) + H2 yields H2(v = 0) + H2. The analytic rate successfully follows the five-orders-of-magnitude change in experimental values for the temperature range 50-2000 K. This approach is now applied to isotope effects in the vibrational relaxation rates of excited HD and D2 in collision with H2: HD(v = 1)+H2 yields HD(v = 0)+H2 and D2(v = 1)+H2 yields D2(v = 0)+H2. The simplicity of the analytic expression for the thermal rate lends itself to convenient application in modeling the evolving vibrational populations of molecular hydrogen in shocked astrophysical environments.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 299-302; NASA/CP-2006-214549
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  • 69
    facet.materialart.
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    In:  CASI
    Publication Date: 2018-06-06
    Description: Spectroscopy of comets, in the X-ray and far-ultraviolet from space, and in the near infrared and millimeter from the ground, have revealed a wealth of new information, particularly about the molecular constituents that make up the volatile fraction of the comet s nucleus. Interpretation of these data requires not only proper wavelengths for identification but also information about the photolytic and excitation processes at temperatures typical of the inner coma (70-100 K) that lead to the observed spectral signatures. Several examples, mainly from Far Ultraviolet Spectroscopic Explorer and Hubble Space Telescope spectra of comets observed during the last few years, will be given to illustrate some of the current issues.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 62-67; NASA/CP-2006-214549
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  • 70
    Publication Date: 2018-06-06
    Description: A detailed knowledge of the formation of carbon-bearing molecules in interstellar ices and in the gas phase of the interstellar medium is of paramount interest to understand the astrochemical evolution of extraterrestrial environments (1). This research also holds strong implications to comprehend the chemical processing of Solar System environments such as icy planets and their moons together with the atmospheres of planets and their satellites (2). Since the present composition of each interstellar and Solar System environment reflects the matter from which it was formed and the processes which have changed the chemical nature since the origin (solar wind, planetary magnetospheres, cosmic ray exposure, photolysis, chemical reactions), a detailed investigation of the physicochemical mechanisms altering the pristine environment is of paramount importance to grasp the contemporary composition. Once these underlying processes have been unraveled, we can identify those molecules, which belonged to the nascent setting, distinguish molecular species synthesized in a later stage, and predict the imminent chemical evolution of, for instance, molecular clouds. Laboratory experiments under controlled physicochemical conditions (temperature, pressure, chemical composition, high energy components) present ideal tools for simulating the chemical evolution of interstellar and Solar System environments. Here, laboratory experiments can predict where and how (reaction mechanisms; chemicals necessary) in extraterrestrial environments and in the interstellar medium complex, carbon bearing molecules can be formed on interstellar grains and in the gas phase. This paper overviews the experimental setups utilized in our laboratory to mimic the chemical processing of gas phase and solid state (ices) environments. These are a crossed molecular beams machine (3) and a surface scattering setup (4). We also present typical results of each setup (formation of amino acids, aldehydes, epoxides; synthesis of hydrogen terminated carbon chains as precursors to complex PAHs and to carbonaceous dust grains in general; nitriles as precursor to amino acids).
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 68-72; NASA/CP-2006-214549
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  • 71
    Publication Date: 2018-06-06
    Description: Our present knowledge of the molecular universe has come primarily from radio observations [ I include here millimeter and submillimeter in this rubric]. There are a number of reasons for this but the primary one is the extremely high spectral resolution. The ease of observing emission from the volume of dense molecular clouds without significant attenuation by scattering from dust has shown this to be the powerful observational tool for molecular astronomy. Finally the relative simplicity of rotational compared to vibrational or electronic spectroscopy allows carrier identification as well as facile evaluation of cloud conditions such as density and temperature. These virtues become tenuous as the astronomical observations are pushed to higher frequencies for enhanced observational sensitivity. Thus precision rest frequencies are mandatory for the search for new species. We may inquire about which new species require particular attention, and which species may be relatively safely predicted on the basis of lower frequency laboratory measurements. For a rigid rotor the three rotational constants are sufficient to completely specify the transition frequencies. The intensities require the three components of the electric dipole moment. For semirigid species, where the centrifugal distortion, may be treated at the quartic level of angular momentum (Bunker et al. 1998), up to five additional constants are required (Watson 1967). There are a number of such species of considerable interest, where laboratory measurements are adequate for astronomical searches.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 133-135; NASA/CP-2006-214549
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  • 72
    Publication Date: 2018-06-06
    Description: The cooling of neutral gas of primordial composition, or with very low levels of metal enrichment, depends crucially on the formation of molecular coolants, such as H2 and HD within the gas. Although the chemical reactions involved in the formation and destruction of these molecules are well known, the same cannot be said for the rate coefficients of these reactions, some of which are uncertain by an order of magnitude. Here we discuss two reactions for which large uncertainties exist the formation of H2 by associative detachment of H- with H and the destruction of H- by mutual neutralization with protons. We show that these uncertainties can have a dramatic impact on the effectiveness of cooling during protogalactic collapse.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 248-251; NASA/CP-2006-214549
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  • 73
    facet.materialart.
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    In:  CASI
    Publication Date: 2018-06-06
    Description: Disks represent a crucial stage in the formation of stars and planets. They are novel astrophysical systems with attributes intermediate between the interstellar medium and stars. Their physical properties are inhomogeneous and are affected by hard stellar radiation and by dynamical evolution. Observing disk structure is difficult because of the small sizes, ranging from as little as 0.05 AU at the inner edge to 100-1000 AU at large radial distances. Nonetheless, substantial progress has been made by observing the radiation emitted by the dust from near infrared to mm wavelengths, i.e., the spectral energy distribution of an unresolved disk. Many fewer results are available for the gas, which is the main mass component of disks over much of their lifetime. The inner disk gas of young stellar objects (henceforth YSOs) have been studied using the near infrared rovibrational transitions of CO and a few other molecules, while the outer regions have been explored with the mm and sub-mm lines of CO and other species. Further progress can be expected in understanding the physical properties of disks from observations with sub-mm arrays like SMA, CARMA and ALMA, with mid infrared measurements using Spitzer, and near infrared spectroscopy with large ground-based telescopes. Intense efforts are also being made to model the observations using complex thermal-chemical models. After a brief review of the existing observations and modeling results, some of the weaknesses of the models will be discussed, including the absence of good laboratory and theoretical calculations for essential microscopic processes.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 34-44; NASA/CP-2006-214549
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  • 74
    Publication Date: 2018-06-06
    Description: The purpose of this investigation was to produce fluorescence spectra of polycyclic aromatic hydrocarbon (PAH) molecules in the gas-phase for comparison with blue luminescence (BL) emission observed in astrophysical sources Vijh et al. (2004, 2005a,b). The BL occurs roughly from 350 to 450 nm, with a sharp peak near 380 nm. PAHs with three to four rings, e.g. anthracene and pyrene, were found to produce luminescence in the appropriate spectral region, based on existing studies. Relatively few studies of the gas-phase fluorescence of PAHs exist; those that do exist have dealt primarily with the same samples commonly available for purchase such as pyrene and anthracene. In an attempt to understand the chemistry of the nebular environment we also obtained several nitrogen substituted PAHs from our colleagues at NASA Ames. In order to simulate the astrophysical environment we also took spectra by heating the PAHs in a flame. The flame environment counteracts the formation of eximers and permits the spectroscopy of free-flying neutral molecules. Experiments with coal tar demonstrate that fluorescence spectroscopy reveals primarily the presence of the smallest molecules, which are most abundant and which possess the highest fluorescence efficiencies. One gas-phase PAH that seems to fit the BL spectrum most closely is phenanthridine. In view of the results from the spectroscopy of coal tar, a compound containing a mixture of PAHs ranging from small to very large PAH molecules, we can not preclude the presence of larger PAHs in interstellar sources exhibiting BL.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 264-267; NASA/CP-2006-214549
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  • 75
    Publication Date: 2018-06-06
    Description: Laboratory astrophysics and complementary theoretical calculations are the foundations of astronomical and planetary research and will remain so for many generations to come. From the level of scientific conception to that of the scientific return, it is our understanding of the underlying processes that allows us to address fundamental questions regarding the origins and evolution of galaxies, stars, planetary systems, and life in the cosmos. In this regard, laboratory astrophysics is much like detector and instrument development at NASA and NSF; these efforts are necessary for the astronomical research being funded by the agencies. The NASA Laboratory Astrophysics Workshop met at the University of Nevada, Las Vegas (UNLV) from 14-16 February, 2006 to identify the current laboratory data needed to support existing and future NASA missions and programs in the Astrophysics Division of the Science Mission Directorate (SMD). Here we refer to both laboratory and theoretical work as laboratory astrophysics unless a distinction is necessary. The format for the Workshop involved invited talks by users of laboratory data, shorter contributed talks and poster presentations by both users and providers that highlighted exciting developments in laboratory astrophysics, and breakout sessions where users and providers discussed each others' needs and limitations. We also note that the members of the Scientific Organizing Committee are users as well as providers of laboratory data. As in previous workshops, the focus was on atomic, molecular, and solid state physics.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 1-15; NASA/CP-2006-214549
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  • 76
    Publication Date: 2018-06-06
    Description: The interpretation of cosmic spectra relies on a vast sea of atomic data which are not readily obtainable from analytic expressions or simple calculations. Rather, their evaluation typically requires state-of-the-art atomic physics calculations, with the inclusion of weaker effects (spin-orbit and configuration interactions, relaxation, Auger broadening, etc.), to achieve the level of accuracy needed for use by astrophysicists. Our NASA-supported research program is focused on calculating data for three important atomic processes, 1) dielectronic recombination (DR), 2) inner-shell photoabsorption, and 3) fluorescence and Auger decay of inner-shell vacancy states. Some additional details and examples of our recent findings are given.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 190-193; NASA/CP-2006-214549
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  • 77
    Publication Date: 2018-06-06
    Description: Recent JPL absolute excitation and charge exchange cross sections, and measurements of lifetimes of metastable levels in highly-charged ions (HCIs) are reported. These data provide benchmark comparisons to results of theoretical calculations. Theoretical approaches can then be used to calculate the vast array of data which cannot be measured due to experimental constraints. Applications to the X-ray emission from comets are given.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 129-132; NASA/CP-2006-214549
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  • 78
    Publication Date: 2018-06-06
    Description: High-resolution measurements of K-shell emission from O, F, and Ne have been performed at the ASDEX Upgrade tokamak in Garching, Germany. Independently measured temperature and density profiles of the plasma provide a unique test bed for model validation. We present comparisons of measured spectra with calculations based on transport and collisional-radiative models and discuss the reliability of commonly used diagnostic line ratios.
    Keywords: Astrophysics
    Type: Proceedings of the NASA Laboratory Astrophysics Workshop; 198-201; NASA/CP-2006-214549
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  • 79
    Publication Date: 2018-06-12
    Description: The Energetic X-ray Imaging Survey Telescope (EXIST), under study to be the Black Hole Finder Probe in NASA's Beyond Einstein Program, would image the sky every 95 min in the energy range 10-600 keV. Although the main scientific objectives of EXIST are the systematic, all-sky survey of heavily obscured AGNs and gamma-ray bursts, there is a substantial capability of EXIST for the observation of transient and persistent hard X-ray lines from several astrophysical sources.
    Keywords: Astrophysics
    Type: New Astronomy Reviews (ISSN 1387-6473); Volume 50; 637-639
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  • 80
    Publication Date: 2018-06-12
    Description: Scheduled to begin its 10 year mission no sooner than 2013, the James Webb Space Telescope (JWST) will search for the first luminous objects of the Universe to help answer fundamental questions about how the Universe came to look like it does today. At 6.5 meters in diameter, JWST will be the world's largest space telescope. This talk reviews science objectives for JWST and how they drive the JWST architecture, e.g. aperture, wavelength range and operating temperature. Additionally, the talk provides an overview of the JWST primary mirror technology development and fabrication status.
    Keywords: Instrumentation and Photography
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  • 81
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    In:  Other Sources
    Publication Date: 2018-06-05
    Description: The three instruments on the Orbiter Boom Sensor System (OBSS) will use a mix of U.S. and Canadian developed laser, television, infrared, and 3D imaging technologies. The sensors are the: 1) Laser Dynamic Range Imager (LDRI); 2) Intensified Television Camera (ITVC); 3) Laser Camera System (LCS).
    Keywords: Instrumentation and Photography
    Type: Aviation Week and Space Technology (ISSN 0005-2175); Volume 162; No. 18; 46
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  • 82
    Publication Date: 2018-06-02
    Description: As part of basic and applied research on advanced instrumentation technologies, the NASA Glenn Research Center is examining applications for sonoluminescence: ultrasonically produced glowing bubbles that are hotter than the Sun. In the last decade, those outside of the ultrasonic community have become interested in understanding sonoluminescence and in using some of its more interesting properties. First discovered in the 1930s as a byproduct of early work on sonar, the phenomenon is defined as the generation of light energy from sound waves. This glow, which was originally thought to be a form of static electricity, was found to be generated in flashes of much less than a billionth of a second that result when microscopic bubbles of air collapse. The temperature generated in the collapsing bubbles is at least 4 times that of the surface of the Sun.
    Keywords: Astrophysics
    Type: Research and Technology 2004; NASA/TM-2005-213419
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  • 83
    Publication Date: 2018-06-06
    Description: Based upon analysis of the entire EGRET data from Mrk 421, it is found that the time-averaged spectra are inconsistent with the predictions of current theoretical models that have had success in describing simultaneous X-ray/TeV observations, and suggest additional components in the GeV band, as well as complex time variability. Current theoretical pictures explain the GeV emission as comptonization of the synchrotron photons in the jet, and predict hard spectra that should join smoothly with the TeV emission. Our analysis shows that the situation is more complex. The spectrum ranges from hard to soft during individual epochs, and shows a convext break in the aggregated data. We also present the mission-averaged EGRET spectrum for PKS 2155-304, which shows a similar (but not as pronounced) convex curvature. We discuss a series of possible explanations for the 10(exp 22) - 10(exp 23) HZ declining part of the EGRET nu F(sub nu), spectrum for Mrk 421, and suggest that it is synchrotron emission from the high energy tail of the electron population that produces the X-rays during the highest X-ray states. Such multi-MeV photons are produced by electrons accelerated close to the limit of diffusive shock acceleration. Simultaneous GLAST and X-ray observations of high X-ray states will address the issue of the convex curvature in the future.
    Keywords: Astrophysics
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  • 84
    facet.materialart.
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    In:  CASI
    Publication Date: 2018-06-06
    Description: The giant flares produced by highly magnetized neutron stars, "magnetars," are the brightest sources of high energy radiation outside our solar system. Serendipitous observations with NASA's Rossi X-ray Timing Explorer (RXTE) of the two most recent flares resulted in the discovery of high frequency oscillations in their X-ray fluxes. The frequencies of these oscillations range from approx. 20 Hz to as high as 1800 Hz, and may represent the first detection of global oscillation modes of neutron stars. Here I will present an observational and theoretical overview of these oscillations and discuss how they might allow us to probe neutron star interiors and dense matter physics.
    Keywords: Astrophysics
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  • 85
    Publication Date: 2018-06-06
    Description: Although the Space Infrared Interferometric Telescope (SPIRIT) was studied as a candidate NASA Origins Probe mission, the real world presents a broader set of options, pressures, and constraints. Fundamentally, SPIRIT is a far-IR observatory for high-resolution imaging and spectroscopy designed to address a variety of compelling scientific questions. How do planetary systems form from protostellar disks, dousing some planets in water while leaving others dry? Where do planets form, and why are some ice giants while others are rocky? How did high-redshift galaxies form and merge to form the present-day population of galaxies? This paper takes a pragmatic look at the mission design solution space for SPIRIT, presents Probe-class and facility-class mission scenarios, and describes optional design changes. The costs and benefits of various mission design alternatives are roughly evaluated, giving a basis for further study and to serve as guidance to policy makers.
    Keywords: Instrumentation and Photography
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  • 86
    Publication Date: 2018-06-06
    Description: We have developed a method for constructing a spectrum of the particle-induced instrumental background of the XMM-Newton EPIC MOS detectors that can be used for observations of the diffuse background and extended sources that fill a significant fraction of the instrument field of view. The strength and spectrum of the particle-induced background, that is, the background due to the interaction of particles with the detector and the detector surroundings, is temporally variable as well as spatially variable over individual chips. Our method uses a combination of the filter-wheel-closed data and a database of unexposed-region data to construct a spectrum of the "quiescent" background. We show that, using this method of background subtraction, the differences between independent observations of the same region of "blank sky" are consistent with the statistical uncertainties except when there is clear evidence of solar wind charge exchange emission. We use the blank sky observations to show that contamination by SWCX emission is a strong function of the solar wind proton flux, and that observations through the flanks of the magnetosheath appear to be contaminated only at much higher solar wind fluxes. We have also developed a spectral model of the residual soft proton flares, which allows their effects to be removed to a substantial degree during spectral fitting.
    Keywords: Astrophysics
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  • 87
    Publication Date: 2018-06-06
    Description: We report the finding of an unusual, weak precursor to a thermonuclear X-ray burst from the accreting millisecond pulsar SAX 51808.4-3658. The burst in question was observed on Oct. 19, 2002 with the Rossi X-Ray Timing Explorer (RXTE) proportional counter array (PCA). The precursor began approx. equal to 1 s prior to the onset of a strong radius expansion burst, lasted for about 0.4 s, and exhibited strong oscillations at the 401 Hz spin frequency. Oscillations are not detected in the approx. equal to 0.5 s interval between the precursor and the main burst. The estimated peak photon flux and energy fluence of the precursor are about 1/25, and 1/500 that of the main burst, respectively. From joint spectral and temporal modeling, we find that an expanding burning region with a relatively low temperature on the spinning neutron star surface can explain the oscillations, as well as the faintness of the precursor with respect to the main part of the burst. We discuss some of the implications of our findings for the ignition and spreading of thermonuclear flames on neutron stars.
    Keywords: Astrophysics
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  • 88
    Publication Date: 2018-06-06
    Description: We have measured the infrared transit of the extrasolar planet HD 209458 b using the Spitzer Space Telescope. We observed two primary eclipse events (one partial and one complete transit) using the 24 micrometer array of the Multiband Imaging Photometer for Spitzer (MIPS). We analyzed a total of 2392 individual images (10-second integrations) of the planetary system, recorded before, during, and after transit. We perform optimal photometry on the images and use the local zodiacal light as a short-term flux reference. At this long wavelength, the transit curve has a simple box-like shape, allowing robust solutions for the stellar and planetary radii independent of stellar limb darkening, which is negligible at 24 micrometers. We derive a stellar radius of R(sub *) = 1.06 plus or minus 0.07 solar radius, a planetary radius of R(sub p) = 1.26 plus or minus 0.08 R(sub J), and a stellar mass of 1.17 solar mass. Within the errors, our results agree with the measurements at visible wavelengths. The 24 micrometer radius of the planet therefore does not differ significantly compared to the visible result. We point out the potential for deriving extrasolar transiting planet radii to high accuracy using transit photometry at slightly shorter IR wavelengths where greater photometric precision is possible.
    Keywords: Astrophysics
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  • 89
    Publication Date: 2018-06-06
    Description: Gamma-ray lines are produced in nature by a variety of different physical processes. They can be valuable astrophysical diagnostics providing information the may be unobtainable by other means. We have carried out an extensive search for gamma-ray lines in the first year of public data from the Spectrometer (SPI) on the INTEGRAL mission. INTEGRAL has spent a large fraction of its observing time in the Galactic Plane with particular concentration in the Galactic Center (GC) region (approximately 3 Msec in the first year). Hence the most sensitive search regions are in the Galactic Plane and Center. The phase space of the search spans the energy range 20-8000 keV, and line widths from 0-1000 keV (FWHM) and includes both diffuse and point-like emission. We have searched for variable emission on time scales down to approximately 1000 sec. Diffuse emission has been searched for on a range of different spatial scales from approximately 20 degrees (the approximate field-of-view of the spectrometer) up to the entire Galactic Plane. Our search procedures were verified by the recovery of the known gamma-ray lines at 511 keV and 1809 keV at the appropriate intensities and significances. We find no evidence for any previously unknown gamma-ray lines. The upper limits range from a few x10(exp -5) per square centimeter per second to a few x10(exp -3) per square centimeter per second depending on line width, energy and exposure. Comparison is made between our results and various prior predictions of astrophysical lines
    Keywords: Astrophysics
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  • 90
    Publication Date: 2018-06-06
    Description: We present new techniques for evolving binary black hole systems which allow the accurate determination of gravitational waveforms directly from the wave zone region of the numerical simulations. Rather than excising the black hole interiors, our approach follows the "puncture" treatment of black holes, but utilizing a new gauge condition which allows the black holes to move successfully through the computational domain. We apply these techniques to an inspiraling binary, modeling the radiation generated during the final plunge and ringdown. We demonstrate convergence of the waveforms and and good conservation of mass-energy, with just over 3% of the system s mass converted to gravitational radiation.
    Keywords: Astrophysics
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  • 91
    Publication Date: 2018-09-11
    Description: A technique involving Fe-55 X-rays provides a straightforward method to measure the response of a detector. The detector's response can lead directly to a calculation of the conversion gain (e(-) ADU(-1) ), as well as aid detector design and performance studies. We calibrate the Fe-15 X-ray energy response and pair production energy of HgCdTe using 8 HST WFC3 1.7 micron flight grade detectors. The results show that each Ka X-ray generates 2273 +/- 137 electrons, which corresponds to a pair-production energy of 2.61 +/- 0.16 eV. The uncertainties are dominated by our knowledge of the conversion gain. In future studies, we plan to eliminate this uncertainty by directly measuring conversion gain at very low light levels.
    Keywords: Astrophysics
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  • 92
    Publication Date: 2018-08-10
    Description: The accurate determination of a detector's fundamental parameters, including read noise, dark current, and QE, relies on a proper measurement of a detector's conversion gain (e- ADU(exp -1)). Charge coupling effects, such as interpixel capacitance, attenuate photon shot noise and result in an overestimation of conversion gain when implementing the photon transfer technique. An approach involving (55)Fe X-rays provides a potentially straightforward measurement of conversion gain by comparing the observed instrumental counts (ADU) to the known charge (e-) liberated by the X-ray. This technique is already preferred within the CCD community, as the pair production energy for silicon is well established. In contrast, to date the pair production energy is unknown for HgCdTe, a material commonly used for near-infrared detectors. In this paper, we derive a preliminary calibration of the (55)Fe X-ray energy response of HgCdTe using 8 HST WFC3 1.7 micrometers flight grade detectors. Our conversion of the X-ray intensities from counts into electrons implements a technique that restores the 'true' gain via classical propagation of errors. For these detectors, our analysis yields preliminary results of good statistical precision: each Ka event generates 1849 +/- 46 electrons, which corresponds to a pair production energy of 3.21+/-f 0.08 eV. We are continuing to assess potential systematic effects to further refine the accuracy of this result.
    Keywords: Instrumentation and Photography
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  • 93
    Publication Date: 2018-08-10
    Description: Aims: The aim of this work is to investigate the dynamic behavior of a C-class solar flare through the evolution of temperature, emission measure, energy loss and velocity. In particular, the variation of these properties with time are studied using multi-wavelength observations in combination with a recently developed 0-D hydrodynamic model. Methods: The temperature and emission measure evolution were studied using several instruments covering a wide range of temperatures - the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI, 〉5 MK), GOES-12 (5- 30 MK), the Transition Region and Coronal Explorer (TRACE 171 A, 1 MK) and the Coronal Diagnostic Spectrometer (CDS, 0.03-8 MK). The temperature and emission measure were analysed through the systematic cooling of flare plasma through the response functions of these instruments. These parameters were then investigated using the Enthalpy Based Thermal Evolution of Loops model (EBTEL). The Doppler shifts at both flare footpoints were analysed using five emission lines seen by CDS. Results: The flare began with clear evidence for pre-flare heating. Upflows of approx.90 km/s and low level emission, both observed in Fe XIX before the main impulsive phase were explained by pre-flare gentle chromospheric evaporation. During the main impulsive phase, the flare plasma was heated to a temperature of 〉13 MK in approximately 10 minutes. Explosive chromospheric evaporation was observed, driving upflows of approx.80 km/s in Fe XIX and simultaneous downflows of approx.20 km/s in He I and O v. At the peak of the Rare, conduction modelled by EBTEL was found to be the dominant loss mechanism, working efficiently to both lower the temperatures and drive gentle chromospheric evaporation. As the temperature fell below approx.8 MK, radiation became the dominant loss mechanism. During the final stages of the decay phase, downflowing plasma was observed at the footpoints in He I, O v and Mg x at velocities of up to approx.40 km/s, suggesting loop draining occurred. Conclusions. This is the first extensive study of the evolution of flare plasma using both spectroscopic and broad-band instruments in conjunction with a comprehensive hydrodynamic model. The flare began with pre-flare heating and then evolved following the predictions of the standard flare model. Detailed analysis of the plasma heating mechanisms was carried out and the heating function most consistent with observations was found to be Gaussian in shape. The simulations suggested that both direct heating and heating by a non-thermal beam played significant roles in this event.
    Keywords: Astrophysics
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  • 94
    Publication Date: 2018-08-10
    Description: The James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec) incorporates two 5 micron cutoff (lambda(sub co) = 5 micron) 2048x2048 pixel Teledyne HgCdTe HAWAII-2RG sensor chip assemblies. These detector arrays, and the two Teledyne SIDECAR application specific integrated circuits that control them, are operated in space at T approx. 37 K. This article focuses on the measured performance of the first flight-candidate, and near-flight candidate, detector arrays. These are the first flight-packaged detector arrays that meet NIRSpec's challenging 6 e(-) rms total noise requirement.
    Keywords: Instrumentation and Photography
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  • 95
    Publication Date: 2018-06-29
    Description: The high resolution X-Ray Spectrometer (XRS) has been designed to provide the Suzaku Observatory with very high spectral resolution, non-dispersive spectroscopy from 0.3 to 12 keV. This energy range encompasses the most diagnostically-rich part of the x-ray band. The sensor consists of a 32 channel array of x-ray of microcalorimeters, each with an energy resolution of about 6 eV. The very low temperature required for operation of the array (60 mK) is provided by a four-stage cooling system containing a single stage ADR, superfluid He Cryostat, solid Ne Dewar, and a single-stage Stirling-cycle cooler. The Suzaku/XRS is the first orbiting x-ray microcalorimeter spectrometer and has been designed to last more than three years in orbit. The early verification phase of the mission demonstrated that the instrument was working properly and that the cryogen consumption rate was low enough to ensure a mission lifetime exceeding 3 years. However, the liquid He cryogen was completely vaporized two weeks after opening the dewar guard vacuum vent. The problem has been traced to inadequate venting of the dewar He and Ne gases out of the spacecraft into space. In this paper we present the design of the XRS instrument and describe the in-flight performance.
    Keywords: Instrumentation and Photography
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  • 96
    Publication Date: 2017-10-02
    Description: An important goal of the Mars Science Laboratory (MSL 09) mission is the determination of definitive mineralogy and chemical composition. CheMin is a miniature X-ray diffraction/X-ray fluorescence (XRD/XRF) instrument that has been chosen for the analytical laboratory of MSL. CheMin utilizes a miniature microfocus source cobalt X-ray tube, a transmission sample cell and an energy-discriminating X-ray sensitive CCD to produce simultaneous 2-D X-ray diffraction patterns and X-ray fluorescence spectra from powdered or crushed samples. A diagrammatic view of the instrument is shown.
    Keywords: Instrumentation and Photography
    Type: Lunar and Planetary Science XXXVI, Part 2; LPI-Contrib-1234-Pt-2
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  • 97
    Publication Date: 2017-10-02
    Description: Many Mars in situ instruments require fine-grained high-fidelity samples of rocks or soil. Included are instruments for the determination of mineralogy as well as organic and isotopic chemistry. Powder can be obtained as a primary objective of a sample collection system (e.g., by collecting powder as a surface is abraded by a rotary abrasion tool (RAT)), or as a secondary objective (e.g, by collecting drill powder as a core is drilled). In the latter case, a properly designed system could be used to monitor drilling in real time as well as to deliver powder to analytical instruments which would perform complementary analyses to those later performed on the intact core. In addition, once a core or other sample is collected, a system that could transfer intelligently collected subsamples of power from the intact core to a suite of analytical instruments would be highly desirable. We have conceptualized, developed and tested a breadboard Powder Delivery System (PoDS) intended to satisfy the collection, processing and distribution requirements of powder samples for Mars in-situ mineralogic, organic and isotopic measurement instruments.
    Keywords: Instrumentation and Photography
    Type: Lunar and Planetary Science XXXVI, Part 18; LPI-Contrib-1234-Pt-18
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  • 98
    Publication Date: 2017-10-02
    Description: Venus is the most Earth-like planet in the Solar System in terms of size, and the densities of the two planets are almost identical when selfcompression of the two planets is taken into account. Venus is the closest planet to Earth, and the simplest interpretation of their similar densities is that their bulk compositions are almost identical. Models of the thermal evolution of Venus predict interior temperatures very similar to those indicated for the regions of Earth subject to solid-state convection, but even global analyses of the coarse Pioneer Venus elevation data suggest Venus does not lose heat by the same primary heat loss mechanism as Earth, i.e., seafloor spreading. The comparative paucity of impact craters on Venus has been interpreted as evidence for relatively recent resurfacing of the planet associated with widespread volcanic and tectonic activity. The difference in the gross tectonic styles of Venus and Earth, and the origins of some of the enigmatic volcano-tectonic features on Venus, such as the coronae, appear to be intrinsically related to Venus heat loss mechanism(s). An important parameter in understanding Venus geological evolution, therefore, is its present surface heat flow. Before the complications of survival in the hostile Venus surface environment were tackled, a prototype fluxplate heat-flow sensor was built and tested for use under synthetic stable terrestrial surface conditions. The design parameters for this prototype were that it should operate on a conforming (sand) surface, with a small, self-contained power and recording system, capable of operating without servicing for at least several days. The precision and accuracy of the system should be 〈 5 mW/sq m. Additional information is included in the original extended abstract.
    Keywords: Instrumentation and Photography
    Type: Lunar and Planetary Science XXXVI, Part 13; LPI-Contrib-1234-Pt-13
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  • 99
    Publication Date: 2017-10-02
    Description: CHAMP (Camera, Handlens And Microscope Probe) is a novel field microscope capable of color imaging with continuously variable spatial resolution from infinity imaging down to diffraction-limited microscopy (3 micron/pixel). As an arm-mounted imager, CHAMP supports stereo-imaging with variable baselines, can continuously image targets at an increasing magnification during an arm approach, can provide precision range-finding estimates to targets, and can accommodate microscopic imaging of rough surfaces through a image filtering process called z-stacking. Currently designed with a filter wheel with 4 different filters, so that color and black and white images can be obtained over the entire Field-of-View, future designs will increase the number of filter positions to include 8 different filters. Finally, CHAMP incorporates controlled white and UV illumination so that images can be obtained regardless of sun position, and any potential fluorescent species can be identified so the most astrobiologically interesting samples can be identified.
    Keywords: Instrumentation and Photography
    Type: Lunar and Planetary Science XXXVI, Part 13; LPI-Contrib-1234-Pt-13
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  • 100
    Publication Date: 2017-10-02
    Description: Introduction: The Life in the Atacama (LITA) project includes rover field tests designed to look for life in the arid environment of the Atacama Desert (Chile). Field instruments were chosen to help remote observers identify potential habitats and the presence of life in these habitats, and included two spectrometers for help in identifying the mineralogy of the field sites. Two field trials were undertaken during the 2004 field season. The remote science team had no prior knowledge of the local geology, and relied entirely on orbital images and rover-acquired data to make interpretations. Each field trial lasted approximately one week: the sites for these trials were in different locations, and are designated "Site B" and "Site C."
    Keywords: Instrumentation and Photography
    Type: Lunar and Planetary Science XXXVI, Part 16; LPI-Contrib-1234-Pt-16
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