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  • 1
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    Su Lyncis, a Hard X-Ray Bright M Giant: Clues Point to a Large Hidden Population of Symbiotic Stars (2016)
    In:  Other Sources
    Details
    Publication Date: 2017-05-23
    Description: Symbiotic star surveys have traditionally relied almost exclusively on low resolution optical spectroscopy. However, we can obtain a more reliable estimate of their total Galactic population by using all available signatures of the symbiotic phenomenon. Here we report the discovery of a hard X-ray source, 4PBC J0642.9+5528, in the Swift hard X-ray all-sky survey, and identify it with a poorly studied red giant, SU Lyn, using pointed Swift observations and ground-based optical spectroscopy. The X-ray spectrum, the optical to UV spectrum, and the rapid UV variability of SU Lyn are all consistent with our interpretation that it is a symbiotic star containing an accreting white dwarf. The symbiotic nature of SU Lyn went unnoticed until now, because it does not exhibit emission lines strong enough to be obvious in low resolution spectra. We argue that symbiotic stars without shell-burning have weak emission lines, and that the current lists of symbiotic stars are biased in favor of shell-burning systems. We conclude that the true population of symbiotic stars has been underestimated, potentially by a large factor.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN41432 , Monthly Notices of the Royal Astronomical Society (ISSN 0035-8711; e-ISSN 1365-8711); Volume 461; No. 1; L1-L5
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  • 2
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    Performance of the PRAXyS X-Ray Polarimeter (2016)
    In:  Other Sources
    Details
    Publication Date: 2017-04-29
    Description: The performance of the Time Projection Chamber (TPC) polarimeter for the Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) Small Explorer was evaluated using polarized and unpolarized X-ray sources. The PRAXyS mission will enable exploration of the universe through X-ray polarimetry in the 2-10 keV energy band. We carried out performance tests of the polarimeter at the Brookhaven National Laboratory, National Synchrotron Light Source (BNL-NSLS) and at NASA's Goddard Space Flight Center. The polarimeter was tested with linearly polarized, monochromatic X-rays at 11 different energies between 2.5 and 8.0 keV. At maximum sensitivity, the measured modulation factors at 2.7, 4.5 and 8.0 keV are 27%, 43% and 59%, respectively and the measured angle of polarization is consistent with the expected value at all energies. Measurements with a broadband, unpolarized X-ray source placed a limit of less than 1% on false polarization in the PRAXyS polarimeter.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN41158 , Nuclear Instruments and Methods in Physics Research A (ISSN 0168-9002); Volume 838; 89-95
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  • 3
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    Faint-Source-Star Planetary Microlensing: The Discovery of the Cold Gas-Giant Planet OGLE-2014-BLG-0676Lb (2016)
    In:  CASI
    Details
    Publication Date: 2019-06-20
    Description: We report the discovery of a planet OGLE-2014-BLG-0676Lb via gravitational microlensing. Observations for the lensing event were made by the following groups: Microlensing Observations in Astrophysics; Optical Gravitational Lensing Experiment; Wise Observatory; RoboNETLas Cumbres Observatory Global Telescope; Microlensing Network for the Detection of Small Terrestrial Exoplanets; and -FUN. All analyses of the light-curve data favoura lens system comprising a planetary mass orbiting a host star. The most-favoured binary lens model has a mass ratio between the two lens masses of (4.78 +/- 0.13) 10(exp -3). Subject to some important assumptions, a Bayesian probability density analysis suggests the lens system comprises a 3.09(+1.02/-1.12) MJ planet orbiting a 0.62(+0.20/-0.22) solar mass host star at a deprojected orbital separation of 4.40(+2.16/-1.46) au. The distance to the lens system is 2.22(+0.96/-0.83) kpc. Planet OGLE-2014-BLG-0676Lb provides additional data to the growing number of cool planets discover redusing gravitational microlensing against which planetary formation theories may be tested. Most of the light in the baseline of this event is expected to come from the lens and thus high-resolution imaging observations could confirm our planetary model interpretation.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN64724 , GSFC-E-DAA-TN42195 , Monthly Notices of the Royal Astronomical Society (ISSN 0035-8711 ) (e-ISSN 1365-2966); 466; 3; 2710-2717
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  • 4
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    Studies of the Coldest Brown Dwarfs with the James Webb Space Telescope (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: The coolest T and Y-class Brown Dwarf objects are very faint and are therefore very poorly understood, since they are barely detectable with the current astronomical instrumentation. The upcoming James Webb Space Telescope now in development for a launch in the Fall of 2018 will have vastly increased sensitivity in the near and mid-infrared compared to any current facilities and will not be affected by telluric absorption over its entire wavelength range of operations. As a result it will be an ideal tool to obtain information about the composition and temperature-pressure structure in these objects' atmospheres. This presentation will outline the JWST guaranteed time observing plans for these studies.
    Keywords: Astrophysics
    Type: ARC-E-DAA-TN30813 , Cool Stars 19; Jun 06, 2016 - Jun 10, 2016; Uppsala; Sweden
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  • 5
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    The Foreign Clast Populations of Anomalous Polymict Urelite Almahata Sitta (Asteroid 2008 TC(sub3) and Typical Polymict Ureilites: Implications for Asteroid-Meteorite Connections (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Almahata Sitta (AhS) is the first meteorite to originate from an asteroid (2008 TC3) that had been studied in space before it hit Earth [1,2]. It is also unique because the fallen fragments comprise a variety of types: approximately 69% ureilites (achondrites) and 31% chondrites [3]. Two models have been proposed for the origin 2008 TC3: 1) an accretionary model [3,4]; or 2) a regolith model [5,6]. Typical polymict ureilites are interpreted to represent regolith, and contain a few % foreign clasts [7,8]. The most common are dark (CC matrix-like) clasts similar to those in many meteoritic breccias [9]. A variety of other chondrites, as well as achondrites (angrites), have also been reported [7,9,10]. We have been working to determine the full diversity of these clasts [10-13] for comparison with AhS. We discuss implications for mixing of materials in the early solar system and the origin of 2008 TC3.
    Keywords: Astrophysics
    Type: JSC-CN-35762 , Asteroid-Meteorite Connections Workshop; Apr 21, 2016 - Apr 22, 2016; Los Angeles,CA; United States
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  • 6
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    The Cosmic Microwave Background: Detection and Interpretation of the First Light (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: A host of astrophysical observations suggest the early Universe was incredibly hot, dense, and homogeneous. A powerful and useful probe of this epoch is provided by the relic radiation, which we refer to today as the Cosmic Microwave Background (CMB). Precision maps of this light contain the earliest glimpse of the Universe after the Big Bang and signatures of the evolution of its contents. By exploiting these clues, constraints on the age, mass density, detailed composition, and geometry of the Universe can be made. A brief survey of the evolution of the radiometric and polarimetric imaging systems used in advancing our understanding of the early Universe will be reviewed. A survey of detector technologies, instrumentation techniques, and experimental challenges encountered in these efforts will be presented.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN29879 , Colloquium; Feb 26, 2016; Villanova, PA; United States
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  • 7
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    Stellar Origins of C-13 and N-15-Enriched Presolar SiC Grains (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Extreme excesses of 13 C ( C (12 C/ 13 C〈10) and 15 N ( N (14 N/ 15 N〈 20) in rare presolar SiC 20) in rare presolar SiClar SiC grains have been considered diagnostic of an origin in classical novae [1], though an origin in core-collapse supernovae (CCSNe) has also been proposed [2]. We report multi-element isotopic data for 19 13 C- and 15 N-enriched presolar SiC grains(12 C/13 C〈16 and 14 N/ 15 N〈~150) from an acid resistant residue of the Murchison meteorite. These grains are enriched in 13 C and15 N, but with quite diverse Si isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures.
    Keywords: Astrophysics
    Type: JSC-CN-35396 , International Conference on Nuclei in the Cosmos (NIC-XIV 2016); Jun 19, 2016 - Jun 24, 2016; Niigata; Japan
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  • 8
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    Taxonomies and Albedos of Near-Earth Asteroids (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Characterizing near-Earth asteroids (NEAs) can help to assess the risk of possible impactors. Over many decades, asteroids have been spectrally classified into numerous taxonomic systems, most notably those of Tholen, Bus, and Bus-DeMeo. By mapping these various taxonomic systems to broader categories called complexes, it is easier to study the relationship between classifications and other physical parameters. There has recently been an increase in the number of objects with measured albedos which is advantageous for characterization because the albedo and absolute magnitude can be used to determine diameter. Knowing an asteroids diameter helps us better understand dangers they may pose.
    Keywords: Astrophysics
    Type: ARC-E-DAA-TN34991
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  • 9
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    Ray-Tracing Simulation and In-Orbit Performance of the ASTRO-H Hard X-Ray Telescope (HXT) (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A ray-trace simulation code for the Hard X-ray Telescope (HXT) on board the Hitomi (ASTRO-H) satellite is beingdeveloped. The half power diameter and effective area simulated based on the code are consistent with groundmeasurements within 10%. The HXT observed the pulsar wind nebula G21.5-0.9 for 105 ksec. We confirmed that theencircled energy function and the half power diameter obtained from the data are consistent with the ground measurements.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN64667 , SPIE ASTRONOMICAL TELESCOPES + INSTRUMENTATION; Jun 26, 2016 - Jul 01, 2016; Edinburgh; United Kingdom|Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray; 9905; 990541
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  • 10
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    The Cosmology Large Angular Scale Surveyor (CLASS) (2016)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from in ation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145/217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad frequency range, large sky coverage, control over systematics, and high sensitivity, CLASS will observe the reionization and recombination peaks of the CMB E- and B-mode power spectra. CLASS will make a cosmic variance limited measurement of the optical depth to reionization and will measure or place upper limits on the tensor-to-scalar ratio, r, down to a level of 0.01 (95% C.L.).
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN35081 , Proc. of SPIE, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy (ISSN 0277-786X); 9914; 99141K|Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy; Jun 26, 2016 - Jul 01, 2016; Edinburgh; United Kingdom
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