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  • 1
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    RX Puppis - Detection of asymmetrical radio structure (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Subarcsecond observations of the RX Puppis symbiotic system with the VLA have resolved 2 cm continuum emission which deviates from a previously reported circularly symmetric radio distribution. The radio structure is comprised of at least three nearly colinear components. Under the assumption that the strongest feature is coincident with the hot star, the other two features lie 230 and 590 AU distant. These radio features are reminiscent of small-scale radio structure detected toward R Aquarii, another symbiotic star system, and probably represents material ejected from the RX Puppis system at an earlier epoch.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 337; 514-519
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  • 2
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    US 943 - A 19th mag eclipsing cataclysmic variable with a period of 2 hr 3.8 min (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The high-latitude, V equals about 19.5, blue variable star US 943 is found to be an eclipsing binary with an orbital period of 2.06 hr. The light curve is dominated by an orbital hump which has an amplitude of 0.9 mag in V and is centered about 0.17 orbital cycles before the 1.5-mag deep eclipse. There is evidence that the eclipse has at least two components. The overall appearance of the star is that of a dwarf nova in quiescence, a conclusion that is supported by the observation of a subsequent bright state (V equals about 15) suggesting a dwarf nova outburst.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 233; 79-86
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  • 3
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    The Exosat spectral survey of AGN (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Results are presented from Exosat observations of 48 hard X-ray selected Seyfert-type active galactic nuclei (AGN). These include all 30 of the emission line AGN in the Piccinotti (1981) sample. Combining Exosat LE and ME data has yielded X-ray spectra over the broad energy range 0.1-10 keV. Spectra in the about 2-10 keV range are found to be well described by a simple power law, with a narrow distribution of spectral indices across the sample about a mean energy index alpha = 0.70. Exosat has also revealed a substantial number of sources with complex soft X-ray spectra. Evidence that soft emission components occur in many Seyferts, together with detection of rapid variability in the soft component, provides a quantitative support for an accretion disk model for AGN. Approximately half of the present sample of AGN show low-energy absorption attributable to substantial cold matter within the host galaxy. A few cases show evidence for column variability and reduced low-energy opacity (by photo-ionization). These results and the observed rarity of intrinsic absorption in the higher luminosity sources suggest the absorbing matter lies close to the central continuum source.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 240; 833-880
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  • 4
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    Discovery of an infrared-loud quasar (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The IRAS source 13349 + 2438 is a quasar with a redshift of z = 0.107, broad (15,000 km/s) emission lines and a luminosity of 2.7 x 10 to the 12th solar luminosity, emitted mostly between 4.8 and 12 microns. The object, a weak radio source, is the first previously unidentified quasar selected through its infrared emission and is the prototype radio-quiet, infrared-bright quasar. A dusty interstellar medium may be responsible for the infrared emission as well as for quenching the visual emission and attenuating the radio emission from the central energy source.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 308; L1-L5
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  • 5
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    Large-scale Galactic dust morphology and physical conditions from IRAS observations (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: In this paper, the zodiacal component is subtracted from the 60 and 100 micron Galactic plane emission by applying an empirical model derived from IRAS data in regions of the sky not dominated by the Galaxy. The corrected observations are used to derive the large-scale physical conditions such as temperature, optical depth, and total FIR brightness of the dust residing in the Galactic disk. (C-12)O, H I, and 5 GHz radio continuum observations are also used to compare the large-scale properties of the gas and dust distributions in the Galaxy. Possible scenarios to explain the findings are suggested.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 322; 101-112
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  • 6
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    Masses, luminosities and dynamics of galactic molecular clouds (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Star formation in galaxies takes place in molecular clouds and the Milky Way is the only galaxy in which it is possible to resolve and study the physical properties and star formation activity of individual clouds. The masses, luminosities, dynamics, and distribution of molecular clouds, primarily giant molecular clouds in the Milky Way are described and analyzed. The observational data sets are the Massachusetts-Stony Brook CO Galactic Plane Survey and the IRAS far IR images. The molecular mass and infrared luminosities of glactic clouds are then compared with the molecular mass and infrared luminosities of external galaxies.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington Star Formation in Galaxies; p 37-59
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  • 7
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    The large scale gas and dust distribution in the galaxy: Implications for star formation (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Infrared Astronomy Observations are presented for the diffuse infrared (IR) emissions from the galactic plane at wavelengths of 60 and 100 microns and the total far infrared intensity and its longitudinal variations in the disk were derived. Using available CO, 5 GHz radio-continuum, and HI data, the IR luminosity per hydrogen mass and the ingrared excess (IRE) ratio in the Galaxy were derived. The longitudinal profiles of the 60 and 100 micron emission were linearly decomposed into three components that are associated with molecular (H2), neutral (HI), and ionized (HII) phases in the interstellar medium (ISM), and the relevant dust properties were derived in each phase. Implications of the findings for various models of the diffuse IR emisison and for star formation in the galactic disk are discussed.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington Star Formation in Galaxies; p 99-102
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  • 8
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    Star formation rates and the far-infrared luminosity of Galactic molecular clouds (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The CO luminosity, far-IR luminosity, and virial mass of 55 molecular clouds are determined and related to star formation rates (SFRs) in the clouds. The SFR of OB stars per unit of available molecular mass is found to be independent of cloud mass and varies widely over a range of about 100 for clouds of mass between 30,000 and five million solar masses. The far-IR luminosity is proportional to the first power of the CO luminosity for clouds undergoing high-mass star formation. There are massive clouds without any current high-mass star formation. The average gas depletion time is about 2.5 billion yr. The far-IR luminosity-to-mass ratio for isolated or weakly interacting spiral galaxies observed by IRAS is twice that for the average Galactic molecular cloud. The star formation mechanism operating in strongly interacting galaxies is five times more efficient than that of the most active Galactic cloud and 30 times that of the average Galactic cloud.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 334; L51-L54
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  • 9
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    Dust energetics in the gas phases of the interstellar medium - The origin of the Galactic large-scale far-infrared emission observed by IRAS (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The large-scale Galactic properties within the most massive gas phases of the ISM are derived along with the distribution of total Galactic FIR luminosity among the three phases. Most of the Galaxy's total FIR luminosity is found to be emitted by cold dust associated with diffuse H I clouds and molecular gas. The total FIR luminosity of dust associated with extended low-density H II regions accounts for less than 10 percent of the Galaxy's total FIR output. The absence of a significant variation with longitude in the observed temperature of the dust associated with H I gas suggests that diffuse neutral clouds contain very small dust grains that are stochastically heated by the interstellar radiation field. The results are consistent with a model in which most of the FIR luminosity of molecular clouds arises from dust that is associated with giant molecular clouds and heated by embedded and nearby OB stars. H II regions in the inner Galaxy have a mean IR excess ratio of about 2.5, suggesting that the dust in these regions is heated primarily by directly absorbed stellar photons.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 336; 762-779
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  • 10
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    Oblique impact: A process for providing meteorite samples of other planets (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Cratering flow calculations for a series of oblique to normal impacts of silicate projectiles onto a silicate halfspace were carried out to determine whether the gas produced upon shock vaporizing both projectile and planetary material could entrain and accelerate surface rocks and thus provide a mechanism for propelling SNC meteorites from the Martian surface. The difficult constraints that the impact origin hypothesis for SNC meteorites has to satisfy are that these meteorites are lightly to moderately shocked and yet were accelerated to speeds in excess of the Martian escape velocity. Two dimensional finite difference calculations demonstrate that at highly probable impact velocities, vapor plume jets are produced at oblique impact angles of 25 deg to 60 deg and have speeds as great as 20 km/sec. These plumes flow nearly parallel to the planetary surface. It is shown that upon impact of projectiles having radii of 0.1 to 1 km, the resulting vapor jets have densities of 0.1 to 1 g/cu.cm. These jets can entrain Martian surface rocks and accelerate them to velocities 5 km/sec. It is suggested that this mechanism launches SNC meteorites to Earth.
    Keywords: ASTROPHYSICS
    Type: NASA-CR-176616 , NAS 1.26:176616
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