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  • Other Sources  (7)
  • NASA Technical Reports  (7)
  • ASTROPHYSICS  (6)
  • FLUID MECHANICS AND HEAT TRANSFER  (1)
  • Geophysics
  • 1985-1989  (7)
  • 1987  (7)
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  • Other Sources  (7)
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  • NASA Technical Reports  (7)
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  • 1985-1989  (7)
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  • 1
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    Microturbulence in the upper photosphere of Alpha Persei (F5 Ib) derived from ultraviolet spectral observations (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: High-resolution ultraviolet spectra of the moderate supergiant Alpha Per (F5 Ib) were studied to determine the dynamic state of its upper photosphere. It was found that the line-of-sight microturbulent velocity component in the region of origin of the UV spectrum is about 5 km/s, and is slightly smaller than the value derived from the visual spectrum. This is ascribed to dissipation of mechanical energy between the higher and lower layers where, respectively, the ultraviolet and visual light lines originate. Between these two levels, which are one scale height apart, the mechanical energy flux decreases to about 0.3 of its photospheric value. The consequent value for the (outward directed) turbulent acceleration is 24 cm/sec-squared, more than one half the observationally determined effective acceleration of gravity.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 185; 1-2,
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  • 2
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    Molecular and atomic clouds associated with infrared cirrus in Ursa Major (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Observations of CO and H I revealed that in Ursa Major the high-latitude far-infrared 'cirrus' emission discovered by the Infrared Astronomical Satellite comes from molecular and atomic clouds. These clouds differ sufficiently from the large clouds in the Galactic plane so that the ratio of H2 column density to velocity-integrated CO radiation temperature, N(H2)/W(CO), derived from Galactic plane surveys, may not apply to them. On the assumption of a constant gas-to-dust ratio, it is argued that the cirrus emission in Ursa Major is a good mass tracer, since both the atomic and the molecular gas are probably optically thin at visual wavelengths, and the grains are heated not by local sources but by the background field of Galactic starlight. The N(H2)/W(CO) ratio thus derived for those diffuse clouds, is significantly lower than the ratio applicable to Galactic plane surveys.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 319; 723-729
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  • 3
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    Diffuse and dark clouds in the interstellar medium (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Observations of clouds in the ISM of the Galaxy and the Magellanic Clouds, obtained with the IUE satellite since its launch in 1978, are reviewed. Consideration is given to the techniques used to analyze IUE Maxwellian growth curves and oscillator strengths, the general structure of the Galactic ISM, the high-velocity clouds, heavy-element depletion, and observations toward strongly reddened stars in the outer portions of dark clouds. Theoretical models of interstellar dust formation and selective and nonselective removal of elements from dust grains are discussed; observations of reflection nebulae and their implications for light scattering by dust are examined; the dynamics and ionization structure of the Galactic halo ISM are described; and the Magellanic Cloud observations are briefly characterized. Diagrams, graphs, and tables of numerical data are provided.
    Keywords: ASTROPHYSICS
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  • 4
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    Efficient numerical simulation of an electrothermal de-icer pad (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: In this paper, a new approach to calculate the transient thermal behavior of an iced electrothermal de-icer pad was developed. The method of splines was used to obtain the temperature distribution within the layered pad. Splines were used in order to create a tridiagonal system of equations that could be directly solved by Gauss elimination. The Stefan problem was solved using the enthalpy method along with a recent implicit technique. Only one to three iterations were needed to locate the melt front during any time step. Computational times were shown to be greatly reduced over those of an existing one dimensional procedure without any reduction in accuracy; the curent technique was more than 10 times faster.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 87-0024
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  • 5
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    A five-level program for ions of astrophysical interest (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: An interactive FORTRAN program is presented which determines the physical conditions in a nebula given an appropriate emission-line intensity ratio, or the line emissivities given a density and temperature. A method for estimating ionic abundances based on the H-beta emissivity is also included. The relevant underlying physics is reviewed and a detailed description of the operation of the program given. Uncertainties in the interpretation of the results are discussed briefly.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society of Canada, Journal (ISSN 0035-872X); 81; 195-220
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  • 6
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    A survey of formaldehyde in high Galactic latitudes (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The discovery of formaldehyde (H2CO) in four out of 15 CO-clouds observed in high Galactic latitudes is reported. For one of these a velocity-integrated formaldehyde map is presented. The clouds are clearly connected to CO clouds described by de Vries et al. (1986), to Lynds bright and dark nebulae (Lynds, 1963), and to the Galactic infrared cirrus (Low et al., 1984). The distribution of CO and H2CO clouds is compared. The depths of the l(10-11)H2CO lines show no correlation to the integrated J = l-0(C-12)O line intensities.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 179; 1-2
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  • 7
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    The laboratory millimeter- and submillimeter-wave spectrum of C-13 methanol (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: A comprehensive millimeter- and submillimeter-wave study of the rotational spectrum of (C-13)H3OH is presented. Approximately 300 new transitions of this species were measured at frequencies up to 650 GHz, and the transitions were analyzed along with previously measured spectra using the internal axis method of Herbst et al. (1984). The resulting spectral constants allow prediction of an additional large number of transitions which should allow astronomers to identify many strong rotational lines of C-13 methanol throughout much of the submillimeter region.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 64; 703-714
    Format: text
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