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  • 1
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    Ionized polycyclic aromatic hydrocarbons in space (1986)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The mid-infrared spectrum of a continuously increasing number of stellar objects, planetary and reflection nebulae, H-II regions and extragalactic sources show a distinctive set of broad emission features at 3.3, 3.4, 6.2, 7.7, 8.6, and 11.3 micron known collectively as the unidentified infrared emission bands. A model is summarized in which the bands arise from positively charged polycyclic hydrocarbons (PAH's) on the basis of their low ionization potential and the excellent agreement between the emission bands and laboratory spectra of auto exhaust which contains these types of molecules. The proposed presence of PAHs in such a variety of objects points to their presence in the interstellar medium. Out of a previously published collection of solid state PAH radical cation spectra five were selected on the basis of the unique thermodynamic stability of their carrier and compared directly to the wavelengths of the DIB's. Although the match seems quite favorable, strongly suggesting that PAH radicals are the long sought after carrier of the diffuse interstellar absorption bands, much laboratory work must be done to test this hypothesis.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington. Interrelationships among Circumstellar, Interstellar and Interplanetary Dust; 2 p
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  • 2
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    Ionized polycyclic aromatic hydrocarbons and the diffuse interstellar bands (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A good case has recently been made that the unidentified infrared emission features arise from positively charged, partially hydrogenated polycyclic aromatic hydrocarbons (PAHs). In this letter it is suggested that these exceedingly stable ions are also the carriers of the diffuse interstellar bands. Although a large variety of PAH isomers is possible, the more condensed forms are substantially more stable than the less condensed forms and are expected to be dominant in the harsh interstellar environment. While neutral PAHs do not absorb in the visible, their ionized counterparts do. Because of their low ionization potential, a substantial fraction of the interstellar PAHs will be ionized. Visible spectra of the most stable PAH cations isolated in glasses are compared directly to the interstellar band spectra. Although the laboratory spectra are on an extremely compressed scale and solid state shifts are present, the comparison is favorable. Since little information is available concerning the spectroscopic properties of these species in the gas phase, a considerable amount of laboratory and theoretical work is called for to test this hypothesis.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 293; L45-L48
    Format: text
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  • 3
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    Far-infrared Spectroscopy of Galaxies: the 158 Micron C(+) Line (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-18
    Description: The C II 158 micron fine structure line in six gas rich galaxies was investigated. These data are combined with other measurements of the C II line (in various galactic sources) and are compared to studies of the CO J = approaches O rotational line at 2.6 mm, the H I 21 cm line, and the far infrared continuum emission in the same objects.
    Keywords: ASTRONOMY
    Type: NASA. Ames Research Center Airborne Astron. Symp.; p 292-297
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  • 4
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    Full-coverage film cooling on flat, isothermal surfaces: Data and predictions (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The heat transfer and fluid mechanics characteristics of full-coverage film cooling were investigated. The results for flat, isothermal plates for three injection geometries (normal, slant, and compound angle) are summarized and data concerning the spanwise distribution of the heat transfer coefficient within the blowing region are presented. Data are also presented for two different numbers of rows of holes (6 and 11). The experimental results summarized can be predicted with a two dimensional boundary layer code, STANCOOL, by providing descriptors of the injection parameters as inputs.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3219 , SU-HMT-23
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  • 5
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    Detection of shocked atomic gas in the Kleinmann-Low nebula (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The 63 micrometer (3)p(1)-(3)P(2) fine structure line emission of neutral atomic oxygen at the center of the Orion nebula with a resolution of 30" is presented. There are three main emission peaks. One is associated with the region of strongest thermal radio continuum radiation close to the Trapezium cluster, and probably arises at the interface between the HII region and the dense Orion molecular cloud. The other two line emission peaks, associated with the Kleinmann Low nebula, are similar in both distribution and velocity to those of the 2 micrometer S(1) line of molecular hydrogen and of the high velocity wings of rotational CO emission. The OI emission from the KL nebula can be produced in the shocked gas associated with the mass outflows in this region and is an important coolant of the shocked gas.
    Keywords: ASTRONOMY
    Type: NASA-TM-85967 , A-9774 , NAS 1.15:85967
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  • 6
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    Mass distribution in the galactic centre (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: New infrared and submillimeter spectroscopic measurements of the gas dynamics in the central 10 pc of the Galaxy make a convincing case that the mass distribution at the center of the Galaxy is more concentrated than a spherical isothermal stellar cluster. The measurements fit a point mass of about 4 million solar masses, but are also consistent with a cluster where stellar density decreases with radius (R) at least as fast as R to the -2.7, or a combination of a point mass and a stellar cluster. The dynamical information combined with previous 2-micron observations favor a large point mass, which is presumably a massive black hole.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 315; 467-470
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  • 7
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    Far-infrared spectroscopy of galaxies - The 158 micron C(+) line and the energy balance of molecular clouds (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Observations of the 158 microns fine-structure line of C(+) toward the nuclei of six gas-rich galaxies are presented. The observations are compared with observations of the CO J = 1-0 and H I 21 cm lines, observations of far-IR continuum emission, and observations of forbidden C II emission with the Galaxy. The forbidden C II line comes from dense, warm gas in UV-illuminated photodissociation regions at the surfaces of molecular clouds. This line is probably optically thin in all but the brightest of galactic sources. The variation of forbidden C II brightness from source to source and its ratio to the integrated infrared continuum intensity agree well with the theoretical prediction that UV absorption by dust controls the C(+) column density. The forbidden C II line is a tracer of molecular clouds, especially those near intense sources of UV radiation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 291; 755-771
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  • 8
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    Petrology of Luna 20 regolith from the lunar highlands. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The Luna 20 regolith sample contains crystalline lithic fragments of mare basalt, the anorthosite-norite-troctolite group, and feldspathic basalt. Discrete mineral fragments and mineral fragments in regolith breccias can generally be assigned, based on chemical criteria, to one or the other of the first two rock types. A complex history is indicated for the regolith fragments involving repeated metamorphism and melting of the highlands due to impact events. The glass fragments and the feldspathic basalts probably are the result of this melting and their composition may be representative of a large portion of the regolith at this site.
    Keywords: SPACE SCIENCES
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  • 9
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    Regional investigation of tectonic and igneous geology in Iran, Pakistan and Turkey (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: There are no author-identified significant results in this report.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: E76-10297 , NASA-CR-146787 , EC/24/M/D10 , QR-1
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  • 10
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    Full-coverage film cooling heat transfer study: Summary of data for normal-hole injection and 30 deg slant-hole injection (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Heat transfer to a full coverage film cooled turbulent boundary layer over a flat surface was studied. The surface consisted of a discrete hole test section containing 11 rows of holes spaced 5 diameters apart in a staggered array and an instrumented recovery region. Ten diameter spacing was also studied by plugging appropriate holes. Two test sections were used, one having holes normal to the surface and the other having holes angled 30 deg to the surface in the downstream direction. Stanton number data were obtained both in the full coverage region and in the downstream recovery region for a range of blowing ratios, or mass flux ratios, from 0 to 1.3. Initial conditions at the upstream edge of the blowing region were varied from 500 to 5000 for momentum thickness Reynolds number and from 100 to 1800 for enthalpy thickness Reynolds number. The range of Reynolds numbers based on hole diameter and mainstream velocity was 6000 to 22000. Initial boundary layer thicknesses range from 0.5 to 2.0 hole diameters. Air was used as the working fluid. The data were taken for the secondary injection temperature equal to the wall temperature and also equal to the mainstream temperature. Superposition was then used to obtain Stanton number as a continuous function of the injectant temperature. The heat transfer coefficient was defined on the basis of a mainstream-to-wall temperature difference. This definition permits direct comparison of performance between film cooling and transpiration cooling.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-2648 , SU-HMT-19
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