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  • ASTRONOMY  (4)
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  • 1
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    Nitrogen sulfide in quiescent dark clouds (1994)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: We report the first detection of interstellar nitrogen sulfide (NS) in cold dark clouds. Several components of the (2)Pi(sub 1/2), J = 3/2 to 1/2 and J = 5/2 to 3/2 transitions were observed in TMC-1 and L134N. The inferred column density for TMC-1 is N(sub NS) approximately 8 x 10(exp 12)/sq cm toward the NH3 peak in that cloud, and in L134N is N(sub NS) approximately 3 x 10(exp 12)/sq cm toward the position of peak NH3 emission. These values correspond to fractional abundances relative to molecular hydrogen of f(sub NS) approximately 8 x 10(exp -10) for TMC-1, and f(sub NS) approximately 6 x 10(exp -10) for L134N. The NS emission is extended along the TMC-1 ridge and is also extended in L134N. The measured abundances are significantly higher than those predicted by some recent gas phase ion-molecule models.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 422; 2; p. 621-625
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Detection of a new interstellar molecule, H2CN (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: We have detected a new interstellar molecule, H2CN (methylene amidogen), in the cold, dark molecular cloud TMC-1. The column density of H2CN is estimated to be approximately 1.5 x 10(exp 11) cm(exp -2) by assuming an excitation temperature of 5 K. This column density corresponds to a fractional abundance relative to H2 of approximately 1.5 x 10(exp -11). This value is more than three orders of magnitude less than the abundance of the related molecule HCN in TMC-1. We also report a tentative detection of H2CN in Sgr B2(N). The formation mechanism of H2CN is discussed. Our detection of the N2CN molecule may suggest the existence of a new series of carbon-chain molecules, CH2C(n)N (N = 0, 1, 2, ...).
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 427; 1; p. L51-L54
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    NASA TECHNICAL REPORTS
  • 3
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    Boundary conditions for the paleoenvironment: Chemical and physical processes in the pre-solar nebula (1987)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Detailed study of the first interstellar hydrocarbon ring, cyclopropenylidene (C3H2), is continuing. The singly deuterated isotope of this molecule, C3HD, was observed in several cold interstellar clouds. The results of a large survey for C3H2 in galactic sources of various types will soon be completed. It appears that cyclopropenylidene is present in virtually all interstellar clouds of at least moderate density. In order to make the first determinations of the CO2/CO abundance ratio in interstellar sources, observations of protonated CO2 were pursued. The spectrum from 18.5 to 22 GHz for several interstellar clouds is being systematically measured. Particular attention is being given to the cold, dark clouds TMC-1 and L124N, which may be formation sites for solar mass stars. The phenomena of maser emission from molecules of methanol is being studied in certain interstellar clouds. A comparison of 1 millimeter continuum emission from dust with the column density of carbon monoxide as determined from the rare C(18)O isotope for 4 molecular clouds in the Galaxy is nearing completion. Papers published during the period of this report are listed.
    Keywords: ASTRONOMY
    Type: NASA-CR-180253 , NAS 1.26:180253 , SASR-8
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Observations of molecular envelopes of late-type stars: CRL 618, CRL 2688, CRL 3068, and CIT 6 (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-08-27
    Description: The HC3N, HC5N, HC7N, CCH, C4H, SiS, and HNC molecules were observed in the circumstellar envelopes of CRL 618, CRL 2688, CIT 6, and CRL 3068 with the Nobeyama 45 m radio telescope. The observed relative abundances of the cyanopolyynes, CCH, and C4H in these late-type stars are similar to those for IRC +10216. However, it was found that the abundance of HNC increased with the physical evolutionary stage of the stars. In CRL 2688, it is also found that HNC is more concentrated in the inner region than SiS. The production mechanism of HNC is discussed by considering ultraviolet radiation from the central stars. The HC3N J = 4-3 transition was observed to have a P Cygni line profile in CRL 618.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 437; 1; p. 410-418
    Format: text
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    NASA TECHNICAL REPORTS
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