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  • ASTROPHYSICS  (2)
  • molecules  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Long-term Evolution of the Outgassing of Comet Hale-Bopp From Radio Observations (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 5-11 
    Details
    ISSN: 1573-0794
    Keywords: Comets ; C/1995 O1 (Hale-Bopp) ; radio observations ; molecules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract C/1995 O1 (Hale-Bopp) has been observed on a regular basis since August 1995 at millimetre and submillimetre wavelengths using IRAM, JCMT, CSO and SEST radio telescopes. The production rates of eight molecular species (CO, HCN, CH3OH, H2CO,H2S, CS, CH3CN,HNC) have been monitored as a function of heliocentric distance(rh from 7 AU pre-perihelion to 4 AU post-perihelion. As comet Hale-Bopp approached and receded from the Sun, these species displayed different behaviours. Far from the Sun, the most volatile species were found in general relatively more abundant in the coma. In comparison to other species, HNC, H2CO and CS showed a much steeper increase of the production rate with decreasing rh. Less than 1.5 AU from the Sun, the relative abundances were fairly stable and approached those found in other comets near 1 AU. The kinetic temperature of the coma, estimated from the relative intensities of the CH3OH and CO lines, increased with decreasing rh, from about10 K at 7 AU to 110 K around perihelion. The expansion velocity of the gaseous species, derived from the line shapes, also increased with a law close torh 3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006229818484
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    Paper (German National Licenses)
    Fulltext
  • 2
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    A tentative detection of the 183-GHz water vapor line in the martian atmosphere: Constraints upon the H2O abundance and vertical distribution (1995)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The 183-GHz water vapor line was tentatively detected on Mars in January 1991, with the IRAM 30-m millimeter antenna, under extremely dry atmospheric conditions. The measurement refers to the whole disk. The spectral line, although marginally detected, can be fit with a constant H2O mixing ratio of 1.0 x 10(exp -5), which corresponds to a water abundance of 1 pr-microns; in any case, an upper limit of 3 pr-microns is inferred. This value is comparable to the very small abundances measured by Clancy (1992) 5 weeks before our observation and seems to imply both seasonal and long-term variations in the martian water cycle.
    Keywords: ASTROPHYSICS
    Type: Icarus (ISSN 0019-1035); 113; 1; p. 110-118
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Millimetre observations of comets P/Brorsen-Metcalf (1989o) and Austin (1989c1) with the IRAM 30-m radio telescope (1990)
    In:  Other Sources
    Details
    Publication Date: 2013-08-29
    Description: Millimeter observations with the IRAM 30 m telescope were conducted in comet P/Brorsen-Metcalf (1989o) on September 1989 and Austin (1989c1) on April and May 1990. The HCN J(1-0) and J(3-2) lines were detected in both comets. The HCN production rate relative to water in P/Brorsen-Metcalf is comparable to that previously measured in comet P/Halley, while that inferred in comet Austin might be smaller by a factor of two. The H2CO(3 sub 12 - 2 sub 11) transition, marginally observed in comet P/Brorsen-Metcalf, was firmly detected in May 1990 in comet Austin. Observations performed at offset positions suggest that the source of H2CO might be distributed. The H2CO abundance is on the order of 0.5 percent that of water for both comets, assuming a scalelength of 10(exp 4) km at 1 AU from the Sun for the distributed source. During the May observing period of comet Austin, two new species were detected for the first time in a comet: hydrogen sulfide (H2S) through its 1(sub 10) - 1(sub 01) ortho line at 169 GHz, and methanol (CH3OH) through J(3-2) delta K = 0 transitions at 145 GHz. Preliminary estimates of their abundances are 1.5 x 10(exp -3) for H2S and 8 x 10(exp -3) for CH3OH.
    Keywords: ASTROPHYSICS
    Type: Southwest Research Inst., Workshop on Observations of Recent Comets (1990); p 80-85
    Format: text
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    NASA TECHNICAL REPORTS
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