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Millimeter-wave observations of Saturn, Uranus, and Neptune - CO and HCN on NeptuneSaturn, Uranus, and Neptune were observed at millimeter wavelengths with the IRAM 30 m telescope. The major result is the detection of CO and HCN in Neptune's stratosphere, with respective mixing ratios of (6.5 +/- 3.5) x 10 exp -7 and (3 +/- 1.5) x 10 exp -10. CO seems to be present in Neptune's troposphere as well and to slowly decrease with altitude (scale height about 200 km). HCN is probably formed from reactions between CH3 and N, which can be supplied in sufficient amounts by escape from Triton's atmosphere. The origin of CO, however, is more problematic, because: (1) thermochemical models fail to reproduce the observed abundance by a factor of about 1000; and (2) an external source would require a very large flux of oxygen. CO appears to be at least 15 times less abundant on Uranus than on Neptune. Finally, an upper limit of 10 exp -7 for CO in Saturn's stratosphere suggests an internal origin for Saturnian CO.
Document ID
19920061133
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Rosenqvist, Jan
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lellouch, Emmanuel
(Paris Observatoire, Meudon, France)
Romani, Paul N.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Paubert, Gabriel
(Instituto de Radioastronomia Milimetrica Granada, Spain)
Encrenaz, Therese
(Paris Observatoire, Meudon, France)
Date Acquired
August 15, 2013
Publication Date
June 20, 1992
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 392
Issue: 2, Ju
ISSN: 0004-637X
Subject Category
Lunar And Planetary Exploration
Accession Number
92A43757
Distribution Limits
Public
Copyright
Other

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