Bibliographic Citation
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Title | Composition of saturn`s atmosphere at northern temperate latitudes from Voyager iris spectra: NH/sub 3/, PH/sub 3/, C/sub 2/H/sub 2/, C/sub 2/H/sub 6/, CH/sub 3/D, CH/sub 4/, and the saturnian D/H isotopic ratio |
Creator/Author | Courtin, R. ; Gautier, D. ; Marten, A. ; Bezard, B. ; Hanel, R. |
Publication Date | 1984 Dec 15 |
OSTI Identifier | OSTI ID: 6025833 |
Other Number(s) | CODEN: ASJOA |
Resource Type | Journal Article |
Resource Relation | Astrophys. J. ; Vol/Issue: 287:2 |
Research Org | Laboratoire d`Astronomie Infra-Rouge (CNRS), Observatoire de Paris-Meudon, France |
Subject | 640107 -- Astrophysics & Cosmology-- Planetary Phenomena; ;SATURN PLANET-- PLANETARY ATMOSPHERES; ABUNDANCE;AMMONIA;CHEMICAL COMPOSITION;DEUTERIUM;HYDROCARBONS;INFRARED SPECTRA;ISOTOPE RATIO;PHOSPHINES |
Related Subject | ATMOSPHERES;HYDRIDES;HYDROGEN COMPOUNDS;HYDROGEN ISOTOPES;ISOTOPES;LIGHT NUCLEI;NITROGEN COMPOUNDS;NITROGEN HYDRIDES;NUCLEI;ODD-ODD NUCLEI;ORGANIC COMPOUNDS;PHOSPHORUS COMPOUNDS;PLANETS;SPECTRA;STABLE ISOTOPES |
Description/Abstract | The abundances of minor atmospheric constituents at northern Saturnian latitudes have been inferred from infrared emission spectra recorded by Voyager.^The NH/sub 3/, PH/sub 3/, C/sub 2/H/sub 2/, and C/sub 2/H/sub 6/ vertical distributions have been determined from spectra selected in a cloud-free region centered approximately at the latitude of the Voyager 2 radio-occultation point (36.5 N).^The NH/sub 3/ mixing ratio in the upper troposphere is found to be compatible with the saturated partial pressure.^The inferred PH/sub 3//H/sub 2/ ratio of 1.4 +- 0.8 x 10/sup -6/ is higher than the value derived from the solar P/H ratio, and the PH/sub 3/ vertical profile may extend somewhat into the stratosphere, up to a few millibars.^The stratospheric C/sub 2/H/sub 2//H/sub 2/ and C/sub 2/H/sub 6//H/sub 2/ ratios are, respectively, 2.1 +- 1.4 x 10/sup -7/ and 3.0 x 1.1 x 10/sup -6/; the latter decreases sharply below the 20-50 mbar level.^A larger selection of spectra yields CH/sub 3/D/H/sub 2/ = 3.9 +- 2.5 x 10/sup -7/ and CH/sub 4//H/sub 2/ = 4.5/sup +2.4//sub -1.9/ x 10/sup -3/.^This result implies an enrichment of Saturn`s upper atmosphere is carbon by at least a factor of 3 over the solar abundance.^The D/H value resulting from our CH/sub 3/D/CH/sub 4/ ratio is 1.6/sup +1.3//sub -1.2/ x 10/sup -5/, significantly lower than previous determinations obtained from HD lines; it is also less than half of the IRIS-inferred Jovian value.^Finally, the interpretation of two NH/sub 3/ lines in the 5 ..mu..m window suggests a NH/sub 3/H/sub 2/ ratio at the 2 bar level below the solar value. |
Country of Publication | United States |
Language | English |
Format | Pages: 899-916 |
System Entry Date | 2001 May 13 |
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