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The first detection of propane on Saturn |
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| Authors: | Thomas K Greathouse John H Lacy Bruno Bézard Matthew J Richter Claudia Knez |
| Institution: | a Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, TX 77058-1113, USA b Department of Astronomy, University of Texas at Austin, Austin, TX 78712, USA c Observatoire de Paris, Section de Meudon, 92195 Meudon cedex, France d University of California Davis, Davis, CA 95616, USA |
| Abstract: | We report the first detection of propane, C3H8, in Saturn's stratosphere. Observations taken on September 8, 2002 UT at NASA's IRTF using TEXES, show multiple emission lines due to the 748 cm−1ν21 band of C3H8. Using a line-by-line radiative transfer code, we are able to fit the data by scaling the propane vertical mixing ratio profile from the photochemical model of Moses et al. 2000. Icarus 143, 244-298]. Multiplicative factors of 0.7 and 0.65 are required to fit the −20° and −80° planetocentric latitude spectra. The resultant profiles are characterized by a 5 mbar mixing ratio of 2.7±0.8×10−8 at −20° and  at −80° latitude. These results suggest that the time scale for meridional circulation lies between the net photochemical lifetimes of C2H2 and C3H8, ≈30-600 years. |
| Keywords: | Abundances atmospheres Infrared observations Saturn |
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