Brown, Michael E. (1997) A Search for a Sodium Atmosphere around Ganymede. Icarus, 126 (1). pp. 236-238. ISSN 0019-1035. http://resolver.caltech.edu/CaltechAUTHORS:20120927-120624917
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Long-slit high-resolution spectra have revealed that Ganymede has an atmospheric sodium column density, between a distance of 7800 and 15600 km from the satellite surface, of less than 1 × 10^8 atoms cm^(−2), a factor of 13 times smaller than the sodium density in the atmosphere of Europa at the same distance. Assuming similar processes creating sodium on both Europa and Ganymede, we estimate that the source rate for sodium production on Ganymede should be within a factor of 2 of that on Europa. Two possibilities for the lack of detectable sodium around Ganymede are that Ganymede's surface is depleted in native sodium compared to Europa's or that Ganymede has a magnetic field capable of standing off impacting energetic particles.
|Additional Information:||© 1997 Academic Press. Received August 26, 1996; revised November 25, 1996. We are indebted to Roger Wiens for discussions about the sputtering and potential surface characteristics of the Galilean satellites, to Richard Hill for help with the observations, to John Spencer and Elisabeth Moyer for valuable comments, and to Don Hunten for supplying the spectrograph. This research is supported by NASA through Grant HF-01056.02.94A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA Contract NAS5-26555.|
|Official Citation:||Michael E. Brown, A Search for a Sodium Atmosphere around Ganymede, Icarus, Volume 126, Issue 1, March 1997, Pages 236-238, ISSN 0019-1035, 10.1006/icar.1996.5675. (http://www.sciencedirect.com/science/article/pii/S0019103596956754)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||28 Sep 2012 18:03|
|Last Modified:||28 Sep 2012 18:03|
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