Detection of exospheric O2+ at Saturn's moon Dione
Abstract
During a close pass of Cassini through the plasma wake of Saturn's moon Dione on April 7, 2010 the Cassini Plasma Spectrometer (CAPS) detected molecular oxygen ions (O2+) on pick up ring velocity distributions, thus providing the first in situ detection of a neutral exosphere surrounding the icy moon. The density of O2+ determined from the CAPS data ranges from 0.01 to 0.09 /cm3 and is used to estimate the exosphere O2 radial column density, obtaining the range 0.9 to 7 × 1011/cm2 . CAPS was unable to directly detect pick up H2O+ from the exosphere but the observations can be used to set an upper limit to their density of ∼10 times the O2+ density.
- Publication:
-
Geophysical Research Letters
- Pub Date:
- February 2012
- DOI:
- 10.1029/2011GL050452
- Bibcode:
- 2012GeoRL..39.3105T
- Keywords:
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- Planetary Sciences: Solar System Objects: Saturn;
- Planetary Sciences: Solar System Objects: Saturnian satellites