The ice-rich crust of dwarf planet 1 Ceres is the source of a tenuous water exosphere, and the behavior of this putative exosphere is investigated with model calculations. Outgassing water molecules seasonally condense around the winter pole in an optically thin layer. This seasonal cap reaches an estimated mass of at least 2 x 10(3) kg, and the aphelion summer pole may even retain water throughout summer. If this reservoir is suddenly released by a solar energetic particle event, it would form a denser transient water exosphere. Our model calculations also explore species other than H2O. Light exospheric species escape rapidly from Ceres due to its low gravity, and hence their exospheres dissipate soon after their respective source has faded. For example, the theoretical turn-over time in a water exosphere is only 7 hr. A significant fraction of CO2 and SO2 molecules can get trapped and stored in perennially shadowed regions at the current spin axis orientation, but not at the higher spin axis tilt, leaving H2O as the only common volatile expected to accumulate in polar cold traps over long timescales. The D/H fractionation during migration to the cold traps is only about 10%.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/626261 |
| Date | 20 November 2017 |
| Creators | Schorghofer, Norbert, Byrne, Shane, Landis, Margaret E., Mazarico, Erwan, Prettyman, Thomas H., Schmidt, Britney E., Villarreal, Michaela N., Castillo-Rogez, Julie, Raymond, Carol A., Russell, Christopher T. |
| Contributors | Univ Arizona |
| Publisher | IOP PUBLISHING LTD |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017. The American Astronomical Society. All rights reserved. |
| Relation | http://stacks.iop.org/0004-637X/850/i=1/a=85?key=crossref.beb66a30f5318a576d8e432947bc9a6d |
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