Observations of Metallic Species in Mercury’s Exosphere During the Three MESSENGER Flybys

Details Observations of Metallic Species in Mercury’s Exosphere During the Three MESSENGER Flybys Observations of Metallic Species in Mercury’s Exosphere During the Three MESSENGER Flybys

Dec 2009

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufm.p24a..05k&link_type=abstract

American Geophysical Union, Fall Meeting 2009, abstract #P24A-05

Other

[0328] Atmospheric Composition And Structure / Exosphere

Scientific paper

Metallic species have been observed in Mercury’s exosphere, including sodium (Na), potassium (K), magnesium (Mg), calcium (Ca) and aluminum (Al). Although Na, K and Ca have been observed previously from ground-based platforms, we present the first map of the Na/K abundance ratio over the observed sunlit disk of the planet. Mg was discovered in Mercury’s exosphere during the second MESSENGER flyby. From an analysis of the observed column abundances, all metallic species observed exhibit a distribution and line width characteristic of high to extreme temperature. The temperatures of refractory species, including Mg and Ca, indicate that the source process for the atoms observed in the tail and corona are consistent with ion sputtering and/or impact vaporization of a molecule with subsequent dissociation into the atomic form. We discuss the results in the context of assumed surface composition, and source and loss processes constrained by the modeled magnetospheric configuration at the time of observation and other ancillary information. We find that the Na/K ratio is highly correlated with the solar Lyman alpha radiation. Estimates of the atomic Mg ejected into the exosphere by impact vaporization and ion-sputtering, respectively, were made assuming a high Mg regolith (18%) and a low Mg regolith (5%). If the Hermean soil contains 18% Mg, then impact vaporization can provide the observed Mg exosphere if the Mg atoms stick to the surface with an average of two ballistic hops. However, the hot Mg tail is consistent with a surface abundance of 5% Mg, with 30% of impact-vaporized material containing Mg remaining as MgO at quenching and half of the impact vapor condensing. Virtually all the ejected MgO molecules would be dissociated to populate the tail with the observed atomic Mg. Because of estimated errors in the fraction of molecules that condense on the order of a factor of 3, we cannot tightly constrain the surface abundance of Mg. Globally, ion sputtering is not modeled to be a major source of Mg, but locally the sputtered source can be an order of magnitude larger than the impact vapor source.

Affiliated with

Also associated with

No associations

Rating

Observations of Metallic Species in Mercury’s Exosphere During the Three MESSENGER Flybys does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Observations of Metallic Species in Mercury’s Exosphere During the Three MESSENGER Flybys, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Observations of Metallic Species in Mercury’s Exosphere During the Three MESSENGER Flybys will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1770147