HR: 1340h
AN: P23A-0246    [Abstracts]
TI: Modeling The Impulsive Meteoritic Impact Vaporization In The Hermean Exosphere
AU: Mangano, V
EM: valeria.mangano@ifsi.rm.cnr.it
AF: IFSI-INAF, Area di Ricerca Tor Vergata via del Fosso del Cavaliere, 100, ROMA, 00133 Italy
AU: Mangano, V
EM: valeria.mangano@ifsi.rm.cnr.it
AF: CISAS, Universit… di Padova via Venezia, 15, PADOVA, 35131 Italy
AU: Lammer, H
EM: helmut.lammer@oeaw.ac.at
AF: IWF-Space Research Institute, Dept. for Extraterrestrial Physics Austrian Academy of Sciences Schmiedlstr. 6, GRAZ, A-8042 Austria
AU: * Milillo, A
EM: anna.milillo@ifsi.rm.cnr.it
AF: IFSI-INAF, Area di Ricerca Tor Vergata via del Fosso del Cavaliere, 100, ROMA, 00133 Italy
AU: Wurz, P
EM: peter.wurz@soho.unibe.ch
AF: University of Bern, Physics Institute Sidlerstrasse 5, BERN, CH-3012 Switzerland
AU: Cremonese, G
EM: cremonese@pd.astro.it
AF: INAF Osservatorio Astronomico, vicolo Osservatorio 5, PADOVA, 35122 Italy
AU: Orsini, S
EM: orsini@ifsi.rm.cnr.it
AF: IFSI-INAF, Area di Ricerca Tor Vergata via del Fosso del Cavaliere, 100, ROMA, 00133 Italy
AU: Biernat, H
EM: helfried.biernat@oeaw.ac.at
AF: IWF-Space Research Institute, Dept. for Extraterrestrial Physics Austrian Academy of Sciences Schmiedlstr. 6, GRAZ, A-8042 Austria
AU: Bruno, M
EM: marco.bruno@unito.it
AF: INAF Osservatorio Astronomico, vicolo Osservatorio 5, PADOVA, 35122 Italy
AU: Marchi, S
EM: marchi@pd.astro.it
AF: Dipartimento di Astronomia, Universit… di Padova vicolo Osservatorio, 5, PADOVA, 35122 Italy
AB: As for many other aspects of Mercury, our knowledge about the Hermean exosphere and its characteristics is very limited. Many models have been studied to account for the poor observational evidences. Among these, the model by Wurz and Lammer (2003) consists of a Monte Carlo simulation of a large number of trajectories of different species ejected through different surface release processes, following ballistic orbits. Inputs are the distinctive energy and ejection angle distribution of the released particles; then the numerical integration provides a large set of trajectories from which exospheric bulk parameters are derived. The resulting exosphere looks comparable with the observed data. Among the source mechanisms, meteoritic impact vaporization has often been considered to have only a secondary role for exospheric refilling; nevertheless recent works evidenced that it could be the main acting process on the night side of the planet, where the PSD and thermal desorption cannot operate anymore. On this subject almost nothing has been investigated about objects with size larger than 1 cm. Such meteoroids have been shown to be ejected from the Main Belt and to intersect the Hermean orbit; then they are expected to become part of the meteoritic contribution. The present work reviews impact vaporization contribution to the model by Wurz and Lammer. Particularly, it is intended to superimpose on the exospheric model the vapour cloud caused by an impulsive event, and then study both the enhancement of the average exospheric density, than its dynamical evolution with time. In fact, during relatively short time periods, many small meteoroids are expected to fall on Mercury; not so frequent to contribute with a constant rate to the exosphere, but surely enough to be detected by devoted instruments on board of space missions like MESSENGER or BepiColombo.
DE: 5409 Atmospheres--structure and dynamics
DE: 5420 Impact phenomena (includes cratering)
DE: 6235 Mercury
DE: 0322 Constituent sources and sinks
DE: 0325 Evolution of the atmosphere
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting