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Short-term variations of Mercury's Na exosphere observed with very high spectral resolution

Authors :
Cesare Barbieri
A. López Ariste
Nicholas M. Schneider
Stefano Massetti
Alain Doressoundiram
François Leblanc
Mea Wedlund
Gabriele Cremonese
V. Mangano
Source :
Geophysical Research Letters. 36
Publication Year :
2009
Publisher :
American Geophysical Union (AGU), 2009.

Abstract

[1] Short time variations of Mercury's exosphere cannot be tracked easily from ground based observatories because of the difficulty of distinguishing them from Earth atmospheric effects. On July 13th 2008, using THEMIS solar telescope, we were able to simultaneously measure brightness, Doppler shift and width of the exospheric sodium D2 emission line during half a day with a resolving power of ∼370,000. Mercury's exosphere displayed an emission brightness peak in the Northern hemisphere which vanished in few hours and a more persistent Southern Hemispheric peak. The bulk Doppler shift of the exosphere suggests a period of strong escape from Mercury. The global changes of the Doppler shift and of the Doppler width suggest that a cloud of sodium atoms ejected before or at the beginning of our sequence of observations passed through THEMIS field of view moving anti-sunward. A preferentially southern ejection of sodium atoms leading to the observed persistent southern emission peak is consistent with the orientation of the Interplanetary Magnetic Field during that period.

Details

ISSN :
00948276
Volume :
36
Database :
OpenAIRE
Journal :
Geophysical Research Letters
Accession number :
edsair.doi...........ae8825ce87f988144cb3fa9dbebef92c
Full Text :
https://doi.org/10.1029/2009gl038089