P088-02
Energy distribution of planetary ions He+, O+ and Na+ in Mercury's magnetosphere
Thursday, 17 December 2020: 04:04
Virtual
Anita Linnea Elisabeth Werner1, Francois Leblanc1, Jean-Yves Chaufray2, Ronan Modolo2, Sae Aizawa3, Jim M Raines4, Willi Exner5,6 and Uwe M Motschmann7,8, (1)LATMOS/IPSL, CNRS, Sorbonne Université, UVSQ, Paris, France, (2)LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, Guyancourt, France, (3)IRAP, Toulouse, France, (4)University of Michigan, Ann Arbor, MI, United States, (5)Technical University of Braunschweig, Institute for Geophysics and extraterrestrial Physics, Braunschweig, Germany, (6)TU Braunschweig, Institute of Theoretical Physics, Braunschweig, Germany, (7)Technische Universität Braunschweig, Institute for Theoretical Physics, Braunschweig, Germany, (8)DLR Institute of Planetary Research, Berlin, Germany
Abstract:
The Mercury plasma environment is enriched in planetary ions from the tenuous neutral exosphere. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) time-of-flight spectrometer Fast Imaging Plasma Spectrometer (FIPS) has revealed important clues about the absolute ion density and spatial distribution of three major planetary ions or groups of ions: He
+, the Na
+-group (including Na
+, Mg
+ and Si
+) and the O
+-group (including O
+ and several water group ions).
We have developed a test-particle model which describes the full equation of motion for planetary ions produced from photo-ionization of the neutral exosphere (modeled with the Exospheric Global Model; EGM; Leblanc et al. 2017). We propagate the test-ions in magnetic and electric fields computed by the two established hybrid models LatHyS (Modolo et al. 2016) and AIKEF (Müller et al. 2011) and compare the resulting density distributions in the Hermean magnetosphere. This approach specifically allows for investigation of non-adiabatic energization of heavy planetary ions and the connection to seasonal asymmetries in the neutral exosphere.
We present the ion density and energy distribution of He+, O+ and Na+ inside and outside the magnetopause. Our results show good agreement with the ion density observed by FIPS and indicate several interesting features outside of FIPS observable energy range (E = 0.05-13 keV). We investigate how our combined results can aid the interpretation of FIPS data and future measurements by BepiColombo.
