On the formation of Ganymede's surface brightness asymmetries: Kinetic simulations of Ganymede's magnetosphere. Issue 10 (20th May 2016)

• Record Type: Journal Article
• Authors: Fatemi, S.; Poppe, A. R.; Khurana, K. K.; Holmström, M.; Delory, G. T.
• Is Part Of: Geophysical research letters. Volume 43:Issue 10(2016)
• Page Start: 4745
• Page End: 4754
• Publication Date: 2016-05-20
• Subjects: Ganymede -- hybrid model -- energetic ion -- surface brightness -- plasma precipitation -- magnetospheric interaction; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL068363
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Ganymede possesses strong surface brightness asymmetries both between its polar cap and equatorial regions and between its leading and trailing hemispheres. Here we test the hypothesis that these asymmetries are due to differential Jovian plasma and energetic particle precipitation to the surface with the combination of a hybrid plasma model (kinetic ions and fluid electrons) and a particle tracing model. We describe the hybrid model, the first of its kind applied to Ganymede, and compare the results to both Galileo observations and previous MHD and MHD‐EPIC models of Ganymede. We calculate spatially resolved precipitating Jovian ion fluxes to the surface of Ganymede for energies 1 < E < 10 4 keV and find (1) precipitating fluxes peak near 100 keV and (2) excellent correlation between the precipitating flux and Ganymede's surface brightness variations. Thus, we conclude that precipitating energetic particle fluxes are the primary driver for altering the surface brightness of Ganymede. Key Points: The first kinetic simulation of jovian plasma and energetic particle interaction with Ganymede's magnetosphere Correlation between energetic ion precipitation to the surface of Ganymede and Ganymede's surface brightness Energetic ion precipitation to Ganymede's surface peaks near 100–300 keV