P53A-2089
Energization and Precipitation of Electrons in Mercury’s Magnetosphere
Friday, 18 December 2015
Poster Hall (Moscone South)
David Schriver1, Pavel M. Travnicek2, George C Ho3, Richard D Starr4, Deborah Lorin Domingue5, Daniel N. Baker6, Petr Hellinger7, Stamatios M Krimigis3, Ralph L McNutt Jr3, Jim M Raines8, James A Slavin9 and Sean C Solomon10, (1)University of California Los Angeles, Los Angeles, CA, United States, (2)University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, United States, (3)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (4)Catholic University of America, Washington, DC, United States, (5)Planetary Science Institute Tucson, Tucson, AZ, United States, (6)University of Colorado at Boulder, Boulder, CO, United States, (7)Organization Not Listed, Washington, DC, United States, (8)University of Michigan Ann Arbor, Department of Atmospheric, Oceanic and Space Sciences, Ann Arbor, MI, United States, (9)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (10)Columbia University of New York, Palisades, NY, United States
Abstract:
Observations by the MESSENGER spacecraft in orbit around Mercury from 2011 to 2015 have established that Mercury’s magnetosphere hosts a quasi-trapped population of electrons with bulk energies of 1–10 keV centered about the magnetic equator. Although there are occasional observations of higher-energy (> 35 keV) electrons within the magnetosphere, there is no high-energy radiation belt present at Mercury similar to those at the other planets in our solar system with global magnetic fields, including Earth, Saturn, Jupiter, Uranus and Neptune. Observations from MESSENGER’s X-Ray Spectrometer and simulations have also established that the 1–10 keV electron population around Mercury precipitates to the surface in an auroral-oval-type pattern with fluxes of ~109–1010 cm-2s-1. Global simulation modeling has determined that the quasi-trapped electrons are energized in Mercury’s magnetotail via a combination non-adiabatic particle acceleration near magnetic reconnection regions and betatron/Fermi acceleration. Precipitating 1–10 keV electrons cause X-rays to be generated and emitted from the surface, and also can result in the ejection of sodium ions into the magnetosphere through the process of electron-stimulated desorption. Long-term electron precipitation may result in space weathering of the surface regolith.
