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MESSENGER observations of suprathermal electrons in Mercury's magnetosphere
Author(s) -
Ho George C.,
Starr Richard D.,
Krimigis Stamatios M.,
Vandegriff Jon D.,
Baker Daniel N.,
Gold Robert E.,
Anderson Brian J.,
Korth Haje,
Schriver David,
McNutt Ralph L.,
Solomon Sean C.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl066850
Subject(s) - physics , mercury (programming language) , electron , magnetosphere , planet , spacecraft , van allen radiation belt , latitude , population , astrophysics , magnetic field , sky , atomic physics , astronomy , nuclear physics , demography , sociology , computer science , programming language , quantum mechanics
The X‐Ray Spectrometer (XRS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft regularly detected fluorescent X‐rays near Mercury induced by low‐energy (1–10 keV) or suprathermal electrons. We devised an algorithm to select these events from XRS records between April 2011 and March 2015 on the basis of their duration, location, and spectral slope. We identified 3102 events during 3900 orbits around Mercury, sampling all Mercury longitudes multiple times over the 4 year period. These suprathermal electrons were present near the planet at all local times, but the majority were on the nightside of the planet, and a dawn‐dusk asymmetry is seen in the data. When the event locations are plotted in a coordinate system based on a simplified magnetic field model, several distinct clusters of events are evident. We infer that all are signatures of accelerated electrons that were injected from Mercury's tail region to form a quasi‐trapped electron population at Mercury.