Title: On
the origin of aurorae on Mars
Source: GEOPHYSICAL
RESEARCH LETTERS 33 (1): Art. No. L01201 JAN 5 2006
Document Type: Article
Language: English
Abstract: We
report observations by Mars Global Surveyor (MGS) of thousands of
peaked electron energy spectra similar to terrestrial auroral
electrons. They are observed on the Martian nightside, near strong
crustal magnetic sources. The spectra have peak energies ranging from
100 eV-2.5 keV, and fluxes near the peak are 10-10000 times higher than
typical nightside spectra. They occur on magnetic field lines that
connect the shocked solar wind to crustal magnetic fields, and on
adjacent closed field lines. Their detection is directly controlled by
the solar wind, suggesting that magnetic reconnection is required for
their observation. We calculate that the most energetic distributions
could produce atmospheric emission with intensity comparable to that
recently reported from the Mars Express (MEX) spacecraft. Half of the
most energetic examples occur during the passage of space weather
events past Mars, suggesting that a disturbed plasma environment is
favorable for electron acceleration along magnetic field lines.
KeyWords Plus: MAGNETIC-FIELD;
PARTICLE PRECIPITATION; IONOSPHERE
Addresses: Brain
DA (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA
94720 USA
Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA
Univ Michigan, Dept Space Sci, Ann Arbor, MI 48109 USA
NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA
Ctr Etud Spatiale Rayonnements, Toulouse, F-31028 France
Publisher: AMER
GEOPHYSICAL UNION, 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA
Subject Category: GEOSCIENCES,
MULTIDISCIPLINARY
IDS Number: 001BX
ISSN: 0094-8276
