Subject will be restored when possible
Säm Krucker Submitted: 2007-10-31 14:09
One of the largest solar hard X-ray (HXR) flares and solar energetic particle (SEP) events recorded by the
Mars Odyssey mission while orbiting Mars occurred on 2002 October 27 and is related to a very fast (∼2300
km s-1 ) coronal mass ejection (CME). 1 From the Earth, the flare site is 40.4 degree behind the solar limb and
only emissions from the high corona at least 150 000 km radially above the main flare site can be seen.
Nevertheless, the Earth-orbiting Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observed
HXR emission up to 60 keV with a relatively flat, nonthermal spectrum (g between 3 and 3.5) that has an onset
simultaneous with the main HXR emission observed above 60 keV by the Gamma-Ray Spectrometer (GRS)
orbiting Mars. While GRS records several smaller enhancements after the main peak, the high coronal source
observed by RHESSI shows a long exponential decay (135 s) with progressive spectral hardening.
The emissions from the high corona originate from an extended source (∼150 000 km in diameter) that expands
(390 km s-1) and moves upwards (750 km s-1) in the same direction as the CME. These observations
reveal the existence of energetic electrons in the high corona in closed magnetic structures related to the CME
that are accelerated at the same time as the main energy release in the flare. Although the number of energetic
electrons in the high corona is only a small fraction of the total accelerated electrons, about 10% of all electrons
in the high coronal source are nonthermal (110 keV).
Authors: Säm Krucker, S. M. White, and R. P. Lin
Publication Status: published
Last Modified: 2007-11-01 07:34