Astronomy and Astrophysics – Astronomy
Scientific paper
Apr 2012
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012apj...749..166h&link_type=abstract
The Astrophysical Journal, Volume 749, Issue 2, article id. 166 (2012).
Astronomy and Astrophysics
Astronomy
Magnetic Fields, Plasmas, Sun: Chromosphere, Sun: Corona, Sun: Flares, Sun: X-Rays, Gamma Rays
Scientific paper
This paper deals with the acceleration of high-energy flare electrons by field-parallel electric fields in an approach tailored after the auroral acceleration process. Electromagnetic energy, derived from the release of magnetic shear stresses, is converted into kinetic energy of particles. The stress release is enabled by field-aligned potential drops generated by anomalous resistivity of highly filamentary currents. The high-energy flare electrons are identified with runaway particles of this process. The magnetic shear stresses originate from Alfvén waves emitted from high-beta loop-top plasma which is produced by braking of the outflow from a reconnection site higher up in the corona. Partial reflection of the waves at the interface to the chromosphere leads to evaporation of chromospheric plasma and creation of a strongly filamentary structure in the sheared coronal field. The energy conversion process propagates spontaneously, like an erosion process in three dimensions. The overall stress release site forms a thin triangular sheet growing along and perpendicular to the field. After about one second, its cross-section perpendicular to B has grown to tens of square kilometers. This spontaneous growth strongly alleviates the demands on the primary filamentary structure posed by the condition of current criticality. Energy flux and mean energy are of the magnitude typical for hard X-rays producing electrons. Their strong dependence on the ambient magnetic field in combination with the fast propagation of the energy conversion sites could lead to energy-dependent time delays of a few 100 ms, much longer than the time-of-flight effects of the electrons.
No associations
LandOfFree
Solar Auroras does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Solar Auroras, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solar Auroras will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1287153