Volume 537, January 2012
|Number of page(s)||5|
|Published online||23 December 2011|
On the physical meaning of n-distributions in solar flares
1 Astronomical Institute of the Academy of Sciences of the Czech Republic, 25165 Ondřejov, Czech Republic
2 Dept. of Astronomy, Physics of the Earth and Meteorology, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava, Slovak Republic
Received: 9 August 2011
Accepted: 28 October 2011
Aims. We investigate the physical meaning of the n-distributions detected in solar flares.
Methods. We consider a Maxwellian velocity distribution with a velocity drift. This distribution is analytically integrated to obtain the energy distribution, and its stability is investigated numerically using a fully electromagnetic particle-in-cell code.
Results. It is shown that the derived moving Maxwellian energy distribution is very similar to the n-distribution, especially in their high-energy parts. Both these distributions are mutually fitted and a relation between their parameters found. Contrary to the n-distribution, the moving Maxwellian distribution has a simple physical meaning, e.g., the electron component of the return current in the beam-plasma system. However, for high drift velocities of such a component, the moving Maxwellian distribution is unstable. Therefore to keep the form of this distribution similar to the n-distribution, some stabilization processes are necessary. If so, then the high intensities of the Si xiid 5.56 Å and 5.82 Å satellite lines and their evolution in solar flares can be explained by moving Maxwellian distributions instead of the n-distributions. Thus, our previous results connected with the n-distributions can be understood in a new, physically profound way.
Key words: Sun: flares / Sun: X-rays, gamma rays
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.