EDP Sciences
Free access
Volume 436, Number 1, June II 2005
Page(s) 347 - 353
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20042269

A&A 436, 347-353 (2005)
DOI: 10.1051/0004-6361:20042269

Microwave emission from the trapped and precipitated electrons in solar bursts

J. E. R. Costa1, 2 and A. C. Rosal1, 2

1  INPE - Instituto Nacional de Pesquisas Espaciais, Brazil
    e-mail: jercosta@craam.mackenzie.br
2  IPM/CRAAM - Instituto Presbiteriano Mackenzie/Centro de Rádio Astronomia e Astrofísica Mackenzie, Brazil

(Received 28 October 2004 / Accepted 7 February 2005)

We analyzed the microwave spectra of a sample of 13 solar flares out of 40 events observed by the Nobeyama Radio Polarimeter in the period of August 8, 1998 through November 24, 2001. The solar burst time profiles were filtered to separate the slow component from the fast structures which were associated with the emission from trapped particles and to the emission from the minor precipitating population, respectively. The spectra of both components suggest a trap in a region with a mean magnetic field of about 600 G and a minor emission from the loop legs with a magnetic field of 1100 G, resulting in a mirror ratio of about two. The spectral indices of the optically thin emission from these two regions indicate pitch angle diffusion by Coulomb collisions.

Key words: Sun: flares -- Sun: activity -- Sun: magnetic fields -- Sun: particle emission -- Sun: radio radiation

© ESO 2005