EDP Sciences
Free access
Volume 395, Number 2, November IV 2002
Page(s) 677 - 683
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20021310

A&A 395, 677-683 (2002)
DOI: 10.1051/0004-6361:20021310

High-frequency slowly drifting structures in solar flares

M. Karlický, F. Fárník and H. Mészárosová

Astronomical Institute of the Academy of Sciences of the Czech Republic, 25165 Ondrejov, Czech Republic
    e-mail: karlicky@asu.cas.cz, ffarnik@asu.cas.cz

(Received 3 May 2002 / Accepted 27 August 2002 )

Radio emission of four solar flares with high-frequency slowly drifting structures is presented. Three sub-classes of these structures were recognized. It is shown that the April 15, 2001 X14.4 flare started with the slowly drifting structure associated with a plasmoid ejection observed by TRACE in the 171 Å line. The August 18, 1998 event presents an example of the drifting pulsation structure (DPS) which is well limited in frequency extent at both sides. A further example of the DPS, but followed by clouds of the narrowband dm-spikes, was observed during the November 23, 2001 flare. Finally, in the case of the April 12, 2001 flare, the drifting pulsation-continuum structure was recorded at the same time as the metric type II radio burst, i.e. in different frequency ranges. The slowly drifting structures were analyzed and in two cases their relation to hard X-ray emission was studied. Possible underlying physical processes are discussed assuming the plasmoid ejection model of eruptive solar flares.

Key words: Sun: activity -- Sun: flares -- Sun: radio radiation

Offprint request: M. Karlický, karlicky@asu.cas.cz

© ESO 2002