Quasi-periodic oscillations in solar X-ray sources

0360451 - ASÚ 2012 RIV GB eng C - Konferenční příspěvek (zahraniční konf.)
Mészárosová, Hana - Karlický, Marian - Fárník, František
Quasi-periodic oscillations in solar X-ray sources.
Advances in Plasma Astrophysics. Cambridge: Cambridge University Press, 2011 - (Bonanno, A.), s. 252-254. IAU Symposium Proceedings Series, IAU S274. ISBN 9780521197410. ISSN 1743-9213.
[Symposium of the International Astronomical Union /274./. Giardini Naxos (IT), 06.09.2010-10.09.2010]
Grant CEP: GA AV ČR(CZ) IAA300030701
Výzkumný záměr: CEZ:AV0Z10030501
Klíčová slova: Sun * flares * X-rays
Kód oboru RIV: BN - Astronomie a nebeská mechanika, astrofyzika

We have searched for quasi-periodic oscillations in the hard X-ray emission of solar flares. We have selected 14 flare events which were divided into two groups: a) the events with the X-ray sources located at the flare loop footpoints and b) the events with the X-ray source above the solar limb, i.e. with the loop-top X-ray source. We found that while in the case with the footpoints X-ray sources the quasi-periods of the recorded oscillations were in the interval 2–380 s, in the events with loop-top sources only the quasi-periods longer than 50 s were recognized. These results are probably connected with the MHD oscillation modes of the flaring loop. While the long periods, which are dominant in loop-top sources, are produced by acoustic oscillations along the whole long loop, in the layers close to the loop footpoints also the MHD wave modes in shorter structures with shorter periods are generated.
Trvalý link: http://hdl.handle.net/11104/0198003