Yoichiro Hanaoka Submitted: 12-Feb-2003 03:40
We started regular observation of polarization and Doppler velocity in the H-alpha line for solar flares in July 2002 at Mitaka, NAOJ. Polarization in H-alpha line is generally interpreted to be impact polarization produced by accelerated protons. Therefore, the combination of RHESSI HXR observations and H-alpha polarization observations is expected to give us a clue to study the relation between the electrons and the protons in flares. For example, in the case of a gradual flare (C5.8) occurred on 2002 October 14, polarization of which the degree exceeds 1 % was detected. This fact implies that significant amount of accelerated protons bombarded the chromosphere, and produced impact polarization in the H-alpha line. On the other hand, the RHESSI observation shows that the hard X-ray spectrum of this flare has no power-law component. Therefore, the proton beam is possibly the principal heating agent in this flare, while this flare shows no detectable high-energy electrons.
Participants: Hanaoka, Y.
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