Polarization diagnostics of proton beams in solar flares
Abstract
We review the problem of proton beam bombardment of solar chromosphere considering the self-consistent NLTE polarized radiation transfer in hydrogen lines. Several observations indicate a linear polarization of the Halpha line of the order of 5% or higher and preferentially in radial direction. This polarization is often explained as anisotropic collisional excitation of the n=3 level by vertical proton beams. Our calculations indicate that deceleration of the proton beam with initial power-law energy distribution together with increased electron and proton densities in the Halpha forming layers lead to a negligible line polarization. Thus the proton beams seem not to be a good candidate for explanation of the observed polarization degree. On the other hand, the effect of electric return currents could perhaps provide a better explanation of the observed linear polarization. We report the new calculations of this effect.
- Publication:
-
Memorie della Societa Astronomica Italiana
- Pub Date:
- 2007
- DOI:
- 10.48550/arXiv.astro-ph/0702060
- arXiv:
- arXiv:astro-ph/0702060
- Bibcode:
- 2007MmSAI..78...83S
- Keywords:
-
- Sun: flares;
- polarization;
- atomic processes;
- line: profiles;
- radiative transfer;
- Astrophysics
- E-Print:
- 6 pages, 6 figures