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Linear Polarization of the Solar Ca I 4227 Å Line: Modeling with Radiative Transfer and Last Scattering Approximation

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dc.contributor.author Anusha, L. S
dc.contributor.author Stenflo, J. O
dc.contributor.author Frisch, H
dc.contributor.author Bianda, M
dc.contributor.author Holzreuter, R
dc.contributor.author Nagendra, K. N
dc.contributor.author Sampoorna, M
dc.contributor.author Ramelli, R
dc.date.accessioned 2011-06-09T16:06:01Z
dc.date.available 2011-06-09T16:06:01Z
dc.date.issued 2011-04
dc.identifier.citation Astronomical Society of the Pacific Conference Series, Vol. 437, pp. 57-66 en
dc.identifier.uri http://hdl.handle.net/2248/5498
dc.description Restricted Access en
dc.description.abstract To model the Ca I 4227 Å line polarization, radiative transfer effects with partial frequency redistribution (PRD) must be taken into account. The numerical solution of the relevant polarized radiative transfer (RT) equations is computationally very demanding. The “last scattering approximation” (LSA) is a concept allowing faster methods to be devised. It is based on the remark that a single scattering of the radiation field is sufficient for creating most of the polarization. Its key ingredient is the anisotropy of the radiation field. If the anisotropy is extracted from the observed center to limb variation of the intensity profile, only the wings of the Q/I spectrum can be modeled (Sampoorna et al. 2009). We show here that the core region may be modeled as well if one takes into account the depth variation of the anisotropy which is obtained from an unpolarized multilevel RT (Anusha et al. 2010). After a validation of the LSA approach by comparison with a polarized RT calculation, we apply both approaches to model recent observations of the Ca I 4227 Å line polarization taken on the quiet Sun. Apart from a global scaling factor, both approaches give a very good fit to the Q/I spectrum for all the wavelengths. As the LSA is 8 times faster than the RT approach, we can recommend it as an efficient method to analyze other strong resonance lines in the second solar spectrum. en
dc.language.iso en en
dc.publisher Astronomical Society of the Pacific en
dc.relation.uri http://aspbooks.org/custom/publications/paper/437-0057.html en
dc.rights © Astronomical Society of the Pacific en
dc.title Linear Polarization of the Solar Ca I 4227 Å Line: Modeling with Radiative Transfer and Last Scattering Approximation en
dc.type Article en

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