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Astron. Astrophys. 333, 1130-1142 (1998)


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Theoretical study of the polarization by resonance scattering of the H [FORMULA] line in spicules

A. de Kertanguy

Laboratoire 'Atomes et Molécules en Astrophysique', CNRS URA 812 - DAMAp, Observatoire de Paris, Section de Meudon, F-92195 Meudon, France (Amaury.deKertanguy@obspm.fr)

Received 22 March 1996 / Accepted 16 October 1997

Abstract

One currently observes spicules in the H [FORMULA] line, the underlying photospheric radiation being scattered by the matter of the spicules. In this paper we solve the equations of statistical equilibrium for a hydrogen atom having an ensemble velocity and being illuminated by the photospheric radiation field. This leads us to the determination of the Stokes parameters [FORMULA] of the radiation diffused by the spicule towards the observer. The calculations include fine structure effects, limb darkening and depolarization by isotropic collisions.

One obtains the linear polarization degree as well as the rotation of the polarization plane as a function of the ascending velocity of matter in spicules.

Key words: line: formation – polarization – Sun: photosphere – Sun: chromosphere

© European Southern Observatory (ESO) 1998

Online publication: April 28, 1998

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