EDP Sciences
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Volume 390, Number 2, August I 2002
Page(s) 783 - 791
Section Physical and chemical processes
DOI http://dx.doi.org/10.1051/0004-6361:20020754

A&A 390, 783-791 (2002)
DOI: 10.1051/0004-6361:20020754

Depolarization rates of resonance lines of Mg, Ca, Sr and Na atoms by collisions with neutral hydrogen

B. Kerkeni

Laboratoire "Atomes et Molécules en Astrophysique", CNRS UMR 8588 - DAMAp, Observatoire de Paris, Section de Meudon, 92195 Meudon, France

(Received 5 February 2002 / Accepted 13 May 2002)

Multipole relaxation and transfer rates due to isotropic collisions with neutral hydrogen atoms are calculated and a general expression for the hyperfine-structured levels are obtained. Evaluation of these rates has been carried out using accurate potential energy curves. The formulae given here for the depolarizing collisional rates should be useful for accurately modelling the complex linear polarization pattern of the Na I doublet in a complement to the ground state's depolarizing collisional rates which were presented in a previous paper (Kerkeni et al. 2000) hereafter referred to as Paper I. Similarly the depolarizing collisional rates of the Mg I, Ca I, Sr I resonance lines should be useful for polarization studies.

Key words: line: formation -- polarization -- atomic processes -- Sun: atmosphere

© ESO 2002