Collisional depolarization of the lines of complex atoms/ions by neutral hydrogen

¹ Observatoire de Paris-Meudon, LERMA UMR CNRS 8112, 5 place Jules Janssen, 92195 Meudon Cedex, France
² Department of Astronomy and Space Physics, Uppsala University, Box 515, 751 20 Uppsala, Sweden e-mail: moncef.derouich@obspm.fr

Received: 16 October 2004
Accepted: 21 December 2004

Abstract

We have developed a new semi-classical method for calculating the depolarization and polarization transfer rates of spectral lines of neutral and ionised atoms by collisions with atomic hydrogen (Derouich et al. 2003a, A&A, 404, 763; 2003b, A&A, 409, 369; 2004a, A&A, 414, 369; 2004b, A&A, 426, 707). Up to now, our depolarization rate calculations have been limited to simple atoms. In the present paper, we extend our theory to more complex atoms and we apply our new results to provide the first calculations associated with the upper levels of multiplet 145 of neutral titanium Ti I which constitutes a remarkable example of the second solar spectrum (Manso Sainz & Landi Degl'Innocenti 2002, A&A, 394, 1093).