Transition probabilities and lifetimes in neutral and singly ionized osmium and the Solar osmium abundance

¹ IPNAS, Université de Liège, Sart Tilman B15, 4000 Liège, Belgium e-mail: E.Biemont@ulg.ac.be
² Astrophysique et Spectroscopie, Université de Mons-Hainaut, 7000 Mons, Belgium e-mail: Pascal.quinet@umh.ac.be
³ Institut d'Astrophysique, Université Libre de Bruxelles, 1050 Bruxelles, Belgium e-mail: [ajorisse;svaneck]@astro.ulb.ac.be
⁴ Department of Physics, Lund Institute of Technology, PO Box 118, 221 00 Lund, Sweden e-mail: Sune.Svanberg@fysik.lth.se
⁵ GRAAL, CNRS UMR 5024, Université Montpellier II, 34095 Montpellier Cedex 5, France e-mail: bertrand.plez@graal.univ-montp2.fr

Received: 19 July 2005
Accepted: 14 October 2005

Abstract

Radiative lifetime measurements have been performed, with a time-resolved laser-induced fluorescence technique, for 12 levels of Os I and for 9 levels of Os II. For 9 levels of Os I and 4 levels of Os II, there were no previous experimental data available. From a comparison with new theoretical calculations, taking configuration interactions and core-polarization effects into account, it has been possible to deduce oscillator strengths for 129 transitions of Os I and 137 transitions of Os II of astrophysical interest appearing in the wavelength range 180.0–870.0 nm. These results have allowed us to revise the abundance of osmium in the solar photosphere ( = 1.25 ± 0.11). The newly derived oscillator strengths have been applied as well to derive the osmium abundance in the carbon-rich metal-poor star HD 187861.