Stellar model atmospheres with magnetic line blanketing

II. Introduction of polarized radiative transfer

¹ Physics and Astronomy Department, University of Western Ontario, London, ON, N6A 3K7, Canada e-mail: skhan@astro.uwo.ca
² Institut für Astronomie, Universität Wien, Türkenschanzstraße 17, 1180 Wien, Austria
³ Tavrian National University, Vernadskogo 4, 95007 Simferopol, Crimea, Ukraine

Received: 29 September 2005
Accepted: 18 November 2005

Abstract

The technique of model atmosphere calculation for magnetic Ap and Bp stars with polarized radiative transfer and magnetic line blanketing is presented. A grid of model atmospheres of A and B stars are computed. These calculations are based on direct treatment of the opacities due to the bound-bound transitions that ensures an accurate and detailed description of the line absorption and anomalous Zeeman splitting. The set of model atmospheres was calculated for the field strengths between 1 and 40 kG. The high-resolution energy distribution, photometric colors and the hydrogen Balmer line profiles are computed for magnetic stars with different metallicities and are compared to those of non-magnetic reference models and to the previous paper of this series. The results of modelling confirmed the main outcomes of the previous study: energy redistribution from UV to the visual region and flux depression at 5200 Å. However, we found that effects of enhanced line blanketing when transfer for polarized radiation takes place are smaller in comparison to those obtained in our first paper where polarized radiative transfer was neglected. Also we found that the peculiar photometric parameter is not able to clearly distinguish stellar atmospheres with abundances other than solar, and is less sensitive than or Z to a magnetic field for low effective temperature ( K). Moreover we found that the back determination of the fundamental stellar atmosphere parameters using synthetic Strömgren photometry does not result in significant errors.