Line profile and magnetic fields in stars of great mass.

VALLVERDÚ, R.; CIDALE, L.; ROHRMANN, R.

Cariló, Argentina

Congreso; Massive Stars: Fundamental Parameters and Circumstellar Interactions.; 2006

IAU

We calculate theoretical models of stellar atmospheres corresponding to B stars with peculiar abundances of helium. We analyze how the magnetic elds modify the line pro les. We center our attention in the line pro files of helium because many B stars show periodic variations in the intensity and in the shape of the line profiles. These stars also show periodic variations in the equivalent widths of the lines of helium.We include to the magnetic eld as a Lorentz force into the hydrostatic equilibrium equation. Then, an effective gravity modi es the distribution of density of particles in the stellar atmosphere. We calculate models of atmospheres in local thermodynamic equilibrium (LTE) and non-local thermodynamic equilibrium (NLTL). Our models show small variations in the shape and intensity of the line pro les. If the abundance of helium remains constant, these variations and the variations in the equivalent widths are smaller than the variations observed in several B stars. For a better approach, we include the Zeeman efect produced by the magnetic fields.