Thesis Supervisor: Markus SchУЖller

Abstract

While magnetic fields in the sun and solar-like stars have been studied intensively, very little is yet known about their existence, origin and role in massive stars, like O and Wolf-Rayet stars. Magnetic fields are accessible through the Zeeman effect: The Zeeman components of spectral lines are polarized and thus permit magnetic fields to be measured even in rapidly rotating massive stars where rotation broadening, etc, prevents the resolution of Zeeman components. Currently, direct measurements are achieved only in about a dozen O stars.

This PhD project aims at studying magnetic field topologies of O stars in detail and the impact of fields on stellar rotation, pulsation, stellar winds, and chemical abundances. The obtained results will test and constrain the theories being developed by several groups working on the physics of massive stars, especially theoretical models including rotation and magnetic fields. Furthermore, the results of magnetic studies will provide important clues about the origin of magnetic fields in hot stars, i.e. whether they are fossil remnants or are produced through dynamo processes.

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