Evelyne Alecian (LESIA)

Magnetism in the intermediate and massive stars - Evelyne Alecian Colloquium

ATNF Marsfield Lecture Theatre

Abstract

A few percent of the intermediate-mass A/B stars have been known for long time to host magnetic fields. The origin of their magnetic fields is still a subject of intense debate. In order to test the favoured fossil field hypothesis, we have conducted a high-resolution spectropolarimetric survey of a large number of pre-main sequence progenitors of the A/B stars.

In the first part of my talk I will present the results and conclusion of this survey. The massive stars are the progenitors of the supernovae and neutron stars, and are not structurally very different from the intermediate-mass stars. In contrast with the later, our knowledge of the basic statistical properties of the magnetic fields in massive stars is seriously incomplete. In particular our knowledge of the origin of the magnetic fields, the impact of these fields on massive star evolution and mass loss, and of the physics of magnetospheres is very poor. In order to shed
light on these problems, a large International collaboration, MiMeS
(Magnetism in Massive Stars), have started a theoretical and observational program, using the new generation of spectropolarimeters ESPaDOnS (at CFHT), and Narval (at TBL).

In the second part of my talk, I will present the latest results of the MiMeS project, expose the basic properties of magnetism in massive stars that we could draw until now, and how they
compare to the intermediate and low-mass stars.