Joint Astrophysics Colloquium

Joint Astrophysics Seminar

Fossil fields: stable magnetic equilibria in stars

Jon Braithwaite

CITA

Observations of various types of non-convective star tend to show a lack of differential rotation, and a magnetic field which has a large scale structure and which does not change over timescales of at least decades. This, and the lack of any suitable dynamo process in these stars, suggests that the magnetic fields are in stable equilibria which can survive for the diffusive timescale (10¹⁰ years in a main-sequence star). I explore the properties of these stable equilibria and their evolution over the diffusive timescale. I also look at some side effects of these magnetic field configurations including their effect on the star's moment of inertia and the consequent possibility of free precession and whether stars are likely to have their magnetic and rotation axes aligned or perpendicular.