Date/Time
Date(s) - 05/03/2014
3:30 pm - 4:30 pm

Title: Surface Magnetic Fields as Windows to Stellar Internal Structure and Evolutionary History

Speaker: Dr. Greg Wade

Institute: Queens University

Location: ABB 102

Description:

Measurements of magnetic fields at the surfaces of stars provide sensitive probes of their current internal structure and evolutionary histories. Recent advances in both observational and computational capabilities now allow us to derive beautifully detailed maps of the 2D and 3D structure of the surface magnetic fields of many important classes of stars, from faint red dwarfs, to solar twins at various stages of evolution, to the hottest and brightest stars in the Galaxy. As a consequence, comprehensive studies of the systematics of stellar magnetic field topologies have been achieved during the last decade.

On the one hand, these investigations have revealed systematic relationships between magnetic field characteristics and the current internal structure of cool, low-mass stars like the Sun. These provide new observational constraints on the dynamo models that explain their magnetic activity, and the evolution of dynamo physics through the early and intermediate phases of stellar evolution. On the other hand, magnetism in hotter, higher-mass stars is found to be remarkably uniform in stars ranging over a factor of nearly 50 in stellar mass. This fundamental result strengthens the view that the fields of higher-mass stars are the remnants of an earlier epoch of their evolution, produced as the consequence of universal elements of their evolutionary history predating the earliest currently-observable phases.

In this talk I will review the observations and methods used to infer the magnetic topologies of distant stars. I will review the most recent observational results, and their implications for our theoretical understanding of dynamo physics, stellar structure and stellar evolution.