Wednesday 28 Nov 2012Magnetism in young stars: origin and impact on their evolution and environment

Dr Nicolas Bessolaz - University of Exeter

Physics, 4th floor 14:00-15:00

Magnetism in pre-main sequence stars plays an important role in stellar formation and evolution processes. I will present different kind of numerical simulations I carried out highlighting some effects of such a stellar magnetic field.
For instance, I will show how the star/disc interaction phase for class II objects can control the angular momentum evolution of young stars during the accretion process. Next, I will discuss the origin of such magnetic fields through dynamo processes built in these stars.
Particularly, studying how convective and magnetic properties of pre-main sequence stars change during their evolution towards the ZAMS is a growing area of research triggered by the development of efficient spectro-polarimeters. Carrying out 3D simulations is an efficient way to identify the key parameters to understand the diversity (strength, topology) of magnetic fields observed for different stellar internal structure (depending on mass, age, ...) and rotation rates, and eventually how this change of magnetic fields influences the further evolution of stars in the goal of designing the next generation of stellar evolution codes. I will present different dynamo simulations of the classical T-Tauri star BP Tau with a first attempt to compare the properties of the large scale magnetic field obtained with spectropolarimetric observations (Donati et al. 2008, 2010).

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