Ghostly Impostors: The Glowing Magnetospheres of Massive Stars

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Date/Time:Friday, 15 Nov 2013 from 4:10 pm to 5:00 pm
Location:Room 0003
Phone:515-294-2958
Channel:Astronomy
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Richard Townsend (Department of Astronomy, University of Wisconsin Madison)

Massive stars aren't expected to be magnetic, due to their lack of a significant sub-surface convection zone driving a field-generating dynamo. However, thanks to recent advances in spectropolarimetry a small subset (5-10%) of these stars are now known to harbor strong, ordered, stable magnetic fields. These fields interact strongly with the stars' hypersonic radiatively driven winds, channeling and confining the wind plasma in circumstellar structures which emit across the full electromagnetic spectrum, from X-rays through to radio. In this talk I'll describe recent progress in using MHD simulations together with so-called 'rigid-field' approaches to model the plasma distribution, state and time evolution throughout these glowing magnetospheres. I'll also highlight some of the remarkable successes achieved in matching the models against observations, including the direct measurement of magnetic braking, at the predicted
rate, in one particular star.