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SUMMARY:Magnetic fields and the damping of stellar oscillations - Cleo Loi
DTSTART:20161115T130000Z
DTEND:20161115T140000Z
UID:TALK68490@talks.cam.ac.uk
CONTACT:Jean Teyssandier
DESCRIPTION:The standard theory of stellar oscillations focuses primarily 
 on the forces of pressure and buoyancy\, while the effects of rotation and
  magnetic fields are assumed to be weak perturbations and usually ignored.
  Recent observations of red giants have suggested that in a substantial fr
 action of these stars the oscillations are subject to a source of damping 
 localised to the core region\, but this has neither been anticipated nor a
 ccounted for by standard theory. Indirect evidence argues for the role of 
 a deeply buried fossil magnetic field within the core\, but so far no conv
 incing mechanism has been proposed that explains how the damping occurs. H
 ere we present a mechanism for damping the observable modes of red giants 
 harbouring magnetised cores that involves resonant interactions with stand
 ing Alfven waves of high harmonic index. The damping rates produced by thi
 s mechanism are quantitatively on par with those associated with turbulent
  convection\, and in the range required to explain observations\, for real
 istic stellar models and magnetic field strengths. Our results suggest tha
 t magnetic fields can provide an efficient means of damping stellar oscill
 ations\, and lay the groundwork for an extension of the theory that incorp
 orates these effects.
LOCATION:MR11\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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