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SUMMARY:Magnetic fields measured by asteroseismolgy in the cores of red gi
 ant stars - Francois Lignières (IRAP\, Toulouse)
DTSTART:20221114T140000Z
DTEND:20221114T150000Z
UID:TALK192254@talks.cam.ac.uk
CONTACT:Zhao Guo
DESCRIPTION:I will present the unambiguous detection of magnetic fields in
  the radiative cores of red giant stars using asteroseismology.\nMagnetic 
 fields are thought to affect stars throughout their evolution. But their s
 trength and topology inside stars\,\nparticularly in the non-convective st
 ably stratified radiative layers\, remain basically unconstrained observat
 ionally\nas well as theoretically. This prevents us from constructing reli
 able models of angular momentum and chemical element transport\, which are
  at\nthe heart of modern stellar evolution theory.\n\nMagnetic fields indu
 ce shifts in the frequencies of oscillation modes and break the symmetry o
 f dipole mode multiplets of slowly rotating stars. We detected such featur
 es and find that they closely follow the predictions of magnetic perturbat
 ions to oscillation modes that we generalized to an arbitrary field. The m
 easured field strengths range from ~30 to ~600 kG in the vicinity of the h
 ydrogen-burning shell\, and we obtain information on the field topology.\n
 \nThe discovery of strong magnetic fields in the cores of red giants confi
 rm that the transport of angular momentum in these objects can have a magn
 etic origin. More generally\, with both rotation rate and magnetic field m
 easurements\, the core of red giants could become a privileged laboratory 
 to study the interactions between magnetic fields and rotation in collisio
 nal plasmas.
LOCATION:In Person MR14 + Online
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