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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:2
UID:UW-Physics-Event-4938
DTSTART:20181029T170500Z
DURATION:PT1H0M0S
DTSTAMP:20260315T135253Z
LAST-MODIFIED:20181026T201610Z
LOCATION:2241 Chamberlin Hall
SUMMARY:Wave Conversion from Stellar Magnetic Fields\, Plasma Physics 
 (Physics/ECE/NE 922) Seminar\, Daniel Lecoanet\, Princeton University
DESCRIPTION:Stars have global oscillation modes\, which can be observe
 d by looking
\nfor periodic brightness variations. If many modes of os
 cillation have been
\nidentified\, one can infer the properties of the
  deep interiors of
\nstars. This was first applied to observations of 
 the Sun\, but recently
\nspace-based telescopes have measured oscillat
 ions in many other stars\,
\nleading to new mysteries in stellar struc
 ture and evolution. Recent work
\nhas suggested that low dipole oscill
 ation amplitudes in red giant branch
\nstars may indicate strong core 
 magnetic fields. Here we present both
\nnumerical simulations and anal
 ytic calculations of the interactions of
\nwaves with a strong magneti
 c field. We can solve the problem very
\naccurately by using the WKB a
 pproximation to reduce the 2D PDE into an
\nODE for each height. We fi
 nd that magnetic fields convert the
\nbuoyancy-driven waves observable
  at the surface of the star to
\nmagnetic waves\, which are not presen
 t at the surface\, in agreement with
\nobservations.
URL:https://www.physics.wisc.edu/events/?id=4938
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