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SUMMARY:Gravito-inertial modes in a differentially-rotating spherical shel
 l and applications to stellar physics - Giovanni Mirouh (Sissa Trieste)
DTSTART:20161128T160000Z
DTEND:20161128T170000Z
UID:TALK67274@talks.cam.ac.uk
CONTACT:Antoine Riols
DESCRIPTION:Massive stars are the main contributors of the interstellar me
 dium enrichment. These stars are usually fast rotators\, with a radiative 
 envelope in which the interaction between stratification and rotation give
 s rise to a differential rotation. Besides\, many of these stars are class
 ical pulsators.\n\nI will present quickly an attempt at modelling a well-d
 escribed fast rotator\, in two dimensions\, using asteroseismic constraint
 s. Even though this first approach was unsuccessful\, it highlighted the n
 eed of a better understanding of the oscillations' properties.\n\nOur work
  focuses therefore on the impact of a differential rotation on the low-fre
 quency oscillation spectrum which contains gravito-inertial modes. These m
 odes are restored by the combination of buoyancy and Coriolis force. They 
 probe deep layers of stars. We study them using two methods: we compute th
 e paths of characteristics in the non-dissipative limit\, and solve the fu
 lly-dissipative eigenvalue problem numerically using a spectral method. We
  find various singularities (attractors\, critical latitudes\, corotation 
 resonances) and regular modes. Some of these modes are excited by baroclin
 ic instabilities that may saturate through non-linear effects. If so\, we 
 have discovered a new excitation mechanism for these modes\, driven by dif
 ferential rotation.
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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