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CATEGORIES:DAMTP Astrophysics Seminars
SUMMARY:Gravito-inertial modes in a differentially-rotatin
g spherical shell and applications to stellar phys
ics - Giovanni Mirouh (Sissa Trieste)
DTSTART;TZID=Europe/London:20161128T160000
DTEND;TZID=Europe/London:20161128T170000
UID:TALK67274AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/67274
DESCRIPTION:Massive stars are the main contributors of the int
erstellar medium enrichment. These stars are usual
ly fast rotators\, with a radiative envelope in wh
ich the interaction between stratification and rot
ation gives rise to a differential rotation. Besid
es\, many of these stars are classical pulsators.\
n\nI will present quickly an attempt at modelling
a well-described fast rotator\, in two dimensions\
, using asteroseismic constraints. Even though thi
s first approach was unsuccessful\, it highlighted
the need of a better understanding of the oscilla
tions' properties.\n\nOur work focuses therefore o
n the impact of a differential rotation on the low
-frequency oscillation spectrum which contains gra
vito-inertial modes. These modes are restored by t
he combination of buoyancy and Coriolis force. The
y probe deep layers of stars. We study them using
two methods: we compute the paths of characteristi
cs in the non-dissipative limit\, and solve the fu
lly-dissipative eigenvalue problem numerically usi
ng a spectral method. We find various singularitie
s (attractors\, critical latitudes\, corotation re
sonances) and regular modes. Some of these modes a
re excited by baroclinic instabilities that may sa
turate through non-linear effects. If so\, we have
discovered a new excitation mechanism for these m
odes\, driven by differential rotation.
LOCATION:MR14\, Centre for Mathematical Sciences\, Wilberf
orce Road\, Cambridge
CONTACT:Antoine Riols
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