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SUMMARY:Modelling and interpreting pulsations of rapidly rotating stars - 
  Daniel Reese
DTSTART:20220606T131500Z
DTEND:20220606T141500Z
UID:TALK175166@talks.cam.ac.uk
CONTACT:Zhao Guo
DESCRIPTION: The majority of intermediate mass and massive main sequence s
 tars rotate rapidly. This affects their structure\, evolution\, lifetime\,
  chemical yields\, and final outcome. Modelling such stars is highly chall
 enging due to the departure from spherical symmetry and is subject to many
  uncertainties.  Hence\, it is necessary to constrain these stars observat
 ionally in order to progress in our understanding of them. Asteroseismolog
 y\, the study of stellar pulsations\, is currently the only approach we ha
 ve at our disposal for probing their internal structure\, and is according
 ly a particularly important source of information.  However\, as will be d
 escribed in this seminar\, it is necessary to overcome a number of hurdles
  to carry out asteroseismic investigations of such stars.\n\nFirst of all\
 , pulsation calculations must be carried out in a 2D context in order to f
 ully include the effects of rotation.  The geometry of the resultant pulsa
 tion modes can differ substantially from that of their non-rotating counte
 rparts thus leading to a different mode classification.  Likewise\, the as
 sociated pulsation frequency spectra follow new patterns which are more co
 mplicated than in the non-rotating case.  This leads to the next major hur
 dle which intervenes when trying to interpret observed pulsation spectra\,
  namely mode identification\, i.e. correctly matching theoretical modes wi
 th observed pulsation frequencies.  Indeed\, direct comparisons between th
 e two typically yield multiple solutions due to the high density of theore
 tical frequencies compared with the observed ones.  Therefore\, current st
 rategies for interpreting observed pulsations involve looking for specific
  frequency spacings\, such as the large frequency separation and the rotat
 ion rate\, and/or applying mode identification techniques based on multico
 lour photometric observations and spectroscopic observations of line profi
 le variations\, both of which need to be adapted to the rapidly rotating c
 ase.  These interpretation strategies will be illustrated through various 
 recent studies of observed stars.
LOCATION:In Person Seminar Room 2\, INI gatehouse
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