The Effect of Rapid Rotation on Main Sequence Line-Profile Variables
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**Session 55 -- Pulsating Variables/Stellar Models**
*Display presentation, Thursday, 2, 1994, 9:20-6:30*

## [55.09] The Effect of Rapid Rotation on Main Sequence Line-Profile Variables

*Maurice J. Clement (University of Toronto)*

The line-profile variables observed on the upper main sequence are
interpreted by some astronomers to be the manifestation of nonaxisymmetric
oscillations. More specifically, many of these stars can be modelled
by prograde (or corotating) equatorial waves. These are sectorial modes
which in the absence of rotation have surface velocity distributions
corresponding to simple spherical harmonics. Unfortunately, the velocity
fields in the presence of rotation are much more difficult to predict.
In this paper, I will report on the results of variational calculations
which account for the effects of rapid rotation on the normal mode
eigenfunctions of $15\,{\rm M}_{\odot}$ stellar models. The principal
conclusion is that nonaxisymmetric modes couple only weakly to rotation
and, consequently, they retain many of the geometrical properties that
apply in the absence of rotation. In fact, it is not easy to
detect the signature of rotation in the line-profile variations,
especially for some long-period gravity modes of low radial order.
This means that if the latter modes are the relevant ones then
observers will not be making large errors in their mode identifications
when they adopt the spherical harmonic model.

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