2 research outputs found
Effects of Uniform and Differential Rotation on Stellar Pulsations
We have investigated the effects of uniform rotation and a specific model for
differential rotation on the pulsation frequencies of 10 \Msun\ stellar models.
Uniform rotation decreases the frequencies for all modes. Differential rotation
does not appear to have a significant effect on the frequencies, except for the
most extreme differentially rotating models. In all cases, the large and small
separations show the effects of rotation at lower velocities than do the
individual frequencies. Unfortunately, to a certain extent, differential
rotation mimics the effects o f more rapid rotation, and only the presence of
some specific observed frequencies with well identified modes will be able to
uniquely constrain the internal rotation of pulsating stars.Comment: 33 pages, 16 figures. Accepted for publication in Ap
Theoretical p Mode Oscillation Frequencies for the Rapidly Rotating Delta Scuti Star Alpha Ophiuchi
A rotating, two dimensional stellar model is evolved to match the approximate
conditions of Alpha Oph. Both axisymmetric and nonaxisymmetric oscillation
frequencies are computed for 2D rotating models which approximate the
properties of Alpha Oph. These computed frequencies are compared to the
observed frequencies. Oscillation calculations are made assuming the
eigenfunction can be fit with six Legendre polynomials, but comparison
calculations with eight Legendre polynomials show the frequencies agree to
within about 0.26% on average. The surface horizontal shape of the
eigenfunctions for the two sets of assumed number of Legendre polynomials
agrees less well, but all calculations show significant departures from that of
a single Legendre polynomial. It is still possible to determine the large
separation, although the small separation is more complicated to estimate. With
the addition of the nonaxisymmetric modes with |m| less than or equal 4, the
frequency space becomes sufficiently dense that it is difficult to comment on
the adequacy of the fit of the computed to the observed frequencies. While the
nonaxisymmetric frequency mode splitting is no longer uniform, the frequency
difference between the frequencies for positive and negative values of the same
m remains 2m times the rotation rate.Comment: ApJ accepte