Properties of rapidly rotating stars and their oscillation modes

Abstract

In this thesis I present a set of scaling relationships for ZAMS rotating models. These relationships are applicable to models whose rotation rate produces a given surface distortion and are shown to be valid for stellar masses from 1.875 M[circle dot] to 2.5 M[circle dot]. Some of the scaling relationships are used to determine intrinsic stellar properties such as the real luminosity and effective temperature of the star based on deduced properties from interferometry and other observations, providing a direct way to place a rotating star into the HR diagram. I also present pulsation calculations of p and g-modes for a set of these rotating models using a 2D linear adiabatic code. I computed and classified more than ten thousand pulsation modes and found scaling relationships for both the p-modes and g-modes between models of different masses with the same surface shape. The p-mode scaling is well-described by the root-mean density relation but the scaling of g-modes is found to depend on properties outside of the convective core. These pulsation mode scaling properties could be useful for selecting optimal stellar models to match the observed oscillation frequencies of individual stars. Finally, I considered the observability of the modeled oscillation modes by perturbing the surface properties of static rotating models and calculating the effect each mode would have on the observed magnitude of the star at different inclinations. The results suggest that there are some modes that could be ruled out from the analysis when comparing the theoretical and observed oscillation spectra of a rotating star for the rotation rates considered.