Asteroseismology of intermediate mass stars : pre-main sequence evolution

Abstract

We investigate in detail the potential of asteroseismology in exploring the structure of intermediate mass (1.6 &#8804 M_&#8857 &#8804 5.0) pre-main sequence stars. It is expected that pre- and post-main sequence stars will produce differing oscillation spectra due to the dependance of oscillation frequencies on the internal structure of that star. We compute densely populated grids of pre- and post-main sequence stellar models, which are then used as a tool to explore the oscillation frequencies of pre-main sequence stars. We examine the cause of the oscillation spectra by correlating the frequencies with changes in stellar structure and comparing fundamental properties of pre-main sequence stars to their post-main sequence counterparts. By fashioning a set of oscillation frequencies designed to mimic observed oscillation spectra, we determine the conditions under which we can distinguish the evolutionary state of a star through its oscillation spectra alone, and explore our ability to constrain stellar parameters as a function of the quality of the observed frequency spectrum. Using the dense grids to construct precise pre-main sequence isochrones, we fit them to two young open clusters. Finally, we present efforts in constraining the stellar parameters of two pre-main sequence stars by matching the observed frequencies to the calculated frequency spectra of all grid models.