Asteroseismology and pulsation timing of the A-type stars observed by Kepler.

Abstract

The A-type stars are arguably some of the most diverse stars found across the HR diagram, encompassing a wide range of physics, including rotation, pulsation, magnetic interactions, and chemical peculiarities. In this thesis, I develop a series of frameworks and tools to investigate a subset of the A-type stars: the delta Scuti and rapidly oscillating Ap (roAp) type stars, primarily using data from the Kepler and TESS space missions. I discuss the roAp stars within the context of the Kepler mission and identify six new members by exploiting irregularities in the sampling cadence. I then provide methods for the precise calculation of luminosities for A-type stars and apply them to the Kepler delta Scuti sample to improve the observational instability strip. I extend this work to a new class of young, high frequency delta Scuti stars discovered in the TESS data, which possess stable and regularly spaced modes, opening them up as potential candidates for mode identification via asteroseismology. I develop a framework for analysing delta Scuti stars in binary systems, through timing of their pulsations, and provide an open-source package to facilitate their analysis. Following this, I search for transits around the delta Scuti stars by iteratively subtracting their pulsations and identify three possible candidates in the Kepler data. Finally, I discuss the eclipsing binaries in the context of the inverse problem, and detail tested methods to rapidly obtain orbital parameters from the light curve with no prior knowledge.