Multiplicity Systems as Metrics for Stellar Evolution Theory: Spectroscopic Eclipsing, Eclipsing, and Unresolved Binaries
Cunningham, Joni Marie Clark
Binary stars serve as the astrophysical laboratory in the extraction of stellar and orbital parameters and as calibration sites for stellar evolution theory. These systems come in three flavors, spectroscopic eclipsing, eclipsing and unresolved. In this dissertation, I combined photometric and spectroscopic observations of binary targets within the observational overlaps to determine stellar and orbital properties, spanning a wide range of mass, temperature and radius ratios. These solutions are then utilized to arrive at age estimates and test stellar evolution theory. The APOGEE field includes 19,635 binary candidates with multiple high resolution spectroscopic observations. Spectroscopic eclipsing binaries with complete orbital and stellar solutions from APOGEE/Kepler overlap (J.M.C. Cunningham et al. 2019) and TESS (J.M.C. Cunningham et al. in prep, 2022) are presented. Depending on the binary system, different methodologies are equipped, including both the Cross Correlation (CCF) and Broadening Function (BF) methods of Radial Velocity extraction. In the TESS/APOGEE overlap targets, I used the BF method of radial velocity extraction to disentangle radial velocity elements for two systems. While, in the Kepler/APOGEE overlap I used the BF to extract primary and secondary solutions for a total of seven spectroscopic eclipsing binaries. With these solutions I compute age estimates for each subset, which I use to determine the degree of coevality for each system (that is, the assumption that binary stars form at the same time). A unique, young eclipsing binary with a tertiary component is presented (J.M.C. Cunningham et al. 2020). Photometric observations from TESS and KELT, and spectroscopic observations from a number of missions were used to solve for stellar and orbital solutions. These solutions and stellar chronometers were then used to determine a most likely age for the system. Gaia proper motion and age estimates established it having likely membership in a newly discovered stellar stream association, Theia-301. Additionally, when I apply the age I derived for this system to AB Dor (by virtue of six shared members between the two associations) the luminosity discrepancy for the star AB Dor disappears. Binary (and higher order multiplicity) systems have such far reaching effects on stellar formation in terms of intermolecular cloud fragmentation and the initial mass function, that incomplete binary fraction estimates prevent true modeling of these foundational processes. Every identification of a multiplicity system, with stellar and orbital solutions, age estimates and galactic motion vectors results in a more complete understanding of stellar evolution and a more complete binary fraction.