부산대학교 도서관

Summary: In addition to M dwarf metallicities, I describe some complementary work to determine the true mass of an extrasolar planet candidate using a combined analysis of high-precision astrometry and radial velocities. I present a dynamical mass for the companion to HD 33636 that indicates it is a low-mass star instead of an exoplanet. This result demonstrates the value of follow-up astrometric observations to determine the true masses of exoplanet candidates detected with the radial velocity method. Finally, I discuss the broader implications of the results presented in this dissertation and the prospect for similar work in the future.