Master of Science (MS), Bowling Green State University, 2017, Physics

We present the results of a 6-year observing campaign conducted using the PROMPT-5 telescope to detect, identify and characterize long-period variable (LPV) stars in the metal-rich globular cluster NGC 6388. LPV stars are asymptotic giant branch stars that exist on a Mira-to-semi-regular-to-irregular continuum in terms of the regularity of their variable behavior. The long time-baseline was found to be fruitful in characterizing that aspect of LPV pulsation that cannot be captured in shorter campaigns. The ISIS image subtraction package is used for variability detection and the production of flux difference photometric data. We have also manually recovered known variable stars with use of their published celestial coordinates. Newly detected sources of variability were ranked on the basis of a variability index. An attempt was also made to quantitatively characterize the positions of LPV stars on the regularity spectrum with a newly defined regularity index, with partial success in the case of known variables. The known and new variables are discussed and characterized and their cluster membership determined with the use of a color-magnitude diagram and the variable's projected distance from the cluster center. Out of 72 variables studied, two of which were found to be duplicated in the literature, 56 are known variables that were detected or recovered. The LPVs detected number to 26 and 16 known and new, respectively. Almost all LPVs' periods are determined using the period-dispersion minimization method. A list of suspected variables, which require higher-resolution observations to confirm, amounts to an additional 22 stars. A period-luminosity relation is determined using the available literature data and our own data.

Committee: Andrew Layden Dr. (Advisor); John Laird Dr. (Committee Member); Dale Smith Dr. (Committee Member) Subjects: Astronomy; Astrophysics; Physics