| Popis: |
Globular cluster M5 (NGC 5904), located in the constellation Serpens, was discovered over 300 years ago. Since then, several studies have sought to characterize and understand its origin and evolution. Of particular interest are the studies involving the cluster’s variable star population. To date nearly two hundred variable stars have been identifed in the cluster. The majority of these are short period variable stars belonging to the category “RR Lyrae”.With advances in photometry and automated observation, recent studies have begun to investigate the cluster’s population of long period variable stars (LPV’s), but further study is needed to fully catalog and characterize them. Seven of the twenty known LPV’s in M5 do have undetermined periods, and more are awaiting discovery. With the use of data acquired with the BGSU half-meter telescope and from the Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes (PROMPT), period analysis was performed on M5’s two II Cepheids, 20 known LPV’s and one newly discovered LPV.The creation of a color-magnitude diagram (CMD) for M5 allows for testing the hypothesis that as a star evolves further along the red giant branch of the CMD, that the star’s periodicity becomes more regular, and will show a larger amplitude of variability. The positions of the stars of interest, and the conclusions drawn from their light curves in our data was compiled and the variability type for each star was assessed. Suggestions for future observational work are provided with the aim of further improving upon the characterization of these LPV’s |
