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Photometry of Long Period Variable Stars in M5

Published onJun 01, 2020
Photometry of Long Period Variable Stars in M5

Long Period Variable (LPV) stars in globular clusters have been poorly studied due to having long pulsation periods ranging from 30-1000 days. Globular clusters provide a unique environment to study LPVs due to member stars having been formed from the same gas cloud, leading to members all having the same composition, age, and distances thus allowing for the relative comparison of properties across different globular clusters. Images of M5 were collected by the PROMPT telescopes at Cerro Tololo Inter-American Observatory from late 2010 through 2011, with additional data provided by the BGSU observatory in 2007, 2009, 2010. This wide time span allows for a thorough characterization of LPVs that has not previously been possible. Image subtraction was utilized to obtain time-series flux differences for light curve analysis. Initial results were very promising, with successful characterization of W Virginis and RV Tauri type variables, along with the known LPVs, V50 and V171. During analysis, additional stars were discovered to be LPVs that were previously considered to have no variability. Fourier analysis was utilized to determine the period of all LPVs in the cluster, and provides updated period values for these objects. Ultimately, this data may be further utilized in future research to better understand stellar evolution and pulsation.

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