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Analysis of the halo globular cluster M30 and its variable stars

by Smitka, Michael T.

Abstract (Summary)
Andrew C. Layden, Advisor Photometry of the metal-poor globular cluster M30 is presented in B, V, R and I bandpasses. A color-magnitude diagram created from this photometry indicates that accurate magnitude measurements were obtained for stars from the red giant branch down to approximately 2.5 magnitudes fainter than the main sequence turnoff. Time-series photometry is presented for six RR Lyrae type variable stars, three of which are newly discovered. Four variable stars of other types, three of them newly discovered, are also discussed. A metallicity value of [Fe/H] = -2.02 was adopted for this study. Using the RR Lyrae stars’ mean colors at minimum light, a reddening of E(B ? V ) = 0.053 ± 0.010 was found for this cluster as well as an extinction value of AV = 0.165±0.031. A distance modulus of µ = 14.504±0.127 and the corresponding distance of 7.958 ± 0.147 kpc was also computed using the RR Lyrae stars’ mean magnitudes. Isochrone fitting of the color-magnitude diagram yielded a cluster age of 15.8 ± 1.8 Gyr. iii
Bibliographical Information:

Advisor:

School:Bowling Green State University

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:stars astronomical photometry astrophysics light curves

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