AAVSO: American Association of Variable Star Observers

Characterization of NGC 5272, NGC 1904, NGC 3201, and Terzan 3

Volume 49 number 2 (2021)

Download this article (pdf)

Paul Hamrick
Stanford Online High School, 415 Broadway Academy Hall, Floor 2, 8853, Redwood City, CA 94063; paulahamrick@gmail.com
Avni Bansal
Stanford Online High School, 415 Broadway Academy Hall, Floor 2, 8853, Redwood City, CA 94063; avnibansal2004@gmail.com
Kalée Tock
Stanford Online High School, 415 Broadway Academy Hall, Floor 2, 8853, Redwood City, CA 94063; kaleeg@stanford.edu

Abstract

Globular clusters are an ideal laboratory for studying and comparing variable stars, since all the variables in a globular cluster formed from the same progenitor gas cloud. Because of this, all of the variables within a given cluster have similar ages, metallicities, reddening, and distances from Earth. Thus we estimated the age, metallicity, reddening, and distance of the clusters NGC 5272, NGC 1904, NGC 3201, and Terzan 3 by doing a visual fit to isochrones. Knowing the characteristics of these clusters as a whole helps us better understand the characteristics of individual variables in these clusters as well. Reddening, metallicity, and age estimates for NGC 1904 and NGC 5272 are consistent with previous literature, but all four of the estimated parameters for Terzan 3 and the metallicity measurement of NGC 3201 differed significantly from literature values. Further research into NGC 3201 and Terzan 3 is recommended.