A new study of the variable star population in the Hercules globular cluster (M13; NGC 6205)
D. Deras, A. Arellano Ferro, C. L\'azaro, I.H. Bustos Fierro, J. H., Calder\'on, S. Muneer, Sunetra Giridhar
TL;DR
This study provides detailed photometric analysis of M13, identifying new variable stars, determining cluster properties like metallicity, distance, and age, and clarifying membership status using Gaia data.
Contribution
It offers new variable star discoveries, refined cluster parameters, and a comprehensive membership analysis combining photometry and Gaia data.
Findings
Identified 7 new variable stars in M13.
Determined cluster metallicity as [Fe/H]zw = -1.58.
Estimated cluster distance as 7.1 kpc.
Abstract
We present the results from CCD time-series photometry of the globular cluster M13 (NGC 6205). From the Fourier decomposition of the light curves of RRab and RRc stars we found an average metallicity of [Fe/H]zw = -1.58 0.09. The distance to the cluster was estimated as 7.1 0.1 kpc from independent methods related to the variable star families RR Lyrae, SX Phe and W Virginis, from the luminosity of the theoretical ZAHB and from the orbit solution of a newly discovered contact binary star. The RR Lyrae pulsation modes are segregated by the red edge of the first overtone instability strip in this OoII type cluster. A membership analysis of 52,800 stars in the field of the cluster is presented based on \textit{Gaia}-DR2 proper motions which enabled the recognition of 23,070 likely cluster members, for 7,630 of which we possess photometry. The identification of member…
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Taxonomy
TopicsStellar, planetary, and galactic studies · Astrophysics and Star Formation Studies · Astronomy and Astrophysical Research