Globular cluster metallicities and distances from disentangling their RR Lyrae light curves

We present mean horizontal branch absolute magnitudes and iron abundances for a sample of 39 globular clusters. These quantities were calculated in an unprecedented homogeneous fashion based on Fourier decomposition of ligt curves of RR Lyrae cluster members. Zero points for the luminosity calibrati...

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Bibliographic Details
Published in:Proceedings of the International Astronomical Union 2022-12, Vol.18 (S376), p.222-238
Main Author: Arellano Ferro, A.
Format: Article
Language:English
Subjects:
Contributed Paper
Globular clusters
Horizontal branch stars
Iron
Light curve
Luminosity
Space telescopes
Online Access:Get full text
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Summary:We present mean horizontal branch absolute magnitudes and iron abundances for a sample of 39 globular clusters. These quantities were calculated in an unprecedented homogeneous fashion based on Fourier decomposition of ligt curves of RR Lyrae cluster members. Zero points for the luminosity calibrations are discussed. Our photometrically derived metallicities and distances compare very well with spectroscopic determinations of [Fe/H] and accurate distances obtained using Gaia and Hubble Space Telescope data. The need to distinguish between the results for RRab and RRc stars for a correct evaluation of the M V –[Fe/H] relation is discussed. For RRab stars, the relation is non-linear, and the horizontal branch structure plays a significant role. For RRc stars, the relation remains linear and tight, and the slope is very shallow. Hence, the RRc stars seem better indicators of the parental cluster distances. Systematic time-series CCD imaging performed over the last 20 years enabled to discover and classify 330 variables in our sample of globular clusters.
ISSN:1743-9213
1743-9221
DOI:10.1017/S1743921323002880