Isochrone Fitting of Galactic Globular Clusters -- VIII. Homogeneous estimates of parameters for 27 clusters

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We use the Stetson, HST, and Gaia DR3 data sets for 22 Galactic globular clusters to select their members and fit their CMDs with isochrones from DSED and BaSTI for $[α/$Fe$]=+0.4$ and an adopted helium mass fraction $Y$. As a result, we estimate the metallicity [Fe/H], age, distance from the Sun, and reddening E(B-V) for these clusters.

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Excerpt

We use the Stetson, HST, and Gaia DR3 data sets for 22 Galactic globular clusters to select their members and fit their CMDs with isochrones from DSED and BaSTI for $[α/$Fe$]=+0.4$ and an adopted helium mass fraction $Y$. As a result, we estimate the metallicity [Fe/H], age, distance from the Sun, and reddening E(B-V) for these clusters. Special attention is paid to identify variable stars among the cluster members. We combine these results with our earlier estimates for five other clusters into a homogeneous set of parameters for 27 clusters and investigate relationships among these parameters and their statistical properties. In particular, we count the giants on the red (RGB), horizontal (HB), and asymptotic branches using the clean data sets cross-identified to cover the entire cluster fields and count each giant only ones. This allows us to calculate the $R$-parameter, the ratio between the numbers of the HB and RGB, with unprecedented accuracy and to examine its relations with other parameters. These relations are much stronger for accreted clusters rejecting a constant $R$ value for them, possibly because of their heterogeneous origins and environments. For all in-situ clust

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