The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXIII. Proper-motion catalogs and internal kinematics

TL;DR

This paper provides the most comprehensive proper-motion catalogs for stars in 57 clusters, enabling detailed internal kinematic studies and extending Gaia data into crowded cluster cores, advancing our understanding of cluster dynamics.

Contribution

It presents a homogeneous collection of proper motions for stars in globular clusters, combining HST data with archival images, and offers new insights into their internal kinematics and dynamical properties.

Findings

Proper-motion catalogs for 56 globular and 1 open cluster.

Analysis of velocity dispersion and anisotropy profiles.

Dynamical distances derived for the clusters.

Abstract

A number of studies based on data collected by the $\textit{Hubble Space Telescope}$ ($\textit{HST}$) GO-13297 program "HST Legacy Survey of Galactic Globular Clusters: Shedding UV Light on Their Populations and Formation" have investigated the photometric properties of a large sample of Galactic globular clusters and revolutionized our understanding of their stellar populations. In this paper, we expand previous studies by focusing our attention on the stellar clusters' internal kinematics. We computed proper motions for stars in 56 globular and one open clusters by combining the GO-13297 images with archival $\textit{HST}$ data. The astro-photometric catalogs released with this paper represent the most complete and homogeneous collection of proper motions of stars in the cores of stellar clusters to date, and expand the information provided by the current (and future) $\textit{Gaia}$ data releases to much fainter stars and into the crowded central regions. We also census the general kinematic properties of stellar clusters by computing the velocity-dispersion and anisotropy radial profiles of their bright members. We study the dependence on concentration and relaxation time, and derive dynamical distances. Finally, we present an in-depth kinematic analysis of the globular cluster NGC 5904.