# Near-Infrared Variability Study of the Central 2.3 arcmin x 2.3 arcmin of the Galactic Centre I. Catalog of Variable Sources

## TL;DR

This study used four-year HST IR observations to identify and classify over 3,800 variable stars in the Galactic Centre, including newly discovered dim variables and rare types like elta Scuti and RR Lyrae, providing a valuable catalog for future research.

## Contribution

The paper presents a comprehensive catalog of variable stars in the Galactic Centre, including new detections and classifications, based on four-year HST observations, enhancing understanding of stellar populations in this region.

## Key findings

- Identified 3,845 long-term and 76 short-term variables.
- First detection of elta Scuti and RR Lyrae stars near the Galactic Centre.
- Catalog includes well-classified stellar types and potential variable candidates.

## Abstract

We used four-year baseline HST/WFC3 IR observations of the Galactic Centre in the F153M band (1.53 micron) to identify variable stars in the central ~2.3'x2.3' field. We classified 3845 long-term (periods from months to years) and 76 short-term (periods of a few days or less) variables among a total sample of 33070 stars. For 36 of the latter ones, we also derived their periods (<3 days). Our catalog not only confirms bright long period variables and massive eclipsing binaries identified in previous works, but also contains many newly recognized dim variable stars. For example, we found \delta Scuti and RR Lyrae stars towards the Galactic Centre for the first time, as well as one BL Her star (period < 1.3 d). We cross-correlated our catalog with previous spectroscopic studies and found that 319 variables have well-defined stellar types, such as Wolf-Rayet, OB main sequence, supergiants and asymptotic giant branch stars. We used colours and magnitudes to infer the probable variable types for those stars without accurately measured periods or spectroscopic information. We conclude that the majority of unclassified variables could potentially be eclipsing/ellipsoidal binaries and Type II Cepheids. Our source catalog will be valuable for future studies aimed at constraining the distance, star formation history and massive binary fraction of the Milky Way nuclear star cluster.