The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. VII. Long-Period Variable Stars in the Nearest Starburst Dwarf Galaxy, IC 10

TL;DR

This study conducted a comprehensive optical monitoring survey of IC 10, identifying and cataloging long-period variable stars, primarily AGBs and RSGs, and validated the detection method through comparison with multiple space and ground-based surveys.

Contribution

First detailed survey of LPVs in IC 10 using the INT, providing a publicly available photometric catalog and demonstrating effective detection techniques.

Findings

Recovered 73% of Spitzer sources

Identified 43% of Spitzer variables

Matched all Gaia DR3 LPVs in IC 10

Abstract

To identify long-period variable (LPV) stars in IC10 - the nearest starburst galaxy of the Local Group (LG) - we conducted an optical monitoring survey using the 2.5-m Isaac Newton Telescope (INT) with the wide-field camera (WFC) in the i-band and V-band from 2015 to 2017. We created a photometric catalog for 53,579 stars within the area of CCD4 of WFC ($\sim$ 0.07 deg$^2$ corresponding to 13.5 kpc$^2$ at the distance of IC10), of which we classified 536 and 380 stars as long-period variable candidates (LPVs), mostly asymptotic giant branch stars (AGBs) and red supergiants (RSGs), within CCD4 and two half-light radii of IC10, respectively. By comparing our output catalog to the catalogs from Pan-STARRS, Spitzer Space Telescope, Hubble Space Telescope (HST), and carbon stars from the Canada-France-Hawai'i Telescope (CFHT) survey, we determined the success of our detection method. We recovered $\sim$ 73% of Spitzer's sources in our catalog and demonstrated that our survey successfully identified 43% of the variable stars found with Spitzer, and also retrieved 40% of the extremely dusty AGB stars among the Spitzer variables. In addition, we successfully identified $\sim$ 70% of HST variables in our catalog. Furthermore, we found all the confirmed LPVs that Gaia DR3 detected in IC10 among our identified LPVs. This paper is the first in a series on IC10, presenting the variable star survey methodology and the photometric catalog, available to the public through the Centre de Donn\'ees Astronomiques de Strasbourg.