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

Abstract

To identify long-period variable (LPV) stars in IC 10—the nearest starburst galaxy of the Local Group—we conducted an optical monitoring survey using the 2.5 m Isaac Newton Telescope 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 (∼0.07 deg ^2 corresponding to 13.5 kpc ^2 at the distance of IC 10), of which we classified 536 and 380 stars as LPV candidates, mostly asymptotic giant branch (AGBs) stars and red supergiants, within CCD4 and two half-light radii of IC 10, 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 survey, we determined the success of our detection method. We recovered ∼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 ∼70% of HST variables in our catalog. Furthermore, we found all the confirmed LPVs that Gaia DR3 detected in IC 10 among our identified LPVs. This paper is the first in a series on IC 10, presenting the variable star survey methodology and the photometric catalog, available to the public through the Centre de Données Astronomiques de Strasbourg.

Keywords

• Local Group
• Asymptotic giant branch stars
• Stellar populations