The red extended structure of IC10, the nearest blue compact galaxy

TL;DR

This study provides a comprehensive analysis of IC10, revealing its extended structure, stellar population distribution, and lack of recent interactions, highlighting its status as one of the most extended dwarf galaxies in the Local Group.

Contribution

It offers the first detailed structural survey of IC10 across multiple stellar populations, showing its extended size and spatial distribution of different age groups.

Findings

IC10 has an effective radius of ~1.25 kpc, making it one of the most extended dwarf galaxies in the Local Group.

Younger stellar populations are offset from the older RGB population, indicating off-center recent star formation.

The galaxy shows no evidence of recent significant interactions with other galaxies.

Abstract

The Local Group starburst galaxy IC10 is the closest example of a blue compact galaxy. Here, we use optical gi imaging from CFHT/MegaCam and near infra-red JHK imaging from UKIRT/WFCAM to conduct a comprehensive survey of the structure of IC10. We examine the spatial distribution of its resolved young, intermediate and old stellar populations to large radius and low effective surface brightness levels. Akin to other dwarfs with multiple populations of different ages, stellar populations of decreasing average age are increasingly concentrated in this galaxy. We find that the young, star-bursting population, and the AGB population, are both offset from the geometric center of the older RGB population by a few hundred parsecs, implying that the younger star formation occurred significantly away from the center of the galaxy. The RGB population traces an extended structure that is typical of blue compact galaxies, with an effective radius of ~5.75 arcmins (~1.25 kpc). These measurements show that IC10 is much more extended than has previously been realized, and this blue compact galaxy is one of the most extended dwarf galaxies in the Local Group. The outermost isophotes of this galaxy are very regular in shape and essentially circular in morphology. Based on this analysis, we do not find any evidence to suggest that IC10 has undergone a recent, significant, interaction with an unknown companion.