A panoramic view of M81: New stellar systems in the debris field

TL;DR

This study uses deep imaging to discover new young stellar systems in the outskirts of M81, revealing star formation in tidal debris and providing insights into galaxy interaction processes.

Contribution

It reports the discovery of new young stellar systems in M81's debris field, highlighting their tidal origin and recent star formation activity.

Findings

Identification of young stellar systems along the HI tidal arm

Star formation occurred approximately 40 million years ago

Properties suggest these systems are of tidal origin

Abstract

Using the MegaCam imager on the Canada-France-Hawaii Telescope, we have resolved individual stars in the outskirts of the nearby large spiral galaxy M81 (NGC 3031) well below the tip of the red giant branch of metal-poor stellar populations over 60 kpc * 58 kpc. In this paper, we report the discovery of new young stellar systems in the outskirts of M81. The most prominent feature is a chain of clumps of young stars distributed along the extended southern HI tidal arm connecting M 81 and NGC 3077. The colour-magnitude diagrams of these stellar systems show plumes of bright main sequence stars and red supergiant stars, indicating extended events of star formation. The main sequence turn-offs of the youngest stars in the systems are consistent with ages of ~40 Myr. The newly reported stellar systems show strong similarities with other known young stellar systems in the debris field around M81, with their properties best explained by these systems being of tidal origin.