Detection of an excess of young stars in the Galactic center Sagittarius B1 region

TL;DR

This study reveals a significant population of young stars in the Sagittarius B1 region of the Galactic center, suggesting active star formation and complex stellar history in this extreme environment.

Contribution

It provides new evidence of substantial young stellar mass and diverse stellar ages in Sgr B1, advancing understanding of star formation in the Galactic center.

Findings

Detection of several 10^5 solar masses of young stars formed ~10 Myr ago.

Presence of intermediate age stars (2-7 Gyr) indicating complex formation history.

Evidence supporting inside-out formation in the Galactic center.

Abstract

The Milky Way's center is the closest galaxy nucleus and the most extreme environment of the Galaxy. Although its volume is less than 1% of that of the Galactic disk, up to 10% of all new-born stars in the Galaxy in the past 100 Myr formed there. Therefore, it constitutes a perfect laboratory to understand star formation under extreme conditions, similar to those in starburst or high-redshift galaxies. However, the only two known Galactic center young clusters account for <10% of the expected young stellar mass. We analyze the star formation history of Sagittarius (Sgr) B1, a Galactic center region associated with strong HII emission, and find evidence for the presence of several $10^5$ solar masses of young stars, that formed $\sim$10 Myr ago. We also detect the presence of intermediate age stars (2-7 Gyr) in Sgr B1 that appear to be rare (or absent) in the inner regions of the nuclear stellar disk, and might indicate inside out formation. Our results constitute a large step toward a better understanding of star formation at the Galactic center, such as the fate of young clusters, and the possibly different initial mass function in this region.