Progressive star formation in the young SMC cluster NGC 602

TL;DR

This study reveals that star formation in the young SMC cluster NGC 602 began approximately 4 million years ago and has been propagating outward, involving both coeval low-mass pre-Main Sequence stars and more recent YSOs.

Contribution

It provides the first detailed analysis of the star formation history in NGC 602, combining optical and infrared data to show ongoing propagation of star formation.

Findings

Pre-Main Sequence stars formed about 4 Myr ago

Recent star formation is ongoing in the outskirts

Star formation propagated outward from the central cluster

Abstract

NGC 602 is a young stellar cluster located in a peripheral region of the Small Magellanic Cloud known as the wing. Far from the main body of the galaxy and abutting the Magellanic Bridge, the SMC's wing is characterized by low gas and stellar content. With deep optical imaging from the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope (HST), we have discovered an extensive pre-Main Sequence (PMS) population, with stellar masses in the range 0.6-3 Solar masses. These low mass PMS stars formed coevally with the central cluster about 4 Myr ago. Spitzer Space Telescope (Spitzer) images of the same region from the Infrared Array Camera (IRAC) also reveal a population of Young Stellar Objects (YSOs), some of which are still embedded in nebular material and most of which likely formed even more recently than the young stars detected with HST/ACS imaging. We infer that star formation started in this region about 4 Myr ago with the formation of the central cluster and gradually propagated towards the outskirts where star formation is presently ongoing.