Star formation time-scales in the nearby, prototype starburst galaxy M82

TL;DR

This paper investigates the history and mechanisms of star formation in M82, highlighting the impact of tidal interactions and the current starburst driven by propagating star formation and tidal debris infall.

Contribution

It provides insights into the timing and causes of starburst activity in M82, emphasizing the roles of tidal interactions and debris infall in shaping star formation.

Findings

Starburst triggered by tidal encounter with M81 500 Myr ago

Current star formation likely due to propagating activity and debris infall

Star formation episodes occurred within a few hundred million years

Abstract

The last tidal encounter between M82 and M81, some 500 Myr ago, had a major impact on what was probably an otherwise normal, quiescent disc galaxy. It caused a concentrated burst of star formation in the form of massive star clusters, which decreased rapidly, within a few 100 Myr. The current starburst in the centre of the galaxy is likely either due to large-scale propagating star formation or possibly related to late infall of tidally disrupted debris from M82 itself. It may, in fact, be a combination of these two mechanisms, in the sense that the star formation in the active core is actually propagating, while the overall evolution of the starburst is due to tidal debris raining back onto the disc of the galaxy, causing the present-day starburst.