Using the sub-giant branch to constrain the star
formation history of intermediate-age clusters
by Chengyuan Li (Macquarie University)
Abstract. The presence of extended
main-sequence turn-off (eMSTO) regions in intermediate-age, 1-2 Gyr-old star
clusters in the Large and Small Magellanic Clouds is often interpreted as
resulting from extended star-formation histories (SFHs) that last ≥ 300
Myr. This strongly conflicts with the traditional view of stellar clusters,
which are thought of as single-aged stellar populations. In this talk, I will
show our investigation into these issues by exploring the morphology of the
sub-giant branch (SGB) of LMC and SMC clusters. We find that for most cases,
the width of the SGB favors the single-aged stellar population interpretation
and rules out an extended SFH. For clusters that have a very low escape
velocity, they have unlikely undergone significant mass loss at an early
stage, thus indicating that they may lack the capacity to capture most of
their initial, expelled gas from stellar evolutionary processes.
