Wednesday 06 Feb 2013: Constraining Age Spreads within Clusters
Dr Nate Bastian - Liverpool John Moores University
Physics, 4th floor 12:00-13:00
Stellar clusters are generally assumed to be simple stellar populations, i.e. that all stars within them formed at the same time and with the same metallicity. However, recent studies have shown that globular clusters host multiple populations (with differing metal and helium contents) within them.
Additionally, intermediate age clusters (1-3 Gyr) in the LMC appear to have more extended main-sequence turnoffs than would be expected if they were single populations, leading to suggestions that star formation proceeded within these clusters for hundreds of Myr. There has been much theoretical work trying to link such spreads to the phenomena observed in globular clusters. If such large spreads are a common feature within massive clusters, younger clusters (100-300 Myr) should also show the same age spread. I will present an HST analysis of two massive (10^5 Msun) young (100-300 Myr) clusters in the LMC and show that both are consistent with a single burst of star formation. I will discuss possible explanations to the extended main sequence turnoffs seen in intermediate age clusters, that do not invoke age spreads.