Research Fellows Directory
Professor Nate Bastian
Liverpool John Moores University
Ancient globular clusters (GCs), once thought to be well approximated as simple stellar populations (i.e. all stars having the same age and chemical abundance), are now known to host a variety of anomalies, such as multiple discrete populations in colour--magnitude diagrams1 and abundance variations in light elements (e.g., Na, O, Al). Additionally, there have been suggestions that massive intermediate age (1-2 billion years) clusters in the Large Magellanic Cloud (LMC) have age spreads of 100s of millions of years within them amongst their stars. Many models have been put forward to explain one or both of these observations, and I have been carrying out new observations to directly test these models. One of the basic predictions of the models is that massive clusters forming today (ages less than ~500 million years) should show clear evidence for multiple discreet or continuous age spreads within them. Unlike older clusters (>1 Gyr), such age spreads should be easily detectable in the young clusters, due to stellar evolution. I have used Hubble Space Telescope Images to look for such age spreads within young (100-200 Myr) clusters in the LMC, and have not found any evidence for them. Instead the clusters are consistent with a single burst of star formation, consistent with the traditional view of cluster formation.
Interests and expertise (Subject groups)