The Puzzle of Multiple Populations in Globular Clusters

January 11, 2018
3:00pm to 4:00pm

Facultad de Ciencias. Sala 201 in Módulo M-15

Specialist level
Nathan Bastian
Liverpool John Moores University

Facultad de Ciencias. Sala 201 in Módulo M-15


Globular clusters (GCs) are traditionally thought of as the quintessential simple stellar populations (i.e., all stars have the same age and abundance), however, we now know that all GCs show abundance spreads in certain elements (He, C, N, O, Na, Al), and that their colour-magnitude diagrams are not well represented by a single isochrone. Various scenarios have been put forward to explain these anomalies, and most invoke multiple star formation events within the clusters. I will present the results of a series of recent studies where we have tested all the proposed scenarios and conclude that none of the proposed models even come close to explaining the observations. Finally, I will present new HST results showing that we may be finally narrowing in on the origin of the phenomenon.