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Seminars at FGG

Globular Clusters - Some simple, some complicated, all interesting!

Speaker: Alistair Walker (Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory)

Date and time: 2009-02-17 12:00

Galactic globular clusters have for several decades been highly useful as examples of single stellar populations of stars almost as old as the Universe, and as such have been critical to calibrating models of stellar evolution for low mass stars, and for understanding galaxy formation and evolution. However, explanations for puzzles such as differing distributions of stars on the Horizontal Branch, and element-element abundance anomalies in individual clusters, have been elusive. Recent, mostly HST-ACS, observations of some globular clusters have complicated the picture but also give strong clues for resolving the remaining issues. After a short overview, I will describe a wide-field imaging program for a selected sample of clusters designed to provide complementary information to the HST and spectroscopic studies, and show some of the first results.