NOAO >   Observing Info >   Approved Programs >   2009A-0116

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Proposal Information for 2009A-0116


PI: Alistair Walker, NOAO/CTIO, awalker@ctio.noao.edu
Address: Casilla 603, La Serena, Chile

CoI: Giuseppe Bono, Rome Observatory
CoI: Santi Cassisi, Teramo Observatory
CoI: Matteo Monelli, Instituto de Astrofisica de Canarias
CoI: Massimo Dall'Ora, Naples Observatory
CoI: Gloria Andreuzzi, TNG, La Palma
CoI: Peter Stetson, Herzberg Institute of Astrophysics

Title: Luminosity Functions of Evolved Populations in Galactic Globular Clusters

Abstract: We propose to complete the observations (see re-submission details later) for a project to produce definitive Color-Magnitude Diagrams (CMDs) for a carefully chosen sample of galactic globular clusters, using the Mosaic Camera on the Blanco telescope. The large field size will enable us to efficiently cover to beyond the published tidal radius for even the larger clusters in our sample. We will combine with available archival HST photometry for the dense cluster cores to measure complete star counts for the evolved populations for each cluster, and where not available, we will provide accurate main sequence photometry, which will allow quantification of the binary fraction and any spread due to composition variations. We will use existing studies of the variable star populations of each cluster to provide extra constraints on the cluster formation and evolution scenarios, given the complex behavior that is increasingly being found for the more massive galactic globular clusters. The empirical results will be compared with theoretical predictions provided by pulsational and evolutionary models, in order to check if they can be reproduced in the framework of canonical stellar theory or, on the contrary, one has to invoke - at least in the case of the more massive clusters - non canonical evolutionary scenarios.


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