S316p.01 — Relative ratios and radial distributions of the multiple populations in the Galactic globular clusters

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Aug 10th at 6:00 PM until 7:30 PM

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Author(s): Javier Alonso-Garcia6, Márcio Catelan6, Pía Amigo6, Rodrigo Contreras Ramos6, Cristián Cortés7, Charles Kuehn8, Frank Grundahl1, Graciela López3, Ricardo Salinas4, Horace Smith4, Peter Stetson2, Allen Sweigart5, Aldo A. R. Valcarce6, Manuela Zoccali6

Institution(s): 1. Aarhus University, 2. Dominion Astrophysical Observatory, 3. Instituut voor Sterrenkunde, 4. Michigan State University, 5. NASA Goddard Space Flight Center, 6. Pontificia Universidad Católica de Chile, 7. Universidad Metropolitana de Ciencias de la Educación, 8. University of Sydney

Recently, the long-standing paradigm that globular clusters are close approximations to simple stellar populations, with all stars formed at precisely the same time from populations having precisely the same chemical composition, has been shattered by a series of photometric and spectroscopic observations that reveal that these objects are more complex than we once thought . In this poster, we present the first results of a survey we are conducting among the Galactic globular clusters using the Strömgren photometric system. We show that the bluest Strömgren filters reveal broadenings or splits in the stellar sequences in the color-magnitude diagrams of the sampled clusters. These features allow us to disentangle successfully the different stellar populations in a given globular cluster, which let us measure their relative ratios, and explore their radial trends and gradients from the cluster center out to its tidal radius.