Browsing by Author "Salinas, Ricardo"

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    New Variable Stars in NGC 6652 and Its Background Sagittarius Stream
    (2019) Salinas, Ricardo; Katherina Vivas, A.; Contreras Ramos, Rodrigo
    We conducted a variable star search on the metal-rich Galactic globular cluster NGC 6652 using archival Gemini-S/Gemini Multiobject Spectrograph data. We report the discovery of nine new variable stars in the NGC 6652 field, of which we classify six as eclipsing binaries and one as an SX Phoenicis star, leaving two variables without classification. Using proper motions from Gaia DR2 and Hubble Space Telescope, albeit with some uncertainties, we find that the cluster, the field, and the background Sagittarius stream each have three of these variables. We also reassess the membership of known variables based on the Gaia proper motions, confirming the existence of one RR Lyrae star in the cluster.
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    Relative ratios and radial distributions of the multiple populations in the Galactic globular clusters
    (2015) Alonso-Garcia, Javier; Catelan, Marcio; Amigo, Pía; Contreras Ramos, Rodrigo; Cortés, Cristián; Kuehn, Charles; Grundahl, Frank; López, Graciela; Salinas, Ricardo; Smith, Horace; Stetson, Peter; Sweigart, Allen; Valcarce, Aldo A. R.; Zoccali, Manuela
    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....