Examinando por Autor "Bica, Eduardo"

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    An Updated Small Magellanic Cloud and Magellanic Bridge Catalog of Star Clusters, Associations, and Related Objects
    (Institute of Physics Publishing, 2020-03) Bica, Eduardo; Pieter, Westera; O.Kerber, Leandro; Dias, Bruno; Maia, Francisco; F.C Santos Jr., João; Barbuy, Beatriz; Oliveira, Raphael
    We present a catalog of star clusters, associations, and related extended objects in the Small Magellanic Cloud (SMC) and the Magellanic Bridge with 2741 entries, a factor 2 more than a previous version from a decade ago. Literature data up until 2018 December are included. The identification of star clusters was carried out with digital atlases in various bands currently available in the Digitized Sky Survey and the Machine Automatique à Mésurer pour l'Astronomie. imaging surveys. In particular, we cross-identified recent cluster samples from the Visible and Infrared Survey Telescope for Astronomy near-infrared YJK s survey of the Magellanic System, Optical Gravitational Lensing Experiment IV, and Survey of the MAgellanic Stellar History surveys, confirming new clusters and pointing out equivalencies. A major contribution of the present catalog consists of the accurate central positions for clusters and small associations, including a new sample of 45 clusters or candidates in the SMC and 19 in the Magellanic Bridge, as well as a compilation of the most reliable age and metallicity values from the literature. A general catalog must also deal with the recent discoveries of 27 faint and ultra-faint star clusters and galaxies projected on the far surroundings of the Clouds, most of them from the Dark Energy Survey. The information on these objects has been complemented with photometric, spectroscopic, and kinematical follow-up data from the literature. The underluminous galaxies around the Magellanic System, still very few as compared to the predictions from Λ Cold Dark Matter simulations, can bring constraints to galaxy formation and hierarchical evolution. Furthermore, we provide diagnostics, when possible, of the nature of the ultra-faint clusters, searching for borders of the Magellanic System extensions into the Milky Way gravitational potential. © 2020. The American Astronomical Society. All rights reserved..
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    FSR 1716: A New Milky Way Globular Cluster Confirmed Using VVV RR Lyrae Stars
    (Institute of Physics Publishing, 2017-03) Minniti, Dante; Palma, Tali; Dékány, Istvan; Hempel, Maren; Rejkuba, Marina; Pullen, Joyce; Alonso-García, Javier; Barbá, Rodolfo; Barbuy, Beatriz; Bica, Eduardo; Bonatto, Charles; Borissova, Jura; Catelan, Marcio; Carballo-Bello, Julio A.; Chene, Andre Nicolas; Clariá, Juan José; Cohen, Roger E.; Contreras Ramos, Rodrigo; Dias, Bruno; Emerson, Jim; Froebrich, Dirk; Buckner, Anne S. M.; Geisler, Douglas; Gonzalez, Oscar A.; Gran, Felipe; Hagdu, Gergely; Irwin, Mike; Ivanov, Valentin D.; Kurtev, Radostin; Lucas, Philip W.; Majaess, Daniel; Mauro, Francesco; Moni-Bidin, Christian; Navarrete, Camila; Alegría, Sebastian Ramírez; Saito, Roberto K.; Valenti, Elena; Zoccali, Manuela
    We use deep multi-epoch near-IR images of the VISTA Variables in the Vía Láctea (VVV) Survey to search for RR Lyrae stars toward the Southern Galactic plane. Here, we report the discovery of a group of RR Lyrae stars close together in VVV tile d025. Inspection of the VVV images and PSF photometry reveals that most of these stars are likely to belong to a globular cluster that matches the position of the previously known star cluster FSR 1716. The stellar density map of the field yields a >100σ detection for this candidate globular cluster that is centered at equatorial coordinates R.A.J2000 = 16:10:30.0, decl.J2000 = -53:44:56 and galactic coordinates l = 329.77812, b = -1.59227. The color-magnitude diagram of this object reveals a well-populated red giant branch, with a prominent red clump at K s = 13.35 ±0.05, and J - K s = 1.30 ±0.05. We present the cluster RR Lyrae positions, magnitudes, colors, periods, and amplitudes. The presence of RR Lyrae indicates an old globular cluster, with an age >10 Gyr. We classify this object as an Oosterhoff type I globular cluster, based on the mean period of its RR Lyrae type ab, days, and argue that this is a relatively metal-poor cluster with [Fe/H] = -1.5 ±0.4 dex. The mean extinction and reddening for this cluster are and E(J - K s) = 0.72 ±0.02 mag, respectively, as measured from the RR Lyrae colors and the near-IR color-magnitude diagram. We also measure the cluster distance using the RR Lyrae type ab stars. The cluster mean distance modulus is (m - M)0 = 14.38 ±0.03 mag, implying a distance D = 7.5 ±0.2 kpc and a Galactocentric distance R G = 4.3 kpc. © 2017. The American Astronomical Society. All rights reserved.