Examinando por Autor "Bica, Eduardo"
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Ítem 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, RaphaelWe 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..Ítem Confirmation of a New Metal-poor Globular Cluster in the Galactic Bulge(Institute of Physics Publishing, 2018-10) Minniti, Dante; Schlafly E.F.; Palma, Tali; Clariá, Juan J.; Hempel, Maren; Alonso-García, Javier; Bica, Eduardo; Bonatto, Charles; Braga, Vittorio F.; Clementini, Gisella; Garofalo, Alessia; Gómez, Matías; Ivanov, Valentin D.; Lucas, Phillip W.; Pullen, Joyce; Saito, Roberto K.; Smith, Leigh C.We use deep near-IR photometry of the VISTA Variables in the V'a L'ctea (VVV) Survey and deep DECam Plane Survey (DECaPS) optical photometry to confirm the physical reality of the candidate globular cluster (GC) Minni 22, which is located in the Galactic bulge. This object, which was detected as a high density region in our maps of bulge red giants, is now confirmed as a real GC based on the optical and near-IR color'magnitude diagrams. We also recover three known fundamental mode (ab type) RR Lyrae stars within 2 arcmin of the cluster center. The presence of RR Lyrae stars also seems to confirm Minni 22 as a bonafide old and metal-poor GC. We estimate a cluster reddening E(J - Ks) = 0.6 mag and determine its heliocentric distance D = 7.4 ± 0.3 kpc. The optical and near-IR color'magnitude diagrams reveal well-defined red giant branches in all cases, including a red giant branch bump at Ks = 13.30 ± 0.05 mag. The comparison with theoretical isochrones yields a mean metallicity of [Fe/H] = -1.3 ± 0.3 dex, and age of t ∼ 11.2 Gyr. This is a good example of a new low-luminosity (MV = -6.2 mag) GC found in the central bulge of the Milky Way. After discussing the different ways to confirm the existence of bulge GC candidates, we find that one of the best methods is to use the CMDs from the combination of the DECaPS + VVV photometries. © 2018 The American Astronomical Society. All rights reserved.Ítem 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, ManuelaWe 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.Ítem The VISCACHA Survey: XII. SL 2: Age gap cluster in the southwestern Large Magellanic Cloud(EDP Sciences, 0025-03) Ferreira, Bernardo P. L.; Dias, Bruno; Santos, João F. C.; Maia, Francisco F. S.; Bica, Eduardo; Kerber, Leandro O.; Armond, Tina; Quint, Bruno; Oliveira, Raphael A. P.; Souza, Stefano O.; Fernández-Trincado, José G; Katime Santrich, OrlandoContext. In the Large Magellanic Cloud (LMC), only seven star clusters have been discovered to be older than ~4 Gyr and younger than ~10 Gyr, placing them in what is known as the age gap. Aims. We aim to analyze the photometric data from the VISCACHA survey in the V and I bands to determine, for the first time, the astrophysical parameters of SL 2, revealing that the cluster is indeed situated within the age gap. Methods. We used our newly developed SIESTA code to carry out a statistical isochrone fitting with synthetic color-magnitude diagrams (CMDs) to determine the cluster age, metallicity, distance, color excess, and binary fraction with two grids of stellar evolution models. In addition, the cluster mass was estimated based on its integrated magnitude. Results. The ages obtained from isochrone fitting are compatible with the age gap, amounting to (7.17 ± 0.35) Gyr when using PARSEC-COLIBRI isochrones and (8.02 ± 0.45) Gyr when using MIST. Notably, SL 2 is the first age gap cluster discovered in the southern region of the LMC. The mass of the cluster is considerably smaller than that of the group of older LMC clusters. Conclusions. SL 2 has a comparable metallicity to the other two age gap clusters with similar ages, namely, ESO 121-03 and KMHK 1592, as well as the LMC field star population. While the discovery of a new cluster with such characteristics could be seen as evidence that age gap clusters were formed in situ, the heliocentric distance of SL2 locates it far from the LMC center, akin to the SMC distance. Therefore, the question of its origin, alongside that of other age gap clusters, remains unresolved and open to further investigation. © 2025 EDP Sciences. All rights reserved.Ítem The VISCACHA Survey: XII. SL 2: Age gap cluster in the southwestern Large Magellanic Cloud(EDP Sciences, 0025) Ferreira, Bernardo P. L.; Dias, Bruno; Santos, João F. C.; Maia, Francisco F. S; Bica, Eduardo; Kerber, Leandro O.; Armond, Tina; Quint, Bruno; Oliveira, Raphael A. P.; Souza, Stefano O.; Fernández-Trincado, José G; Katime Santrich, OrlandoContext. In the Large Magellanic Cloud (LMC), only seven star clusters have been discovered to be older than ~4 Gyr and younger than ~10 Gyr, placing them in what is known as the age gap. Aims. We aim to analyze the photometric data from the VISCACHA survey in the V and I bands to determine, for the first time, the astrophysical parameters of SL 2, revealing that the cluster is indeed situated within the age gap. Methods. We used our newly developed SIESTA code to carry out a statistical isochrone fitting with synthetic color-magnitude diagrams (CMDs) to determine the cluster age, metallicity, distance, color excess, and binary fraction with two grids of stellar evolution models. In addition, the cluster mass was estimated based on its integrated magnitude. Results. The ages obtained from isochrone fitting are compatible with the age gap, amounting to (7.17 ± 0.35) Gyr when using PARSEC-COLIBRI isochrones and (8.02 ± 0.45) Gyr when using MIST. Notably, SL 2 is the first age gap cluster discovered in the southern region of the LMC. The mass of the cluster is considerably smaller than that of the group of older LMC clusters. Conclusions. SL 2 has a comparable metallicity to the other two age gap clusters with similar ages, namely, ESO 121-03 and KMHK 1592, as well as the LMC field star population. While the discovery of a new cluster with such characteristics could be seen as evidence that age gap clusters were formed in situ, the heliocentric distance of SL2 locates it far from the LMC center, akin to the SMC distance. Therefore, the question of its origin, alongside that of other age gap clusters, remains unresolved and open to further investigation. © 2025 EDP Sciences. All rights reserved.