Browsing by Author "Gran, F."

Now showing 1 - 15 of 15
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    A machine learned classifier for RR Lyrae in the VVV survey
    (2016) Elorrieta López, Felipe; Eyheramendy Duerr, Susana; Jordán Colzani, Andrés Cristóbal; Dekany, Istvan; Catelan, Márcio; Angeloni, Rodolfo; Alonso, J.; Contreras, R.; Gran, F.; Hajdu, G.; Espinoza, N.; Saito, R.; Minniti, D.
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    Bulge RR Lyrae stars in the VVV tile b201
    (2015) Gran, F.; Minniti, D.; Saito, R. K.; Navarrete, C.; Dékány, I.; McDonald, I.; Contreras Ramos, Rodrigo Andrés; Catelan, Márcio
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    CAPOS: The bulge Cluster APOgee Survey. I. Overview and initial ASPCAP results
    (2021) Geisler, D.; Villanova, S.; O'Connell, J. E.; Cohen, R. E.; Moni Bidin, C.; Fernández-Trincado, J. G.; Muñoz, C.; Minniti, D.; Zoccali, M.; Rojas-Arriagada, A.; Contreras Ramos, R.; Catelan, Márcio; Mauro, F.; Cortés, C.; Ferreira Lopes, C. E.; Arentsen, A.; Starkenburg, E.; Martin, N. F.; Tang, B.; Parisi, C.; Alonso-García, J.; Gran, F.; Cunha, K.; Smith, V.; Majewski, S. R.; Jönsson, H.; García-Hernández, D. A.; Horta, D.; Mészáros, S.; Monaco, L.; Monachesi, A.; Muñoz, R. R.; Brownstein, J.; Beers, T. C.; Lane, R. R.; Barbuy, B.; Sobeck, J.; Henao, L.; González-Díaz, D.; Miranda, R. E.; Reinarz, Y.; Santander, T. A.
    Context. Bulge globular clusters (BGCs) are exceptional tracers of the formation and chemodynamical evolution of this oldest Galactic component. However, until now, observational difficulties have prevented us from taking full advantage of these powerful Galactic archeological tools. Aims: CAPOS, the bulge Cluster APOgee Survey, addresses this key topic by observing a large number of BGCs, most of which have only been poorly studied previously. Even their most basic parameters, such as metallicity, [α/Fe], and radial velocity, are generally very uncertain. We aim to obtain accurate mean values for these parameters, as well as abundances for a number of other elements, and explore multiple populations. In this first paper, we describe the CAPOS project and present initial results for seven BGCs. Methods: CAPOS uses the APOGEE-2S spectrograph observing in the H band to penetrate obscuring dust toward the bulge. For this initial paper, we use abundances derived from ASPCAP, the APOGEE pipeline. Results: We derive mean [Fe/H] values of −0.85 ± 0.04 (Terzan 2), −1.40 ± 0.05 (Terzan 4), −1.20 ± 0.10 (HP 1), −1.40 ± 0.07 (Terzan 9), −1.07 ± 0.09 (Djorg 2), −1.06 ± 0.06 (NGC 6540), and −1.11 ± 0.04 (NGC 6642) from three to ten stars per cluster. We determine mean abundances for eleven other elements plus the mean [α/Fe] and radial velocity. CAPOS clusters significantly increase the sample of well-studied Main Bulge globular clusters (GCs) and also extend them to lower metallicity. We reinforce the finding that Main Bulge and Main Disk GCs, formed in situ, have [Si/Fe] abundances slightly higher than their accreted counterparts at the same metallicity. We investigate multiple populations and find our clusters generally follow the light-element (anti)correlation trends of previous studies of GCs of similar metallicity. We finally explore the abundances of the iron-peak elements Mn and Ni and compare their trends with field populations. Conclusions: CAPOS is proving to be an unprecedented resource for greatly improving our knowledge of the formation and evolution of BGCs and the bulge itself....
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    Discovery of RR lyrae stars in the nuclear bulge of the Milky Way
    (2016) Minniti, D.; Ramos, R. C.; Zoccali, Manuela; Rejkuba, M.; González, O. A.; Valenti, E.; Gran, F.
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    FSR 1716: A New Milky Way Globular Cluster Confirmed Using VVV RR Lyrae Stars
    (2017) Hempel, Maren; Catelan, Márcio; Carballo Bello, J. A.; Ramos, R. C.; Gran, F.; Hagdu, G.; Navarrete, C.; Zoccali, Manuela; Minniti, D.; Palma, T.; Dekany, Istvan; Rejkuba, M.; Pullen, J.; Alonso Garcia, J.; Barba, R.; Barbuy, B.; Bica, E.; Borissova, J.; Chene, A. N.; Claria, J. J.; Cohen, R. E.; Dias, B.; Emerson, J.
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    Near-IR period-luminosity relations for pulsating stars in omega Centauri (NGC 5139)
    (2017) Navarrete Silva, Camila Andrea; Catelan, Márcio; Contreras, R.; Alonso, J.; Gran, F.; Dekany, Istvan; Minniti, D.
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    Near-IR period-luminosity relations for pulsating stars in ω Centauri (NGC 5139) (Corrigendum)
    (2017) Navarrete, C.; Catelan, Márcio; Contreras Ramos, Rodrigo; Alonso-García, J.; Gran, F.; Dékány, I.; Minniti, D.
    Erratum for: "An incorrect zero point for the empirical period-luminosity-metallicity (PL-Z) relations for RR Lyrae (RRL) stars in ω Centauri (NGC 5139) was inadvertently reported in Table 2 and Eqs. (4) and (5) of our original paper. The corrected table and equations are given below. The actual analysis that is described in the paper was based on the correct zero points, and so all of the results reported in our original publication remain unchanged".
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    Proper motions in the VVV Survey: Results for more than 15 million stars across NGC 6544
    (2017) Contreras Ramos, Rodrigo Andrés; Zoccali, Manuela; Rojas, F.; Rojas Arriagada, A.; Gárate, M.; Huijse, P.; Gran, F.; Valcarce Bravo, Aldo Alfonso Raúl; Estévez, P. A.; Minniti, D.
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    RR Lyrae stars in omega Centauri: Near-IR properties and period-luminosity relations
    (2016) Navarrete, C.; Catelan , Marcio; Contreras Ramos, R.; Gran, F.; Alonso-Garcia, J.
    Omega Centauri contains a rich harvest of variable stars. Here we report on a deep, wide-field, near-infrared (IR) variability survey for this cluster, carried out using ESO's 4.1m VISTA telescope. Our time-series data includes more than 180 RR Lyrae light curves in both J and Ks, allowing us to derive an unprecedented homogeneous and complete near-IR catalog of RR Lyrae in the field of omega Cen. Near-IR period-luminosity relations are derived and used to determine an updated (pulsational) distance modulus for the cluster....
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    Searches for variability in the Milky Way bulge with the VVV Survey
    (2014) Saito, R. K.; Minniti, D.; Catelan, Marcio; Gran, F.; Iglesias, D.; Muro, G.; Beamin, J. C.; Dékány, I.
    VVV is an ongoing near-IR, multi-band, time-series survey of the Galactic bulge and plane. Here we summarize the first results from a search for variability in selected fields of the VVV bulge area....
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    Spectroscopic analysis of VVV CL001 cluster with MUSE
    (2022) Olivares Carvajal, J.; Zoccali, M.; Rojas-Arriagada, A.; Contreras Ramos, R.; Gran, F.; Valenti, E.; Minniti, J. H.
    Like most spiral galaxies, the Milky Way contains a population of blue, metal-poor globular clusters and another of red, metal-rich ones. Most of the latter belong to the bulge, and therefore they are poorly studied compared to the blue (halo) ones because they suffer higher extinction and larger contamination from field stars. These intrinsic difficulties, together with a lack of low-mass bulge globular clusters, are reasons to believe that their census is not complete yet. Indeed, a few new clusters have been confirmed in the last few years. One of them is VVV CL001, the subject of the present study. We present a new spectroscopic analysis of the recently confirmed globular cluster VVV CL001, made by means of MUSE@VLT integral field data. Individual spectra were extracted for stars in the VVV CL001 field. Radial velocities were derived by cross-correlation with synthetic templates. Coupled with proper motions from the VVV (VISTA Variables in the Via Lactea) survey, these data allow us to select 55 potential cluster members, for which we derive metallicities using the public code The Cannon. The mean radial velocity of the cluster is V-helio = -324.9 +/- 0.8 km s(-1), as estimated from 55 cluster members. This high velocity, together with a low metallicity [Fe/H] = -2.04 +/- 0.02 dex, suggests that VVV CL001 could be a very old cluster. The estimated distance is d = 8.23 +/- 0.46 kpc, placing the cluster in the Galactic bulge. Furthermore, both its current position and the orbital parameters suggest that VVV CL001 is most probably a bulge globular cluster.
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    The VISTA Variables in the Via Lactea extended (VVVX) ESO public survey: Completion of the observations and legacy
    (2024) Saito, R. K.; Hempel, M.; Alonso-Garcia, J.; Lucas, P. W.; Minniti, D.; Alonso, S.; Baravalle, L.; Borissova, J.; Caceres, C.; Chene, A. N.; Cross, N. J. G.; Duplancic, F.; Garro, E. R.; Gomez, M.; Ivanov, V. D.; Kurtev, R.; Luna, A.; Majaess, D.; Navarro, M. G.; Pullen, J. B.; Rejkuba, M.; Sanders, J. L.; Smith, L. C.; Albino, P. H. C.; Alonso, M. V.; Amores, E. B.; Angeloni, R.; Arias, J. I.; Arnaboldi, M.; Barbuy, B.; Bayo, A.; Beamin, J. C.; Bedin, L. R.; Bellini, A.; Benjamin, R. A.; Bica, E.; Bonatto, C. J.; Botan, E.; Braga, V. F.; Brown, D. A.; Cabral, J. B.; Camargo, D.; Garatti, Caratti O. A.; Carballo-Bello, J. A.; Catelan, M.; Chavero, C.; Chijani, M. A.; Claria, J. J.; Coldwell, G. V.; Pena, C. Contreras; Contreras Ramos, R.; Corral-Santana, J. M.; Cortes, C. C.; Cortes-Contreras, M.; Cruz, P.; Daza-Perilla, I. V.; Debattista, V. P.; Dias, B.; Donoso, L.; D'Souza, R.; Emerson, J. P.; Federle, S.; Fermiano, V.; Fernandez, J.; Fernandez-Trincado, J. G.; Ferreira, T.; Ferreira Lopes, C. E.; Firpo, V.; Flores-Quintana, C.; Fraga, L.; Froebrich, D.; Galdeano, D.; Gavignaud, I.; Geisler, D.; Gerhard, O. E.; Gieren, W.; Gonzalez, O. A.; Gramajo, L. V.; Gran, F.; Granitto, P. M.; Griggio, M.; Guo, Z.; Gurovich, S.; Hilker, M.; Jones, H. R. A.; Kammers, R.; Kuhn, M. A.; Kumar, M. S. N.; Kundu, R.; Lares, M.; Libralato, M.; Lima, E.; Maccarone, T. J.; Marchant Cortes, P.; Martin, E. L.; Masetti, N.; Matsunaga, N.; Mauro, F.; McDonald, I.; Mejias, A.; Mesa, V.; Milla-Castro, F. P.; Minniti, J. H.; Moni Bidin, C.; Montenegro, K.; Morris, C.; Motta, V.; Navarete, F.; Navarro Molina, C.; Nikzat, F.; Nilo Castellon, J. L.; Obasi, C.; Ortigoza-Urdaneta, M.; Palma, T.; Parisi, C.; Pena Ramirez, K.; Pereyra, L.; Perez, N.; Petralia, I.; Pichel, A.; Pignata, G.; Ramirez Alegria, S.; Rojas, A. F.; Rojas, D.; Roman-Lopes, A.; Rovero, A. C.; Saroon, S.; Schmidt, E. O.; Schroeder, A. C.; Schultheis, M.; Sgro, M. A.; Solano, E.; Soto, M.; Stecklum, B.; Steeghs, D.; Tamura, M.; Tissera, P.; Valcarce, A. A. R.; Valotto, C. A.; Vasquez, S.; Villalon, C.; Villanova, S.; Vivanco Cadiz, F.; Zelada Bacigalupo, R.; Zijlstra, A.; Zoccali, M.
    Context. The ESO public survey VISTA Variables in the Via Lactea (VVV) surveyed the inner Galactic bulge and the adjacent southern Galactic disk from 2009-2015. Upon its conclusion, the complementary VVV extended (VVVX) survey has expanded both the temporal as well as spatial coverage of the original VVV area, widening it from 562 to 1700 sq. deg., as well as providing additional epochs in JHKs filters from 2016-2023.
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    The VVV Templates Project
    (2014) Contreras Ramos, R.; Catelan, Marcio; Gran, F.; Navarrete, C.; Angeloni, R.; Alonso-García, J.; Dékány, I.; Hajdu, G.; Hempel, M.; Jordán, A.; Townsend, B.; Borissova, J.; Navarro, C.; Pichara, K.; Eyheramendy, S.
    Until now, stellar variability in the near-IR has been a relatively ill-explored research field. In particular, the number of high-quality light curves is very limited and, even worse, many variability classes have not yet been observed in a sufficiently extensive way in the near-IR, so that good light curves are entirely lacking for some such classes. Since VVV is the first ever large survey dedicated to stellar variability in the near-infrared, the first problem we had to face has thus been the construction of a proper statistically significant database of high-quality (i.e., template) near-IR light curves for a significant sample of stars taken to be representative of the different variability classes under study. The main purpose of the VVV Templates Project is thus to build a large database of well-defined, high-quality, near-IR light curves for variable stars of different types, which will form the basis of the VVV automated classification algorithms...
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    Updated census of RR Lyrae stars in the globular cluster omega Centauri (NGC 5139)
    (2015) Navarrete, C.; Contreras, R.; Catelan, Márcio; Clement, C.; Gran, F.; Alonso, J.; Angeloni, Rodolfo; Hempel, M.; Dekany, I.; Minniti, D.
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    Variability Survey of ω Centauri in the Near-IR: Period-Luminosity Relations
    (2017) Navarrete, C.; Catelan, Marcio; Contreras Ramos, R.; Gran, F.; Alonso-García, J.; Dékány, I.
    ω Centauri is by far the most massive globular star cluster in the Milky Way, and possibly the remnant of a dwarf galaxy. As such, it contains a large number of variable stars of different classes. Here we report on an extensive, wide-field time-series study of ω Cen in the J and K S bands, which has allowed us to study the near-IR period-luminosity relations for different variability classes, including the first such relations for the SX Phoenicis stars.