Browsing by Author "Navarro, M. G."

Now showing 1 - 9 of 9
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    The asymptotic evolution of the stellar merger V1309 Sco : a Blue Straggler in the making?
    (2019) Ferreira, T.; Saito, R. K.; Minniti, D.; Navarro, M. G.; Contreras Ramos, Rodrigo Andrés; Smith, L.; Lucas, P. W.
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    The most variable VVV sources: eruptive protostars, dipping giants in the Nuclear Disc and others
    (2023) Lucas, Phil; Smith, Leigh; Guo, Zhen; Contreras Peña, Carlos; Minniti, Dante; Miller, Niall; Alonso-Garcia, Javier; Catelan, Marcio; Borissova, J.; Saito, Roberto; Kurtev, Radostin; Navarro, M. G.; Morris, Calum; Muthu, Hariharan; Froebrich, Dirk; Ivanov, Valentin; Bayo, Amelia; Caratti, Alessio; Sanders, Jason
    We have performed a comprehensive search of a VISTA Variables in the Via Lactea (VVV) data base of 9.5 yr light curves for variable sources with ΔKs ≥ 4 mag, aiming to provide a large sample of high amplitude eruptive young stellar objects (YSOs) and detect unusual or new types of infrared variable source. We find 222 variable or transient sources in the Galactic bulge and disc, most of which are new discoveries. The sample mainly comprises novae, YSOs, microlensing events, Long Period Variable stars (LPVs), and a few rare or unclassified sources. Additionally, we report the discovery of a significant population of aperiodic late-type giant stars suffering deep extinction events, strongly clustered in the Nuclear Disc of the Milky Way. We suggest that these are metal-rich stars in which radiatively driven mass loss has been enhanced by super-solar metallicity. Among the YSOs, 32/40 appear to be undergoing episodic accretion. Long-lasting YSO eruptions have a typical rise time of ∼2 yr, somewhat slower than the 6–12 month time-scale seen in the few historical events observed on the rise. The outburst durations are usually at least 5 yr, somewhat longer than many lower amplitude VVV events detected previously. The light curves are diverse in nature, suggesting that multiple types of disc instability may occur. Eight long-duration extinction events are seen wherein the YSO dims for a year or more, attributable to inner disc structure. One binary YSO in NGC 6530 displays periodic extinction events (P=59 d) similar to KH 15D.
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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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    unVEil the darknesS of The gAlactic buLgE (VESTALE)
    (2018) Bono, G.; Dall'Ora, M.; Fabrizio, M.; Crestani, J.; Braga, V. F.; Fiorentino, G.; Altavilla, G.; Botticella, M. T.; Calamida, A.; Castellani, M.; Catelan, Marcio; Chaboyer, B.; Chiappini, C.; Clarkson, W.; Contreras Ramos, R.; Creevey, O.; da Silva, R.; Debattista, V.; Degl'Innocenti, S.; Ferraro, I.; Gilligan, C. K.; Gonzalez, O.; Hambleton, K.; Iannicola, G.; Inno, L.; Kunder, A.; Lemasle, B.; Magrini, L.; Magurno, D.; Marconi, M.; Marengo, M.; Marinoni, S.; Marrese, P. M.; Martinez-Vazquez, C. E.; Matsunaga, N.; Monelli, M.; Prada Moroni, P. G.; Musella, I.; Navarro, M. G.; Neeley, J.; Nonino, M.; Pietrinferni, A.; Pulone, L.; Rich, M. R.; Ripepi, V.; Sacco, G.; Saha, A.; Salaris, M.; Sneden, C.; Stetson, P. B.; Street, R. A; Szabo, R.; Tantalo, M.; Tognelli, E.; Torelli, M.; Valenti, E.; Walker, A. R.; Zoccali, M.
    The main aim of this experiment is to provide a complete census of old (t > 10 Gyr, RR Lyrae, type II Cepheids, red horizontal branch), intermediate age (red clump, Miras) and young (classical Cepheids) stellar tracers across the Galactic Bulge. To fully exploit the unique photometric quality of LSST images, we plan to perform a Shallow minisurvey (ugrizy, -20 < l < 20 deg, -15 < b < 10 deg) and a Deep minisurvey (izy, -20 < l < 20 deg, -3 < b < 3 deg). The former one is aimed at constraining the 3D structure of the galactic Bulge across the four quadrants, and in particular, the transition between inner and outer Bulge. The u,g,r,i,z,y LSST bands provide fundamental diagnostics to constrain the evolutionary properties of low and intermediate-mass stars when moving from a metal-poor to a metal-rich regime. The deep minisurvey is aimed at tracing RR Lyrae, Red Clump stars, Miras and classical Cepheids in highly reddened regions of the Galactic center. These images will allow us to investigate the role that baryonic mass and dark matter played in the early formation and evolution of the MW....
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    Unveiling short-period binaries in the inner VVV bulge
    (2021) Botan, E.; Saito, R. K.; Minniti, D.; Kanaan, A.; Ramos, R. Contreras; Ferreira, T. S.; Gramajo, L., V; Navarro, M. G.
    Most of our knowledge of the structure of the Milky Way has come from the study of variable stars. Among these variables, mimicking the periodic variation of pulsating stars, are eclipsing binaries. These stars are important in astrophysics because they allow us to directly measure the radii and masses of the components, as well as the distance to the system, thus being useful in studies of Galactic structure alongside pulsating RR Lyrae and Cepheids. Using the distinguishing features of their light curves, one can identify them using a semi-automated process. In this work, we present a strategy to search for eclipsing variables in the inner VVV bulge across an area of 13.4 deg(2) within 1.68 degrees < l < 7.53 degrees and -3.73 degrees < b < -1.44 degrees, corresponding to the VVV tiles b293-b296 and b307-b310. We accurately classify 212 previously unknown eclipsing binaries, including six very reddened sources. A preliminary analysis suggests that these eclipsing binaries are located in the most obscured regions of the foreground disc and bulge of the Galaxy. This search is therefore complementary to other variable-star searches carried out at optical wavelengths.
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    VVV Survey Microlensing : Candidate Events with a Source in the Far Disk
    (2020) Navarro, M. G.; Minniti, D.; Contreras Ramos, Rodrigo Andrés
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    VVV Survey Microlensing : Catalog of Best and Forsaken Events
    (2020) Navarro, M. G.; Contreras Ramos, Rodrigo Andrés; Minniti, D.; Pullen, J.; Capuzzo Dolcetta, R.; Lucas, P. W.
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    VVV Survey Microlensing : The Galactic Latitude Dependence
    (2020) Navarro, M. G.; Minniti, D.; Pullen, J.; Contreras Ramos, Rodrigo Andrés
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    VVV-WIT-04 : an extragalactic variable source caught by the VVV Survey
    (2019) Saito, R. K.; Minniti, D.; Ivanov, V. D.; Masetti, N.; Navarro, M. G.; Fernandes, R. C.; Ruschel Dutra, D.; Smith, L. C.; Lucas, P. W.; Contreras Ramos, Rodrigo Andrés; González Fernández, C.