Browsing by Author "Catelan, M."

Now showing 1 - 9 of 9
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    An investigation of low-mass-ratio EW systems from the Catalina Sky Survey
    (SLOVAK ACADEMY SCIENCES ASTRONOMICAL INST, 2020) Lalounta, E.; Papageorgiou, A.; Christopoulou, P. E.; Catelan, M.
    We have conducted a survey of overcontact binary systems (EW) with mass ratio <= 0.25 from the Catalina Sky Survey (CSS) that are considered strong merger candidates and are probable progenitors of FK Com-type stars and blue stragglers. The discovery of such extreme mass ratio overcontact binaries is vital to resolve the critical mass ratio ambiguity to merge, the mass loss process, and to refine the current theoretical models. So far only a few tens of such systems have been identified. To increase this sample, we selected and derived the physical parameters (mass, temperature and radius ratios, inclination and fill-out factor, along with their respective uncertainties) of 92 newly discovered totally eclipsing low-mass-ratio (LMR) EW systems based on their VCSS light curves, using PHOEBE-0.31a scripter and Monte Carlo methods.
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    Discovery of VVV CL001 A low-mass globular cluster next to UKS 1 in the direction of the Galactic bulge
    (EDP SCIENCES S A, 2011) Minniti, D.; Hempel, M.; Toledo, I.; Ivanov, V. D.; Alonso Garcia, J.; Saito, R. K.; Catelan, M.; Geisler, D.; Jordan, A.; Borissova, J.; Zoccali, M.; Kurtev, R.; Carraro, G.; Barbuy, B.; Claria, J.; Rejkuba, M.; Emerson, J.; Moni Bidin, C.
    Context. It is not known how many globular clusters may remain undetected towards the Galactic bulge.
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    Humps and bumps: the effects of shocks on the optical light curves of fundamental-mode RR Lyrae stars
    (EDP SCIENCES S A, 2020) Prudil, Z.; Dekany, I.; Smolec, R.; Catelan, M.; Grebel, E. K.; Kunder, A.
    We present the most extended and homogeneous study carried out so far of the main and early shocks in 1485 RR Lyrae stars in the Galactic bulge observed by the Optical Gravitational Lensing Experiment. We selected nonmodulated fundamental-mode RR Lyrae stars with good-quality photometry. Using a self-developed method, we determined the centers and strengths of main and early shock features in the phased light curves. We found that the positions of both humps and bumps are highly correlated with the pulsation properties of the studied variables. Pulsators with a pronounced main shock are concentrated in the low-amplitude regime of the period-amplitude diagram, while stars with a strong early shock have average and above-average pulsation amplitudes. A connection between the main and early shocks and the Fourier coefficients is also observed. In the color-magnitude diagram, we see a separation between stars with strong and weak shocks. Variables with a pronounced main shock cluster close to the fundamental red edge of the instability strip (IS), while stars with a strong early shock tend to clump in the center and near the fundamental blue edge of the IS. The appearance of shocks and their properties appear to be independent of the direction of evolution estimated from the period change rate of the studied stars. In addition, the differences in the period change rate between the two main Oosterhoff groups found in the Galactic bulge suggest that stars of Oosterhoff type I are located close to the zero-age horizontal branch while Oosterhoff type II variables are on their way toward the fundamental red edge of the instability strip, and have therefore already left the zero-age horizontal branch.
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    Informative Bayesian model selection for RR Lyrae star classifiers
    (2021) Pérez-Galarce, F.; Pichara, K.; Huijse, P.; Catelan, M.; Mery Quiroz, Domingo Arturo
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    Milky Way demographics with the VVV survey I. The 84-million star colour-magnitude diagram of the Galactic bulge
    (EDP SCIENCES S A, 2012) Saito, R. K.; Minniti, D.; Dias, B.; Hempel, M.; Rejkuba, M.; Alonso Garcia, J.; Barbuy, B.; Catelan, M.; Emerson, J. P.; Gonzalez, O. A.; Lucas, P. W.; Zoccali, M.
    Context. The Milky Way (MW) bulge is a fundamental Galactic component for understanding the formation and evolution of galaxies, in particular our own. The ESO Public Survey VISTA Variables in the Via Lactea is a deep near-IR survey mapping the Galactic bulge and southern plane. Particularly for the bulge area, VVV is covering similar to 315 deg(2). Data taken during 2010 and 2011 covered the entire bulge area in the JHKs bands.
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    The VVV Infrared Variability Catalog (VIVA-I)
    (2020) Ferreira Lopes, E. C.; Cross, N. J. G.; Catelan, M.; Minniti, D.; Hempel, M.; Lucas, W. P.; Angeloni, R.; Jablonsky, F.; Braga, F. V.; Leao, C. I.; Herpich, F. R.; Alonso-Garcia, J.; Papageorgiou, A.; Pichara, K.; Saito, K. R.; Bradley, A.; Beamin Muhlenbrock Juan Carlos; Cortes, C.; De Medeiros, J. R.; Russell, Christopher
    Thanks to the VISTA Variables in the Via Lactea (VVV) ESO Public Survey it is now possible to explore a large number of objects in those regions. This paper addresses the variability analysis of all VVV point sources having more than 10 observations in VVVDR4 using a novel approach. In total, the near-IR light curves of 288,378,769 sources were analysed using methods developed in the New Insight Into Time Series Analysis project. As a result, we present a complete sample having 44, 998, 752 variable star candidates (VVV-CVSC), which include accurate individual coordinates, near-IR magnitudes (ZYJHKs), extinctions A(Ks), variability indices, periods, amplitudes, among other parameters to assess the science. Unfortunately, a side effect of having a highly complete sample, is also having a high level of contamination by non-variable (contamination ratio of non-variables to variables is slightly over 10:1). To deal with this, we also provide some flags and parameters that can be used by the community to de-crease the number of variable candidates without heavily decreasing the completeness of the sample. In particular, we cross-identified 339,601 of our sources with Simbad and AAVSO databases, which provide us with information for these objects at other wavelegths. This sub-sample constitutes a unique resource to study the corresponding near-IR variability of known sources as well as to assess the IR variability related with X-ray and Gamma-Ray sources. On the other hand, the other 99.5% sources in our sample constitutes a number of potentially new objects with variability information for the heavily crowded and reddened regions of the Galactic Plane and Bulge. The present results also provide an important queryable resource to perform variability analysis and to characterize ongoing and future surveys like TESS and LSST.
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    VISTA Variables in the Via Lactea (VVV): The public ESO near-IR variability survey of the Milky Way
    (ELSEVIER, 2010) Minniti, D.; Lucas, P. W.; Emerson, J. P.; Saito, R. K.; Hempel, M.; Pietrukowicz, P.; Ahumada, A. V.; Alonso, M. V.; Alonso Garcia, J.; Arias, J. I.; Bandyopadhyay, R. M.; Barba, R. H.; Barbuy, B.; Bedin, L. R.; Bica, E.; Borissova, J.; Bronfman, L.; Carraro, G.; Catelan, M.; Claria, J. J.; Cross, N.; de Grijs, R.; Dekany, I.; Drew, J. E.; Farina, C.; Feinstein, C.; Fernandez Lajus, E.; Gamen, R. C.; Geisler, D.; Gieren, W.; Goldman, B.; Gonzalez, O. A.; Gunthardt, G.; Gurovich, S.; Hambly, N. C.; Irwin, M. J.; Ivanov, V. D.; Jordan, A.; Kerins, E.; Kinemuchi, K.; Kurtev, R.; Lopez Corredoira, M.; Maccarone, T.; Masetti, N.; Merlo, D.; Messineo, M.; Mirabel, I. F.; Monaco, L.; Morelli, L.; Padilla, N.; Palma, T.; Parisi, M. C.; Pignata, G.; Rejkuba, M.; Roman Lopes, A.; Sale, S. E.; Schreiber, M. R.; Schroeder, A. C.; Smith, M.; Sodre, L., Jr.; Soto, M.; Tamura, M.; Tappert, C.; Thompson, M. A.; Toledo, I.; Zoccali, M.; Pietrzynski, G.
    We describe the public ESO near-IR variability survey (VVV) scanning the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high. The survey will take 1929 h of observations with the 4-m VISTA telescope during 5 years (2010-2014), covering similar to 10(9) point sources across an area of 520 deg(2), including 33 known globular clusters and similar to 350 open clusters. The final product will be a deep near-IR atlas in five passbands (0.9-2.5 mu m) and a catalogue of more than 106 variable point sources. Unlike single-epoch surveys that, in most cases, only produce 2-D maps, the VVV variable star survey will enable the construction of a 3-D map of the surveyed region using well-understood distance indicators such as RR Lyrae stars, and Cepheids. It will yield important information on the ages of the populations. The observations will be combined with data from MACHO, OGLE, EROS, VST, Spitzer, HST, Chandra, INTEGRAL, WISE, Fermi LAT, XMM-Newton, GAIA and ALMA for a complete understanding of the variable sources in the inner Milky Way. This public survey will provide data available to the whole community and therefore will enable further studies of the history of the Milky Way, its globular cluster evolution, and the population census of the Galactic Bulge and center, as well as the investigations of the star forming regions in the disk. The combined variable star catalogues will have important implications for theoretical investigations of pulsation properties of stars. (C) 2009 Elsevier B.V. All rights reserved.
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    VVV DR1: The first data release of the Milky Way bulge and southern plane from the near-infrared ESO public survey VISTA variables in the Via Lactea
    (EDP SCIENCES S A, 2012) Saito, R. K.; Hempel, M.; Minniti, D.; Lucas, P. W.; Rejkuba, M.; Toledo, I.; Gonzalez, O. A.; Alonso Garcia, J.; Irwin, M. J.; Gonzalez Solares, E.; Hodgkin, S. T.; Lewis, J. R.; Cross, N.; Ivanov, V. D.; Kerins, E.; Emerson, J. P.; Soto, M.; Amores, E. B.; Gurovich, S.; Dekany, I.; Angeloni, R.; Beamin, J. C.; Catelan, M.; Padilla, N.; Zoccali, M.; Pietrukowicz, P.; Bidin, C. Moni; Mauro, F.; Geisler, D.; Folkes, S. L.; Sale, S. E.; Borissova, J.; Kurtev, R.; Ahumada, A. V.; Alonso, M. V.; Adamson, A.; Arias, J. I.; Bandyopadhyay, R. M.; Barba, R. H.; Barbuy, B.; Baume, G. L.; Bedin, L. R.; Bellini, A.; Benjamin, R.; Bica, E.; Bonatto, C.; Bronfman, L.; Carraro, G.; Chene, A. N.; Claria, J. J.; Clarke, J. R. A.; Contreras, C.; Corvillon, A.; de Grijs, R.; Dias, B.; Drew, J. E.; Farina, C.; Feinstein, C.; Fernandez Lajus, E.; Gamen, R. C.; Gieren, W.; Goldman, B.; Gonzalez Fernandez, C.; Grand, R. J. J.; Gunthardt, G.; Hambly, N. C.; Hanson, M. M.; Helminiak, K. G.; Hoare, M. G.; Huckvale, L.; Jordan, A.; Kinemuchi, K.; Longmore, A.; Lopez Corredoira, M.; Maccarone, T.; Majaess, D.; Martin, E. L.; Masetti, N.; Mennickent, R. E.; Mirabel, I. F.; Monaco, L.; Morelli, L.; Motta, V.; Palma, T.; Parisi, M. C.; Parker, Q.; Penaloza, F.; Pietrzynski, G.; Pignata, G.; Popescu, B.; Read, M. A.; Rojas, A.; Roman Lopes, A.; Ruiz, M. T.; Saviane, I.; Schreiber, M. R.; Schroeder, A. C.; Sharma, S.; Smith, M. D.; Sodre, L., Jr.; Stead, J.; Stephens, A. W.; Tamura, M.; Tappert, C.; Thompson, M. A.; Valenti, E.; Vanzi, L.; Walton, N. A.; Weidmann, W.; Zijlstra, A.
    Context. The ESO public survey VISTA variables in the Via Lactea (VVV) started in 2010. VVV targets 562 sq. deg in the Galactic bulge and an adjacent plane region and is expected to run for about five years.
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    VVV-WIT-01 : highly obscured classical nova or protostellar collision?
    (2020) Lucas, P. W.; Minniti, D.; Kamble, A.; Kaplan, D. L.; Cross, N.; Dekany, Istvan; Ivanov, V. D.; Kurtev, R.; Saito, R. K.; Smith, L. C.; Catelan, M.; Masetti, N.; Toledo, I.; Hempel, M.; Thompson, M. A.; Pena, C. C.; Forbrich, J.; Krause, M.; Dale, J.; Borissova, J.; Emerson, J.; Lucas, P. W.; Minniti, D.; Kamble, A.; Kaplan, D. L.; Cross, N.; Dekany, Istvan; Ivanov, V. D.; Kurtev, R.; Saito, R. K.; Smith, L. C.; Catelan, M.; Masetti, N.; Toledo, I.; Hempel, M.; Thompson, M. A.; Pena, C. C.; Forbrich, J.; Krause, M.; Dale, J.; Borissova, J.; Emerson, J.