Browsing by Author "Ivanov, Valentin D."

Now showing 1 - 5 of 5
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    Candidate star clusters toward the inner Milky Way discovered on deep-stacked K-S-band images from the VVV Survey
    (2017) Ivanov, Valentin D.; Piatti, Andrés E,; Beamin Muhlenbrock, Juan Carlos; Minniti, D.; Borissova, Jordanka; Kurtev, Radostin; Hempel, Maren; Saito, Roberto K
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    Confirmation of a New Metal-poor Globular Cluster in the Galactic Bulge
    (2018) Minniti, D.; Schlafly, E. F.; Palma, Tali; Claria, Juan J.; Hempel, Maren; Alonso-Garcia, Javier; Bica, Eduardo; Bonatto, Charles; Braga, Vittorio F.; Clementini, Gisella; Garofalo, Alessia; Gomez, Matias; Ivanov, Valentin D.; Lucas, Phill
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    Dwarf galaxies in the Antlia cluster: first results
    (2007) Castelli, A.V.S.; Bassino, L.P.; Cellone, S.A.; Richtler, T.; Dirsch, B.; Infante Lira, Leopoldo; Aruta, C.; Gómez, M.; Saviane, Ivo; Ivanov, Valentin D.; Borissova, Jordanka
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    Millimagnitude photometry for transiting extrasolar planetary candidates.: II. transits of OGLE-TR-113-B in the optical and near-ir
    (2007) Diaz, Rodrigo F.; Ramirez, Sebastían; Fernandez, José Miguel; Gallardo, José; Gieren, Wolfgang; Ivanov, Valentin D.; Mauas, Pablo; Minniti, Dante; Pietrzynski, Grzegorz; Perez, Felipe; Ruiz, Maria Teresa; Udalski, Andrzej; Zoccali, Manuela
    We present precise V-and K-s-band transit photometry for the planetary host star OGLE-TR-113. Using the Ks-band photometry, we confirm the dwarf nature of OGLE-TR-113 and obtain new estimates for its effective temperature, distance, and reddening. We employ the V-band photometry to obtain planetary and orbit parameters from the transit fit, alpha = 0.0232 +/- 0: 0038 AU, orbital period P = 1.4324752 +/- 0.0000015 day, i = 86.7-90, and R-p 1.09 +/- 0.09 R-J. These values are in excellent agreement with previous works. Assuming a mass M-p 1.32 +/- 0.19 M-J for the planet, we obtain its mean density p = 1.26 +/- 0.50 g cm(-3), also in agreement with previous works. The transit observed in the K-s-band has a larger scatter, and we find its amplitude to be consistent with that in the V band. In this way, we find an independent confirmation of the planetary nature of OGLE-TR-113b.
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    VARIABILITY OF THE INFRARED EXCESS OF EXTREME DEBRIS DISKS
    (2012) Meng, Huan Y. A.; Rieke, George H.; Su, Kate Y. L.; Ivanov, Valentin D.; Vanzi, Leonardo; Rujopakarn, Wiphu
    Debris disks with extremely large infrared excesses (fractional luminosities > 10(-2)) are rare. Those with ages between 30 and 130 Myr are of interest because their evolution has progressed well beyond that of protoplanetary disks (which dissipate with a timescale of order 3 Myr), yet they represent a period when dynamical models suggest that terrestrial planet building may still be progressing through large, violent collisions that could yield large amounts of debris and large infrared excesses. For example, our Moon was formed through a violent collision of two large protoplanets during this age range. We report two disks around the solar-like stars ID8 and HD 23514 in this age range where the 24 mu m infrared excesses vary on timescales of a few years, even though the stars are not variable in the optical. Variations this rapid are difficult to understand if the debris is produced by collisional cascades, as it is for most debris disks. It is possible that the debris in these two systems arises in part from condensates from silicate-rich vapor produced in a series of violent collisions among relatively large bodies. If their evolution is rapid, the rate of detection of extreme excesses would indicate that major collisions may be relatively common in this age range.