Examinando por Autor "Catelan M."

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    An Automated Tool to Detect Variable Sources in the Vista Variables in the Vía Láctea Survey: The VVV Variables (V4) Catalog of Tiles d001 and d002
    (Institute of Physics Publishing, 2018-09) Medina N.; Borissova J.; Bayo A.; Kurtev R.; Navarro Molina C.; Kuhn M.; Kumar N.; Lucas P.W.; Catelan M.; Minniti D.; Smith L.C.
    Time-varying phenomena are one of the most substantial sources of astrophysical information, and their study has led to many fundamental discoveries in modern astronomy. We have developed an automated tool to search for and analyze variable sources in the near-infrared K s band using the data from the VISTA Variables in the Vía Láctea (VVV) ESO Public Large Survey. This process relies on the characterization of variable sources using different variability indices calculated from time series generated with point-spread function (PSF) photometry of sources under analysis. In particular, we used two main indices, the total amplitude and the eta index η, to identify variable sources. Once the variable objects are identified, periods are determined with generalized Lomb-Scargle periodograms and the information potential metric. Variability classes are assigned according to a compromise between comparisons with VVV templates and the period of the variability. The automated tool is applied on VVV tiles d001 and d002 and led to the discovery of 200 variable sources. We detected 70 irregular variable sources and 130 periodic ones. In addition, nine open-cluster candidates projected in the region are analyzed, and the infrared variable candidates found around these clusters are further scrutinized by cross-matching their locations against emission star candidates from VPHAS+ survey Hα color cuts. © 2018. The American Astronomical Society. All rights reserved.
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    Discovery of a thin stellar stream in the SLAMS survey
    (Oxford University Press, 2018) Jethwa P.; Torrealba G.; Navarrete C.; Carballo-Bello J.A.; de Boer T.; Erkal D.; Koposov S.E.; Duffau S.; Geisler D.; Catelan M.; Belokurov V.
    We report the discovery of a thin stellar stream - which we name the Jet stream - crossing the constellations of Hydra and Pyxis. The discovery was made in data from the Search for the Leading Arm of Magellanic Satellites (SLAMS) survey, which comprises deep g and r imaging for a 650 deg2 region above the Galactic disc performed by the CTIO Blanco + DECam. SLAMS photometric catalogues have been made publicly available. The stream is approximately 0.18 deg wide and 10 deg long, though it is truncated by the survey footprint. Its colour-magnitude diagram is consistent with an old, metal-poor stellar population at a heliocentric distance of approximately 29 kpc. We corroborate thismeasurement by identifying a spatially coincident overdensity of likely blue horizontal branch stars at the same distance. There is no obvious candidate for a surviving stream progenitor. © 2018 The Author(s).
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    The globular cluster NGC7492 and the Sagittarius tidal stream: Together but unmixed
    (Oxford University Press, 2018-03) Carballo-Bello J.A.; Corral-Santana J.M.; Catelan M.; Martínez-Delgado D.; Muñoz R.R.; Sollima A.; Navarrete C.; Duffau S.; Côté P.; Mora M.D.
    We have derived from VIMOS spectroscopy the radial velocities for a sample of 71 stars selected from CFHT/Megacam photometry around the Galactic globular cluster NGC7492. In the resulting velocity distribution, it is possible to distinguish two relevant non-Galactic kinematic components along the same line of sight: a group of stars at 〈vr〉~125 km s-1 which is compatible with the velocity of the old leading arm of the Sagittarius tidal stream, and a larger number of objects at 〈 vr〉 ~ -110 km s-1 that might be identified as members of the trailing wrap of the same stream. The systemic velocity of NGC7492 set at vr ~-177 km s-1 differs significantly from that of both components, thus our results confirm that this cluster is not one of the globular clusters deposited by the Sagittarius dwarf spheroidal in the Galactic halo, even if it is immersed in the stream. A group of stars with 〈 vr〉 ~ - 180 km s-1 might be comprised of cluster members along one of the tidal tails of NGC7492. © 2017 The Author(s).