Examinando por Autor "Surot, Francisco"

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    M dwarfs in the b201 tile of the VVV survey: Colour-based selection, spectral types and light curves
    (EDP Sciences, 2014-11) Rojas-Ayala, Bárbara; Iglesias, Daniela; Minniti, Dante; Saito, Roberto K.; Surot, Francisco
    Context. The intrinsically faint M dwarfs are the most numerous stars in the Galaxy, have main-sequence lifetimes longer than the Hubble time, and host some of the most interesting planetary systems known to date. Their identification and classification throughout the Galaxy is crucial to unraveling the processes involved in the formation of planets, stars, and the Milky Way. The ESO Public Survey VVV is a deep near-IR survey mapping the Galactic bulge and southern plane. The VVV b201 tile, located in the border area of the bulge, was specifically selected for the characterisation of M dwarfs. Aims. We used VISTA photometry to identify M dwarfs in the VVV b201 tile, to estimate their subtypes, and to search for transit-like light curves from the first 26 epochs of the survey. Methods. UKIDSS photometry from SDSS spectroscopically identified M dwarfs was used to calculate their expected colours in the YJHKs VISTA system. A colour-based spectral subtype calibration was computed. Possible giants were identified by a (J-Ks,HJ) reduced proper motion diagram. The light curves of 12.8
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    The structure behind the Galactic bar traced by red clump stars in the VVV survey
    (Oxford University Press, 2018-11) Gonzalez, Oscar A.; Minniti, Dante; Valenti, Elena; Alonso-García, Javier; Debattista, Victor P.; Zoccali, Manuela; Rejkuba, Marina; Dias, Bruno; Surot, Francisco; Hempel, Maren; Saito, Roberto K.
    Red clump stars are commonly used to map the reddening and morphology of the inner regions of the Milky Way. We use the new photometric catalogues of the VISTA Variables in the Vía Láctea survey to achieve twice the spatial resolution of previous reddening maps for Galactic longitudes - 10° < l < 10° and latitudes -1.5° < b < 1.5°. We use these dereddened catalogues to construct the Ks luminosity function around the red clump in the Galactic plane. We show that the secondary peak (fainter than the red clump) detected in these regions does not correspond to the bulge red-giant branch bump alone, as previously interpreted. Instead, this fainter clump corresponds largely to the over-density of red clump stars tracing the spiral arm structure behind the Galactic bar. This result suggests that studies aiming to characterize the bulge red-giant branch bump should avoid low galactic latitudes (|b| < 2°), where the background red clump population contributes significant contamination. It furthermore highlights the need to include this structural component in future modelling of the Galactic bar. © 2018 The Author(s).