Examinando por Autor "Kammers, R."

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    A new near-IR window of low extinction in the Galactic plane
    (EDP Sciences, 2018-08) Minniti, D.; Saito, R.K.; Gonzalez, O.A.; Alonso-García, J.; Rejkuba, M.; Barbá, R.; Irwin, M.; Kammers, R.; Lucas, P.W.; Majaess, D.; Valenti, E.
    Aims. The windows of low extinction in the Milky Way (MW) plane are rare but important because they enable us to place structural constraints on the opposite side of the Galaxy, which has hither to been done rarely. Methods. We use the near-infrared (near-IR) images of the VISTA Variables in the Vía Láctea (VVV) Survey to build extinction maps and to identify low extinction windows towards the Southern Galactic plane. Here we report the discovery of VVV WIN 1713-3939, a very interesting window with relatively uniform and low extinction conveniently placed very close to the Galactic plane. Results. The new window of roughly 30 arcmin diameter is located at Galactic coordinates (l, b) = (347.4, -0.4) deg. We analyse the VVV near-IR colour-magnitude diagrams in this window. The mean total near-IR extinction and reddening values measured for this window are A Ks = 0.46 and E(J - K s ) = 0.95. The red clump giants within the window show a bimodal magnitude distribution in the K s band, with peaks at K s = 14.1 and 14.8 mag, corresponding to mean distances of D = 11.0 ± 2.4 and 14.8 ± 3.6 kpc, respectively. We discuss the origin of these red clump overdensities within the context of the MW disk structure. © ESO 2018.
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    VVV WIN 1733−3349: a low extinction window to probe the far side of the Milky Way bulge
    (Oxford University Press, 2020-02) Saito, R. K.; Minniti, D.; Benjamin, R. A.; Navarro, M. G.; Alonso-García, J.; . Gonzalez, O. A; Kammers, R.; Surot, F.
    Windows of low extinction in the Milky Way (MW) have been used along the past decades for the study of the Galactic structure and the stellar population across the inner bulge and disc. Here, we report the analysis of another low extinction near-IR window discovered by the VISTA Variables in the Viá Láctea Survey (VVV). VVV WIN 1733-3349 is about half a degree in size and is conveniently located right in the MW plane, at Galactic coordinates (l, b) = (-5.2,-0.3). The mean extinction of VVV WIN 1733-3349 is $A-{K-{\mathrm{ s}}}$ = 0.61 ± 0.08 mag, which is much smaller than the extinction in the surrounding area. The excess in the star counts is consistent with the reduced extinction and complemented by studying the distribution of red clump (RC) stars. Thanks to the strategic low-latitude location of VVV WIN 1733-3349, we are able to interpret their RC density fluctuations with the expected overdensities due to the presence of the spiral arms beyond the bulge. In addition, we find a clear excess in the number of microlensing events within the window, which corroborates our interpretation that VVV WIN 1733-3349 is revealing the far side of the MW bulge. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.