Browsing by Author "Smith, L. C."
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- ItemAn 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(2018) Medina, N.; Borissova, J.; Bayo, A.; Kurtev, R.; Navarro Molina, C.; Kuhn, M.; Kumar, N.; Lucas, P.W.; Catelan, Márcio; Minniti, D.; Smith, L. C.
- ItemLarge-amplitude periodic outbursts and long-period variables in the VVV VIRAC2-β data base(2022) Guo, Zhen; Lucas, P. W.; Smith, L. C.; Clarke, C.; Contreras Peña, C.; Bayo, A.; Briceño, C.; Elias, J.; Kurtev, R. G.; Borissova, J.; Alonso-García, J.; Minniti, D.; Catelan, Márcio; Nikzat, F.; Morris, C.; Miller, N.The VISTA Variables in the Via Lactea (VVV) survey obtained near-infrared photometry towards the Galactic bulge and the southern disc plane for a decade (2010-2019). We designed a modified Lomb-Scargle method to search for large-amplitude ($\Delta K_{s, 2-98{{\ \rm per\ cent}}}$ > 1.5 mag) mid to long-term periodic variables (P> 10 d) in the 2nd version of VVV Infrared Astrometric Catalogue (VIRAC2-β). In total, 1520 periodic sources were discovered, including 59 candidate periodic outbursting young stellar objects (YSOs), based on the unique morphology of the phase-folded light curves, proximity to Galactic H II regions and mid-infrared colours. Five sources are spectroscopically confirmed as accreting YSOs. Both fast-rise/slow-decay and slow-rise/fast-decay periodic outbursts were found, but fast-rise/slow-decay outbursts predominate at the highest amplitudes. The multiwavelength colour variations are consistent with a variable mass accretion process, as opposed to variable extinction. The cycles are likely to be caused by dynamical perturbations from stellar or planetary companions within the circumstellar disc. An additional search for periodic variability amongst YSO candidates in published Spitzer-based catalogues yielded a further 71 candidate periodic accretors, mostly with lower amplitudes. These resemble cases of pulsed accretion but with unusually long periods and greater regularity. The majority of other long-period variables are pulsating dusty Miras with smooth and symmetric light curves. We find that some Miras have redder W3 - W4 colours than previously thought, most likely due to their surface chemical compositions....
- ItemNear-infrared photometry and spectroscopy of the low Galactic latitude globular cluster 2MASS-GC 03(2016) Carballo Bello, Julio A.; Ramírez Alegría, S.; Borissova, J.; Smith, L. C.; Kurtev, R.; Lucas, P. W.; Moni Bidin, Ch.; Alonso García, J.; Minniti, D.; Palma, T.; Dekany, Istvan
- ItemVVV high proper motion stars - I. The catalogue of bright K-S <= 13.5 stars(OXFORD UNIV PRESS, 2017) Kurtev, R.; Gromadzki, M.; Beamin, J. C.; Folkes, S. L.; Ramirez, K. Pena; Ivanov, V. D.; Borissova, J.; Villanueva, V.; Minniti, D.; Mendez, R.; Lucas, P. W.; Smith, L. C.; Pinfield, D. J.; Kuhn, M. A.; Jones, H. R. A.; Antonova, A.; Yip, A. K. P.Knowledge of the stellar content near the Sun is important for a broad range of topics ranging from the search for planets to the study of Milky Way (MW) structure. The most powerful method for identifying potentially nearby stars is proper motion (PM) surveys. All old optical surveys avoid, or are at least substantially incomplete, near the Galactic plane. The depth and breadth of the 'VISTA Variables in Via Lactea' (VVV) near-IR survey significantly improves this situation. Taking advantage of the VVV survey data base, we have measured PMs in the densest regions of the MW bulge and southern plane in order to complete the census of nearby objects. We have developed a custom PM pipeline based on VVV catalogues from the Cambridge Astronomy Survey Unit, by comparing the first epoch of JHKS with the multiepoch K-S bands acquired later. Taking advantage of the large time baseline between the Two Micron All Sky Survey (2MASS) and the VVV observations, we also obtained 2MASS-VVV PMs. We present a near-IR PMcatalogue for the whole area of the VVV survey, which includes 3003 moving stellar sources. All of these have been visually inspected and are real PM objects. Our catalogue is in very good agreement with the PM data supplied in IR catalogues outside the densest zone of the MW. The majority of the PM objects in our catalogue are nearby M-dwarfs, as expected. This new data base allows us to identify 57 common PM binary candidates, among which are two new systems within 30 pc of the Sun.
- ItemVVV-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.
- ItemVVV-WIT-04 : an extragalactic variable source caught by the VVV Survey(2019) Saito, R. K.; Minniti, D.; Ivanov, V. D.; Masetti, N.; Navarro, M. G.; Fernandes, R. C.; Ruschel Dutra, D.; Smith, L. C.; Lucas, P. W.; Contreras Ramos, Rodrigo Andrés; González Fernández, C.