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In the efforts to map the Milky Way structure, the central regions have remained very difficult to probe. The VISTA Variables in the Vía Láctea Survey (VVV) is a near-IR variability Survey that scans 560 sq.deg. across the Milky Way bulge and an adjacent section of the southern mid-plane. The main goal of the VVV Survey is to build a 3D map of the structure of the inner Galaxy and characterize its stellar populations. This survey has discovered different kinds of objects, such as globular clusters, Microlensing events, RR Lyrae stars, Cepheids, WITs, among others. The extension of the Survey (VVVX) is observing until 2020, tripling the areal coverage, and complementing the variability studies done by the VVV Survey. [ABSTRACT FROM AUTHOR]

Stellar mergers are estimated to be common events in the Galaxy. The best studied stellar merger case to date is V1309 Sco (= Nova Scorpii 2008) which was originally misclassified as a Nova event. Later identified as the merger of the components of a cool overcontact binary system with 1.52 M⊙ and 0.16 M⊙, V1309 Sco showed an initial period of P  = 1.4 d before the merger. Post-outburst evolution demonstrated that V1309 Sco was unlike the typical Classical Novae and Symbiotic Recurrent Novae with significant dust production around it, and indicated that the system may become a post-AGB (or pre-PN) soon. Here we present a study of V1309 Sco about 10 yr after the outburst, based on near-IR variability and colour data from the ESO surveys VISTA Variables in the Vía Láctea (VVV) and VVV eXtended (VVVX). We find that reasonable equilibrium in this stellar merger is being reached and that the star has settled into a nearly constant magnitude. A dramatic change in its near-IR colours from (J − K s) = 1.40 in 2010 to (J − K S) = 0.42 in 2015 and a possible low-amplitude periodic signal with P  = 0.49 d in the post-outburst data are consistent with a 'blue straggler' star, predicted to be formed from a stellar merger. [ABSTRACT FROM AUTHOR]