Context. VISTA Variables in the Vía Láctea (VVV) is one of six ESO Public Surveys using the 4 meter Visible and Infrared Survey Telescope for Astronomy (VISTA). The VVV survey covers the Milky Way bulge and an adjacent section of the disk, and one of the principal objectives is to search for new star clusters within previously unreachable obscured parts of the Galaxy. Aims. The primary motivation behind this work is to discover and analyze obscured star clusters in the direction of the inner Galactic disk and bulge. Methods. Regions of the inner disk and bulge covered by the VVV survey were visually inspected using composite JHK S color images to select new cluster candidates on the basis of apparent overdensities. DR1, DR2, CASU, and point spread function photometry of 10 × 10 arcmin fields centered on each candidate cluster were used to construct color-magnitude and color-color diagrams. Follow-up spectroscopy of the brightest members of several cluster candidates was obtained in order to clarify their nature. Results. We report the discovery of 58 new infrared cluster candidates. Fundamental parameters such as age, distance, and metallicity were determined for 20 of the most populous clusters.

Aims. The characterisation of the stellar population in young high-mass star-forming regions allows fundamental cluster properties like distance and age to be constrained. These are essential when using high-mass clusters as probes for conducting Galactic studies. Methods. NGC 7538 is a star-forming region with an embedded stellar population unearthed only in the near-infrared (NIR). We present the first near-infrared spectro-photometric study of the candidate high-mass stellar content in NGC 7538. We obtained H and K spectra of 21 sources with both the multi-object and long-slit modes of LIRIS at the WHT, and complement these data with subarcsecond JHK s photometry of the region using the imaging mode of the same instrument. Results. We find a wide variety of objects within the studied stellar population of NGC 7538. Our results discriminate between a stellar population associated to the H ii region, but not contained within its extent, and several pockets of more recent star formation.We report the detection of CO bandhead emission toward several sources, as well as other features indicative of a young stellar nature. We infer a spectro-photometric distance of 2.7 ± 0.5 kpc, an age spread in the range 0.5−2.2 Myr and a total mass ∼1.7 × 10 3 M for the older population.

We use deep multi-epoch near-IR images of the VISTA Variables in the Vía Láctea (VVV) Survey to search for RR Lyrae stars towards the Southern Galactic plane. Here we report the discovery of a group of RR Lyrae stars close together in VVV tile d025. Inspection of the VVV images and PSF photometry reveals that most of these stars are likely to belong to a globular cluster, that matches the position of the previously known star cluster FSR 1716. The stellar density map of the field yields a > 100 sigma detection for this candidate globular cluster, that is centered at equatorial coordinates RA J2000 =16:10:30.0, DEC J2000 = −53:44:56; and galactic coordinates l =329.77812, b = −1.59227. The color-magnitude diagram of this object reveals a well populated red giant branch, with a prominent red clump at K s = 13.35 ± 0.05, and J − K s = 1.30 ± 0.05. We present the cluster RR Lyrae positions, magnitudes, colors, periods and amplitudes. The presence of RR Lyrae indicates an old globular cluster, with age > 10 Gyr. We classify this object as an Oosterhoff type I globular cluster, based on the mean period of its RR Lyrae type ab, < P >= 0.540 days, and argue that this is a relatively metal-poor cluster with [F e/H] = −1.5 ± 0.4 dex. The mean extinction and reddening for arXiv:1703.02033v1 [astro-ph.GA] 6 Mar 2017 2 this cluster are A Ks = 0.38 ± 0.02, and E(J − K s ) = 0.72 ± 0.02 mag, respectively, as measured from the RR Lyrae colors and the near-IR color-magnitude diagram. We also measure the cluster distance using the RR Lyrae type ab stars. The cluster mean distance modulus is (m − M ) 0 = 14.38 ± 0.03 mag, implying a distance D = 7.5 ± 0.2 kpc, and a Galactocentric distance R G = 4.3 kpc.