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Register a new userNew Galactic Star Clusters Discovered in the VVV Survey
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VISTA Variables in the V{i}a Lactea (VVV) is one of the six ESO Public Surveys operating on the new 4-meter Visible and Infrared Survey Telescope for Astronomy (VISTA). VVV is scanning the Milky Way bulge and an adjacent section of the disk, where star formation activity is high. One of the principal goals of the VVV Survey is to find new star clusters of different ages. In order to trace the early epochs of star cluster formation we concentrated our search in the directions to those of known star formation regions, masers, radio, and infrared sources. The disk area covered by VVV was visually inspected using the pipeline processed and calibrated $K_{rm S}$-band tile images for stellar overdensities. Subsequently, we examined the composite $JHK_{rm S}$ and $ZJK_{rm S}$ color images of each candidate. PSF photometry of $15times15$ arcmin fields centered on the candidates was then performed on the Cambridge Astronomy Survey Unit reduced images. After statistical field-star decontamination, color-magnitude and color-color diagrams were constructed and analyzed. We report the discovery of 96 new infrared open clusters and stellar groups. Most of the new cluster candidates are faint and compact (with small angular sizes), highly reddened, and younger than 5,Myr. For relatively well populated cluster candidates we derived their fundamental parameters such as reddening, distance, and age by fitting the solar-metallicity Padova isochrones to the color-magnitude diagrams.
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We show the preliminary analysis of some Galactic stellar clusters (GSCls) candidates and the results of the analysis of two new interesting GSCls found in the VISTA Variables in the Via Lactea (VVV) Survey. The VVV photometric data are being used also to improve the knowledge of the Galactic structure. The photometric data are obtained with the new automatic photometric pipeline VVV-SkZ_pipeline.
The VISTA Variables in the Via Lactea eXtended (VVVX) ESO Public Survey is a near-infrared photometric sky survey that covers nearly 1700 sq. deg towards the Galactic disk and bulge. It is well-suited to search for new open clusters, hidden behind dust and gas. The pipeline processed and calibrated Ks-band tile images of 40% of the disk area covered by VVVX was visually inspected for stellar over-densities. Then, we identified cluster candidates by examination of the composite JHKs color images. The color-magnitude diagrams of the cluster candidates are constructed. Whenever possible the Gaia DR2 parameters are used to calculate the mean proper motions, radial velocities, reddening and distances. We report the discovery of 120 new infrared clusters and stellar groups. Approximately, half of them (47%) are faint, compact, highly reddened, and they seem to be associated with other indicators of recent star formation, such as nearby Young Stellar Objects, Masers, H II regions or bubbles. The preliminary distance determinations allow us to trace the clusters up to 4.5 kpc, but most of the cluster candidates are centered at 2.2 kpc. The mean proper motions of the clusters, show that in general, they follow the disk motion of the Galaxy.
This project is a massive near-infrared (NIR) search for variable stars in highly reddened and obscured open cluster (OC) fields projected on regions of the Galactic bulge and disk. The search is performed using photometric NIR data in the $J$-, $H$- and $K_s$- bands obtained from the Vista Variables in the Via Lactea (VVV) Survey. We performed in each cluster field a variability search using Stetsons variability statistics to select the variable candidates. Later, those candidates were subjected to a frequency analysis using the Generalized Lomb-Scargle and the Phase Dispersion Minimization algorithms. The number of independent observations range between 63 and 73. The newly discovered variables in this study, 157 in total in three different known OCs, are classified based on their light curve shapes, periods, amplitudes and their location in the corresponding color-magnitude $(J-K_s,K_s)$ and color-color $(H-K_s,J-H)$ diagrams. We found 5 possible Cepheid stars which, based on the period-luminosity relation, are very likely type II Cepheids located behind the bulge. Among the newly discovered variables, there are eclipsing binaries, $delta$ Scuti, as well as background RR Lyrae stars. Using the new version of the Wilson & Devinney code as well as the Physics Of Eclipsing Binaries (PHOEBE) code, we analyzed some of the best eclipsing binaries we discovered. Our results show that these studied systems turn out to be ranging from detached to double-contact binaries, with low eccentricities and high inclinations of approximately $80^{circ}$. Their surface temperatures range between $3500$K and $8000$K.
Only four globular cluster planetary nebulae (GCPN) are known so far in the Milky Way. About 50 new globular clusters have been recently discovered towards the Galactic bulge. We present a search for planetary nebulae within 3 arcmin of the new globular clusters, revealing the identification of new candidate GCPN. These possible associations are PN SB 2 with the GC Minni 06, PN G354.9-02.8 with the GC Minni 11, PN G356.8-03.6 with the GC Minni 28, and PN Pe 2-11 with the GC Minni 31. We discard PN H 2-14 located well within the projected tidal radius of the new globular cluster FSR1758 because they have different measured radial velocities. These are interesting objects that need follow-up observations (especially radial velocities) in order to confirm membership, and to measure their physical properties in detail. If confirmed, this would double the total number of Galactic GCPN.
We report the serendipitous discovery of three new open clusters, named UFMG 1, UFMG 2 and UFMG 3 in the field of the intermediate-age cluster NGC 5999, by using Gaia DR2 data. A colour-magnitude filter tailored for a proper selection of main-sequence stars and red clump giants turned evident the presence of NGC 5999 and these three new stellar groups in proper motion space. Their structural parameters were derived from King-profile fittings over their projected stellar distributions and isochrone fits were performed on the clusters cleaned colour-magnitude diagrams built with Gaia bands to derive their astrophysical parameters. The clusters projected sky motion were calculated for each target using our members selection. Distances to the clusters were inferred from stellar parallaxes through a bayesian model, showing that they are marginally consistent with their isochronal distances, considering the random and systematic uncertainties involved. The new clusters are located in the nearby Sagittarius arm (d ~ 1.5 kpc) with NGC 5999 at the background (d ~ 1.8 kpc). They contain at least a few hundred stars of nearly solar metallicity and have ages between 100 and 1400 Myr.
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