Hundreds of new cluster candidates in the VISTA variables in the Via
  Lactea survey DR1
  VISTA variables in the Via Lactea is an ESO Public survey dedicated to scan
the bulge and an adjacent portion of the Galactic disk in the fourth quadrant
using the VISTA telescope and the near-infrared camera VIRCAM. One of the
leading goals of the VVV survey is to contribute to the knowledge of the star
cluster population of the Milky Way. To improve the census of the Galactic star
clusters, we performed a systematic scan of the JHKs images of the Galactic
plane section of the VVV survey. Our detection procedure is based on a
combination of superficial density maps and visual inspection of promising
features in the NIR images. The material examined are color-composite images
corresponding to the DR1 of VVV. We report the discovery of 493 new star
cluster candidates. The analysis of the spatial distribution show that the
clusters are very concentrated in he Galactic plane, presenting some local
maxima around the position of large star-forming complexes, such as G305, RCW
95, and RCW 106. The vast majority of the cluster candidates are quite compact
and generally surrounded by bright and/or dark nebulosities. IRAS point sources
are associated with 59% of the sample, while 88% are associated with MSX point
sources. GLIMPSE 8 mum images of the cluster candidates show a variety of
morphologies, with 292 clusters dominated by knotty sources, while 361 clusters
show some kind of nebulosity. Spatial cross-correlation with young stellar
objects, masers, and extended green-object catalogs suggest that a large sample
of the new cluster candidates are extremely young. In particular, 104 star
clusters associated to methanol masers are excellent candidates for ongoing
massive star formation. Also, there is a special set of sixteen cluster
candidates that present clear signspot of star-forming activity having
associated simultaneosly dark nebulae, young stellar objects, EGOs, and masers.
