New Galactic Star Clusters Discovered in the VVV Survey

TL;DR

This paper reports the discovery of 96 new infrared star clusters in the Milky Way using the VVV survey, employing image analysis, photometry, and isochrone fitting to characterize their properties.

Contribution

The study introduces a systematic method for identifying and analyzing new star clusters in the VVV survey data, expanding the catalog of known young clusters in the Milky Way.

Findings

Discovered 96 new infrared star clusters and stellar groups.

Most clusters are faint, compact, highly reddened, and younger than 5 million years.

Derived fundamental parameters like reddening, distance, and age for well-populated clusters.

Abstract

VISTA Variables in the V\'{\i}a L\'actea (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 $15\times15$ 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.