Unveiling Hidden Stellar Aggregates in the Milky Way: 1656 New Star Clusters Found in Gaia EDR3

Abstract

We report 1656 new star clusters found in the Galactic disk (∣b∣ < 20°) beyond 1.2 kpc, using Gaia EDR3 data. Based on an unsupervised machine-learning algorithm, DBSCAN, and following our previous studies, we utilized a unique method to do the data preparation and obtain the clustering coefficients, which proved to be an effective way to search blindly for star clusters. We tabulate the physical parameters and member stars of the new clusters, and present some interesting examples, including a globular cluster candidate. The cluster parameters and member stars are available in machine-readable format in the online journal. We examine the new discoveries and discuss their statistical properties. The proper-motion dispersions and radii of the star clusters are the same as those previously reported. The new clusters beyond 1.2 kpc are older than those in the solar neighborhood, and the new objects found in the third Galactic quadrant present the lowest line-of-sight extinctions. Combined with our previous results, the total population of new clusters and candidates detected through our method is 2541, corresponding to 55% of all newly published clusters in the Gaia era. The number of cataloged Gaia star clusters was also increased to nearly 6000. In the near future, it will be necessary to make a unified confirmation and member star determination for all reported clusters.