The Cosmostatistics Initiative (COIN), an international collaboration that consists of experts in astrophysics, statistics and machine learning, has discovered 41 new groups of stars known as “open clusters” in a nearby region of the Galaxy in the direction of the Perseus spiral arm.
Open clusters are groups of stars composed of dozens up to several thousand members born in the same region. The cluster members share common properties, like age, distance from the Sun, and velocity, and are distributed all over the Galactic disk. Since the early 1800s, astronomers have shown great interest in these systems as they reveal important information about the way stars form and evolve and even about the structure of the Milky Way itself.
During the COIN Residence Program #5 - held in September of 2018 in Chania in the island of Crete, Greece - new insights arose concerning the population of nearby open clusters.
The results are based on Gaia satellite data, which provided velocities and distances for billions of stars in our Galaxy. The unprecedented accuracy of Gaia measurements gives the opportunity of previously infeasible discoveries. The COIN collaboration has developed a fully automated algorithm which combines machine learning and statistical techniques in order to spot potential clusters by studying stellar positions and velocities. The output of the algorithm was then visually inspected by the team’s experts in order to make the final validation. An increment of ~20% of the previously known cluster population is reported.
All these newly discovered star clusters are found within ~6000 light years from the Sun, a relatively short distance. Although, we thought that we knew our neighborhood well enough, this result comes to challenge the status quo and leaves ample room for additional discoveries.
Text by R. Skalidis, K. Tassis and the CRP #5 team