Multiple populations in young clusters detected by Gaia.

The second release of Gaia is revolutionizing the study of star formation and young clusters. In this talk I discussed the potential in detecting multiple populations in young clusters, and the importance of a membership well defined as a starting point. I presented, as an example, the results on the multiple population of one of the closest low-mass star forming region, the Chamaeloen I. Using the Gaia data we found the region to be at slightly higher distance than previously thought. We confirmed the presence of two populations with a peculiar spatial distribution, which might be influenced by the filamentary molecular cloud present in the region. Presenting the method applied to find kinematically the multiple populations, I discussed the effect on the results of taking into account the correlations between parallaxes and proper motions. I finally presented the impact of the refined distance of young stars and clusters using the Gaia data on other fields of star formation, e.g. the study of the evolution of protoplanetary disks and the disk structure.