Open clusters and associations in the Gaia era

TL;DR

This paper reviews the role of open clusters and associations in understanding star formation, stellar evolution, and galactic structure, emphasizing Gaia's transformative impact on this research area.

Contribution

It summarizes current knowledge and methods for studying young stellar groups, highlighting Gaia's potential to advance understanding of galactic properties.

Findings

Gaia will significantly improve measurements of cluster properties.

Open clusters serve as key probes for galactic structure and evolution.

Methods for deriving stellar population statistics are evolving with new data.

Abstract

Open clusters and associations are groups of young stars, respectively bound and unbound, that share the same origin and disperse over time into the galactic field. As such, their formation and evolution are the key to understand the origin and properties of galactic stellar populations. Moreover, since their members have about the same age, they are ideal laboratories to study the properties of young stars and constrain stellar evolution theories. In this contribution, I present our current knowledge on open clusters and associations. I focus on the methods used to derive the statistical properties (IMF, spatial distribution, IMF) of young stars and briefly discuss how they depend on the environment. I then describe how open clusters can be used as probes to investigate the structure, dynamics and chemical composition of the Milky Way. I conclude by presenting the Gaia mission and discuss how it will revolutionize this field of research.