It is today well known that most stars form in clusters with N>100 members. The cluster environment at stellar birth may significantly impact the properties of young stars through, e.g., gravitational encounters, ionizing radiation field, etc. This is particularly true in dense and rich young clusters. A fundamental issue then is to disentangle properties that are the direct imprint of the star formation process from those that have been subsequently affected by the cluster’s environment.
What are the initial conditions of cluster formation ? Is mass segregation the consequence early dynamical evolution in the embedded cluster or is it an intrinsic property of the formation process ? What is the origin of the mass distribution of stars, brown dwarfs, and planetary mass objects in stellar clusters ? How does the environment impact the properties of young stars and brown dwarfs ?
To address these issues, we aim at :
This work prepares the exploitation of Gaia data that will revolutionize our understanding of stellar clusters. We are involved in ground-based surveys to complement Gaia results, such as the Gaia-ESO-Survey to measure radial velocities and the DANCE project to derive proper motion of faint cluster members.
Another important part of our research on this theme is related to the angular momentum evolution of young stars. Clusters are most useful in this regard as they provide us with a temporal scale to trace the evolution of the rotational properties of stars as they age. To account for the observed evolution of rotational period distributions, we develop parametric models of the angular momentum evolution of low-mass stars as well as MHD simulations of the star-disk interaction. So far, our observational studies and modeling efforts have mostly concentrated on the pre-main sequence phase, and will be extended to the protostellar stage.
Staff members : Jérome Bouvier, Isabelle Joncour, Estelle Moraux Postdocs : Francisco Maia, Colin Folsom