Research objectives and content
Star open clusters and associations are clues of our understanding of many aspects of stellar evolution, of the structure, kinematics, dynamics and evolution of the Galaxy, but they are also some of the basic objects for establishing the first steps of the cosmic distance scale.
The first part of our research project will use Hipparcos and Tycho data of stars in the closest open clusters, to renew the study of clusters structure, luminosity and mass functions, mass segregation and energy equipartition, internal dynamics (expansion or contraction, possible rotation), age determination, relation between chemical composition and position in the HR diagram, position in the Galaxy. The second part will aim at improving our knowledge on the kinematics of OB-associations, and their dynamical internal evolution.
The whole set of new parameters determined for the clusters and associations will be interpreted in terms of star formation, galactic structure and of stellar and galactic evolution. In particular, new constraints will be obtained on galactic dynamics, spiral structure and rotation parameters. Knowing the age and motion of a cluster or of an association, and using an analytical form of the galactic potential, it will be possible to fix the place in the Galaxy where these objects formed and to retrace the history of the star formation in the disk, to impose strong constraints to galactic models.
Training content (objective, benefit and expected impact)
A stay in Leiden Observatory would introduce me to the physics of star associations, to their state of evolution and behaviour in the general potential of our Galaxy. I would also get a complete training to the understanding and use of analytical models of the Galaxy as are being developed in Leiden, and to the interpretation of all the above results (on clusters and associations) in terms of star formation and galactic dynamical and chemical evolution.