GEPI

Sujet : By early 2017, the Gaia mission will provide astrometric solutions (parallaxes, proper motions) for most of the sky, as well as radial velocities for the brightest stars (G < 16) and related astrophysical parameters. This data, complemented by follow-up spectroscopic surveys (RAVE, GES, APOGEE, GALAH), will allow to derive the essential of stellar motions, chemo-dynamical relations, and ages for hundred thousands of stars.
Thus, without waiting for the publication of the final Gaia catalogue ( 2022), the next years will already provide an unique ensemble of observational data to interpret. The interested student will start to learn how to make use of the tremendous amount of data Gaia will deliver to reconstruct and interpret stellar motions.

Last year, we have proposed a M1 internship aiming at developing a new model of the Galactic mass distribution which implements a massive thick disk — something completely disregarded in models so far — with properties in agreement with the most recent observational determinations (Pouliatsis et al, in preparation). This year, we aim at extending this model, by including also stellar asymmetries, such a bar, to the gravitational potential.

The aim of this work is to reconstruct orbits of known stars in the Galaxy, to quantify to what extent the presence of a massive thick disk component and a stellar bar can affect them, and ultimately to reconstruct the links between Galactic stellar populations, making use of the kinematic information derived from the orbit integrations, and link them to known chemical properties.