18 février 2020A New Milky Way Disc Model

Andreas JUST
ARI Heidelberg, Allemagne

Many fundamental questions about the structure and evolution of the Milky Way disc are still under debate: What are the radial scale lengths of thin and thick disc? Why is there a thin-thick disc dichotomy? What is the star formation history in the solar neighbourhood? Has the thin disc grown inside-out? What is the origin of the dynamical heating of the stellar sub-populations? Is radial mixing important to understand the dynamical and abundance properties of the disc stars? All these aspects are strongly correlated in any consistent physical model of the Milky Way. I will present the status of our new self-consistent analytic disc model. It is based on laws for the star formation history, the dynamical evolution and chemical enrichment. The new model reproduces SDSS star counts towards the North Galactic Pole five times better than the TRILEGAL or the Besancon model. We work presently on an extension to a 6-D model in dynamics and radial extension including a more detailed chemical enrichment. Large spectral surveys like SEGUE and RAVE provide radial velocities and stellar parameters of large homogeneous samples including element abundance ratios. These data combined with proper motions and distances provide powerful tests of Milky Way models.