35) Chemical evolution models for the thick and thin disks

Abstract: I will discuss the chemical evolution of the thick and thin disks of the Milky Way by comparing detailed chemical evolution models with recent data from the AMBRE project. The data suggest that the stars in the thick and thin disks form two distinct sequences, with the thick disk stars showing higher [α/Fe] ratios. We adopt two different approaches to model the evolution of the thick and thin disks. In particular, we adopt: i) a two-infall approach where the thick disk forms fast and before the thin disk and by means of a fast gas accretion episode, whereas the thin disk forms by means of a second accretion episode on a longer time-scale; ii) a parallel approach, where the two disks form in parallel but at different rates. By comparing our model results with the observed abundance patterns and metallicity distribution functions in the two Galactic components, we conclude that the parallel approach can account for a group of α-enhanced metal-rich stars present in the data, whereas the two-infall approach cannot explain these stars unless they are the result of stellar migration. Understanding the chemical evolution of the Milky Way thick and thin disks can then help us in shedding light on the formation mechanisms of a chemical bimodality in other disk galaxies.

Bio: Dr. Valeria Grisoni is a postdoctoral researcher at SISSA (Trieste, Italy). In 2020, she obtained the PhD in Physics from the University of Trieste with a thesis entitled "Galactic Archaeology in the Era of Large Surveys". She works on the development of detailed chemical evolution models in order to interpret the most recent spectroscopic data from Galactic surveys and reconstruct the history of formation and chemical evolution of the Galaxy.