Evolutionary models for ultracool dwarfs : implications for the Trappist-1 star

Ultra-cool dwarfs are excellent targets when searching for eclipsing earth-like exoplanets. The signature of a transit carries the information about the system dynamics and the physical properties of the exoplanet with respect with its host-star. Therefore, it becomes relevant to address the star itself. From observations, we can estimate the stellar luminosity and from the transit the stellar density, but for single-stars we can't account for its mass and radius. At the university of Liège, we have adapted our stellar evolutionary model (CLES) to account for the ultra-cool dwarf regime down to effective temperatures of approximately 2000K, and have constructed a set of grids spanning across different metallicities to study the physical properties and evolution for these objects. We tested our models for various ultra-cool dwarf objects and study the implications for characterizing the TRAPPIST-1 star.