3D chemical simulations of the first stages of protoplanetary disk formation

By Ugo Hincelin (Laboratoire d'Astrophysique de Bordeaux)

Room L269 (former D18, 2nd floor) at ENS, 24 rue Lhomond, 13:30 to 14:30

Low mass stars, like our Sun, are born from the collapse of a molecular cloud, which is composed of interstellar matter. This matter (gas and grain) falls in the center of the cloud, creating a protostar and a protoplanetary disk. Planets and other solar system bodies will be formed in the disk, so the chemical composition and its evolution during the formation of the disk are important to better understand the formation process of these objects.

I use the Nautilus gas-grain chemical model, with a physical structure evolving with time computed from the 3D radiative magneto-hydrodynamics model Ramses (in collaboration with Benoit Commerçon) to simulate the collapse of the prestellar core.

I will present Nautilus, our modelling steps (from the molecular cloud to the first core of Larson), and our preliminary results.

A methodology is proposed to develop data models. The idea is to transform objects described using our human language into mathematical objects which can be used directly in information systems. It is based on defining topological spaces and algebra to model data types. This will be illustrated using the example of the physical quantities, a well known object, and a database object, the measurement sets, which binds the measurements to their experimental contexts. The result is high expressiveness by formulating equations and database operations by means of lambda-calculi.
I use the theory of categories, a branch in maths, and parametric polymorphism, to formalize and implement this. The theory of the measurement set encapsulates the relational model. Using topoi, it is a generalization, a category above the sets.