Molecular cloud collapse to stellar densities: models on moving geodesic vs. unstructured tetrahedron vs. nested meshes

Abstract

The results of a study of a collapsing cold molecular cloud with three computational models based on different mesh methods are presented. Collapse of a gas with a molecular cloud core density (≈ 10–18 g cm–3) to stellar densities (≈ 10–2 g cm–3) is considered. To simulate the collapse, the equation of state for an ideal gas and three mesh computational models are used. These are: a model based on multilevel nested meshes, a model based on moving geodesic meshes, and a model based on nonuniform tetrahedral meshes. The restrictions on the resolution in solving the Poisson equation and on the reproduction of the gravitational potential gradient on geodesic and tetrahedral meshes do not allow reproducing well the onset of collapse (in the case of moving geodesic meshes) or the maximum density (in the case of tetrahedral meshes). The results of computational experiments show that the process of collapse is reproduced well on multilevel nested meshes with sufficient spatial resolution.