Modelling accretion in protobinary systems

Abstract

A method for following fragmentation simulations further in time using\nsmoothed particle hydrodynamics (SPH) is presented. In a normal SPH simulation\nof the collapse and fragmentation of a molecular cloud, high-density regions of\ngas that form protostars are represented by many particles with small\nseparations. These high-density regions require small time steps, limiting the\ntime for which the simulation can be followed. Thus, the end result of the\nfragmentation can never be definitively ascertained, and comparisons between\ncloud fragmentation calculations and the observed characteristics of stellar\nsystems cannot be made. In this paper, each high-density region is replaced by\na single, non-gaseous particle, with appropriate boundary conditions, which\ncontains all the mass in the region and accretes any infalling mass. This\nenables the evolution of the cloud and the resulting protostars to be followed\nfor many orbits or until most of the original cloud mass has been accreted.\n