Fragmentation and Evolution of Molecular Clouds. I. Algorithm and First Results

We present a series of simulations of the fragmentation of a molecular cloud,leading to the formation of a cluster of protostellar cores. The purpose ofthese simulations is to address a specific numerical problem called artificialfragmentation, that plagues SPH simulations of cloud fragmentation. We arguethat this is a serious problem that needs to be addressed, and that the onlyreasonable and practical way to address it is to use a relatively new techniquecalled particle splitting. Our largest simulation has an effective resolutionof 256^3 particles (much higher than most previous SPH simulations of cloudfragmentation) and results in the formation of a dense cluster containing ~3000protostellar cores. It is the first simulation of this kind to properly resolvethe Jeans mass throughout the entire system, at all times, thus preventingartificial fragmentation.Comment: 47 pages, 15 figures (2 grayscale, one color), ApJ Suppl, in pres