Fragmentation in Rotating Isothermal Protostellar Clouds

Extract

In this paper we report briefly the results of an extensive set of 3-D hydrodynamic calculations that have been performed during the past two and one-half years to investigate the susceptibility of rotating clouds to gravitational fragmentation. Because of the immensity of parameter space and the expense of computations, we have chosen to restrict this investigation to strictly isothermal collapse sequences. Isothermality is, fortunately, a fairly accurate description of the optically thin phases of collapse of protostellar clouds: a one solar mass, Jeans unstable interstellar cloud, having a temperature of 10 K and density ~ 10⁶ particles/cm³, for example, will collapse isothermally through about 6 orders of magnitude in density before heating up significantly (Gerola and Glassgold, 1978). The assumption also applies to protogalactic clouds (Silk, 1977). The results, therefore, should add specifically to our understanding of the dynamics of the earliest phases in a protostellar (or protogalactic) cloud’s evolution. A much more complete discussion of these calculations can be found in Bodenheimer, Tohline and Black (1980), hereafter referred to as BTB.