An ISOPHOT Survey of Pre-stellar Cores

Abstract

We present the results of an ISOPHOT study of isolated pre-stellar cores (originally known as pre-protostellar cores). The pre-stellar phase is one in which a dense core in a molecular cloud is gravitationally bound, but contains no embedded luminosity source. This takes place prior to the protostellar Class 0 phase. Hence pre-stellar cores are believed to represent the initial conditions of isolated star formation. They were not detected by IRAS, but have been detected by ISOPHOT at 200 and 170μm, but typically not at 90μm. The lack of detections at 90μm shows that there is no significant quantity of warm dust in these cores. Colour temperature maps can be made by ratio-ing the 170 and 200μm data. An example of this is shown, and an inside-out temperature gradient is observed, confirming the lack of a central protostellar heating source. Subsequently, a modified black-body is fitted to both the ISOPHOT and millimetre/submillimetre data, which allows submillimetre measurements to be converted into more accurate mass estimates.