A SCUBA survey of the NGC 2068/2071 protoclusters

We report the results of a submillimeter dust continuum survey of the proto clusters NGC 2068 and NGC 2071 in Orion B carried out at 850 mum and 450 mu m with SCUBA on JCMT. The mapped region is similar to 32' x 18' in size (si milar to4 pc x 2 pc) and consists of filamentary dense cores which break up into small-scale (similar to5 000 AU) fragments, including 70 starless con densations and 5 circumstellar envelopes/disks. The starless condensations, seen on the same spatial scales as protostellar envelopes, are likely to b e gravitationally bound and pre-stellar in nature. Their mass spectrum, ran ging from similar to0.3 M-circle dot to similar to5 M-circle dot, is remini scent of the stellar initial mass function (IMF). Their mass-size relation suggests that they originate from gravitationally-driven fragmentation. We thus argue that pre-collapse cloud fragmentation plays a major role in shap ing the IMF.