Large and small scale structures of molecular clouds in the taurus perseus complex

Abstract

The gaseous components studied in HI and OH absorption against the extragalactic radiosources 3C123 and 3C111 are found to be the low-density edges of condensations of a few 100 MThe densest part of one of these condensations has a structure similar to that found in other dark clouds −1 it is fragmented into several cores of a few Mo, with an orbital velocity dispersion ≈ 2 kms . In turn, the extended low-density layer, optically thick in CO (2-1), is not a common feature. It depends on the ambient UV field but the dust temperature in the core may control its existence, even more critically: the lower is the dust temperature, the less massive is the core and the more extended is the envelope around it, for a given total mass in a given external pressure.