A study of the Chamaeleon dark cloud complex: survey, structure and embedded sources

A 2 μm-survey of a significant fraction of the Chamaeleon dark cloud complex is presented. IR (JHK) photometry and CVF spectrophotometry of the sources found provide the following significant results. Discrimination between background field stars and cloud members shows an increase in the number of pre-main-sequence (PMS) members (over that found optically) by more than 50 per cent, corresponding to a star formation efficiency of the order of 12 per cent over the whole cloud. The number density of PMS objects within the Cloud ( > 8 pc-3) is close to that required by a theoretical model to account for molecular velocity fields within dark clouds. The density structure of the Cloud, derived from the reddening of background field stars shows that small-scale clustering of two groups of PMS members seems to occur preferentially near steep density gradients in the cloud. Dust shell models have been computed for comparison with the derived intrinsic infrared colours of the PMS objects. (author)