ISOCAM observations of low-luminosity young stellar objects in the Chamaeleon dark clouds

We report the first results from an ISOCAM survey for low-luminosity, young stellar objects (YSOs) in nearby star formation regions. The present Letter concerns three regions within the Chamaeleon dark clouds, with a total area coverage of 0.8 square degrees, representing 35 % of the presently approved survey programme. The survey is conducted in two broad-band filters, LW2 (6.75 m) and LW3 (15 m), with a somewhat variable sensitivity limit in order to avoid saturation. For the nominal setup with 2.1 seconds integration time and 6 arcsec per pixel the detection limit is 1.9 mJy and 2.5 mJy in LW2 and LW3, respectively. The Chamaeleon observations demonstrate that embed- ded YSOs can be effectively separated from background stars through distinctly different (15/6.75) colour indices. This allows us to identify 65 YSO candidates, of which more than 40% were not previously known. The observed LW3 luminosity function of the identified YSOs seems to be truncated by the sensitivity limit of the survey.