ISOCAM OBSERVATIONS OF LOW-LUMINOSITY YOUNG STELLAR OBJECTS IN THE CHAMELEON DARK CLOUDS

We report the first results from an ISOCAM survey for low-luminosity, young stellar objects (YSOs) in nearby star formation regions. The pre sent Letter concerns three regions within the Chamaeleon dark clouds, with a total area coverage of similar to 0.8 square degrees, represent ing 35 % of the presently approved survey programme. The survey is con ducted in two broad-band filters, LW2 (6.75 mu m) and LW3 (15 mu m), w ith 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 embedded YS Os can be effectively separated from background stars through distinct ly different [15/6.75] colour indices. This allows us to identify 65 Y SO candidates, of which more than 40 % were not previously known. The observed LW3 luminosity function of the identified YSOs seems to be tr uncated by the sensitivity limit of the survey.