Astronomy and Astrophysics Letters dedicated to ISO

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

L. Nordh1 & G. Olofsson, A. Abergel Ph. André, J. Blommaert, S. Bontemps, F. Boulanger, M. Burgdorf, C.J. Césarsky, D. Césarsky, E. Copet, J. Davies, E. Falgarone, M. Huldtgren, A.A. Kaas, G. Lagache, T. Montmerle, M. Perault, P. Persi, T. Prusti, J.L. Puget, F. Sibille


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 microns) and LW3 (15 microns), 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 embedded 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.

Infrared: stars - Stars: formation - Stars: pre-main sequence - Stars: luminosity function, mass function

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