Near-infrared and ISOCAM observations of the Chamaeleon II dark cloud

Abstract

An infrared study including ISOCAM images at 6.75 and 14.3 mu m of a large portion (28 arcmin x 26 arcmin) of the Chamaeleon II dark cloud and sub-arcsec resolution JHK_s images of the central (4.9 arcmin x 4.9 arcmin) area is presented. Combining the ISOCAM observations with J and K_s photometry obtained with DENIS, we have found 12 young stars, of which 8 are previously identified sources. Of the new candidate YSOs, ISO-ChaII13 shows a clear mid-IR excess with an infrared luminosity of ~ 0.02 L_sun and a stellar luminosity >=0.01 L_sun. This last value of luminosity corresponds to that expected for a sub-stellar object with an age between 1-10 Myr. The analysis of the J-H/H-K diagram of the sources detected in the central part of the dark cloud has allowed us to identify 10 very faint sources not found by ISOCAM with possible near-IR excesses that may be embedded young brown dwarfs. Finally, the center of the dark cloud is characterized by the presence of the Class I YSO IRAS 12553-7651 (ISO-ChaII28) with L_bol= 1.49 L_sun, and associated with a faint nebulosity observed at 2.2 mu m.

Based on observations collected at the European Southern Observatory, Chile, ESO proposal N.65.I-0054, CTIO(Chile), and ISOCAM observations N.11500619, and 11500620.

Tables 1 and 2 are only available in electronic at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or via http:cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/399/995