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

Abstract

An infrared study including ISOCAM images at 6.75 and 14.3 $\,\mu \rm m$ of a large portion (28´ $\times$ 26´) of the Chamaeleon II dark cloud and sub-arcsec resolution JHK s images of the central (4.9´ $\times$ 4.9´) 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 $L_\odot$ and a stellar luminosity ≥ 0.01 $L_\odot$. 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 $L_{{\rm bol}}=$ 1.49 $L_\odot$, and associated with a faint nebulosity observed at 2.2 $\,\mu \rm m$.