New Young Stellar Object candidates in the Chamaeleon I molecular cloud discovered by DENIS

We present an analysis of point sources discovered by DENIS in an area of 1: 5 3: around the Chamaeleon I molecular cloud. Most of the 30000 objects detected in the J band are background stars that were previously used to derive an accurate extinction map of the full area (Cambr´ esy et al., 1997) using star counts. Here, we investigate the young stellar popula- tion of the cloud using the IJKs photometric DENIS data. The whole sample of 126 already known YSOs, which are mainly T Tauri stars, are identified in the DENIS catalogue. Besides, we propose 54 sources as new candidates of YSOs. These new faint objects are selected according to their extremely red near infrared colour, that cannot be explained only by the redden- ing of the cloud. Moreover they are concentrated near the most obscured areas of the cloud. Pending spectroscopic measure- ments, the sources are interpreted as probable classical T Tauri stars that have escaped previous spectroscopic, IRAS or X-ray observations and pertaining to the low-end of the luminosity function. Assuming that they are reliable YSOs with massive accretion disks, and using theoretical pre-main-sequence tracks we estimate the age of this sample to be ranging from 510 5 to 410 6 years, an elapse of time that spans the range between the end of the star formation in the cloud and the maximum life time of the circumstellar disk.