Astron. Astrophys. 338, 977-987 (1998)

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

L. Cambrésy ¹, E. Copet ¹, N. Epchtein ², B. de Batz ¹, J. Borsenberger ³, P. Fouqué ^{1, 5}, S. Kimeswenger ⁴ and D. Tiphène <sup>1

1</sup> Observatoire de Paris, F-92195 Meudon Cedex, France
² Observatoire de la Côte d'Azur, BP 4229, F-06304 Nice Cedex, France
³ Institut d'Astrophysique de Paris, 98 bis Bd. Arago F-75014 Paris, France
⁴ Institut für Astronomie der Leopold-Franzens-Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
⁵ European Southern Observatory, La Silla, Chile

Received 19 January 1998 / Accepted 22 June 1998

Abstract

We present an analysis of point sources discovered by DENIS in an area of   around the Chamaeleon I molecular cloud. Most of the objects detected in the J band are background stars that were previously used to derive an accurate extinction map of the full area (Cambrésy et al., 1997) using star counts. Here, we investigate the young stellar population of the cloud using the 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 reddening of the cloud. Moreover they are concentrated near the most obscured areas of the cloud. Pending spectroscopic measurements, 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 to 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.

Key words: stars: formation stars: pre-main sequence ISM: clouds ISM: individual objects: Chamaeleon I

* Based on observations collected at the European Southern Observatory, La Silla, Chile

Send offprint requests to: Laurent Cambrésy, (Laurent.Cambresy@obspm.fr)

SIMBAD Objects

Contents

• 1. Introduction
• 2. Observations and results
• 3. Selection method
  • 3.1. Description
  • 3.2. Validity
• 4. Discussion
  • 4.1. Nature of the sources
  • 4.2. Evolutionary status of the new candidates
  • 4.3. The luminosity function
• 5. Conclusion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: September 17, 1998
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