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Astron. Astrophys. 326, 373-385

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IRAS 12553-7651 in Chamaeleon II: a low mass PMS star
with a C18O outflow?*

L. Olmi1, M. Felli2, and R. Cesaroni2

1Cornell University, Arecibo Observatory, P.O. Box 995, Arecibo, 00613, Puerto Rico**
2Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy

Received 14 August 1996 / Accepted 2 April 1997


We present new multi-line, multi-isotope observations of the PMS candidate IRAS 12553-7651 in the nearby Chamaeleon II dark cloud. Previous far infrared and molecular observations towards three selected objects in Cha II determined that IRAS 12553-7651 was the most likely candidate to be a young (proto)stellar object. We thus mapped the IRAS 12553-7651 region in the 12CO FORMULA , 13CO FORMULA , and C18O FORMULA rotational transitions to use probes more sensitive to higher density gas and not affected by optical depth effects. We also observed and detected the C34S FORMULA transition. Our observations confirm the presence of a high-density clump at the position of the IRAS source with FORMULA km s-1, and reveal a C18O velocity shift aligned along an axis SW-NE, of about 2 km s-1 pc-1, which is likely to be an outflow. Based upon this assumption, the 13CO spectra of Olmi et al. (1994) have been re-analyzed and found to show a deviation from a Gaussian shape. This asymmetry can be interpreted in terms of a line component which migrates in velocity with respect to the ambient cloud. We show that a model in which the bipolar outflow interacts with the ambient gas around IRAS 12553-7651 may reproduce qualitatively the observational data.

Key words: interstellar medium: clouds: Chamaeleon II - interstellar medium: molecules - radio lines: interstellar

*Based on data collected at SEST, ESO
**Present address: LMT Project and FCRAO, 815 Lederle G.R.C., University of Massachusetts, Amherst, MA 01003, USA (olmi@fcrao1.phast.umass.edu)

Send offprint requests to: L. Olmi

© European Southern Observatory (ESO) 1997

Online publication: September 9, 1997
Last change: April 20, 1998