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Astron. Astrophys. 326, 373-385 (1997)

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IRAS 12553-7651 in Chamaeleon II: a low mass PMS star with a C [FORMULA] O outflow?

L. Olmi 1, M. Felli 2 and R. Cesaroni 2

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

Received 14 August 1996 / Accepted 2 April 1997

Abstract

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 12 CO [FORMULA], 13 CO [FORMULA], and C18 O [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 C34 S [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 C18 O 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 13 CO 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

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© European Southern Observatory (ESO) 1997

Online publication: April 20, 1998
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