1997A&A...326..373O

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 J=2->1, ¹³CO J=2->1, and C¹⁸O J=1->0 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 J=2->1 transition. Our observations confirm the presence of a high-density clump at the position of the IRAS source with V_LSR≃3km/s, and reveal a C¹⁸O velocity shift aligned along an axis SW-NE, of about 2km/s/pc, which is likely to be an outflow. Based upon this assumption, the ¹³CO spectra of Olmi et al. (1994A&A...288..591O) 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.