C18O (3-2) observations of the Cometary Globule CG 12: a cold core and a C18O hot spot

Abstract

The feasibility of observing the C18O (3-2) spectral line in cold clouds with the APEX telescope has been tested. As the line at 329.330 GHz lies in the wing of a strong atmospheric H2O absorption it can be observed only at high altitude observatories. Using the three lowest rotational levels instead of only two helps to narrow down the physical properties of dark clouds and globules. The centres of two C18O maxima in the high latitude low mass star forming region CG 12 were mapped in C18O (3-2) and the data were analyzed together with spectral line data from the SEST. The T_MB(3-2)/T_MB(2-1) ratio in the northern C18O maximum, CG 12 N, is 0.8, and in the southern maximum, CG 12 S, ~2. CG 12 N is modelled as a 120'' diameter (0.4pc) cold core with a mass of 27 Msun. A small size maximum with a narrow, 0.8 kms-1, C18O (3-2) spectral line with a peak temperature of T_MB ~11 K was detected in CG 12 S. This maximum is modelled as a 60'' to 80'' diameter (~0.2pc) hot (80 K < Tex < 200 K) ~1.6 Msun clump. The source lies on the axis of a highly collimated bipolar molecular outflow near its driving source. This is the first detection of such a compact, warm object in a low mass star forming region.

arXiv commentAPEX A&A special issue, accepted

References in corpus (5)

• Physical structure and CO abundance of low-mass protostellar envelopes
• Does IRAS 16293-2422 have a hot core? Chemical inventory and abundance changes in its protostellar environment
• Chemistry and Dynamics in Pre-Protostellar Cores
• Molecular freeze-out as a tracer of the thermal and dynamical evolution of pre- and protostellar cores
• The initial conditions of isolated star formation: IV - C18O observations and modelling of the pre-stellar core L1689B

Cited by in corpus (5)

• Planck Early Results: The submillimetre properties of a sample of Galactic cold clumps
• Dense and warm molecular gas in the envelopes and outflows of southern low-mass protostars
• Near infrared imaging of the cometary globule CG12
• The structure of the cometary globule CG 12: a high latitude star forming region
• Star formation in Cometary globule 1: the second generation