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Astron. Astrophys. 336, 329-338 (1998)

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The Cometary Globules CG 30/31/38 in the Gum nebula

A radio line spectroscopic investigation *

A.S. Nielsen 1, M. Olberg 2, J. Knude 1 and R.S. Booth 2

1 Niels Bohr Institute for Astronomy, Physics and Geophysics, Astronomical Observatory, DK-2100 Copenhagen, Denmark
2 Onsala Space Observatory, S-439 00 Onsala, Sweden

Received 17 July 1996 / Accepted 24 April 1998

Abstract

We present radio line observations from the SEST. On the basis of 13CO (J=1-0) measurements we estimate the H2 mass associated with the globules CG 30/31A-C/38 to be [FORMULA]43 [FORMULA]. The gas kinetic temperature of the globules is in the range 5 to 14 K. Line wings seen in the 12CO spectra as well as higher dipole moment molecules towards CG 30, indicate that a dense molecular outflow is present. Especially the red wing reveals itself very clearly and is collimated, whereas the blue wing is weak and the emission is smeared out. The mass of the outflow is [FORMULA]0.3 [FORMULA] and the dynamical time scale is 1.7[FORMULA]104 years. The mechanical luminosity is 0.11 [FORMULA] for an assumed inclination of 90o. The 13CO (J=1-0) data have revealed that CG 30 is a possible double globule, the small companion (here named CG 30B) having a mass of [FORMULA]25% of the larger globule, corresponding to [FORMULA]2 [FORMULA].

Key words: stars: low-mass, brown dwarfs – stars: formation – ISM: individual objects: CG30 – ISM: individual objects: CG31 – ISM individual objects: CG38 – ISM: kinematics and dynamics

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

Send offprint requests to: A.S. Nielsen, (alan@astro.ku.dk)

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© European Southern Observatory (ESO) 1998

Online publication: July 7, 1998
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