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Observations of the 18.3-GHz Transition of C3H2 towards Sgr B2

Published online by Cambridge University Press:  25 April 2016

R.S. Peng
Affiliation:
School of Physics, University of NSW, PO Box 1 Kensington, NSW 2033
J.B. Whiteoak
Affiliation:
Australia Telescope National Facility, CSIRO
J.E. Reynolds
Affiliation:
Australia Telescope National Facility, CSIRO
T.B.H. Kuiper
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology
W.L. Peters
Affiliation:
Steward Observatory, University of Arizona

Abstract

We have mapped the molecular clouds of Sgr B2 in the 110 → 101 ortho-transition of C3H2 at 18.3 GHz, using the 70-m NASA telescope at Tidbinbilla (beamwidth 55 arcsec). Three clouds show absorption against the Sgr B2 continuum emission at radial velocities of 50, 65 and 80 km s−1. The 65-km s−1 cloud covers most of the observed area (4 × 6 arcmin in right ascension and declination), has a peak optical depth of 2.7 and a corresponding C3H2 column density of 7.6 × 1015 cm−2. The C3H2 fractional abundance relative to H2 is 1.5 × 10−9. The 80-km s−1 cloud, located north of the Sgr B2 continuum peak, has a peak optical depth of 0.9 and a C3H2 column density of 1.9 × 1015 cm−2. The 50-km s−1 cloud is centred 2 arcmin south of the continuum peak; here the minimum optical depth of 0.5 yields a column density of 5.3 × 1014cm−2.

Type
Galactic and Stellar
Copyright
Copyright © Astronomical Society of Australia 1992

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