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Astron. Astrophys. 341, 882-895 (1999)

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Vibrationally excited HC3N toward hot cores

F. Wyrowski 1,2, P. Schilke 2 and C.M. Walmsley 3

1 I. Physikalisches Institut der Universität zu Köln, Zülpicherstrasse 77, D-50937 Köln, Germany
2 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
3 Osservatorio Astrofisico di Arcetri, Largo E.Fermi 5, I-50125 Firenze, Italy

Received 15 July 1998 / Accepted 22 October 1998


We report IRAM 30-m observations of vibrationally excited rotational transitions of HC3N toward a sample of six ultra-compact HII regions. In addition, Effelsberg 100-m and Plateau de Bure Interferometer measurements were conducted toward the region G10.47+0.03. We detected the [FORMULA] state of cyanoacetylene toward all six regions and the [FORMULA] line toward five of them. Toward G10.47+0.03, we detected lines from 11 different vibrationally excited states with excitation energies up to 1600 K above ground. Of these, six are first detections. We also have detected several transitions of 13C substituted cyanoacetylene in the [FORMULA], [FORMULA], and [FORMULA] states and provide improved rest frequencies for several of these. The population distribution of the vibrationally excited HC3N molecules is analyzed and it is concluded that our results are consistent with thermalised level populations at a temperature of 270 K. From the interferometer results we find the source of HC3N emission to be coincident with NH3(4,4) and CH3CN emission within the positional error of [FORMULA].

In an appendix, we report the first astronomical detection of lines from vibrationally excited HNCO in G10.47+0.03.

Key words: ISM: clouds – ISM: H ii regions – ISM: molecules – radio lines: ISM

Present address: University of Maryland, Department of Astronomy, College Park, MD 20742, USA

Send offprint requests to: F. Wyrowski, Maryland address

Correspondence to: wyrowski@astro.umd.edu

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© European Southern Observatory (ESO) 1999

Online publication: December 16, 1998