Astronomy and Astrophysics, volume 341, 882-895 (1999/1-3)
Vibrationally excited HC3N toward hot cores.
WYROWSKI F., SCHILKE P. and WALMSLEY C.M.
Abstract (from CDS):
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 v7=1 state of cyanoacetylene toward all six regions and the v6=1 line toward five of them. Toward G10.47+0.03, we detected lines from 11 different vibrationally excited states with excitation energies up to 1600K above ground. Of these, six are first detections. We also have detected several transitions of 13C substituted cyanoacetylene in the v6=1, v7=1, and v7=2 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 270K. 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 1". In an appendix, we report the first astronomical detection of lines from vibrationally excited HNCO in G10.47+0.03.
ISM: clouds - ISM: HII regions - ISM: molecules - radio lines: ISM