The results of a survey of 63 galactic star-forming regions in the 6_K-5_K and 5_K-4_K methyl acetylene lines at 102 and 85 GHz, respectively, are presented. Fourty-three sources were detected at 102 GHz, and twenty-five at 85 GHz. Emission was detected towards molecular clouds with kinetic temperatures 20-60 K (so-called ``warm clouds''). The CH3CCH abundances in these clouds appeared to be about several units X 10^(-9). Five mapped sources were analyzed using the maximum entropy method. The sizes of the mapped clouds fall within the range between 0.1 and 1.7 pc, virial masses - between 90-6200 Msun, and densities - between 6 X 10^4 and 6 X 10^5 cm^(-3). The CH3CCH sources spatially coincide with the CO and CS sources. Chemical evolution simulations showed that the typical methyl acetylene abundance in the observed clouds corresponds to an age of ~ 6 X 10^4 years.
@article{arxiv.astro-ph/0205349,
title = {Parameters of Warm Molecular Clouds from Methyl Acetylene Observations},
author = {A. V. Alakoz and S. V. Kalenskii and V. G. Promislov and L. E. B. Johansson and A. Winnberg},
journal= {arXiv preprint arXiv:astro-ph/0205349},
year = {2009}
}
Comments
14 pages, 8 figures, 5 tables. Accepted for publication in Astronomy Reports