Multiple HC3N line observations towards 19 Galactic massive star-forming regions

We performed observations of the HC3N (24-23, 17-16, 11-10, 8-7) lines towards a sample consisting of 19 Galactic massive star-forming regions with the Arizona Radio Observatory 12-m and Caltech Submillimeter Observatory 10.4-m telescopes. HC3N (24-23, 17-16, 1110, 8-7) lines were detected in sources except for W44, where only HC3N (17-16, 11-10) were detected. Twelve of the nineteen sources showed probable line wing features. The excitation temperatures were estimated from the line ratio of HC3N (24-23) to HC3N (17-16) for 18 sources and are in the range 23-57 K. The line widths of higher-J transitions are larger than lower-J ones for most sources. This indicates that the inner dense warm regions have more violent turbulence or other motions (such as rotation) than outer regions in these sources. A possible cutoff tendency was found around LIR ∼ 10 L in the relation between LIR and full width at half maximum line widths. 1 ar X iv :2 10 3. 02 53 1v 2 [ as tr oph .G A ] 8 M ar 2 02 1