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, 11–10, 8–7) lines were detected in sources except for W 44, 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 ∼ 106 L⊙ in the relation between LIR and full width at half maximum line widths.

中文翻译：

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对 19 个银河系大质量恒星形成区的多次 HC3N 线观测

我们使用亚利桑那射电天文台 12 m 和加州理工学院亚毫米天文台 10.4 m 望远镜对由 19 个银河大质量恒星形成区域组成的样本进行了 HC3N（24-23、17-16、11-10、8-7）线的观测. HC3N (24-23, 17-16, 11-10, 8-7) 系在除 W 44 之外的源中检测到，其中仅检测到 HC3N (17-16, 11-10)。十九个来源中的十二个显示了可能的线翼特征。激发温度是根据 18 个源的 HC3N (24-23) 与 HC3N (17-16) 的线比估计的，范围为 23-57 K。高 J 跃迁的线宽大于低 J 跃迁的线宽大多数来源的。这表明内部密集的温暖区域比这些源中的外部区域具有更剧烈的湍流或其他运动（例如旋转）。