We have analyzed the rotational properties of 12 clumps using $^{13}$CO (1--0) and C$^{18}$O (1--0) maps of the Five College Radio Astronomy Observatory 13.7 m radio telescope. The clumps, located within molecular clouds, have radii ($R$) in the range of 0.06 -- 0.27\,pc. The direction of clump elongation is not correlated with the direction of the velocity gradient. We measured the specific angular momentum (J/M) to be between 0.0022 and 0.025 pc\,km\,s$^{-1}$ based on $^{13}$CO images, and between 0.0025 and 0.021 pc\,km\,s$^{-1}$ based on C$^{18}$O images. The consistency of $J/M$ based on different tracers indicates the $^{13}$CO and C$^{18}$O in dense clumps trace essentially the same material despite significantly different opacities. We also found that $J/M$ increases monotonically as a function of $R$ in power--law form, $J/M~\propto~R^{1.58~\pm~0.11}$. The ratio between rotation energy and gravitational energy, $\beta$, ranges from 0.0012 to 0.018. The small values of $\beta$ imply that rotation alone is not sufficient to support the clump against gravitational collapse.

中文翻译：

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分子云中两微米全巡天团的旋转

我们使用五所大学射电天文台 13.7 m 射电望远镜的 $^{13}$CO (1--0) 和 C$^{18}$O (1--0) 地图分析了 12 个团块的旋转特性. 位于分子云内的团块的半径 ($R$) 在 0.06 -- 0.27\,pc 范围内。团块伸长的方向与速度梯度的方向无关。我们根据 $^{13}$CO 图像测得的特定角动量 (J/M) 介于 0.0022 和 0.025 pc\,km\,s$^{-1}$ 之间，并且介于 0.0025 和 0.021 pc\之间， km\,​​s$^{-1}$ 基于 C$^{18}$O 图像。基于不同示踪剂的 $J/M$ 的一致性表明，尽管不透明度显着不同，但致密团块中的 $^{13}$CO 和 C$^{18}$O 跟踪的材料基本相同。我们还发现 $J/M$ 以幂律形式作为 $R$ 的函数单调增加，$J/M~\propto~R^{1。58~\pm~0.11}$。旋转能和重力能的比值 $\beta$ 的范围从 0.0012 到 0.018。$\beta$ 的小值意味着仅旋转不足以支持团块对抗重力坍塌。