http://arxiv.org/abs/2006.04309
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.
X. Xu, D. Li, Y. Dai, et. al.
Tue, 9 Jun 20
70/94
Comments: Accepted by Astrophysical Journal
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