Rotation of Two Micron All Sky Survey Clumps in Molecular Clouds

Abstract

Abstract We have analyzed the rotational properties of 12 clumps using 13CO (1–0) and C18O (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 0.0022–0.025 pc km s−1 based on 13CO images, and between 0.0025–0.021 pc km s−1 based on C18O images. The consistency of J/M based on different tracers indicates the 13CO and C18O 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, . The ratio between rotation energy and gravitational energy, β, ranges from 0.0012 to 0.018. The small values of β imply that rotation alone is not sufficient to support the clump against gravitational collapse.