Rotation of Starless BOK Globules

Fifteen small Bok globules showing no signs of current star formation were mapped at high spatial and especially spectral resolution in the (J=1-> 0) rotational lines of \co, \13co, and \c18o, using the 14 meter radio telescope of the Five College Radio Astronomy Observatory. Maps were made with the fifteen-element 3\mm array receiver QUARRY and the 15x 1024 channel autocorrelator spectrometer FAAS. From 120 to 360 positions per globule, sampled with half-beam spacing, were observed in the \13co line, while 30 to 60 full-beam-sampled \c18o and \co positions per globule were observed. \13co and \c18o were observed with a velocity resolution of less than 0.007 \kms channel(-1) ; \co was observed with 0.013 \kms channel(-1) resolution. Gaussian fitting of the emission lines was used to establish mean radial velocities and uncertainties. Each globule radial velocity distribution on the sky was fit to a plane (solid body rotation) to yield mean velocity gradients with position, and rotation axis directions. The globules were found to be rotating at rates more than an order of magnitude faster than velocity shifts attributable to local differential Galactic rotation. For globule assumed mean distances of 600 pc, the gradients range from 0.089\kms\pc(-1) (omega about !=xpo{3}{-15} s(-1) ) to 0.950\kms\pc(-1) (omega about !=xpo{3}{-14} s(-1) ). Half show gradients less than about 0.3\kms\pc(-1) , and half show gradients greater than about 0.6\kms\pc(-1) , distributed in a distinctly bimodal fashion. Detailed examination of the globule rotation curves indicated that the kinematics of ten of fifteen globule cores are well-approximated by solid-body rotation. Differential rotation and shearing motions due to external influences (ram pressure stripping and/or bow shocks) are also seen.