THE NEARBY 2M-CIRCLE-DOT BOK GLOBULE LBN-11 - SUB-SONIC MOLECULAR CLUMPS IN A MAGNETIC ENVIRONMENT

We have mapped the nearby small Bok globule LBN 11 (size approximately 0.3 pc, distance approximately 110 pc) in the millimeter lines of CO at very high dispersion (65 m s-1 per channel), obtained co-added IRAS survey images of the cloud, and measured the optical linear polarization of sixteen stars close to the cloud center. The molecular lines and IRAS images reveal a low mass cloud (approximately 2 M .) with a moderately dense core (nBAR less-than-or-equal-to 10(4.5) cm-3) which has not formed stars. The high spectral resolution CO lines reveal the presence of several individual kinematic and spatial components ("clumps") within the cloud, which exhibit subsonic linewidths. Such distinct clumping in so small a cloud has not previously been seen. CS and SO maps of the (CO)-C-13 core region made at 25" resolution confirm the presence of the dense gas expected from the radial density distribution inferred from the (CO)-C-13 observations. Overall, the cloud is in a state of rotation, with a rotation rate of 3.6+/-1.0 km s-1 pc-1, for the region strongest in (CO)-C-13 emission. The rotation direction, determined from a solid body fit to the CO isotopic lines, lies along P.A.=-86+/-11-degrees. This is parallel to the long axis of the cloud, as well as nearly parallel to the direction of the embedded magnetic field traced by the optical polarizations measured for the 16 stars, P.A.=81.6+/-0.5-degrees. The dispersion of the projected magnetic field direction is quite small (approximately 6-degrees), but is shown to be largest for characteristic spatial separations of 0.1-0.2 pc between pairs of stars. The distributions of CO and (CO)-C-13 clump sizes also peak near 0.15 pc, suggesting a possible connection between the magnetic field and the clumpy state of the cloud. The (CO)-C-13 clumps may arise from fragmentation of the rapidly rotating core and could signify the presence of a very young protobinary. The CO clumps are transitory and may be due to Alfven waves driven into the cloud periphery.