RADIAL AND ROTATIONAL VELOCITIES OF YOUNG STARS IN CHAMELEON AND LUPUS

We present a kinematic study of 26 T Tauri stars in the Chamaeleon and Lupus molecular clouds, based on high resolution CASPEC spec tra and CORAVEL radial velocity scanner observations. After discarding stars w ith high rotational velocities, noisy spectra or apparently variable v elocities, we find a velocity dispersion of 0.9 +/- 0.3 km s(-1) for t he remaining 10 stars of the Cha I T Tauri association. We also observ e the J = 10 line of (CO)-C-13 towards our target stars in Cha I, and find no significant gas motions to within 0.3 km s(-1), corresponding to the accuracy of the measurements. We derive a value of 0.5 +/- 0.4 km s(-1) for the difference between the mean stellar radial velocity a nd the mean gas velocity. The stars and the gas in Cha I are thus stil l closely linked kinematically. In the Lupus 3 clouds our sample of st ars is smaller, and we merely note that the stars observed divide into two kinematically distinct subgroups, one of which belongs to the bac kground Carina arm. Clearly a larger number of measurements would be d esirable. We argue, however, that the accuracy of the stellar radial v elocities may be difficult to improve because of the presence of undet ected long-period spectroscopic binaries and large star spots. In addi tion, the determination of the gas motions is limited by complex line profiles due to cloud structure along the line-of-sight.