1996A&A...308..107D

We present a kinematic study of 26 T Tauri stars in the Chamaeleon and Lupus molecular clouds, based on high resolution CASPEC spectra and CORAVEL radial velocity scanner observations. After discarding stars with high rotational velocities, noisy spectra or apparently variable velocities, we find a velocity dispersion of 0.9±0.3km/s for the remaining 10 stars of the Cha I T Tauri association. We also observe the J=1-0 line of ¹³CO towards our target stars in Cha I, and find no significant gas motions to within 0.3km/s, corresponding to the accuracy of the measurements. We derive a value of 0.5±0.4km/s for the difference between the mean stellar radial velocity and the mean gas velocity. The stars and the gas in Cha I are thus still closely linked kinematically. In the Lupus 3 clouds our sample of stars is smaller, and we merely note that the stars observed divide into two kinematically distinct subgroups, one of which belongs to the background Carina arm. Clearly a larger number of measurements would be desirable. We argue, however, that the accuracy of the stellar radial velocities may be difficult to improve because of the presence of undetected long-period spectroscopic binaries and large star spots. In addition, the determination of the gas motions is limited by complex line profiles due to cloud structure along the line-of-sight.