Abstract
We conducted measurements of projected rotational velocities in the quite young σ-Ori cluster using 169 spectra with a resolution of 8 km/s, obtained with the Hectoechelle spectograph attached to the 6.5 MMT telescope. The vsini obtained values are more precise than those reported so far in the literature. Rotational velocities were determined via the cross-correlation technique using the package FXCOR in IRAF for 60 low mass star members. Our preliminary results confirm the presence of both fast and slow rotators among the sample, being the latter group less massive as suggested by previous studies.
