NEW ROTATIONAL VELOCITIES FOR ECLIPSING BINARIES, AND A COMPARISON OFSPECTROSCOPIC AND PHOTOMETRIC ROTATIONS

Rotational velocities are determined spectroscopically for 38 eclipsin g binaries, including many long-period, nominally semidetached, system s. We note that spectroscopic rotations may differ from rotations deri ved from light-curve modeling using the Wilson-Devinney program. In '' direct-impact'' mass-transferring systems, or in most systems with per iods smaller than about 7 days, observations suggest that the two rota tions are usually about the same. In cases where the stream misses the gainer and an accretion disk forms, however, photometric rotation est imates often exceed spectroscopic determinations. The possible physica l significance of this situation is briefly discussed. Doubt is cast o n the likelihood that the rotation of the hot component of U Sge has c hanged detectably in the last 30 years.