  We present projected rotational velocities and new measurements of the
rotational profile of some 180 nearby stars with spectral types A-F. The
overall broadening profile is derived analysing spectral line shape from
hundreds of spectral lines by the method of least-squares deconvolution. Rigid
and differential rotation can be distinguished in 56 cases. Ten stars with
significant differential rotation rates are identified.
  As of now, 33 differential rotators detected by line profile analysis have
been confirmed. The frequency of differential rotators decreases towards high
effective temperature and rapid rotation. There is evidence for two populations
of differential rotators with a gap in between at spectral type early-F. The
gap can only partly be explained by an upper bound found for the horizontal
shear of F stars. Apparently, the physical conditions of differential rotation
change at early-F spectral types.

Solar and Stellar Astrophysics