Relative differential rotation α_90^° vs. estimated period for all differential rotators detected by profile analysis. The dotted and dashed-dotted lines indicate the dependence of α on period for constant absolute shear ΔΩ = 1.0   rad   d^-1 and 0.1   rad   d^-1, resp. Open symbols indicate dwarfs and filled symbols evolved stars with log g ≤ 3.5. Symbol size scales with effective temperature as indicated in the legend. The straight solid lines relate the data points to the values derived for 10^◦ thus illustrating the error due to inclination. Errors intrinsic to α_90^° and α_10^° are omitted for clarity but might be substantial. The scaling of symbol size with effective temperature allows one to compare with the theoretical predictions for an F8 star (vertically hashed) and a G2 star (horizontally hashed) (Küker & Rüdiger 2005, width of relations given by cases c_v = 0.15 and 4/15). The vertical lines indicate period limits accessible to measurement. The vertical solid line gives the shortest rotational period of the stars with a measurement of the rotational profile while the other vertical lines denote the periods corresponding to the vsini limit of CES for a dwarf star (short-dashed) of 1 solar radius and an evolved star (long-dashed) of 8 solar radii. The FEROS limit will be at even shorter periods. The location of the Sun is also shown ( ⊙ ). The grey solid line gives the upper envelope to mid and late-F type differential rotators discussed in the text.