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We present Hα observations of two rapidly-rotating G2 dwarfs in the Alpha Persei cluster and of AB Dor, a young K0 dwarf. All three stars have projected rotational velocities of about 90 km s−1 and axial rotation periods ranging from 11 to 15 hours. He 520 and AB Dor show very clear transient features that move through the profile. The most likely explanation for these features is that they are huge prominences in co-rotation with the star. We also use the recently developed technique of least squares deconvolution to present simultaneous dynamic profiles of the stars’ photospheric lines which show the locations of the surface spots. This technique has allowed us to extend our studies to a greater range of stars.