THE EVOLUTION OF SURFACE-STRUCTURES ON AB DORADUS

We present the third set of a long-term series of Doppler images of th e starspot distribution on AB Doradus, a rapidly rotating active KO dw arf. The images were obtained from simultaneous spectroscopic and phot ometric observations taken on the Anglo-Australian Telescope and the E uropean Southern Observatory in 1993 November. Our images show two act ive latitudes, a low-latitude band producing most of the photometric m odulation, and a high-latitude band centred at 60 degrees. The spot di stribution at low latitudes is very stable and persists over 5 stellar rotations. It is also remarkably similar to the distribution found in 1992 December. The high-latitude structure is more variable and seems to change on the order of a few rotation periods. In agreement with m easurements from 1992 January, we find no indication for differential rotation on AB Doradus.