Astronomy and Astrophysics Supplement Series, Vol. 120, November II 1996, 127-138
Laboratoire d'Astrophysique, Observatoire de Grenoble,
Université Joseph Fourier, B.P. 53X, 38041 Grenoble Cedex,
Canada-France-Hawaii Telescope Corporation, P.O. Box 1597, Kamuela, HI 96743, U.S.A.
Received February 7; accepted April 15, 1996
Abstract:The UBVRI light curves of 7 late-type dwarfs amongst the fastest rotators of the Alpha Per cluster (140 km s ) are presented. The shape of the light curves suggests that the photometric variations are most often dominated by a single group of cool spots located at intermediate or high latitude on the stellar surface. Assuming that starspots are good tracers of the stellar magnetic field, the smooth light curves indicate the existence of a large scale, slowly varying magnetic structure at the surface of these ultrafast rotators.
Key words: stars: magnetic fields --- stars: rotation --- stars: activity --- stars: late type --- open clusters and associations: individual: Alpha Persei