Fast rotating cool stars are characterised by high magnetic activity levels
and frequently show dark spots up to polar latitudes. Their distinctive surface
distributions of magnetic flux are investigated in the context of the
solar-stellar connection by applying the solar flux eruption and surface flux
transport models to stars with different rotation rates, mass, and evolutionary
stage. The rise of magnetic flux tubes through the convection zone is primarily
buoyancy-driven, though their evolution can be strongly affected by the
Coriolis force. The poleward deflection of the tube's trajectory increases with
the stellar rotation rate, which provides an explanation for magnetic flux
eruption at high latitudes. The formation of proper polar spots likely requires
the assistance of meridional flows both before and after the eruption of
magnetic flux on the stellar surface. Since small radiative cores support the
eruption of flux tubes at high latitudes, low-mass pre-main sequence stars are
predicted to show high mean latitudes of flux emergence. In addition to flux
eruption at high latitudes, main sequence components of close binary systems
show spot distributions which are non-uniform in longitude. Yet these
`preferred longitudes' of flux eruption are expected to vanish beyond a certain
post-main sequence evolutionary stage.Comment: 8 pages, 12 figures, in Memorie della Societa Astronomica Italiana
Vol. 78 n. 2, p. 27
