Cool Stars 14 - Submitted Abstract # 231 This version created on 05 October 2006 On magnetic braking of young cool stars Joao Miguel Ferreira, University of Azores Alexandre Aibeo, Centro de Astrofisica da Universidade do Porto Joao Lima, Centro de Astrofisica da Universidade do Porto The observation of significant magnetic flux at high latitudes on rapidly rotating cool stars is likely to lead to a coronal field topology radically different from the solar case. In addition, the angular momentum loss induced by the wind and magnetic field on these stars can also be significantly altered with important implications to the star's rotational evolution. Here, we investigate whether magnetic flux concentration towards the pole leads to a decrease in angular momentum loss rate. We solve the wind equations on a prescribed totally open field as in the classical Weber & Davis model (1967) but with a surface magnetic flux distribution concentrated towards high latitudes. However, we do not assume the poloidal field to be radial and expand as a split monopole while maintaining the surface latitudinal flux distribution, as this completely ignores force balance across the field. Instead, we obtain analytical potential field solutions with an equatorial current sheet. We find that coronal field lines are pushed from high to low latitudes and rapidly approach the split monopole field with no memory of the surface flux distribution. The braking rate of the highly concentrated field is very similar to the uniform field. We conclude that the concentration of magnetic flux towards the poles does not directly imply a reduced angular momentum loss rate. We suggest that this effect may still contribute to a reduced braking if it leads to a reduction in the amount of open magnetic flux (cf. Mestel & Spruit 1987). ----------------------------------