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Rotation evolution of late-type stars is dominated by magnetic braking andthe underlying factors that control this angular momentum loss are importantfor the study of stellar spin-down. In this work, we study angular momentumloss as a function of two different aspects of magnetic activity using acalibrated Alfv\'en wave-driven magnetohydrodynamic wind model: the strengthsof magnetic spots and their distribution in latitude. By driving the modelusing solar and modified solar surface magnetograms, we show that the topologyof the field arising from the net interaction of both small-scale andlarge-scale field is important for spin-down rates and that angular momentumloss is not a simple function of large scale magnetic field strength. We findthat changing the latitude of magnetic spots can modify mass and angularmomentum loss rates by a factor of two. The general effect that causes thesedifferences is the closing down of large-scale open field at mid- andhigh-latitudes by the addition of the small-scale field. These effects mightgive rise to modulation of mass and angular momentum loss through stellarcycles, and present a problem for ab initio attempts to predict stellarspin-down based on wind models. For all the magnetogram cases considered here,from dipoles to various spotted distributions, we find that angular momentumloss is dominated by the mass loss at mid-latitudes. The spin-down torqueapplied by magnetized winds therefore acts at specific latitudes and is notevenly distributed over the stellar surface, though this aspect is unlikely tobe important for understanding spin-down and surface flows on stars.

The dependence of stellar mass and angular momentum losses on latitude and on active region and dipolar magnetic fields