A new version of Reimers' law of mass loss based on a physical approach

We present a new semiempirical relation for the mass loss of cool stellar winds, which so far has frequently been described by Reimers' law. Originally, this relation was based solely on dimensional scaling arguments without any physical interpretation. In our approach, the wind is assumed to result from the spillover of the extended chromosphere, possibly associated with the action of waves, especially Alfven waves, which are used as guidance in the derivation of the new formula. We obtain a relation akin to the original Reimers law, but which includes two new factors. They reflect how the chromospheric height depends on gravity and how the mechanical energy flux depends, mainly, on the effective temperature. The new relation is tested and sensitively calibrated by modeling the blue end of the horizontal branch of globular clusters. The most significant difference from mass-loss rates predicted by the Reimers relation is an increase by up to a factor of 3 for luminous late-type (super) giants, in good agreement with observations.