The rotation rates and magnetic activity of Sun-like and low-mass ( \la 1.4 M _ { \odot } ) main-sequence stars are known to decline with time , and there now exist several models for the evolution of rotation and activity .
However , the role that chemical composition plays during stellar spin-down has not yet been explored .
In this work , we use a structural evolution code to compute the rotational evolution of stars with three different masses ( 0.7 , 1.0 , and 1.3 M _ { \odot } ) and six different metallicities , ranging from [ Fe/H ] = -1.0 to [ Fe/H ] = +0.5 .
We also implement three different wind-braking formulations from the literature ( two modern and one classical ) and compare their predictions for rotational evolution .
The effect that metallicity has on stellar structural properties , and in particular the convective turnover timescale , leads the two modern wind-braking formulations to predict a strong dependence of the torque on metallicity .
Consequently , they predict that metal rich stars spin-down more effectively at late ages ( \ga 1 Gyr ) than metal poor stars , and the effect is large enough to be detectable with current observing facilities .
For example , the formulations predict that a Sun-like ( solar-mass and solar-aged ) star with [ Fe/H ] = -0.3 will have a rotation period of less than 20 days .
Even though old , metal poor stars are predicted to rotate more rapidly at a given age , they have larger Rossby numbers and are thus expected to have lower magnetic activity levels .
Finally , the different wind-braking formulations predict quantitative differences in the metallicity-dependence of stellar rotation , which may be used to test them .