= Stellar activity Rossby number
{title2=$\operatorname{Ro}_*=P_{\rm rot}/\tau_c$}
For a convective star, the activity convention compares its rotation period with a convective turnover time. It differs by fixed factors from the fluid <Rossby number> estimated from speed, length and angular velocity. Small $\operatorname{Ro}_*$ denotes strong rotational influence on <convection>. Magnetic activity usually rises as this ratio decreases in the unsaturated regime, but levels off in a saturated rapid-rotation regime.
Back to article page
