In my (and many others’) models of stars, instead of using gravity I use “effective gravity” - the combination of gravity and the centripetal force (as our star is rotating!).
The corotation radius is the radius at which this “effective gravity” = 0, and any object at this radius would “corotate” with the stellar surface (like a geostationary satellite!).
For the sun this radius is really far out and thus is not very important...but for “young suns” which rotate very quickly, this radius can be only a few stellar radii and have drastic effects on the physics! In fact it could even help to explain why prominences (stellar clouds ☁️ ⭐️) can be found very far out in these systems, but not for the sun! ☀️ And could also mean that planets around these young suns are more likely to be hit by CMEs (not great for any lifeforms👽)