Rotating Parker wind

Abstract: We reconsider the structure of thermally driven rotating Parker wind. Rotation, without \Bf, changes qualitatively the structure of the subsonic region: solutions become non-monotonic and do not extend to the origin. For small angular velocities solutions have two critical points - X-point and O-points, which merge at the critical angular velocity of the central star $\Omega_{crit} = G M_\ast/(2 \sqrt{2} c_s R_{b}^2)$ (where $M_\ast$ and $R_{b}$ are mass and radius of the central star, $c_s$ is the sound speed in the wind). For larger spins there is no critical points in the solution. For disk winds (when the base of the wind rotates with Keplerian velocity) launched equatorially the coronal sound speed should be smaller than $\approx 0.22 v_K$ in order to connect to the critical curve ($v_K$ is the Keplerian velocity at a given location on the disk).