TAPIR Seminar

In person: 370 Cahill. To Join via Zoom: 868 5298 8404

ABSTRACT: We discuss the role of the azimuthal stellar wind flow in the stellar-rotation braking mechanism. The stellar rotation is shown to cause the slow magnetosonic critical point to occur lower in the corona, so the stellar wind experiences a stronger afterburner (as in an aircraft jet engine) action in the corona, and hence an enhanced stellar wind acceleration. Stellar rotation effects are shown to produce considerably enhanced stellar wind acceleration even for moderate rotators like Sun. For strong rotators, the stellar wind is shown to experience an immensely enhanced acceleration in a narrow shell adjacent to the star. For strong rotators the magnetosonic critical point is shown to be determined only by the basic stellar parameters like mass and angular velocity of the star. Parker's isothermal solar wind model is then extended to incorporate polytropic gas effects that become relevant for variable extended heating of the corona. The polytropic gas conditions are found to favor an enhanced conversion of thermal energy in the solar wind into kinetic energy of the outward flow. Stability of the steady rotating wind solution is then investigated via an analytical development to shed light on the possibility that this solution is a "stable attractor" of the underlying dynamical system.