On the Possible Reason for the Super-Slow Rotation of Some Ap Stars

In this paper, we consider one possible mechanism leading to the ultra-slow rotation of individual magnetic stars called super-slowly rotating Ap stars (ssrAp stars). The periods of such objects sometimes exceed hundreds of years. It is believed that they acquired their slow rotation even before the stars entered the main sequence (MS). To explain this phenomenon, we turned to a propeller mechanism model for a magnetic star moving in the interstellar medium. As an example of the potential efficiency of the proposed mechanism, we considered the typical ssrAp star, 33 Lib (HD 137949). A detailed justification using modeling requires solving a multiparameter problem. At the same time, it can be argued that in certain cases, the considered version of ‘‘magnetic’’ braking is capable of effectively slowing the rotation of a star.