Neutron Stars in the Subsonic Propeller Stage

In the evolutionary tracks of magnetized compact stars the subsonic propeller state is intermediate between the supersonic propeller and accretor states. The rotation rate of a star in this stage decreases because of the interaction of its magnetosphere with the surrounding hot quasistatic shell. The radius of the magnetosphere is less than the corotation radius, and the boundary of the magnetosphere is stable with respect to inter-change instabilities. The mass flow rate from the inner radius of the shell to the surface of the compact object is limited by the rate at which plasma diffuses into the magnetic field of the star. Because of this, a subsonic propeller will show up as a low (or moderate) luminosity accretion pulsar with a soft x-ray spectrum.__________Translated from Astrofizika, Vol. 48, No. 3, pp. 477–490 (August 2005).