``Propeller'' Regime of Disk Accretion to Rapidly Rotating Stars
Abstract
We present results of axisymmetric magnetohydrodynamic simulations of the interaction of a rapidly rotating, magnetized star with an accretion disk. The disk is considered to have a finite viscosity and magnetic diffusivity. The main parameters of the system are the star's angular velocity and magnetic moment, and the disk's viscosity and diffusivity. We focus on the ``propeller'' regime where the inner radius of the disk is larger than the corotation radius. Two types of magnetohydrodynamic flows have been found as a result of simulations: ``weak'' and ``strong'' propellers. The strong propellers are characterized by a powerful disk wind and a collimated magnetically dominated outflow or jet from the star. The weak propellers have only weak outflows. We investigated the time-averaged characteristics of the interaction between the main elements of the system: the star, the disk, the wind from the disk, and the jet. Rates of exchange of mass and angular momentum between the elements of the system are derived as a function of the main parameters. The propeller mechanism may be responsible for the fast spinning down of the classical T Tauri stars in the initial stages of their evolution and for the spinning down of accreting millisecond pulsars.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2006
- DOI:
- 10.1086/503379
- arXiv:
- arXiv:astro-ph/0603249
- Bibcode:
- 2006ApJ...646..304U
- Keywords:
-
- Accretion;
- Accretion Disks;
- Magnetic Fields;
- Stars: Magnetic Fields;
- X-Rays: Stars;
- Astrophysics
- E-Print:
- 18 pages, 16 figures, ApJ (accepted), added references, corrected typos