The Propeller Regime of Disk Accretion to a Rapidly Rotating Magnetized Star
Abstract
The propeller regime of disk accretion to a rapidly rotating magnetized star is investigated here for the first time by axisymmetric 2.5D magnetohydrodynamic simulations. An expanded, closed magnetosphere forms in which the magnetic field is predominantly toroidal. A smaller fraction of the star's poloidal magnetic flux inflates vertically, forming a magnetically dominated tower. Matter accumulates in the equatorial region outside magnetosphere and accretes to the star quasi-periodically through elongated funnel streams which cause the magnetic field to reconnect. The star spins-down owing to the interaction of the closed magnetosphere with the disk. For the considered conditions, the spin-down torque varies with the angular velocity of the star omega* as omega*^1.3 for fixed mass accretion rate. The propeller stage may be important in the evolution of X-ray pulsars, cataclysmic variables and young stars. In particular, it may explain the present slow rotation of the classical T Tauri stars.
Keywords
Cite
@article{arxiv.astro-ph/0502266,
title = {The Propeller Regime of Disk Accretion to a Rapidly Rotating Magnetized Star},
author = {Marina M. Romanova and Galina V. Ustyugova and Alexander V. Koldoba and Richard V. E. Lovelace},
journal= {arXiv preprint arXiv:astro-ph/0502266},
year = {2009}
}
Comments
5 pages with 4 figures, LaTeX, macros: emulapj.sty, avi movies are available at http://www.astro.cornell.edu/us-russia/disk_prop.htm