Institute of Applied Astronomy of the Russian Academy of Sciences
UDK 53 Физика
UDK 520 Инструменты, приборы и методы астрономических наблюдений, измерений и анализа
UDK 521 Теоретическая астрономия. Небесная механика. Фундаментальная астрономия. Теория динамической и позиционной астрономии
UDK 523 Солнечная система
UDK 524 Звезды и звездные системы. Вселенная Солнце и Солнечная система
UDK 52-1 Метод изучения
UDK 52-6 Излучение и связанные с ним процессы
GRNTI 41.00 АСТРОНОМИЯ
GRNTI 29.35 Радиофизика. Физические основы электроники
GRNTI 29.31 Оптика
GRNTI 29.33 Лазерная физика
GRNTI 29.27 Физика плазмы
GRNTI 29.05 Физика элементарных частиц. Теория полей. Физика высоких энергий
OKSO 03.06.01 Физика и астрономия
OKSO 03.05.01 Астрономия
OKSO 03.04.03 Радиофизика
BBK 2 ЕСТЕСТВЕННЫЕ НАУКИ
BBK 223 Физика
TBK 614 Астрономия
TBK 6135 Оптика
BISAC SCI004000 Astronomy
BISAC SCI005000 Physics / Astrophysics
The process of accretion onto a neutron star with strong magnetic field is discussed. The equilibrium radius, which is defined by equating the pressure of the accreting material with the magnetic pressure due to the dipole magnetic field of the neutron star, is estimated for the cases of a spherical accretion flow and a Keplerian accretion disk. It is emphasized that the magnetospheric radius of an accreting star is defined by equating the mass accretion rate observed in the system with the rate of plasma diffusion into the magnetic field of the neutron star at the magnetospheric boundary. Following this definition we obtained a system of equations, which are the continuity equation and the pressure balance equation. We show that the radius of magnetosphere evaluated in this way significantly differs from the equilibrium radius. In particular, the Alfven radius (which is just the equilibrium radius in a peculiar case of a spherically symmetric accretion flow) under the same conditions exceeds the magnetospheric radius of an accreting neutron star by more than an order of magnitude.
accretion, accretion disks; pulsars: general; magnetic fields
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