Accretion by rotating magnetic neutron stars. II. Radial and vertical structure of the transition zone in disk accretion.
Accretion by rotating magnetic neutron stars. II. Radial and vertical structure of the transition zone in disk accretion.
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DOI：
10.1086/157285
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发表时间：
1979-08
期刊：
影响因子：
--
通讯作者：
P. Ghosh;F. Lamb
中科院分区：
文献类型：
--
作者：
P. Ghosh;F. Lamb
研究了中子星星吸积盘物质时，恒星磁场与吸积等离子体在磁层边界的相互作用。恒星磁场通过开尔文-亥姆霍兹不稳定性、湍流扩散和重联穿透盘的内部，产生一个宽阔的过渡区，将远离星星的未扰动盘流与靠近星星的磁层流连接起来。利用二维磁流体方程，计算了该带的内外半径及其径向和垂向结构。过渡区由两个性质不同的区域组成，一个是角速度为开普勒的宽的外部区域，一个是角速度明显偏离开普勒值的窄的内部区域或边界层。星星的磁场只有轻微变形的边界层内，但变得越来越扭曲，在更大的radios.We讨论的影响流的解决方案，发现在这里为中子-星星模型的吸积X射线源，依次考虑从磁盘的内部边缘的物质流的表面的星星，所产生的吸积扭矩，和模式下降等离子体在恒星表面。由于大约20%的星星磁通量穿过其内边缘之外的圆盘，因此由磁层场引导的等离子体福尔斯落入磁极处的圆环中。«少
We invesgitage the interaction between the stellar magnetic field and the accreting plasma at the magnetospheric boundary of a neutron star accreting matter from a disk. The stellar magnetic field penetrates the inner part of the disk via the Kelvin-Helmholtz instability, turbulent diffusion, and reconnection, producing a broad transition zone joining the unperturbed disk flow far from the star to the magnetospheric flow near the star. Using the two-dimensional hydromagnetic equations, we calculate the inner and outer radii of this zone and its radial and vertical structure. The transition zone is composed of two qualitatively different regions, a broad outer zone where the angular velocity is Keplerian and a narrow inner zone or boundary layer where it departs significantly from the Keplerian value. The star's magnetic field is only slightly deformed within the boundary layer but becomes increasingly distorted at larger radii.We discuss the implications of the flow solutions found here for neutron-star models of accreting X-ray sources, considering in turn the flow of matter from the inner edge of the disk to the surface of the star, the resulting accretion torque, and the pattern of falling plasma at the stellar surface. Because approx.20% of the star's magnetic flux threadsmore » the disk outside its inner edge, plasma channeled by the magnetospheric field falls in a circular ring at the magnetic poles.« less