论文标题
具有开放和闭合磁性拓扑的中子星的差异旋转
Differential rotation in neutron stars with open and closed magnetic topologies
论文作者
论文摘要
已经提出了分析论证，即中子恒星中的差异旋转程度取决于内部磁场的拓扑是开放还是封闭的。为了测试这一断言，采用理想的磁性水力动力学求解器冥王星用于数值研究不可压缩的，可粘性的流体的流动，该磁场是由磁场螺纹的，带有开放和封闭的拓扑，在导电，差异旋转的球形壳中。与外球体的刚体脉络在Alfvén的时间尺度上执行，沿着连接外球的北半球和南半球的磁场线。但是，沿其他场线，行为更加复杂。例如，初始点偶极场会演变成产生近似闭合的赤道通量管，该赤道通量管至少包含一个主要是环形的，近似闭合的磁场线被一堆主要是环形的但开放的野外线包围。在赤道通量管内，场线平均磁张力接近零，流体旋转差异，调整其在粘性时间尺度上的角速度，以匹配磁带环形表面上的边界条件。在赤道通量管外面，随着沿开放田线平均的磁张力减小，差异旋转增加。
Analytic arguments have been advanced that the degree of differential rotation in a neutron star depends on whether the topology of the internal magnetic field is open or closed. To test this assertion, the ideal-magnetohydrodynamics solver PLUTO is employed to investigate numerically the flow of an incompressible, viscous fluid threaded by a magnetic field with open and closed topologies in a conducting, differentially rotating, spherical shell. Rigid body corotation with the outer sphere is enforced on the Alfvén time-scale, along magnetic field lines that connect the northern and southern hemispheres of the outer sphere. Along other field lines, however, the behavior is more complicated. For example, an initial point dipole field evolves to produce an approximately closed equatorial flux tube containing at least one predominantly toroidal and approximately closed field line surrounded by a bundle of predominantly toroidal but open field lines. Inside the equatorial flux tube, the field-line-averaged magnetic tension approaches zero, and the fluid rotates differentially, adjusting its angular velocity on the viscous time-scale to match the boundary conditions on the flux tube's toroidal surface. Outside the equatorial flux tube the differential rotation increases, as the magnetic tension averaged along open field lines decreases.
