Coexistence of oppositely flowing multi-ψ-currents : Key to large toroidal magnetic fields within stars
Coexistence of oppositely flowing multi-ψ-currents : Key to large toroidal magnetic fields within stars
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相反流动的多ψ电流的共存：恒星内大环形磁场的关键
DOI：
10.1093/mnras/stt541
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发表时间：
2013
影响因子：
4.8
通讯作者：
Kotaro Fujisawa and Yoshiharu Eriguchi
中科院分区：
文献类型：
--
作者：
室田信一;Kotaro Fujisawa and Yoshiharu Eriguchi
我们将通过分析表面电流与恒星内部体电流方向相反的磁化恒星的定态，说明反向流动的φ电流共存对维持恒星内部强环形磁场的重要性。我们已经为电流和环形磁场施加了边界条件，使其在恒星之外消失。值得注意的是，这些边界条件为恒星内部的总电流设定了上限。这个总电流的上限导致了恒星环形磁场能量大小的上限。如果恒星的表面环电流与内部环电流的方向相反，则正向流动的内部环电流可以变得比没有表面环电流的配置的电流的上限值更强。因此，环向磁场的能量可以比没有表面环向电流的磁化恒星的能量大得多。我们还分析了同样的现象出现在球形不可压缩星的偶极类磁场与或没有表面环电流通过采用零通量边界方法。我们将这些具有表面环形电流的配置应用于磁星，并讨论了它们的耀斑，通过这些耀斑，恒星表面外部可能会出现磁螺旋。
We will show the importance of coexistence of oppositely flowing φ currents for magnetized stars to sustain strong toroidal magnetic fields within the stars by analysing stationary states of magnetized stars with surface currents which flow in the opposite direction with respect to the bulk currents within the stars. We have imposed boundary conditions for currents and toroidal magnetic fields to vanish outside the stars. It is important to note that these boundary conditions set an upper limit for the total current within the stars. This upper limit for the total current results in the presence of an upper limit for the magnitude of the energy for the toroidal magnetic fields of the stars. If the stars could have the toroidal surface currents which flow in the opposite directions to the internal toroidal currents, the positively flowing internal toroidal currents can become stronger than the upper limit value of the current for configurations without surface toroidal currents. Thus, the energies for the toroidal magnetic fields can become much larger than those for the magnetized stars without surface toroidal currents. We have also analysed the same phenomena appearing in spherical incompressible stars for dipole-like magnetic fields with or without surface toroidal currents by employing the zero-flux-boundary method. We have applied those configurations with surface toroidal currents to magnetars and discussed their flares through which magnetic helicities could arise outside the stellar surfaces.