A Model of Solar Flares
A Model of Solar Flares
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DOI：
10.1007/978-94-011-6815-1_70
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发表时间：
1968
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影响因子：
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通讯作者：
P. Sturrock
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文献类型：
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作者：
P. Sturrock
提出了一个太阳耀斑模型，其中耀斑前状态包括一个双极磁场结构与双极光球磁区。在低高度处，磁场线是闭合的，但是在足够高的高度处，磁场线被拉出到包括双极通量管的开放结构中，该双极通量管包含“中性片”或“片夹”。这种片箍缩可能与日冕流光有关。闭合场区的能量来自光球运动，而开放场区的能量来自加热日冕并驱动太阳风的非热能通量，耀斑本身被认为是撕裂模电阻不稳定性引起的磁场重联。如果片箍缩的厚度由电阻性扩散和1天量级的双极区的生长时间确定，则横向尺寸将为约104 cm。撕裂模不稳定性的上升时间只有几秒钟，与III型射电暴的特征时间相一致。我们可以理解，如果重联过程是通过Petscheck机制进行的，那么重联过程的时间尺度是102-103秒，并将电阻扩散替换为更快的玻姆扩散。根据这个模型，耀斑的演化似乎符合耀斑的一些观测特征。
A model of solar flares is proposed in which the preflare state comprises a bipolar magnetic-field structure associated with a bipolar photospheric magnetic region. At low heights, the magnetic-field lines are closed but, at sufficiently great heights, the lines are drawn out into an open structure comprising a bipolar flux tube containing a ‘neutral sheet’ or ‘sheet pinch’. Such a sheet pinch is probably related to a coronal streamer. The energy stored in the closed-field region is derived from photospheric motion whereas energy stored in the open-field region is derived from the non-thermal energy flux which heats the corona and drives the solar wind.The flare itself is identified with reconnection of magnetic field by the tearing-mode resistive instability. If the thickness of the sheet pinch is determined by resistive diffusion and a growth time of the bipolar region of order 1 day, the transverse dimension will be about 104 cm. The rise time of the tearing-mode instability is then a few seconds, compatible with the characteristic time of Type-III radio bursts. One can understand that the time-scale of the reconnection process is of order 102–103 sec if reconnection proceeds by the Petscheck mechanism, with the modification that resistive diffusion is replaced by the more rapid Bohm diffusion.The evolution of a flare, according to this model, appears to fit a number of the observational characteristics of flares.