Activated solar filaments and flares
Activated solar filaments and flares
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激活的太阳能灯丝和耀斑
DOI：
10.1098/rsta.1980.0233
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发表时间：
1980
期刊：
影响因子：
--
通讯作者：
Z. Svestka
中科院分区：
文献类型：
--
作者：
Z. Svestka
暗Ha细丝的激活和破坏是太阳上非常常见的现象。它们先于最强大的双带状太阳耀斑，但它们也远离任何活动区域，没有任何色球耀斑。因此，直到最近，灯丝断裂被认为是有趣的，但物理上微不足道的耀斑前兆。只有天空实验室的观测表明，灯丝的断裂实际上代表了太阳活动的基本和最重要的机制之一。这些观测揭示了(1)许多日冕瞬变起源于没有色球耀斑的爆发细丝，(2)Bruzek慢模波起源于被破坏的细丝而不是耀斑本身，(3)许多日冕x射线增强在活动区外也是新形成的环的顶部，类似于在活动区里的细丝被破坏后观察到的耀斑后环。对这些数据的一种解释源于Kopp & Pneuman的耀斑后循环理论：破坏细丝的过程打开了磁场，导致沿磁场线的质量流大大增强。开放的磁场线随后重新连接，从日冕底部开始向上移动。这个过程可能持续好几个小时。热环首先在x射线中出现，后来在极紫外线（e.u.v）线中出现，经过适当的冷却时间后，在Hx中作为环日珥系统出现。环的可见性取决于等离子体密度。几个观测到的太阳耀斑的特性表明，主要的加速发生在磁场线重新连接的时候。因此，两个带状耀斑中的粒子加速过程可以持续数小时。因为重新连接基本上是在所有灯丝断裂之后完成的，活跃区域外的“差速突”也应该加速粒子。
Activations and disruptions of dark Ha filaments are very common phenomena on the Sun. They precede the most powerful two-ribbon solar flares, but they also appear far from any active region without any chromospheric flaring. Therefore, until very recently, filament disruptions were considered as interesting, but physically insignificant, flare precursors. Only Skylab observations have shown that the filament disruptions actually represent one of the basic and most important mechanisms of solar activity. These observations have revealed (1) that many coronal transients originate in eruptive filaments without chromospheric flares, (2) that Bruzek’s slow-mode waves originate in disrupted filaments and not in flares themselves, and (3) that many coronal X-ray enhancements outside active regions are also tops of newly formed loops, similar to the post-flare loops observed after filament disruptions in active regions. An interpretation of these data stems from Kopp & Pneuman’s theory of postflare loops: the process that disrupts a filament opens the magnetic field and causes a greatly enhanced mass-flow along the field lines. The open field lines subsequently reconnect, starting from the bottom of the corona and proceeding upwards. This process can last for many hours. Hot loops are first seen in X-rays, later in extreme ultraviolet (e.u.v.) lines, and, after an appropriate cooling time, in Hx as the loop prominence systems. The visibility of loops depends on plasma density. Several observed properties of solar flares indicate that the primary acceleration occurs as the field lines reconnect. Thus the process of particle acceleration in two ribbon flares can last for hours. Because reconnection is accomplished after essentially all filament disruptions, ‘disparitions brusques’ outside active regions should also accelerate particles.