ON THE POSSIBILITY OF LIGHTNING IN THE PROTOSOLAR NEBULA
ON THE POSSIBILITY OF LIGHTNING IN THE PROTOSOLAR NEBULA
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关于原太阳星云中闪电的可能性
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
G. Morfill
中科院分区：
文献类型：
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作者：
S. Gibbard;E. Levy;G. Morfill
摘要球粒陨石是原始陨石的重要组成部分。它们的热史包括快速融化，然后以几分钟到几小时的时间尺度冷却。几十年来，这种极端的、短暂的热漂移背离了普遍的、温和得多的星云平衡条件，其背后的机制一直难以理解。长期以来，人们一直认为，原行星星云中的闪电--大规模的静电放电--是可能解释球粒形成的主要机制之一。在这篇文章中，我们探索了由降水或其他类似于地球和其他行星上闪电的过程提供动力的原行星星云中可能发生的这种静电放电。我们的分析包括水-冰或其他固体颗粒碰撞中的电荷分离，并包括由自由电子和离子的产生与颗粒表面损失之间的平衡决定的自洽星云电导率。我们发现，在原恒星星云的特征条件下，不会产生足以产生放电的大范围电场。这主要是因为环境的高电导率和相对较低的固体颗粒密度结合在一起，产生了一种情况，其中大范围的电场以及分离在颗粒上的电荷被高流动性的电子和离子短路。我们还考虑了在尘埃密度高于标准尘埃密度的蚀变星云环境中发生闪电的可能性，例如尘埃子盘。
Abstract Chondrules constitute a significant fraction of primitive meteorites. Their thermal history includes rapid melting followed by cooling on timescales of minutes to hours. The mechanism underlying such extreme, short-lived thermal excursions away from the prevailing, much milder nebular equilibrium conditions has eluded understanding for many decades. Among the prime candidate mechanisms long thought to provide a possible explanation of chondrule formation is lightning—large-scale electrostatic discharges—in the protoplanetary nebula. In this paper, we explore the possible occurrence of such electrostatic discharges in the protoplanetary nebula powered by precipitation or other processes analogous to that believed to cause lightning on Earth and other planets. Our analysis incorporates charge separation in collisions of water-ice or other solid particles, and includes a self-consistent nebular electrical conductivity determined by a balance between production of free electrons and ions and loss to grain surfaces. We find that development of a large-scale electric field strong enough to produce discharges does not occur under conditions characteristic of protostellar nebulae. This is mainly a result of the fact that the high electrical conductivity of the environment and the relatively low density of solid particles combine to yield a situation in which the large scale electric fields, as well as the electric charges segregated on the particles are short circuited by the highly mobile electrons and ions. We also consider the possibility of lightning in altered nebula environments with higher than canonical dust density, such as a dust subdisk.