IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS VI: PROPERTIES OF LARGE-SCALE DISCHARGE EVENTS
IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS VI: PROPERTIES OF LARGE-SCALE DISCHARGE EVENTS
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DOI：
10.1088/0004-637x/784/1/43
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发表时间：
2014-03-20
影响因子：
4.9
通讯作者：
Stark, C. R.
中科院分区：
文献类型：
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作者：
Bailey, R. L.;Helling, Ch.;Stark, C. R.
亚恒星大气中的矿物云作为各种电荷过程的催化剂起着特殊的作用。如果云层带电，周围的环境就会被电激活，带电颗粒的集合就会放电（例如，通过闪电），这极大地影响了当地的化学反应，创造了类似于早期行星大气中生命的条件。我们注意到，这种闪电放电也有助于大气的电离状态。我们将实验室测量和数值实验所得的放电过程的标度定律应用到DRIFT-PHOENIX模型大气结果中，以模拟放电在大气云层中的向下（如闪电）和向上（如精灵）传播。我们评估了闪电放电的空间范围和能量学。受影响的大气体积（例如，温度或电子数的增加）在褐矮星大气中(10(8)- 10（10)m(3)）比在巨大的气体行星中(10(4)- 10（6)m(3)）更大。我们的结果表明，一个事件的总耗散能量为
Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged grains are electrically discharging (e.g., by lightning), which significantly influences the local chemistry creating conditions similar to those thought responsible for life in early planetary atmospheres. We note that such lightning discharges contribute also to the ionization state of the atmosphere. We apply scaling laws for electrical discharge processes from laboratory measurements and numerical experiments to DRIFT-PHOENIX model atmosphere results to model the discharge's propagation downward (as lightning) and upward (as sprites) through the atmospheric clouds. We evaluate the spatial extent and energetics of lightning discharges. The atmospheric volume affected (e.g., by increase of temperature or electron number) is larger in a brown dwarf atmosphere (10(8)- 10(10) m(3)) than in a giant gas planet (10(4)- 10(6) m(3)). Our results suggest that the total dissipated energy in one event is