极热光源激发的极低密度氢的光发射;在天体物理学中的应用
Light emission of very low density hydrogen excited by an extremely hot light source; applications in astrophysics
摘要：
斯特龙格伦研究了极热的热源对稀释的纯氢云的作用;形成了一个被中性氢原子包围的高度电离的球形氢等离子体。一个相对较薄的、部分电离的中间氢壳层被原子的辐射冷却。斯特龙格伦没有意识到，这种等离子体类似于气体激光器的等离子体，可以在氢原子的几个本征频率上产生超辐射;由于光学模式的竞争，与球体相切发射的超辐射射线似乎是由不连续的环造成的。超辐射强烈地减少了激发能级，包括质子-电子碰撞的连续谱，通过级联跃迁组合成共振多光子跃迁，使得气体在斯特龙格伦球半径之外被残酷地冷却。光源发射的光线的极高亮度允许多光子非共振吸收，导致稳态或电离连续区。这种吸收与超辐射射线引起的多光子扩散中的超辐射发射相结合。虽然它的亮度仍然高于超辐射射线，但如果通过小的立体角观察，则源变得不可见。球内发射的谱线在到达内部区域时更加微弱，原子数更低，并且由于能量向热辐射的参数转移而更加红化，该热辐射由仅存在于球中的受激原子氢催化。斯特罗姆格伦球似乎有助于简单地解释超新星1987 A的外观和光谱。
英文摘要：
Stromgren studied the action of an extremely hot source on a diluted pure hydrogen cloud; a very ionized, spherical hydrogen plasma surrounded by neutral atomic hydrogen is formed. A relatively thin intermediate, partially ionized, hydrogen shell, is cooled by the radiation of the atoms. Stromgren was unaware of that this plasma, similar to the plasma of a gas laser, can be superradiant at several eigen frequencies of atomic hydrogen; the superradiant rays emitted tangentially with the sphere appear resulting from a discontinuous ring because of the competition of optical modes. The superradiance intensely depopulates the excited levels, including the continuum of proton-electron collisions, by cascades of transitions combined into resonant multiphotonic transitions so that the gas is cooled brutally beyond the radius of the Stromgren sphere. The extreme brightness of the rays emitted by the source allows a multiphotonic non-resonant absorption leading in stationary states or the ionization continuum. This absorption combines with the superradiant emissions in a multiphotonic diffusion induced by the superradiant rays. Although its brightness remains higher than that of the superradiant rays, the source becomes invisible if it is observed through a small solid angle. The lines emitted inside the sphere are all the more weak as they arrive of an internal area, lower in atoms, and more reddened also by a parametric transfer of energy towards the thermal radiation catalyzed by excited atomic hydrogen present in the sphere only. The Stromgren sphere appears to help to simply explain the appearance and the spectrum of supernova 1987A.
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