氢的远UV激发和光发射;在天体物理学中的应用
Far UV excitation of hydrogen and light emission; applications in astrophysics
摘要：
假设一个球对称，极端的紫外线发射的一个非常热的来源电离低压分子氢，使一个透明的气泡H II（质子和电子）。随着半径的增大，极紫外强度和温度降低，等离子体中含有的原子越来越多。出现了一个主要由中性原子（H I）组成的球形壳层。如果这个壳层在H I的莱曼频率处是光学厚的，则它是超辐射的，并且模式的竞争选择与许多原子被激发的球体相切的模式。因此，等离子体壳层向给定方向发射切向射线，显示出一个环，其中选定的模式更亮。在莱曼频率下，光源发出的射线的吸收激发了能够放大超辐射的原子，更强大的超辐射放大来自辐射束的诱导散射，其延伸到英尺的线并逐渐扩展到整个光谱。热力学认为，径向光束和切向光束的亮度趋于相等;如果观察环的立体角比光源的立体角大得多，则几乎所有光源发出的光都转移到环上，光源变得不可见。奇怪的是，由于光源周围的非相干散射和杂质而产生的辉光仍然可见。由于散射随着径向强度的减小而减小，因此环的亮度随着半径而减小。这些特征在超新星遗迹1987 A中被发现。
英文摘要：
Assuming a spherical symmetry, the extreme UV emitted by a very hot source ionizes low pressure molecular hydrogen making a transparent bubble of H II (Protons and electrons). For an increase of radius, intensity of extreme UV and temperature decrease, so that the plasma contains more and more atoms. A spherical shell, mainly of neutral atoms (H I) appears. If this shell is optically thick at Lyman frequencies of H I, it is superradiant and a competition of modes selects modes tangent to a sphere for which many atoms are excited. Thus, a shell of plasma emits, into a given direction, tangential rays showing a ring in which selected modes are brighter. While at Lyman frequencies, absorption of rays emitted by the source excites the atoms able to amplify the superradiance, a more powerful amplification of superradiance results from an induced scattering of the radial beams, which extends to feet of lines and progressively to the whole spectrum. Thermodynamics says that the brightness of radial and tangential beams tends to be equal; if the solid angle of observation is much larger for the ring than for the source, almost the whole light emitted by the source is transferred to the rings, and the source becomes invisible. Paradoxically, a glow due to incoherent scattering and impurities around the source remains visible. As the scattering decreases with the decrease of the radial intensity, the brightness of the ring decreases with radius. These characteristics are found in supernova remnant 1987A.
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