The emissivity for the two photons decay from the metastable level 2s has been computed in the case of a gaseous nebula of pure hydrogen, with both radiative and collisional excitation of the states.
The populations of 2s and 2p levels are deduced from the condition of equilibrium with other levels. Electron temperatures between 104 and 4×104K and electron densities between 104 and 106 cm−3 have been investigated.
For the optically thin case Ly α intensity has also been computed.
In the case of collisional excitation a much greater efficiency for the two photons process is found, which profoundly affects the appearance of the continuous spectrum.
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Gerola, H., Panagia, N. On the spectrum of a gaseous nebula of pure hydrogen, I. Astrophys Space Sci 2, 285–301 (1968). https://doi.org/10.1007/BF00650904
- Electron Temperature
- Continuous Spectrum
- Great Efficiency