Absorption spectrum of very low pressure, relatively cold atomic hydrogen: Lyman forest and Karlsson's formula.

Jacques Moret-Bailly (1)

1 Chercheur indépendant

Light of a very hot blackbody crosses assumed pure, very low pres- sure, relatively cold (20 000K) atomic hydrogen. Absorption of Lyman lines generates states in which periods of quadrupolar resonances are longer than the lengths ( 1 ns) of pulses which make incoherent light. Assuming that collisional time is also longer than 1 ns, an "impulsive stimulated Raman scattering" (ISRS) decreases frequencies of light until a strongly absorbed line gets Lyman alpha frequency. As long as fall of radiance resulting from Planck's law does not reach Lyman beta frequency, states of principal quantum number n larger than 1 pro- vide a weak frequency shift or feed n=1 states, so that an oscillation occurs, which adds relative frequency shifts putting absorbed Lyman beta and gamma lines to Lyman alpha frequency. Lyman forest and Karlsson's formula are obtained.

Mots clés: 290.5910 Scattering; stimulated Raman; 190.2640 Nonlinear optics

Domaines: Optique [physics.optics]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]

Jacques Moret-Bailly. Absorption spectrum of very low pressure, relatively cold atomic hydrogen: Lyman forest and Karlsson's formula.. 2014. ⟨hal-00995803⟩