On the L-alpha line in the spectra of young stars.

It is shown that the observed L-alpha line profiles in the spectra of young stars differ substantially from the real profiles due to radiation absorption in this line by interstellar hydrogen. Nevertheless, enough evidence is available to suggest that the observed L-alpha profile characteristics are consistent with the hypothesis of the origin of L-alpha emission in the optically thick HII region ahead of an accretion shock wave front rather than in strong chromospheres. The observed profile shape and intensity of the L-alpha line in the spectra of T Tauri and Herbig Ae stars are examined in the context of the theory of disk accretion onto magnetized young stars.