LAUSR

The article considers the poorly studied states of hydrogen gas (called here “quasi-resonant”) with anomalously high intensity ratios of the lines in the Balmer series, $$I({{{\text{H}}}_{\alpha }}){\text{/}}I({{{\text{H}}}_{\beta }})$$ . It is shown that such states arise in the case of large optical thicknesses of the emitting gas occurring at the frequencies of the Balmer lines, when the gas tends to a thermalization state. The influence on the formation of such states of basic model parameters as temperature, atomic density, and the characteristic size of the emitting region, as well as the presence of external radiation, is studied on simple models. It is shown that quasi-resonant states can exist in the magnetospheres of T Tauri stars at moderate accretion rates.