Theoretical profiles of light alkali resonance lines for brown dwarf atmosphere conditions

The analysis of the far wings of resonance lines of alkali elements in brown dwarf spectra requires their accurate determination. A unified theory of collisional line profiles has been applied for the evaluation of absorption profiles of alkalis perturbed by helium and molecular hydrogen. The study of the dependence on temperature of the far wings of Li–He and Li–H2 collisional profiles is reported.