SIMBAD references

The opacity of alkali atoms, most importantly of Na and K, plays a crucial role in the atmospheres of brown dwarfs and exoplanets. We present a comprehensive study of Na-H₂ collisional profiles at temperatures from 500 to 3000K, the temperatures prevailing in the atmosphere of brown dwarfs and Jupiter-mass planets. The relevant H₂ perturber densities reach several 10¹⁹cm^–3 in hot (T_eff≥1500K) Jupiter-mass planets and can exceed 10²⁰cm^–3 for more massive or cooler objects. Accurate pressure-broadened profiles that are valid at high densities of H₂ should be incorporated into spectral models. Unified profiles of sodium perturbed by molecular hydrogen were calculated in the semi-classical approach using up-to-date molecular data. New Na-H₂ collisional profiles and their effects on the synthetic spectra of brown dwarfs and hot Jupiters computed with petitCODE are presented.