# New study of the line profiles of sodium perturbed by H2

## TL;DR

This paper provides a detailed analysis of sodium line profiles perturbed by molecular hydrogen at high temperatures and densities, crucial for modeling the atmospheres of brown dwarfs and exoplanets.

## Contribution

It introduces new semi-classical collisional profiles for NaH2 interactions applicable at high densities and temperatures, enhancing spectral modeling accuracy.

## Key findings

- New NaH2 collisional profiles computed using semi-classical approach.
- Profiles significantly affect synthetic spectra of brown dwarfs and hot Jupiters.
- Profiles valid for high H2 densities in planetary atmospheres.

## Abstract

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 NaH2 collisional profiles at temperatures from 500 to 3000 K, the temperatures prevailing in the atmosphere of brown dwarfs and Jupiter-mass planets.The relevant H2 perturber densities reach several 10^19 cm^-3 in hot Teff > 1500 K Jupiter-mass planets and can exceed 10^20 cm^-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 NaH2 collisional profiles and their effects on the synthetic spectra of brown dwarfs and hot Jupiters computed with petitCODE are presented.