In recent years, significant advances have been made in exoplanet and brown dwarf observations. By using state-of-the-art models, astronomers can determine properties of their atmospheres, such as temperatures, the presence of clouds, or the chemical abundances of molecules and atoms. Accurate and up-to-date opacities are crucial to avoid inconclusive or biased results, but it can be challenging to compute opacity cross-sections from the line lists provided by various online databases. We introduce pyROX, an easy-to-use Python package to calculate molecular and atomic cross-sections. Since pyROX works on CPUs, it can compute a small line list on a regular workstation, but it is also easily parallelised on a cluster for larger line lists. In addition to line opacities, pyROX also supports calculations of collision-induced absorption. Tutorials are provided in the online documentation which explain the configuration parameters and different functionalities of pyROX.
@article{arxiv.2510.20870,
title = {pyROX: Rapid Opacity X-sections},
author = {Sam de Regt and Siddharth Gandhi and Louis Siebenaler and Darío González Picos},
journal= {arXiv preprint arXiv:2510.20870},
year = {2025}
}
Comments
4 pages. Submitted to the Journal of Open Source Software (JOSS)