# Calculation of molecular line intensity in stellar atmospheres

## TL;DR

This paper discusses methods for calculating molecular line intensities in stellar atmospheres, introduces a new spectrum synthesis code for cool stars, and demonstrates its application to various spectral features.

## Contribution

It presents a comprehensive description of molecular line calculations and introduces a new, publicly available spectrum synthesis code for cool star analysis.

## Key findings

- Successful application to molecular bands in UV, visible, and near-infrared
- Comparison with reference star spectra validates the methods
- User-friendly tools facilitate spectrum synthesis for cool stars

## Abstract

Molecular line intensity calculations are not a straightforward task. We present a description of the basics for including molecular linesin synthetic spectra, and of the input data needed. We aim both at describing ways in which molecular lines are computed in the context of photospheres of F-G-K stars, and to present a new online available version of our code for spectrum synthesis of cool stars. We apply calculations to molecular bands in the ultraviolet, visible and near-infrared main features, and comparisons with spectra of reference stars are shown. We provide user-friendly tools for the free use of the code PFANT. The code is available at http://trevisanj.github.io/PFANT.