Partition functions and equilibrium constants for diatomic molecules and atoms of astrophysical interest

TL;DR

This paper provides comprehensive partition functions and dissociation constants for 291 diatomic molecules and 284 atomic species, covering temperatures up to 10,000 K, to aid astrophysical modeling of various low-density environments.

Contribution

It offers updated and extensive spectroscopic data for diatomic molecules and atoms, improving the accuracy of astrophysical models compared to previous datasets.

Findings

Partition functions for 291 diatomic molecules across a wide temperature range.

Atomic data for all elements from H to U are included.

The data set enhances modeling of astrophysical environments like star-forming regions.

Abstract

Partition functions and dissociation equilibrium constants are presented for 291 diatomic molecules for temperatures in the range from near absolute zero to 10000 K, thus providing data for many diatomic molecules of astrophysical interest at low temperature. The calculations are based on molecular spectroscopic data from the book of Huber and Herzberg with significant improvements from the literature, especially updated data for ground states of many of the most important molecules by Irikura. Dissociation energies are collated from compilations of experimental and theoretical values. Partition functions for 284 species of atoms for all elements from H to U are also presented based on data collected at NIST. The calculated data are expected to be useful for modelling a range of low density astrophysical environments, especially star-forming regions, protoplanetary disks, the interstellar medium, and planetary and cool stellar atmospheres. The input data, which will be made available electronically, also provides a possible foundation for future improvement by the community.