An Equation of State of CO for use in Planetary Modeling

TL;DR

This paper provides a comprehensive equation of state for carbon monoxide (CO) across a wide range of temperatures and densities relevant to planetary interiors, filling gaps left by previous limited studies.

Contribution

It introduces a new, extensive CO equation of state applicable to planetary modeling, based on a general-purpose computational method and offering a downloadable lookup table.

Findings

Matches previous experimental and theoretical results within limited ranges.

Extends the equation of state to full relevant temperature-density range.

Provides a community-accessible lookup table for planetary modeling.

Abstract

Although carbon monoxide (CO) is an abundant molecule and may have great importance for planetary interiors, measurements of its properties are difficult due to its extreme volatility. We calculate the equation of state for CO over a range of temperature and density that is applicable to the conditions in planetary interiors. Previous experimental and theoretical studies cover only a limited temperature-density range. Our calculations match these early results well, but now cover the full range of relevance. The method of calculation is based on the general-purpose quotidian equation of state described by More et al. (1988), which is here used in order to generate a freely downloadable look-up table to be used by the community.