Density and Refractive Index of Carbon Monoxide Ice at Different Temperatures

This paper is intended to study the density and the refractive index of the solid carbon monoxide in the interval 13-28 K to improve our understanding of the dynamics in the astrophysical environments where they are present. A series of deposition experiments have been performed under high vacuum conditions to study the properties of this ice under astrophysical conditions. Ice density has been experimentally calculated at different deposition temperatures of astrophysical interest, which complement the scarce values present in the literature. The refractive index has also been experimentally determined. The data have been used to obtain an experimental relationship between refractive index and density. Values of density are necessary to interpret observations of astrophysical objects or to design irradiation experiments to understand how irradiation affects ices present in these objects. The experimental relationship found between density and refractive index allows us to estimate density from a known refractive index, even for temperatures not reached using our experimental setup.