Optical properties of silicon carbide for astrophysical applications

Aims. The SiC optical constants are fundamental inputs for radiative transfer (RT) models of astrophysical dust environments. However, previously published values contain errors and do not adequately represent the bulk physical properties of the cubic (β) SiC polytype usually found around carbon stars. We provide new, uncompromised optical constants for β- and α-SiC derived from single-crystal reflectance spectra and investigate quantitatively (i) whether there is any difference between α- and β-SiC that can be seen in infrared (IR) spectra and optical functions and (ii) whether weak features from λ ~ 12.5-13.0 μm need to be fitted.