2025ApJ...993..172R

Polycyclic aromatic hydrocarbon (PAH) molecules have long been theorized to be present in a multitude of interstellar environments. The radio-frequency detections of specific cyanosubstituted PAH molecules in the Taurus Molecular Cloud have provided new evidence that PAHs can be abundant in the interstellar medium. In particular, the recent detection of cyanocoronene strongly implies the existence of interstellar coronene. In this paper, we determined the infrared index of refraction and band strengths of coronene thin films vacuum-deposited at 5.1 K. Our values of the imaginary part of the index of refraction and the corresponding coronene band strengths are generally smaller in magnitude than those determined by previous efforts. These index of refraction and band strength values will be useful for interpreting infrared observations of high-extinction interstellar regions or planetary or exoplanetary atmospheres where condensed-phase coronene is likely to be present or for calculating upper limits on the interstellar coronene abundances.