Abstract

Spectroscopic observations of exoplanets are leading to unprecedented constraints on their atmospheric chemical compositions. Molecular abundances can be derived from atmospheric spectra using sophisticated models and retrieval methods. However these are degenerate with molecular absorption cross-sections, crucial inputs to atmospheric models. New, high-temperature molecular transition line lists are now available and we are in a position to investigate these inputs. In this talk I will address the results of our recent paper on the effects of pressure broadening on molecular absorption cross sections and the affect we anticipate on observations of exoplanet atmospheres. This has included estimates of the uncertainties in molecular cross sections which will directly impact abundance measurements. I will discuss how the measurements across wide ranges of pressure, temperature and resolution impact the accuracy of molecular cross sections, particularly in the context of future instruments and exoplanet targets. We find that the effect of pressure broadening on molecular absorption cross-sections can be significant, over 100%, for high spectral resolutions that can be obtained by present and upcoming instruments, and especially for low temperature atmospheres.