Paul Molliere

The hunt for isotop(ologu)es in exoplanet atmospheres

Using high-resolution spectra, the unique identification of molecules such as water and carbon monoxide in exoplanet atmospheres has been possible. In addition, this powerful technique allows to infer atmospheric temperatures and absorber abundances. It can even be used to measure atmospheric wind speeds, as well as planetary spin rates. For such inferences the line shape and position of detected atmospheric absorbers is used. In my presentation, I will show how upcoming and next-generation observing facilities may allow us to detect the presence of molecular isotopologues (such as 13C16O and HDO) in exoplanet atmospheres. As I will discuss, such detections can potentially constrain the accretion and evolution history of planetary atmospheres, where the accretion of icy bodies such as comets, and the evaporation due to the stellar irradiation, can lead to high D/H ratios.
You can read Paul and Ignas’ paper here.

Apparent spectrum of Proxima Cen b at a distance of 1.29 pc, assuming it is identical to Earth. The planet synthetic thermal spectrum, assuming the Earth’s P–T profile and abundances, is shown as a black solid line. The red solid line shows the reflected light assuming a surface albedo of 30%, including the attenuation of the planetary atmosphere. At the wavelength range shown here, nearly all lines are due to HDO absorption.