Composition Dependent Molecular Opacity Database for High-Metallicity Exoplanet Atmospheres
Abstract
Planet formation models suggest broad compositional diversity in the super-Earth to sub-Neptune regime, with a high likelihood for large atmospheric metal content (100-1000xSolar). With this comes the prevalence of numerous plausible bulk atmospheric constituents including H2O, CO, CO2, CH4, and N2. Given this compositional diversity there is a critical need to investigate the influence of the background gas on the broadening of the molecular opacities and the subsequent influence on observed spectra. This foreign broadening can become significant and the near universal use of H2/He or "air" broadening is no longer appropriate. To explore this effect, we propose to 1) generate an opacity database for key atmospheric absorbers (i.e., H2O, CH4, CO2, and CO) broadened by "Self" or foreign broadeners (e.g., H2O by H2O or H2O by CO2), 2) determine the impact of mixtures of broadeners (e.g., H2O and CH4 broadening of CO2) on the opacity data (absorption cross sections) and 3) incorporate these composition-dependent opacities into exoplanet atmosphere modeling tools to re-interpret and evaluate archival HST data and make predictions for future HST observations of these worlds.
- Publication:
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HST Proposal
- Pub Date:
- June 2019
- Bibcode:
- 2019hst..prop15796G