The initial submitted proposal was in "AR Legacy Theory" category. However, that proposal was modified and converted into the "AR regular-Theory" proposal, and resubmitted. 1807445948 Assigned ID: 103 ----- Attempting Submission 1 (Tue Apr 02 20:41:13 GMT 2019) ----- HST Phase I Proposal 103 (2019_HST_Proposal_1.apt) successfully submitted. Receipt: # 103-1 ----- Attempting Submission 2 (Wed Apr 03 18:56:26 GMT 2019) ----- 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. Our team consists of highly experience molecular/atomic line specialists and exoplanet/brown dwarf atmospheric modelers. PI Gharib-Nezhad is a postdoctoral researcher with experience in both theoretical computation and laboratory measurements of molecular opacities. He will oversee the project operations and execute a majority of the tasks. PI Gharib-Nezhad will collaborate closely with Co-PI Line. Line is a world leading expert in exoplanet atmospheric retrieval modeling on HST data of transiting exoplanets, and will oversee/assist with the modeling implementation of the proposed opacity database. Line is also aware of all of the relevant HST spectra/publications that will be re-interpreted with this analysis. PI will also collaborate with Co-I Kempton on radiative transfer modeling of high-metallicity exo-atmopsheres. Co-I Kempton is a leading expert on atmopheric modeling of the reflected, thermally emitted, and transmitted spectra from atmospheric absorbers and cloud particles. Co-I Lyons is an expert in atomic and molecular spectroscopy as well as atmospheric chemistry. He will advise the team on relevant sources of laboratory derived pressure broadening coefficients and plausible atmospheric chemical compositions. Co-I Hayes is an expert in laboratory molecular cross-section measurements and opacity computations and will assist with determining approximations for pressure broadening to speed up computations. Co-Is Marley and Freedman are world leading brown dwarf modeling and opacity experts. Freedman has decades of experience in collating line lists and broadening information from the scattered literature. Their experience and assistance will be an invaluable resource to this project. Planets and Planet Formation 0 Regular false false false true false SUPPORTED