Date: Monday 01-Nov-2021
Time: 11:15-12:15
Location: ATL 1250 and via Zoom (link sent out to the PALS distribution list prior to the talk)
Speaker: Teal (University of Maryland)
Title: Impacts of host star UV uncertainty on exoplanet atmospheres
The upcoming launch of JWST will advance our ability to characterize exoplanet atmospheres. Disequilibrium chemical processes dominate the cooler atmospheres, requiring accurate photochemical modeling of such environments. The host star's UV spectrum is an important input to these models, but most exoplanet hosts lack UV observations. For cases in which the host UV spectrum is unavailable, a reconstructed or model spectrum must be used in its place. We use the MUSCLES catalog and UV line scaling relations to understand how well reconstructed host star spectra reproduce photochemically modeled atmospheres in lieu of real UV observations. We focus on two cases; a modern Earth-like atmosphere and an Archean Earth-like atmosphere that forms significant amounds of hydrocarbon haze. We find that modern Earth-like environments are well-reproduced with UV reconstructions, whereas haze-bearing (Archean Earth) atmospheres suffer from changes at the observable level. Both stellar UV emission lines and continuum significantly influence the chemical state and haze production in our modeled Archean atmospheres, resulting in observable differences in their transmission spectra. Our modeling results indicate that UV observations of individual exoplanet host stars are needed to accurately characterize hazy terrestrial atmospheres. In the absence of UV data, reconstructed spectra accounting for both UV emission lines and continuum flux are the next best option, though model accuracy will suffer.
For further information contact PALS coordinators Drs. Quanzhi Ye (qye@umd.edu) and Matej Malik (malik@umd.edu).
SPECIAL ACCOMMODATIONS:Special accommodations for individuals with disabilities can be made by calling (301) 405-3001. It would be appreciated if we are notified at least one week in advance.
