MUSCLES Extension for Atmospheric Transmission Spectroscopy: Essential Ultraviolet Stellar Characterization for Guaranteed JWST Transiting Planet Targets
Abstract
JWST will launch during HST cycle 28 and begin an unprecedented era in atmospheric characterization for all types of exoplanets. Atmospheric spectroscopy of warm rocky planets, sub-Neptune, and Jupiter-mass planets will be obtained through a robust set of guaranteed transiting planet observations (the JWST ERS and GTO programs). To accurately model and interpret observations of these planets' atmospheres, we must understand the high-energy SED of their host stars: FUV and NUV-driven photochemistry shapes an atmosphere's molecular abundances and the formation of hazes, EUV irradiation can erode a planet's gaseous envelope, and flares can affect long term stability.
A number of recent surveys have used HST's UV capabilities to characterize the energetic irradiance spectra across a range of stellar masses, ages, and activity levels. While these surveys have proven invaluable for predicting photochemical tracers and evolution of an exoplanet's atmosphere, they have also shown scatter in behavior and irradiance properties for stars of similar type. As a result, direct UV observations remain the gold standard for understanding the effects of the stellar irradiance on a specific exoplanet. We propose to obtain temporally-resolved UV (1150-3200 Ang) stellar spectroscopy of the 13 JWST guaranteed time targets with no UV characterization data in the HST archive. Our proposed observations will provide the UV context necessary to determine the likelihood of atmospheric formation and retention, the identification and interpretation of atmospheric chemistry, and the impacts of stellar activity on the exoplanet atmospheric stability.- Publication:
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HST Proposal
- Pub Date:
- May 2020
- Bibcode:
- 2020hst..prop16166F