Principal Investigator: Michael Line
PI Institution: Arizona State University
Investigators
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Title: Maximizing the Science Return from HST UV Observations of Transiting Exoplanet Atmospheres
Cycle: 30
Abstract
Spectroscopic characterization of transiting exoplanets with HST has led to a sea of change in our understanding of extra-solar atmospheres, from ultra-hot Jovians to temperate super-Earth worlds. Transmission spectra are sensitive to molecular and atomic absorbers, clouds/hazes, molecular weight, and average temperature at high altitudes along the limbs of the planet. Much of the theoretical and observational focus has been on understanding/interpreting the atmospheric properties that can be informed by optical/near-IR spectra--primarily due to the nominal observing mode/capabilities of HST and Spitzer. However, recent advances in HST observing modes and data processing (e.g., WFC3/UVIS-G280) have enabled simultaneous broadband NUV-to-Optical spectroscopy of transiting planets. However, there has been little theoretical development in understanding just how diagnostic NUV spectra, and their combination with longer wavelengths, can be. NUV spectra, owing to large refractory, gaseous opacities, are thought to be diagnostic of the onset of condensate cloud formation, vertical mixing, and refractory composition in planetary atmospheres. Our proposed theoretical work will develop a foundation for understanding the exoplanet atmospheric processes that benefit from NUV observations. We will develop an atmospheric population synthesis framework, leveraging state-of-the-art radiative convective models, to generate predictive atmospheric process hypotheses that can be tested with NUV observations and directly compared to publish datasets. This theoretical foundation will have implications for over a dozen planets over a dozen NUV HST programs and beyond.