Optical to near-infrared transmission spectra of three cool gas giants

Ian Wong


Transmission spectroscopy has emerged as a powerful tool in studying the chemical composition of exoplanet atmospheres. By measuring the variations in transit depth as a function of wavelength, this technique directly probes the atmosphere along the day-night terminator and is sensitive to various atmospheric components through their absorption signatures in the transmission spectrum. Unfortunately, a large number of recent transmission spectroscopy studies have been confounded by the presence of clouds and hazes. As part of the ongoing effort to better understand the prevalence and diversity of clouds and hazes in exoplanetary atmospheres, I present the latest results from transmission spectroscopy analyses of a trio of relatively cool gas giants — HAT-P-12b, WASP-29b, and WASP-80b. Combining spectroscopic observations obtained using HST/WFC3 and HST/STIS with Spitzer/IRAC broadband photometry yields high-quality spectra spanning 0.3–5.0 microns. My analysis is supplemented by secondary eclipse measurements at 3.6 and 4.5 microns. In interpreting the results, both state-of-the-art self-consistent atmospheric retrievals and predictions from microphysical cloud models are used to constrain the atmospheric properties of these planets. Comparisons of the retrieved cloud properties with the forward model results reveal the limitations of our current understanding of the physical and chemical processes that govern exoplanetary atmospheres.

Date: Jeudi, le 14 février 2019
Heure: 11:30
Lieu: Université de Montréal
  Pavillon Roger-Gaudry, Local D-460
Contact: Björn Benneke