Results from the GEMINI/GMOS transmission spectral survey of close-in gas giant exoplanets
Estimating the nature and abundances of chemical species and clouds in exoplanetary atmospheres forms the backbone of comparative exoplanetology. We present the results from a long-term ground-based survey of a dozen of transiting hot Jupiters observed in the visible bandpass using the multi-object spectroscopy technique with the Gemini Multi-Object Spectrograph (GMOS). By observing multiple transits of an ensemble of hot Jupiters spanning a range of masses, radii, and host star types, and using a consistent methodology for extracting the transmission spectra across the sample, we derive common properties for their atmospheres. Ultimately, this survey aims at holistically understanding the diversity of physical processes in play in exoplanetary atmospheres. In addition to retrieving the chemical and cloud composition, and overall atmospheric properties for the planets in our sample, we also describe the analysis and correction for dominant noise sources in the transmission spectra. We show that the characteristics of the cloud particles and their effect on the continuum pressure level are crucial in interpreting multi-wavelength observations of hot Jupiters from existing and planned instruments, including JWST.