Transmission spectra of hot Jupiters

Hubble transmission spectral sequence of hot Jupiters from Sing et al. (2016). Data gathered with the STIS and the WFC3 instruments as well as with NASA’s Spitzer Space Telescope are shown, along with fitted atmospheric models, with prominent spectral features indicated. The spectra have been ordered by the altitude difference between the blue-optical and mid-infrared. Planets with clear atmospheres (top) show prominent alkali and H2O absorption, with infrared radii commensurate with, or higher than, the optical altitudes. Very hazy and cloudy planets (bottom) have strong optical scattering slopes, narrow alkali lines and H₂O absorption that is partially or completely obscured.