Transmission Spectrum — WASP-107 b (Hubble WFC3, Webb NIRCam, and Webb MIRI)

This transmission spectrum, captured using the NASA/ESA/CSA Hubble and James Webb space telescopes, shows the amounts of different wavelengths (colours) of starlight blocked by the atmosphere of the gas-giant exoplanet WASP-107 b .

The spectrum includes light collected over four separate observations using a total of three different instruments: the NASA/ESA Hubble Space Telescope’s WFC3 (0.8–1.6 microns), Webb’s NIRCam (2.4–4.0 microns and 3.9–5.0 microns), and Webb’s MIRI (5–12 microns). Each set of measurements was made by observing the planet–star system for about 10 hours before, during, and after the transit as the planet moved across the face of the star.

By comparing the brightness of light filtered through the planet’s atmosphere (transmitted light) to unfiltered starlight, it is possible to calculate the amount of each wavelength that is blocked by the atmosphere. Since each molecule absorbs a unique combination of wavelengths, the transmission spectrum can be used to constrain the abundances of various gases.

This spectrum shows clear evidence for water (H2O), carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), sulphur dioxide (SO2), and ammonia (NH3) in the planet’s atmosphere, allowing researchers to estimate its interior temperature and the mass of its core.

This wavelength coverage from optical to mid-infrared is the broadest of any exoplanet transmission spectrum to date, and includes the first reported detection of ammonia in an exoplanet atmosphere.

[Image description: Transmission Spectrum of Hubble WFC3 Grism Spectroscopy; Webb NIRCam Grism Spectroscopy; Webb MIRI Low-Resolution Spectroscopy showing a graph of Amount of Light blocked vs. Wavelength of Light, with peaks for water, carbon dioxide, carbon monoxide, methane, sulfur dioxide, and ammonia labeled. ]

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