WASP-39 b Atmospheric Composition (NIRSpec G395H)

The atmospheric composition of the hot gas giant exoplanet WASP-39 b has been revealed by the NASA/ESA/CSA James Webb Space Telescope.

A transmission spectrum is made by comparing starlight filtered through a planet’s atmosphere as it moves in front of the star, to the unfiltered starlight detected when the planet is beside the star. Each of the data points (white circles) on these graphs represents the amount of a specific wavelength of light that is blocked by the planet and absorbed by its atmosphere. Wavelengths that are preferentially absorbed by the atmosphere appear as peaks in the transmission spectrum.

The blue line is a best-fit model that takes into account the data, the known properties of WASP-39 b and its star (e.g., size, mass, temperature), and assumed characteristics of the atmosphere. Researchers can vary the parameters in the model – changing unknown characteristics like cloud height in the atmosphere and abundances of various gases – to get a better fit and further understand what the atmosphere is really like.

This graph displays data from Webb's NIRSpec instrument, indicating signatures of water, sulfur dioxide (SO2), carbon dioxide (CO2), and carbon monoxide (CO).