Simulated Thermal Emission Spectrum of Exoplanet LHS 3844 b

Possible thermal emission spectrum of the hot super-Earth exoplanet LHS 3844 b, as measured by Webb’s Mid-Infrared Instrument. A thermal emission spectrum shows the amount of light of different infrared wavelengths (colors) that are emitted by the planet. Researchers use computer models to predict what a planet’s thermal emission spectrum will look like assuming certain conditions, such as whether or not there is an atmosphere and what the surface of the planet is made of. 

This particular simulation assumes that LHS 3844 b has no atmosphere and the day side is covered in the dark volcanic rock basalt. (Basalt is the most common volcanic rock in our solar system, making up volcanic islands like Hawaii and most of Earth’s ocean floor, as well as large portions of the surfaces of the Moon and Mars.)

For comparison, the gray line represents a model spectrum of basaltic rock based on laboratory measurements. The pink line is the spectrum of granite, the most common igneous rock found on Earth’s continents. The two types of rock have very different spectra because they are made of different minerals, which absorb and emit different amounts of different wavelengths of light. 

After Webb observes the planet, researchers will compare the actual spectrum to model spectra of various rock types like these to figure out what the surface of the planet is made of.