Thermal emission spectrum of rocky planet LHS 3844 b reveals surface composition clues

LHS 3844 b is a rocky super-Earth orbiting a nearby Red dwarf. Because it lacks a significant atmosphere and does not have a molten magma ocean on its dayside, it serves as a unique laboratory for studying the surface of planets outside our solar system. By analyzing the planet’s heat signatures, researchers can infer what kind of rock covers its surface.

The James Webb Space Telescope captured detailed mid-infrared light emissions from the planet, combining data from eleven separate eclipse observations to achieve high precision. Infrared light allows researchers to see heat patterns that reveal the chemical makeup of solid surfaces, similar to how different minerals on Earth reflect specific wavelengths of light.

The collected data shows that the planet emits heat much like a perfect thermal radiator, known as a blackbody, at shorter infrared wavelengths. However, researchers identified a subtle, tentative feature in the light spectrum between 10 and 12 micrometers. If this signal is confirmed to originate from the planet, it may suggest the presence of minerals like fayalite, a type of iron-rich olivine, or other volcanic materials.

Key findings
- Obtained the highest-quality infrared emission spectrum for a rocky exoplanet to date.
- Observed thermal emission that closely matches a blackbody curve at wavelengths shorter than 10 micrometers.
- Detected a tentative spectral feature between 10 and 12 micrometers that may indicate specific surface minerals.
- Identified fayalite, spinel, or silicon carbide as potential candidates for the planet's surface composition.
- Disfavored the presence of a transparency feature, which helps constrain the grain size and porosity of surface materials.

Scientific study

Improved Constraints on the Surface of LHS 3844 b from its Mid-Infrared Spectrum (external link)