Ground-based spectroscopy reveals hydrogen sulfide in the atmosphere of super-Earth L 98-59 d

Star system: L 98-59 | Distance from the Sun: 34.6 light years

Scientists have used high-resolution transmission spectroscopy from the Gemini-South telescope to study the atmosphere of the temperate super-Earth exoplanet L 98-59 d. This approach, typically used for larger and hotter planets, was successfully applied to a smaller, more temperate world, demonstrating the capability of ground-based facilities to characterize super-Earth atmospheres.

The team confirmed the presence of hydrogen sulfide (H2S) in the atmosphere of L 98-59 d, supporting earlier tentative findings from JWST. This marks the first time a molecular species has been detected in a super-Earth’s atmosphere using ground-based observations. The data suggest a cloud-free atmosphere with H2S abundances between one and ten times that of the Sun. The study also ruled out high levels of methane (CH4) and ammonia (NH3), and the results are consistent with the idea that volcanic outgassing may be producing H2S in the planet’s atmosphere.

These findings highlight the potential for future ground-based studies to further constrain the atmospheric composition of super-Earth exoplanets using high-resolution spectroscopy.

Key findings
- First ground-based detection of hydrogen sulfide in a super-Earth’s atmosphere (L 98-59 d).
- Cloud-free atmosphere with H2S abundance between one and ten times solar metallicity.
- High levels of methane and ammonia are ruled out, supporting volcanic outgassing as a source of H2S.

Scientific study

Ground-based Atmospheric Characterization of Super-Earth L 98-59 d at High Spectral Resolution (external link)