Scientists have provided tentative evidence for a sulfur-rich atmosphere on L 98-59 d, a super-Earth located 35 light years away. If confirmed, this would mark the smallest known exoplanet with an atmosphere. The potential presence of sulfur dioxide (SO₂) and hydrogen sulfide (H₂S) suggests a molten or volcanic surface.
L 98-59 d, discovered in 2019 by NASA's TESS space telescope, is 1.5 times the size of Earth. Most exoplanets are detected using the transit method, which measures dips in starlight as planets pass in front of their stars. The James Webb Space Telescope (JWST) conducted observations during one such transit, allowing scientists to obtain the planet's transmission spectrum.
This spectrum hinted at the possible presence of SO₂ and H₂S, contrasting sharply with the atmospheres of rocky planets in our solar system, where water vapor and carbon dioxide are more prevalent. The absence of common gases and the presence of sulfur compounds suggest unique atmospheric processes on L 98-59 d.
Further observations are necessary to confirm these findings, as detecting atmospheres on small, rocky planets poses significant challenges. The extreme conditions on L 98-59 d, including its close proximity to its host star, could lead to volcanic activity similar to that observed on Jupiter's moon Io.
While this exoplanet may not be suitable for life as we know it, studying its atmosphere and potential volcanism offers valuable insights into the diversity of planetary evolution in the galaxy.