Major discovery as 'Super Earth' planet found - but its neighbour 'stinks of rotten eggs'

Astronomers have confirmed a fifth planet orbiting the nearby red dwarf L 98‑59, which lies in the star’s habitable zone. The newly detected world, L 98‑59 f, is a super-Earth with a minimum mass of 2.8 Earth masses and an orbital period of 23 days, detected via archival HARPS and ESPRESSO radial velocity data.

Charles Cadieux, lead author of the discovery paper and researcher at the University of Montreal’s Institute for Research on Exoplanets (iREx), said: “It gives us key targets for future atmospheric studies with the James Webb Space Telescope.” He added: “Finding a temperate planet in such a compact system makes this discovery particularly exciting.” The L 98‑59 system, about 35 light-years away, also hosts three inner planets previously studied using the James Webb Space Telescope. JWST recently detected sulfur dioxide in the atmosphere of planet b, likely due to volcanic activity.

René Doyon, co-author of the study and director of iREx, said: “With its diversity of rocky worlds and range of planetary compositions, L 98‑59 offers a unique laboratory to address some of the field’s most pressing questions: How do planets form and evolve? Can rocky planets around red dwarfs retain atmospheres over time?”

Because L 98‑59 f does not transit, astronomers cannot yet measure its radius or atmospheric composition.

However, future observatories—such as the Extremely Large Telescope (ELT) and proposed direct-imaging missions like LUVOIR—may be able to characterize its atmosphere.

The discovery of L 98‑59 f highlights a nearby super-Earth in the habitable zone, making it a strong candidate for further investigation in the search for life beyond Earth.

The habitable zone—often called the "Goldilocks zone"—is the region around a star where conditions are just right for liquid water to exist on a planet’s surface.

If a planet orbits too close to its star, temperatures become too high, causing water to evaporate; too far, and water freezes solid.

Since liquid water is essential for life as we know it, the habitable zone is a primary focus when searching for potentially life-supporting exoplanets.

Its exact boundaries depend on the star’s size, temperature, and brightness, varying significantly between different types of stars.

Understanding the habitable zone matters because it helps astronomers prioritize which planets to study in the quest to find life beyond Earth.

Planets within this zone have the potential to maintain stable climates conducive to biology.

While being in the habitable zone doesn't guarantee a planet is actually habitable—factors like atmosphere, magnetic field, and geological activity also matter—it remains the best initial filter for identifying promising worlds.

Another research team previously discovered that nearby planet L 98-59 d, which is bigger and heavier than Earth, could 'reek of burnt matches and rotten eggs' due to its sulfur-rich atmosphere. Agnibha Banerjee, one of the researchers, previously told Mashable: "If these findings can be confirmed and turn out to be true, this planet won't be pleasant on human noses.

"Then again, if a human in the far future were to ever visit, the smell would be the least of their problems — in the midst of crushing pressure, boiling temperatures, and toxic gases."