OXFORD, UNITED KINGDOM — Astronomers from the University of Oxford identified a completely new class of molten planet Monday orbiting a red dwarf star 35 light-years away, according to research published in Nature Astronomy, immediately upending established planetary classification systems worldwide.
The discovery shatters the binary categorization system that previously classified 100% of similar small exoplanets as either rocky gas dwarfs or water-rich ice worlds. Researchers confirmed Monday that the extreme greenhouse effect on L 98-59 d sustains a liquid silicate mantle thousands of kilometers deep, fundamentally altering how space agencies will target future exploratory missions.
The reclassification directly impacts hundreds of astrophysicists mapping the cosmos across three major space agencies. The findings dictate new operational parameters for at least two upcoming multi-billion-dollar observatory projects, which must now recalibrate their instruments to screen for this distinct sulfur-rich signature.
Simulation models spanning five billion years reviewed by this newsroom show the planet did not form in its current state. The data indicates L 98-59 d initially materialized as a massive sub-Neptune world heavily saturated with volatile gases, before shrinking rapidly due to extreme stellar radiation that burned away its outer layers.
In the United States, NASA engineers operating the James Webb Space Telescope captured critical sulfur dioxide readings high in the planet’s atmosphere during initial 2024 observation runs. Meanwhile, in the United Kingdom, the University of Oxford team spent two years processing complex thermodynamic models to prove those specific molecules were venting from a global underground lava reservoir.
Technical documents examined by reporters reveal the magma ocean refuses to cool down. Gravitational friction from neighboring planets generates internal heat mimicking the extreme volcanic loops seen on Jupiter’s moon Io, locking the planet in a permanent molten state.
NASA JWST Exposes Permanent Magma Ocean On L 98-59 d
The extreme internal temperatures create an atmospheric profile entirely unique in the known universe. Observers noted the atmosphere contains massive concentrations of hydrogen sulfide, giving the entire planet the distinct chemical signature of rotten eggs.
“Current categories astronomers use to describe small planets may be too simple,” lead author Harrison Nicholls said.
This atmospheric sulfur acts as a geologic fingerprint, confirming the continuous cycle of volcanic activity. Ultraviolet-driven chemical reactions triggered by the host star break down the gases, which then cycle back into the molten interior over geologic timescales, according to the official publication in Nature Astronomy.
The new molten classification system requires planets to meet three specific criteria:
- Orbiting closely to a host star causing severe ultraviolet reactions
- Atmospheric saturation of heavy sulfur molecules
- A molten silicate mantle cycling gases over geologic timescales
Before this discovery, planetary science relied on a rigid framework that left anomalous worlds miscategorized. The updated observational data establishes clear boundaries between the newly defined planetary types.
| Planet Class | Primary Surface Composition | Dominant Atmospheric Signature |
|---|---|---|
| Gas Dwarf | Solid rocky core | Thick hydrogen envelope |
| Water World | Deep liquid oceans and ice | High water vapor concentration |
| Molten Sulfur World | Liquid silicate magma | Hydrogen sulfide and sulfur dioxide |
Molten Planet L 98-59 d Unlocks Earths Early Formation
The discovery provides an unprecedented window into the deepest history of our own solar system. Magma oceans represent the initial developmental state of all rocky planets, including Earth and Mars.
Because our home planet cooled and solidified billions of years ago, the geological evidence of its molten phase eroded under tectonic shifting and oceans of water. The perpetual lava state of L 98-59 d offers researchers a frozen-in-time snapshot of planetary infancy.
“We can use computer models to uncover the hidden interior,” co-author Raymond Pierrehumbert said.
These same models will immediately apply to incoming datasets from next-generation space hardware. The European Space Agency plans to launch the Ariel mission in 2029, followed shortly by the PLATO observatory.
Both missions will prioritize scanning for the newly identified sulfur signatures across neighboring star systems. The Oxford research team continues calibrating their thermodynamic framework to process the anticipated flood of new atmospheric data.
