Astronomers have identified a possible new type of planet outside the Solar Systemwith a molten interior and an atmosphere rich in sulfur. The object, called L 98-59 d, is about 35 light years from Earth and was analyzed with data from the James Webb Space Telescope and ground observatories. The study was published in the scientific journal Nature Astronomy.
The planet is about 1.6 times the size of Earth, but has a lower density than expected. Observations indicated the presence of sulfur-containing gases, such as hydrogen sulfide, in the atmosphere. Until now, scientists would classify such a world as a rocky planet with gas or a planet covered by deep oceans, but the new data suggests it doesn’t fit into either of those categories.
Simulations carried out by researchers at the University of Oxford and other universities indicate that the planet’s interior may be formed by , similar to lava. Models point to the existence of a global magma ocean that extends thousands of kilometers below the surface. This hot material would allow it to store large amounts of sulfur over billions of years.
According to scientists, this internal reservoir helps the planet maintain an atmosphere, rich in hydrogen and sulfur gases, which would normally be lost to space because of radiation from the star around which it revolves. Chemical reactions between the molten interior and the atmosphere would have shaped the features observed today.
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The researchers say the planet could be the first known example of a new class of worlds, with an interior molten for long periods and a large amount of gases. Although it hasn’t, the discovery shows that the variety of planets in the galaxy may be greater than previously imagined.
The study authors say new observations with space telescopes should help to better understand this type of planet and reveal how many other unusual worlds may exist beyond the Solar System.
