Thousands of kilometers of deep magma ocean: A new type of exoplanet found
Rocky planets have so far been known in two different forms. However, an exoplanet has now been discovered that does not fit into either category.
Artistic representation of L 98-59 d
(Image: Mark A. Garlick / markgarlick.com)
A research group has discovered an exoplanet with a magma ocean thousands of kilometers deep using the James Webb Space Telescope. This contributes to the planet being able to retain a dense, hydrogen-rich atmosphere. This was published by the British University of Oxford, which explains that the celestial body apparently belongs to a new class of exoplanets. The celestial body is designated L 98-59 d and could be the first known member of a larger population of gas-rich and sulfur-containing exoplanets that can sustain long-lived magma oceans: "If so, the diversity of worlds in our galaxy may be even greater than previously imagined."
A new category of exoplanet
The discovery suggests that the currently used categories for classifying small exoplanets are too simplistic, according to study leader Harrison Nicholls. The exoplanet L 98-59 d, located 35 light-years away, has an unusually low density while being about 1.6 times the size of our Earth. Previously, it would have been classified as a "rocky gas dwarf" with a hydrogen-rich atmosphere, or as a water-rich world with a deep ocean or an ice crust. However, neither applies to the exoplanet; instead, it is unusually rich in heavy sulfur molecules.
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The vast magma ocean can absorb extreme amounts of sulfur and store it for immense periods, the team explains. This also suggests that the celestial body must have been much larger in the past and has only shrunk to its current size during its slow cooling process. At the same time, the research group points out that all rocky planets – including Earth and Mars – are initially surrounded by large magma oceans. The study of L 98-59 d could therefore now provide insights into their physics. The study was published by the research group in the journal Nature Astronomy.
(mho)
