An international team of researchers, using the Cheops space telescope, has detected an unusual exoplanet system whose structure contradicts traditional ideas about cosmic evolution. Four objects orbit the star LHS 1903, located 117 light-years away, whose arrangement baffles scientists: a rocky planet is significantly farther from the star than its gaseous neighbors. This is reported by Reuters, writes UNN.
Details
Usually, planets forming near a star are small and rocky due to high temperatures, while gas giants are born in colder outer regions. However, in the LHS 1903 system, the inner planet is rocky, the next two are gaseous "mini-Neptunes," and the fourth again turns out to be a solid "super-Earth."
The paradigm of planet formation states that planets close to their star should form small and rocky, with little or no gas or ice. This is because this environment is too hot to support significant amounts of gas or ice, and any atmospheres that do form are likely to be stripped away by radiation from their star. Conversely, planets at greater distances are thought to build up in colder regions with abundant gas and ice, creating gas-rich worlds with large atmospheres. This system challenges that, giving us a rocky planet beyond the gas-rich planets.
Wilson described this discovery as a "system built from the inside out," making it a unique case among more than six thousand already known exoplanets.
Compactness and characteristics of objects
All four planets in the LHS 1903 system are located extremely close to their parent star – even the farthest one is closer to the star than Mercury is to our Sun. This is because the star itself is a red dwarf, which is 50% less massive than the Sun. The two rocky planets in this system belong to the super-Earth class, having a mass several times greater than Earth's, and the gas worlds are classified as mini-Neptunes.
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