A new way to understand the formation and evolution of rocky planets

An international team, with participation of the CAB, has discovered a planetary system whose innermost exoplanet has the size of the Earth but a composition similar to Mercury. The existence of this type of planets is more common than previously thought and with this finding a new path is opened to know the processes that gave rise to the appearance of the rocky planets of the Solar System.

The discovered system is located around the star K2-229, which is similar to the Sun in temperature and age, and was detected with the Kepler space observatory by the method of planetary transits (occultations similar to eclipses). The most striking object found within this system has been the innermost (K2-229b), which is the size of the Earth but has a composition similar to that of Mercury, both considered rocky planets, next to Venus and Mars. < / div>

The study, published in the journal Nature Astronomy and in which it participates CAB researcher David Barrado indicates that K2-229b orbits much closer to its star than does Mercurio del Sol, and its "daytime" temperature can reach 2,330K. "This proximity possibly causes its mantle, the outermost part of the planet, to volatilize and form an atmosphere of silicate vapors," says Barrado. Part of that matter could have been lost in space, which would explain the unique composition of the planet. "An alternative explanation would be the impact with large asteroids, analogous to what happened to Earth when the Moon formed," he adds.

The exoplanet K2-229b is, therefore, an excellent laboratory to know the conditions of formation of analogues of Mercury, which will be studied by the European probe BepiColombo (whose launch is scheduled later this year), and also the rest of the rocky planets of the Solar System.


Figure: Mercury image obtained by NASA's Messenger spacecraft that reveals small flaws in its surface. © NASA / JHUAPL / Carnegie Institution of Washington / USGS / Arizona State University

 

Fuente: UCC-CAB

 

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