In the immensity of space, a planet intrigues astronomers with its extreme properties. Nestled in the K2-360 system, the planet K2-360 b, a very special super-Earth, could well redefine our understanding of rocky worlds.
750 light years from Earth, K2-360 b orbits its star in just 21 hours. It has a radius 1.6 times greater than that of our planet, but its mass, almost eight times greater, testifies to a density extraordinary, equivalent to that of lead. This unique characteristic makes it the densest planet in its category.
Such density is explained by a massive core probably composed of iron, representing almost half of its total mass. This feature suggests that K2-360 b is the remnant of a once larger world, stripped of its outer layers under the effect of intense stellar radiation. Astronomers assume that the surface of this planet is covered by an ocean of magma. A direct consequence of its proximity to its star, which subjects it to extreme temperatures. This heat could also explain the disappearance of a possible atmosphere primitive.
In the same system, another planet, K2-360 c, is also intriguing. More massive, it completes one revolution around the star in 9.8 days. Its presence would have played a role in the current positioning of K2-360 b via a gravitational mechanism called “high-speed migration”. eccentricity“.
According to this process, the orbit of K2-360 b would initially have been very elliptical. Tidal forces exerted by the star would then have stabilized this trajectory into a near circular orbit. These interactions highlight the complexity planetary dynamics.
The discovery of K2-360 b, made possible by NASA’s K2 mission and confirmed by ground-based telescopes, provides a unique opportunity to study planet formation in extreme environments. This particular system calls into question existing models, particularly on the evolution of super-Earths.
These ultra-dense worlds are rare, and their extraordinary characteristics allow us to better understand the diversity of planetary architectures in the Universe. K2-360 b could thus serve as a model to explore the fate of other exoplanets close to their star.
What is high eccentricity migration?
High eccentricity migration is a process dynamic which shapes the orbit of planets around their star. This phenomenon occurs when gravitational interactions between several celestial bodies disrupt the initial orbit of a planet. In this scenario, a planet can see its orbit become extremely elliptical, bringing it alternately very close and very far from its star. For K2-360 b, this migration would have been caused by interactions with K2-360 c, its neighboring planet. These forces would explain how such a massive planet could find itself in an orbit so close to its star.
Astronomers use this mechanism to explain the presence of giant or rocky planets located very close to their star, defying traditional models of planetary formation.
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