Discovered a handful of years ago, exoplanet K2-25 b is giving planet formation specialists a hard time. Its main feature? Its astonishing density for its size which could challenge theories on the subject!
As the NASA exoplanet catalog states, K2-25 b is a Neptune-like exoplanet orbiting a spectral-like star. Discovered in 2015, this planet is currently challenging theories on the formation of planets according to a publication of the Association of Universities for Research in Astronomy (AURA) of August 4, 2020.
You should know that K2-25 b is a little smaller than the Earth, but weighs 11.6 times its weight ! At 600 million years old, this exoplanet is therefore much denser than other planets of similar age and size. What might seem like a "funny anomaly" is actually a real headache for researchers.
According to current knowledge, a planet forms from large amounts of fragmented material orbiting a massive celestial body like a star. We then speak of a protoplanetary disk to characterize this dispersion of material. Over time, dust, gas and other pieces of rock and ice will gradually agglomerate under the effect of gravitational force.
Result, a beginning planet that will continue to grow by attracting more and more materials. As time goes on, the planet will become quite large and heavy and then will be characterized by a gravitational force sufficient to capture a huge gaseous envelope . However, this dynamic will be at work until the planet has "cleaned up" its orbit.
Only here, the case of K2-25 b is very special. Much more massive than Earth, but also slightly smaller, the exoplanet has a very reduced gaseous envelope. However, all this goes against what scientists usually observe. Nothing seems to be able to explain the reasons for this excessive mass. No explanation either for this virtual absence of a gaseous envelope, while the gravitational force of K2-25 b is very strong!
Planet formation specialists are therefore perplexed. They even mentioned the possibility that the theories accepted so far are false! Many questions remain unanswered, so experts will have to observe K2-25 b for a very long time before finding satisfactory answers.
