Are Mini-Neptunes just giant Super-Earths?
To get a grasp on the size of exoplanets, researchers often compare them to familiar bodies in the Solar System.
Mini-Neptunes, for example, describe bodies that are larger than Earth but smaller than Neptune.
They typically contain rocky cores and puffy, gaseous atmospheres — not unlike actual Neptune itself.
Researchers observed two losing their atmospheres — suggesting that they may eventually morph into a different type of planet.
Radiation from their stars strips away the puffy outer layers of gas, which will cause the planets to transform over the next few million years.
These rocky bodies are smaller than Mini-Neptunes and common among exoplanets found in the Milky Way.
Without their gaseous atmospheres, the cores of the two Mini-Neptunes could become rocky planets, not unlike Earth and Mars.
W. M. Keck Observatory/Adam Makarenko
But more evidence is needed to confirm if Mini-Neptunes actually transform into Super-Earths.
If confirmed, this discovery could help explain why there aren’t many exoplanets that fall between Mini-Neptune and Super-Earth size.
It could simply be due to the fact that smaller Mini-Neptunes are just transitioning into Super-Earths.