Astronomers Solve Mystery of Missing Super-Earths and Mini-Neptunes

New research reveals planetary migration and atmospheric changes as key factors in the observed gap in exoplanet sizes.

Astronomers from Germany and Switzerland have discovered that the migration of icy sub-Neptunes and the evaporation of water ice on super-Earths explain the gap in the size distribution of exoplanets.
The phenomenon, known as the radius valley, shows a scarcity of exoplanets around two Earth radii, puzzling researchers for years.
Computer simulations demonstrate that as icy sub-Neptunes move closer to their central star, they appear larger due to forming a thick water vapor atmosphere.
Conversely, smaller rocky planets, or super-Earths, lose part of their gaseous envelope, causing their measured radius to shrink.
The findings, published in Nature Astronomy, could also suggest the existence of water worlds with deep oceans, potentially hosting life.