Gap in Exoplanet Size Shifts with Age.
Source: By Katherine Kornei, Eos/AGU.
Excerpt: Smaller planets are scarcer in younger systems and larger planets are lacking in older systems, according to new research that analyzed hundreds of exoplanets. ...Planets just a bit larger than Earth appear to be relatively rare in the exoplanet canon. A team has now used observations of hundreds of exoplanets to show that this planetary gap isn’t static but instead evolves with planet age—younger planetary systems are more likely to be missing slightly smaller planets, and older systems are more apt to be without slightly larger planets. This evolution is consistent with the hypothesis that atmospheric loss—literally, a planet’s atmosphere blowing away over time—is responsible for this so-called “radius valley,” the researchers suggested....