Exoplanets Shrink Due to 'Core-Powered Mass Loss', Study Finds

The process, driven by radiation from the planet's core, could explain the observed gap in exoplanet sizes.

Scientists have found evidence suggesting that some exoplanets, particularly those larger than Earth but smaller than Neptune, are shrinking due to a process known as 'core-powered mass loss'.
This process, where radiation from the planet's hot core pushes away its atmosphere, could explain the observed gap in exoplanet sizes, with few planets found to be 1.5 to 2 times the size of Earth.
The research team, led by Jessie Christiansen from Caltech, analyzed data from NASA's Kepler 2 mission, focusing on sub-Neptunes orbiting stars in two star clusters: The Praesepe or Beehive cluster, and the Hyades cluster.
The team found that most planets around stars more than 800 million years old had lost their atmospheres, suggesting that core-powered mass loss is likely the reason for atmospheric escape on these planets.
The findings, published in The Astronomical Journal, could help scientists understand the diverse range of exoplanet sizes and compositions.