A new study by Rice University researchers Sho Shibata and Andre Izidoro presents a compelling new model for the formation of super-Earths and mini-Neptunes—planets that are 1 to 4 times the size of Earth and among the most common in our galaxy. Using advanced simulations, the researchers propose that these planets emerge from distinct rings of planetesimals, providing fresh insight into planetary evolution beyond our solar system. The findings were recently published in The Astrophysical Journal Letters.

For decades, scientists have debated how super-Earths and mini-Neptunes form. Traditional models have suggested that planetesimals—the tiny building blocks of planets—formed across wide regions of a young star’s disk. But Shibata and Izidoro suggest a different theory: These materials likely come together in narrow rings at specific locations in the disk, making planet formation more organized than previously believed.

“This paper is particularly significant as it models the formation of super-Earths and mini-Neptunes, which are believed to be the most common types of planets in the galaxy,” said Shibata, a postdoctoral fellow of Earth, environmental and planetary sciences. “One of our key findings is that the formation pathways of the solar system and exoplanetary systems may share fundamental similarities.”