Clear density distinction between rocky and water-rich small planets

Density, not radius, separates rocky and water-rich small planets orbiting M dwarf stars
https://www.science.org/doi/10.1126/science.abl7164

ArXiv link:
https://arxiv.org/abs/2209.03871

Hugh Osborne summary
https://twitter.com/exohugh/status/1567977482976100353

Quote :

A remarkable insight from a couple of my colleagues - many small planets orbiting M-dwarfs seem to line up perfectly along the 50% H2O trend line. This would suggest they form like Neptunes beyond the snow line and then migrate in.