Puzzling Six-Exoplanet System Disovered With Resonant Rhythmic Movement

[The Astronomer]

Note that the 'puzzling' part refers to how their densities are all over the place, with no clear trend from one planet to the next, which contradicts with our current understanding of planetary formation. For reference, the latest update on TRAPPIST-1 suggests all seven planets' uncompressed densities are roughly the same (and are on average ~9% less dense than Earth).