Peas-in-a-pod across the Radius Valley: Rocky Systems Are Less Uniform in Mass but More Uniform in Size and Spacing

Abstract

The ubiquity of “peas-in-a-pod” architectural patterns and the existence of the radius valley each presents a striking population-level trend for planets with R _p ≤ 4 R _⊕ that serves to place powerful constraints on the formation and evolution of these subgiant worlds. As it has yet to be determined whether the strength of this peas-in-a-pod uniformity differs on either side of the radius valley, we separately assess the architectures of systems containing only small ( R _p ≤ 1.6 R _⊕ ), rocky planets from those harboring only intermediate-sized (1.6 R _⊕ 2 σ significance) that the enhanced size uniformity of rocky systems is dominated by the presence of super-Earths (1 R _⊕ ≤ R _p ≤ 1.6 R _⊕ ), while their enhanced mass diversity is driven by the presence of sub-Earth ( R _p < 1 R _⊕ ) worlds.

Keywords

• Exoplanet astronomy
• Exoplanet evolution
• Exoplanet formation
• Exoplanet structure
• Exoplanets
• Exoplanet systems