Peas in a Pod? Radius correlations in Kepler multi-planet systems

Abstract

We address the claim of Weiss et al. (2018) that the radii of adjacent planets in Kepler multi-planet systems are correlated. We explore two simple toy models---in the first the radii of the planets are chosen at random from a single universal distribution, and in the second we postulate several types of system with distinct radius distributions. We show that an apparent correlation between the radii of adjacent planets similar to the one reported by Weiss et al. (2018) can arise in both models. In addition the second model fits the radius and signal-to-noise distribution of the observed planets. We also comment on the validity of a commonly used correction that is used to estimate intrinsic planet occurrence rates, based on weighting planets by the inverse of their detectability.

arXiv comment13 pages, 8 figures, 1 appendix v2 several points clarified, accepted to AJ. 14 pages, 8 figures, 1 appendix

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• Architectures of Exoplanetary Systems. III: Eccentricity and Mutual Inclination Distributions of AMD-stable Planetary Systems
• A Tale of Planet Formation: From Dust to Planets
• The New Generation Planetary Population Synthesis (NGPPS). VI. Introducing KOBE: Kepler Observes Bern Exoplanets. Theoretical perspectives on the architecture of planetary systems: Peas in a pod
• A framework for the architecture of exoplanetary systems. I. Four classes of planetary system architecture
• The intrinsic multiplicity distribution of exoplanets revealed from the radial velocity method
• Intra-system uniformity: a natural outcome of dynamical sculpting
• Deep orbital search for additional planets in the HR 8799 system
• On the Orbital Spacing Pattern of Kepler Multiple Planet Systems
• The Demographics of Exoplanets
• Size evolution of close-in super-Earths through giant impacts and photoevaporation
• Signatures of impact-driven atmospheric loss in large ensembles of exoplanets
• When the Peas Jump around the Pod: How Stellar Clustering Affects the Observed Correlations between Planet Properties in Multi-Planet Systems
• Quantifying the Similarity of Planetary System Architectures
• Hiding Planets Near and Far: The Parameter Space of Hidden Companions for Known Planetary Systems
• Planets similar in size are often dissimilar in interior
• Biases from Missing a Small Planet in High Multiplicity Systems
• On the Ordering of Exoplanet Systems
• Accounting for Transit Timing Detectability: Biases in Planetary Radius and Orbital Period
• Split Peas in a Pod: Intra-System Uniformity of Super-Earths and Sub-Neptunes