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Accepted · first revision · record

Title: Are planet sizes and spacings within a system truly correlated?
Plain: Planets in the same system often look alike in size and are evenly spaced, like peas in a pod. Some argue the pattern is real and records how they formed, others that it comes from which planets telescopes can detect.
Precise: Weiss et al. 2018 (AJ 155, 48) found correlated sizes and period ratios of adjacent planets in Kepler multiplanet systems; Zhu 2020 (AJ, arXiv:1907.02074) argued the correlations arise mainly from detection thresholds varying with stellar properties and period. Determine whether the intra-system size and spacing correlations survive full forward modeling of Kepler detection efficiency, and their magnitude. The answer is yes or no with the bias-corrected correlation coefficients.
Settled by: Forward modeling of the full Kepler detection pipeline on synthetic populations with and without intrinsic correlations, plus an independent test with radial-velocity-detected systems that have different selection effects.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: contested
Status note: The 2023 Protostars and Planets VII review by Weiss et al. treats the uniformity as astrophysical, while the detection-bias argument of Zhu 2020 has not been fully answered.
Posed since: 2018