When the Peas Jump around the Pod: How Stellar Clustering Affects the Observed Correlations between Planet Properties in Multi-Planet Systems

Abstract

Recent studies have shown that the radii and masses of adjacent planets within a planetary system are correlated. It is unknown how this 'peas-in-a-pod' phenomenon originates, whether it is in place at birth or requires evolution, and whether it (initially) applies only to neighboring planets or to all planets within a system. Here we address these questions by making use of the recent discovery that planetary system architectures strongly depend on ambient stellar clustering. Based on Gaia's second data release, we divide the sample of planetary systems hosting multiple planets into those residing in stellar position-velocity phase space overdensities and the field, representing samples with elevated and low degrees of external perturbation, respectively. We demonstrate that the peas-in-a-pod phenomenon manifests itself in both samples, suggesting that the uniformity of planetary properties within a system is not restricted to direct neighbors and likely already exists at birth. The radius uniformity is significantly elevated in overdensities, suggesting that it can be enhanced by evolutionary effects that either have a similar impact on the entire planetary system or favour the retention of similar planets. The mass uniformity may exhibit a similar, but weaker dependence. Finally, we find ordering in both samples, with the planet radius and mass increasing outwards. Despite its prevalence, the ordering is somewhat weaker in overdensities, suggesting that it may be disrupted by external perturbations arising from stellar clustering. We conclude that a comprehensive understanding of the 'peas-in-a-pod' phenomenon requires linking planet formation and evolution to the large-scale stellar and galactic environment.

arXiv comment11 pages, 3 figures, 1 table; Accepted to ApJ Letters

References in corpus (24)

• The NumPy array: a structure for efficient numerical computation
• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Characteristics of planetary candidates observed by Kepler, II: Analysis of the first four months of data
• Kepler planets: a tale of evaporation
• Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
• Probabilistic Forecasting of the Masses and Radii of Other Worlds
• The California Kepler Survey VII. Precise Planet Radii Leveraging Gaia DR2 Reveal the Stellar Mass Dependence of the Planet Radius Gap
• An Excess of Jupiter Analogs in Super-Earth Systems
• The Gaia-Kepler Stellar Properties Catalog. II. Planet Radius Demographics as a Function of Stellar Mass and Age
• Kepler Multi-Planet Systems Exhibit Unexpected Intra-system Uniformity in Mass and Radius
• On The Relative Sizes of Planets Within Kepler Multiple Candidate Systems
• Re-visiting the relations: Galactic thin disc age-velocity dispersion relation
• The bright end of the exo-Zodi luminosity function: Disk evolution and implications for exo-Earth detectability
• Stellar clustering shapes the architectures of planetary systems
• Prevalent externally-driven protoplanetary disc dispersal as a function of the galactic environment
• The California-Kepler Survey. VI: Kepler Multis and Singles Have Similar Planet and Stellar Properties Indicating a Common Origin
• The Kepler Peas in a Pod Pattern is Astrophysical
• On the patterns observed in Kepler multi-planet systems
• Forming Diverse Super-Earth Systems in Situ
• Peas in a Pod? Radius correlations in Kepler multi-planet systems
• Do planets remember how they formed?
• Bridging the Planet Radius Valley: Stellar Clustering as a Key Driver for Turning Sub-Neptunes into Super-Earths

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• 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
• Exploring the link between star and planet formation with Ariel
• The influence of the environment on the spin evolution of low-mass stars. I. External photoevaporation of circumstellar disks
• Hot Jupiters, cold kinematics: High phase space densities of host stars reflect an age bias
• Evolution of circumstellar discs in young star-forming regions
• Making hot Jupiters in stellar clusters: the importance of binary exchange
• On the Ordering of Exoplanet Systems