The Prevalence of Resonance Among Young, Close-in Planets

• DOI: 10.48550/arxiv.2406.06885
• Publication Date: 2024-06-10
• Authors: Fei Dai; Max Goldberg; Konstantin Batygin; Jennifer L. van S...; Eugene Chiang; Nick Choksi; Rixin Li; Erik A. Petigura; Gregory J. Gilbert; Sarah Millholland; Yuan-Zhe Dai; Luke G. Bouma; Lauren M. Weiss; Joshua N. Winn
• Keywords: Exoplanet migration; Earth and Planetary Astrophysics (astro-ph.EP); Exoplanet dynamics; Exoplanet evolution; Astronomy; 0103 physical sciences; FOS: Physical sciences; QB1-991; Exoplanet systems; 01 natural sciences; Astrophysics - Earth and Planetary Astrophysics

Multiple planets undergoing disk migration may be captured into a chain of mean-motion resonances with the innermost planet parked near disk's inner edge. Subsequent dynamical evolution disrupt these resonances, leading to non-resonant configurations typically observed among {\it Kepler} that are Gyrs old. In this scenario, resonant expected more common in younger systems. This prediction can now tested, thanks recent discoveries young planets, particularly those stellar clusters, by NASA's TESS} mission. We divided known planetary systems three age groups: ($<$100-Myr-old), adolescent (0.1-1-Gyr-old), and mature ($>1$-Gyr-old). The fraction neighboring pairs having period ratios within few percent first-order commensurability (e.g.~4:3, 3:2, or 2:1) is 70$\pm$15\% for pairs, 24$\pm$8\% 15$\pm$2\% pairs. at least one nearly commensurable pair (either first second-order) 86$\pm13$\% systems, 38$\pm12$\% 23$\pm3$\% First-order commensurabilities prevail across all groups, an admixture second-order commensurabilities. Commensurabilities high multiplicity low mutual inclinations. Observed often deviate from perfect $\sim$1\% even too large explained repulsion equilibrium eccentricity tides. also find super-Earths radius gap ($1.5-1.9R_\oplus$) less likely near-resonant (11.9$\pm2.0\%$) compared Earth-sized ($R_p<1R_\oplus$; 25.3$\pm4.4\%$) mini-Neptunes ($1.9R_\oplus \leq R_p<2.5R_\oplus$; 14.4$\pm1.8\%$).