ExoMOD II. A Statistical Model of Transit Timing Variations in Kepler Multi-Planet Systems
Abstract
In Paper I (Nesvorný et al. 2026), we forward modeled transit observations of the Kepler telescope to characterize the orbital properties of close-in planetary systems. The new population model, ExoMOD, was calibrated on Kepler's DR25 data. Here we use ExoMOD to statistically predict Transit Timing Variations (TTVs) from gravitationally interacting planets in the close-in systems, and compare these predictions with TTVs actually detected in the Kepler data. We find that planet-planet interactions are not expected to produce significant {\it short-period} TTVs, PTTV/Porb<10, where PTTV and Porb are the TTV and orbital periods, often enough to explain the short-period TTV signals inferred from the Kepler data. Most measured short-period signals must therefore have a different origin. The statistics of {\it long-period} TTVs -- likely arising from the gravitational interaction between planets -- indicates that single transiting planets have TTV-inducing companions nearly as often as doubles, thus ruling out multiplicity distributions with a prevalence of intrinsic singles. The fraction of planets with measured long-period TTVs increases to ≃ 15-18\% for observed multiplicities m ≥ 3, suggesting a change in the orbital architecture. High-multiplicity planetary systems have low gap complexities and probably retained a memory of their formation conditions. Ultimately, our work aims at developing a more informative feedback between observations and planet formation theories.
Related
- ExoEcho: Exoplanet Ephemerides Change Observations. III. A JWST Survey for Transit Timing Variations of 37 Exoplanets
- ExoEcho: Exoplanet Ephemerides Change Observations. III. A JWST Survey for Transit Timing Variations of 37 Exoplanets
- Evidence for LP 890-9d via Transit Timing Variations
- JWST and HST Confirm Transit Timing Variations for the Ultra-Hot Jupiter TOI-2109 b
- Toddlers in Resonance I: low masses and eccentricities of the 17 Myr giant planets HIP 67522 bc from transit timing variations
BibTeX
@misc{nesvorny2026exomod,
title = {{ExoMOD II. A Statistical Model of Transit Timing Variations in Kepler Multi-Planet Systems}},
author = {David Nesvorny and Daniel A. Yahalomi and David Kipping and Cristian Beauge and Sarah C. Millholland},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.28550},
eprint = {2608.28550},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.28550},
}
RIS
TY - UNPB
TI - ExoMOD II. A Statistical Model of Transit Timing Variations in Kepler Multi-Planet Systems
AU - David Nesvorny
AU - Daniel A. Yahalomi
AU - David Kipping
AU - Cristian Beauge
AU - Sarah C. Millholland
PY - 2026
DA - 2026/08/28
PB - arXiv
DO - 10.48550/arxiv.2608.28550
UR - https://arxiv.org/abs/2608.28550
AB - In Paper I (Nesvorný et al. 2026), we forward modeled transit observations of the Kepler telescope to characterize the orbital properties of close-in planetary systems. The new population model, ExoMOD, was calibrated on Kepler's DR25 data. Here we use ExoMOD to statistically predict Transit Timing Variations (TTVs) from gravitationally interacting planets in the close-in systems, and compare these predictions with TTVs actually detected in the Kepler data. We find that planet-planet interactions are not expected to produce significant {\it short-period} TTVs, P_TTV/P_orb<10, where P_TTV and P_orb are the TTV and orbital periods, often enough to explain the short-period TTV signals inferred from the Kepler data. Most measured short-period signals must therefore have a different origin. The statistics of {\it long-period} TTVs -- likely arising from the gravitational interaction between planets -- indicates that single transiting planets have TTV-inducing companions nearly as often as doubles, thus ruling out multiplicity distributions with a prevalence of intrinsic singles. The fraction of planets with measured long-period TTVs increases to ≃ 15-18\% for observed multiplicities m ≥ 3, suggesting a change in the orbital architecture. High-multiplicity planetary systems have low gap complexities and probably retained a memory of their formation conditions. Ultimately, our work aims at developing a more informative feedback between observations and planet formation theories.
ER -