Orbital migration and Resonance Offset of the Kepler-25 and K2-24 systems

TL;DR

This study analyzes how Type-I migration influences the orbital resonance and period ratios of the Kepler-25 and K2-24 planetary systems, explaining observed deviations from exact resonance.

Contribution

It provides an analytical and numerical model demonstrating how stellar and orbital parameters cause resonance offsets in planetary systems.

Findings

Period ratios deviate from 2/1 resonance due to migration effects.

Model matches observed resonance offsets in Kepler-25 and K2-24.

Resonance offset depends on stellar flare activity and proximity to star.

Abstract

Based on the model described in Ramos et al., 2017, we present an analytical+numerical study of the resonance capture under Type-I migration for the Kepler-25 (Marcy et al., 2014) and K2-24 (Petigura et al., 2016) Kepler systems, both close to a 2/1 mean-motion resonance. We find that, depending on the flare index and the proximity to the central star, the average value of the period-ratio between two consecutive planets show a significant deviation with respect to the resonant nominal value, up to values well in agreement with the observations.