On the Period-Ratio-Mass-Ratio Correlation of Extra-Solar Multi-Planet Systems

TL;DR

This study investigates the relationship between period ratios and mass ratios of adjacent planets in multi-planet systems, revealing a moderate correlation that suggests planet-planet interactions influence planetary formation.

Contribution

It provides the first quantitative analysis of period-ratio-mass-ratio correlation in exoplanet systems, highlighting the role of planet interactions during formation.

Findings

Moderate correlation (r=0.5779) for adjacent planet pairs.

Lower correlation (r=0.2820) for non-adjacent pairs.

Evidence of planet-planet interactions affecting system architecture.

Abstract

In order to gain possible hints for planet formation from the current data of known extra-solar planets, the period-ratios and mass-ratios of adjacent planet pairs in multi-planet systems are determined. A moderate period-ratio-mass-ratio correlation is found to have a correlation coefficient r=0.5779 with 99% confidence interval (0.464, 0.672). In contrast, for non-adjacent planet pairs, the correlation coefficient is r=0.2820 with 99% confidence interval (0.133, 0.419). Our results reveal the imprint of planet-planet interactions of the adjacent planet pairs in a certain fraction of the multi-planet systems during the stage of planet formation.