Short-Period Small Planets with High Mutual Inclinations are more Common around Metal-Rich Stars

Fuente: arXiv
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Autori principali: Hua, Xinyan, Wang, Sharon Xuesong, An, Dongsheng, Wang, Songhu, Huang, Yang, Chen, Dichang, Buchner, Johannes, Zhu, Wei, Dai, Fei, Xie, Jiwei
Natura: Preprint
Pubblicazione: 2025
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author Hua, Xinyan
Wang, Sharon Xuesong
An, Dongsheng
Wang, Songhu
Huang, Yang
Chen, Dichang
Buchner, Johannes
Zhu, Wei
Dai, Fei
Xie, Jiwei
author_facet Hua, Xinyan
Wang, Sharon Xuesong
An, Dongsheng
Wang, Songhu
Huang, Yang
Chen, Dichang
Buchner, Johannes
Zhu, Wei
Dai, Fei
Xie, Jiwei
contents We present a correlation between the stellar metallicities and the mutual inclinations of multi-planet systems hosting short-period small planets (a/Rs<12, Rp<4Re). We analyzed 89 multi-planet systems discovered by Kepler, K2, and TESS, where the innermost planets have periods shorter than 10 days. We found that the mutual inclinations of the innermost two planets are higher and more diverse around metal-rich stars. The mutual inclinations are calculated as the absolute differences between the best-fit inclinations of the innermost two planets from transit modeling, which represent the lower limits of the true mutual inclinations. The mean and variance of the mutual inclination distribution of the metal-rich systems are 3.1+-0.5 and 3.1+-0.4 degrees, while for the metal-poor systems they are 1.3+-0.2 and 1.0+-0.2 degrees. This finding suggests that inner planetary systems around metal-rich stars are dynamically hotter. We summarized the theories that could plausibly explain this correlation, including the influence of giant planets, higher solid densities in protoplanetary disks around metal-rich stars, or secular chaos coupled with an excess of angular momentum deficits. Planet formation and population synthesis models tracking the mutual inclination evolution would be essential to fully understand this correlation.
format Preprint
id arxiv_https___arxiv_org_abs_2502_00442
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Short-Period Small Planets with High Mutual Inclinations are more Common around Metal-Rich Stars
Hua, Xinyan
Wang, Sharon Xuesong
An, Dongsheng
Wang, Songhu
Huang, Yang
Chen, Dichang
Buchner, Johannes
Zhu, Wei
Dai, Fei
Xie, Jiwei
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
We present a correlation between the stellar metallicities and the mutual inclinations of multi-planet systems hosting short-period small planets (a/Rs<12, Rp<4Re). We analyzed 89 multi-planet systems discovered by Kepler, K2, and TESS, where the innermost planets have periods shorter than 10 days. We found that the mutual inclinations of the innermost two planets are higher and more diverse around metal-rich stars. The mutual inclinations are calculated as the absolute differences between the best-fit inclinations of the innermost two planets from transit modeling, which represent the lower limits of the true mutual inclinations. The mean and variance of the mutual inclination distribution of the metal-rich systems are 3.1+-0.5 and 3.1+-0.4 degrees, while for the metal-poor systems they are 1.3+-0.2 and 1.0+-0.2 degrees. This finding suggests that inner planetary systems around metal-rich stars are dynamically hotter. We summarized the theories that could plausibly explain this correlation, including the influence of giant planets, higher solid densities in protoplanetary disks around metal-rich stars, or secular chaos coupled with an excess of angular momentum deficits. Planet formation and population synthesis models tracking the mutual inclination evolution would be essential to fully understand this correlation.
title Short-Period Small Planets with High Mutual Inclinations are more Common around Metal-Rich Stars
topic Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2502.00442