A Disk-driven Resonance as the Origin of High Inclinations of Close-in Planets

Petrovich, Cristobal and Muñoz, Diego J. and Kratter, Kaitlin M. and Malhotra, Renu (2020) A Disk-driven Resonance as the Origin of High Inclinations of Close-in Planets. The Astrophysical Journal Letters, 902 (1). L5. ISSN 2041-8205

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Abstract

The recent characterization of transiting close-in planets has revealed an intriguing population of sub-Neptunes with highly tilted and even polar orbits relative to their host star's equator. Any viable theory for the origin of these close-in, polar planets must explain (1) the observed stellar obliquities, (2) the substantial eccentricities, and (3) the existence of Jovian companions with large mutual inclinations. In this work, we propose a theoretical model that satisfies these requirements without invoking tidal dissipation or large primordial inclinations. Instead, tilting is facilitated by the protoplanetary disk dispersal during the late stage of planet formation, initiating a process of resonance sweeping and parametric instability. This mechanism consists of two steps. First, a nodal secular resonance excites the inclination to large values; then, once the inclination reaches a critical value, a linear eccentric instability is triggered, which detunes the resonance and ends inclination growth. The critical inclination is pushed to high values by general relativistic precession, making polar orbits an inherently post-Newtonian outcome. Our model predicts that polar, close-in sub-Neptunes coexist with cold Jupiters in low stellar obliquity orbits.

Item Type: Article
Subjects: STM Digital > Physics and Astronomy
Depositing User: Unnamed user with email support@stmdigital.org
Date Deposited: 19 May 2023 07:27
Last Modified: 18 Jun 2024 07:43
URI: http://research.asianarticleeprint.com/id/eprint/884

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