The Effects of Disk-induced Apsidal Precession on Planets Captured into Mean Motion Resonance

Murray, Zachary; Hadden, Sam; Holman, Matthew J.

doi:10.3847/1538-4357/ac68f2

“…By virtue of attempting to place model-independent constraints on these quantities through the kind of simplified parametric framework used in this study, we forego modeling the effects of physical phenomena, which are likely to play a role in shaping the early stages of giant planet evolution. For example, Murray et al (2022) found that disk precession could significantly alter resonance capture from the gas-free case and lead to larger amplitude libration-potentially paving the path toward easier instability triggering relative to the scenarios considered in this work. Additionally, chains of giant planets are likely to carve mutual gaps in a disk, the effect of which on planet-to-planet variations in the strength of eccentricity damping is still unclear, particularly in low-viscosity disks (Lega et al 2021;Griveaud et al 2023).…”

Section: Discussionmentioning

confidence: 91%

Breaking Giant Chains: Early-stage Instabilities in Long-period Giant Planet Systems

Nagpal,

Goldberg,

Batygin

2024

ApJ

0

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Orbital evolution is a critical process that sculpts planetary systems, particularly during their early stages where planet–disk interactions are expected to lead to the formation of resonant chains. Despite the theoretically expected prominence of such configurations, they are scarcely observed among long-period giant exoplanets. This disparity suggests an evolutionary sequence wherein giant planet systems originate in compact multiresonant configurations, but subsequently become unstable, eventually relaxing to wider orbits—a phenomenon mirrored in our own solar system’s early history. In this work, we present a suite of N-body simulations that model the instability-driven evolution of giant planet systems, originating from resonant initial conditions, through phases of disk dispersal and beyond. By comparing the period ratio and normalized angular momentum distributions of our synthetic aggregate of systems with the observational census of long-period Jovian planets, we derive constraints on the expected rate of orbital migration, the efficiency of gas-driven eccentricity damping, and typical initial multiplicity. Our findings reveal a distinct inclination toward densely packed initial conditions, weak damping, and high giant planet multiplicities. Furthermore, our models indicate that resonant chain origins do not facilitate the formation of Hot Jupiters via the coplanar high-eccentricity pathway at rates high enough to explain their observed prevalence.

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“…This is because mean-motion resonances (MMRs), which we have ignored, could play an important dynamical role (see also the next paragraph), questioning the validity of secular approximation. For instance, for a Jupiter-mass planet, the nominal location of the 2:1 MMR -namely, a 2:1 = 2 2/3 a p (i.e., neglecting potential offsets due to the disk-induced precession; Murray et al 2022)-would be within the disk at a 2:1 /a in ≈ 1.07 if e p = 0.10 but at a 2:1  a in if e p = 0.30 (assuming M c = 1M e and using Equation (1) to relate a p and a in ).…”

Section: Discussionmentioning

confidence: 99%

Massive Debris Disks May Hinder Secular Stirring by Planetary Companions: An Analytic Proof of Concept

Sefilian

2024

ApJ

0

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Debris disks or exo-Kuiper belts, detected through their thermal or scattered emission from their dusty components, are ubiquitous around main-sequence stars. Since dust grains are short-lived, their sustained presence is thought to require dynamical excitation, i.e., “stirring,” of a massive reservoir of large planetesimals, such that mutual collisions are violent enough to continually supply fresh dust. Several mechanisms have been proposed to explain debris disk stirring, with the commonly accepted being long-term, secular planet–debris disk interactions. However, while effective, existing planet-stirring models are rudimentary; namely, they ignore the (self-)gravity of the disk, treating it as a massless reservoir of planetesimals. Here, using a simple analytical model, we investigate the secular interactions between eccentric planets and massive, external debris disks. We demonstrate that the disk gravity drives fast apsidal precession of both planetesimal and planetary orbits, which, depending on the system parameters, may well exceed the planet-induced precession rate of planetesimals. This results in strong suppression of planetesimal eccentricities and thus relative collisional velocities throughout the disk, often by more than an order of magnitude when compared to massless disk models. We thus show that massive debris disks may hinder secular stirring by eccentric planets orbiting near, e.g., the disk’s inner edge, provided the disk is more massive than the planet. We provide simple analytic formulae to describe these effects. Finally, we show that these findings have important implications for planet inferences in debris-bearing systems, as well as for constraining the total masses of debris disks (as done for β Pic).

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“…Furthermore, Murray et al (2022) demonstrated that if a resonant planet pair migrates into the cavity, the eccentricity of the inner planet can be excited to high values (e > 0.5) through disk-driven differential precession between the pair. In this scenario, the disk must be heavy enough to produce a high differential precession rate between the two planets in resonance, and the disk dispersal must proceed slowly enough to avoid destabilizing the resonant planet pair.…”

Section: Eccentricity Excitation Through Disk-planet Interactionsmentioning

confidence: 99%

The PFS View of TOI-677 b: A Spin–Orbit Aligned Warm Jupiter in a Dynamically Hot System*

Hu,

Rice,

Wang

et al. 2024

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TOI-677 b is part of an emerging class of “tidally detached” gas giants (a/R ⋆ ≳ 11) that exhibit large orbital eccentricities and yet low stellar obliquities. Such sources pose a challenge for models of giant planet formation, which must account for the excitation of high eccentricities without large changes in the orbital inclination. In this work, we present a new Rossiter–McLaughlin measurement of the tidally detached warm Jupiter TOI-677 b, obtained using high-precision radial velocity observations with Magellan’s Planet Finder Spectrograph (PFS). Combined with previously published observations from the Very Large Telescope’s ESPRESSO spectrograph, we derive one of the most precisely constrained sky-projected spin–orbit angle measurements to date for an exoplanet. The combined fit offers a refined set of self-consistent parameters, including a low sky-projected stellar obliquity of λ = 3 .° 2 − 1. ∘ 5 + 1. ∘ 6 and a moderately high eccentricity of e = 0.460 − 0.018 + 0.019 , which further constrain the puzzling architecture of this system. We examine several potential scenarios that may have produced the current TOI-677 orbital configuration, ultimately concluding that TOI-677 b most likely had its eccentricity excited through disk–planet interactions. This system adds to a growing population of aligned warm Jupiters on eccentric orbits around hot (T eff > 6100 K) stars.

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The Effects of Disk-induced Apsidal Precession on Planets Captured into Mean Motion Resonance

Cited by 4 publications

References 45 publications

Breaking Giant Chains: Early-stage Instabilities in Long-period Giant Planet Systems

Breaking Giant Chains: Early-stage Instabilities in Long-period Giant Planet Systems

Massive Debris Disks May Hinder Secular Stirring by Planetary Companions: An Analytic Proof of Concept

The PFS View of TOI-677 b: A Spin–Orbit Aligned Warm Jupiter in a Dynamically Hot System*

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