Tidal synchronization trapping in stars and planets with convective envelopes

Fuente: arXiv
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Main Author: Dewberry, Janosz W.
Format: Preprint
Published: 2024
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author Dewberry, Janosz W.
author_facet Dewberry, Janosz W.
contents Tidal torques can alter the spins of tidally interacting stars and planets, usually over shorter timescales than the tidal damping of orbital separations or eccentricities. Simple tidal models predict that, in eccentric binary or planetary systems, rotation periods will evolve toward a "pseudosynchronous" ratio with the orbital period. However, this prediction does not account for "inertial" waves that are present in stars or gaseous planets with (i) convective envelopes and (ii) even very slow rotation. We demonstrate that tidal driving of inertial oscillations in eccentric systems generically produces a network of stable "synchronization traps" at ratios of orbital to rotation period that are simple to predict but can deviate significantly from pseudosynchronization. The mechanism underlying spin synchronization trapping is similar to tidal resonance locking, involving a balance between torques that is maintained automatically by the scaling of inertial mode frequencies with the rotation rate. In contrast with many resonance locking scenarios, however, the torque balance required for synchronization trapping need not drive mode amplitudes to nonlinearity. Synchronization traps may provide an explanation for low-mass stars and hot Jupiters with observed rotation rates that deviate from pseudosynchronous or synchronous expectations.
format Preprint
id arxiv_https___arxiv_org_abs_2403_06979
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Tidal synchronization trapping in stars and planets with convective envelopes
Dewberry, Janosz W.
Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
Tidal torques can alter the spins of tidally interacting stars and planets, usually over shorter timescales than the tidal damping of orbital separations or eccentricities. Simple tidal models predict that, in eccentric binary or planetary systems, rotation periods will evolve toward a "pseudosynchronous" ratio with the orbital period. However, this prediction does not account for "inertial" waves that are present in stars or gaseous planets with (i) convective envelopes and (ii) even very slow rotation. We demonstrate that tidal driving of inertial oscillations in eccentric systems generically produces a network of stable "synchronization traps" at ratios of orbital to rotation period that are simple to predict but can deviate significantly from pseudosynchronization. The mechanism underlying spin synchronization trapping is similar to tidal resonance locking, involving a balance between torques that is maintained automatically by the scaling of inertial mode frequencies with the rotation rate. In contrast with many resonance locking scenarios, however, the torque balance required for synchronization trapping need not drive mode amplitudes to nonlinearity. Synchronization traps may provide an explanation for low-mass stars and hot Jupiters with observed rotation rates that deviate from pseudosynchronous or synchronous expectations.
title Tidal synchronization trapping in stars and planets with convective envelopes
topic Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
url https://arxiv.org/abs/2403.06979