Measuring Tidal Dissipation in Giant Planets from Tidal Circularization

TL;DR

This study constrains the tidal quality factor of giant planets, finding a typical value around 10^5 with no clear frequency dependence, based on analysis of 78 planetary systems and their eccentricities.

Contribution

It introduces a frequency-dependent model for tidal dissipation and applies it to a large sample of systems to derive constraints on $Q_{pl}'$ for hot Jupiters.

Findings

Typical $oxed{ ext{log}_{10}Q_{pl}'}$ is 5.0±0.5 for hot Jupiters.

No clear evidence of frequency dependence in $Q_{pl}'$.

Constraints are consistent across multiple systems, supporting a common dissipation model.

Abstract

In this project, we determined the constraints on the modified tidal quality factor, $Q_{pl}'$, of gas-giant planets orbiting close to their host stars. We allowed $Q_{pl}'$ to depend on tidal frequency, accounting for the multiple tidal waves with time-dependent frequencies simultaneously present on the planet. We performed our analysis on 78 single-star and single-planet systems, with giant planets and host stars with radiative cores and convective outer shells. We extracted constraints on the frequency-dependent $Q_{pl}'$ for each system separately and combined them to find general constraints on $Q_{pl}'$ required to explain the observed eccentricity envelope while simultaneously allowing the observed eccentricities of all systems to survive to the present day. Individual systems do not place tight constraints on $Q_{pl}'$. However, since similar planets must have similar tidal dissipation, we require that a consistent, possibly frequency-dependent, model must apply. Under that assumption, we find that the value of $\log_{10}Q_{pl}'$ for HJs is $5.0\pm0.5$ for the range of tidal period from 0.8 to 7 days. We did not see any clear sign of frequency dependence of $Q_{pl}'$.