Magnetic effect on equilibrium tides and its influence on the orbital evolution of binary systems

TL;DR

This paper investigates how magnetic fields influence equilibrium tides, revealing that magnetic effects can significantly accelerate orbital evolution in binary systems, aligning theoretical predictions with observations.

Contribution

It introduces the impact of magnetic fields on equilibrium tides, showing they enhance dissipation and speed up orbital changes, a novel extension to standard hydrodynamic tide theory.

Findings

Magnetic fields increase turbulent Ohmic dissipation.

Magnetic effects accelerate orbital migration and decay.

Predictions match observed orbital behaviors.

Abstract

In the standard theory of equilibrium tides, hydrodynamic turbulence is considered. In this paper we study the effect of magnetic fields on equilibrium tides. We find that the turbulent Ohmic dissipation associated with a tidal flow is much stronger than the turbulent viscous dissipation such that a magnetic field can greatly speed up the tidal evolution of a binary system. We then apply the theory to three binary systems: the orbital migration of 51 Pegasi b, the orbital decay of WASP-12b, and the circularization of close binary stars. Theoretical predictions are in good agreement with observations, which cannot be clearly interpreted with hydrodynamic equilibrium tides.