Magnetic effect on dynamical tide in rapidly rotating astronomical objects

Abstract

By numerically solving the equations of rotating magnetohydrodynamics (MHD), the magnetic effect on dynamical tide is studied. It is found that magnetic field has a significant impact not only on the flow structure, i.e. the internal shear layers in rotating flow can be destroyed in the presence of a moderate or stronger magnetic field (in the sense that the Alfvén velocity is at least of the order of 0.1 of the surface rotational velocity), but also on the dispersion relation of waves excited by tidal force such that the range of tidal resonance is broadened by magnetic field. A major result is that the total tidal dissipation scales as square of the field strength, which can be used to estimate the strength of internal magnetic field in the astronomical object of a binary system. Moreover, with a moderate or stronger field the ratio of the magnetic dissipation to the viscous dissipation is almost inversely proportional to magnetic Prandtl number (i.e. the ratio of viscosity to magnetic diffusivity), and therefore in the astrophysical situation at small magnetic Prandtl number magnetic dissipation dominates over viscous dissipation with a moderate or stronger field.

References in corpus (4)

• Tidal dissipation in stars and giant planets
• Tidal dissipation in rotating fluid bodies: the presence of a magnetic field
• Calculating rotating hydrodynamic and magneto-hydrodynamic waves to understand magnetic effects on dynamical tides
• Linear and nonlinear responses to harmonic force in rotating flow

Cited by in corpus (14)

• Tidal dissipation in evolving low-mass and solar-type stars with predictions for planetary orbital decay
• Influence of stellar structure, evolution and rotation on the tidal damping of exoplanetary spin-orbit angles
• Wave propagation in semi-convective regions of giant planets
• The effects of nonlinearities on tidal flows in the convective envelopes of rotating stars and planets in exoplanetary systems
• Layered semi-convection and tides in giant planet interiors - II. Tidal dissipation
• Does magnetic field impact tidal dynamics inside the convective zone of low-mass stars along their evolution?
• The complex interplay between tidal inertial waves and zonal flows in differentially rotating stellar and planetary convective regions I. Free waves
• The impact of tidal friction evolution on the orbital decay of ultra-short period planets
• Magnetic effect on equilibrium tides and its influence on the orbital evolution of binary systems
• Interplay between tidal flows and magnetic fields in nonlinear simulations of stellar and planetary convective envelopes
• Tidal excitation of autoresonant oscillations in stars with close-by planets
• Ohmic dissipation in the Earth's outer core resulting from the free inner core nutation
• Wave reflection and transmission at interface of convective and stably stratified regions in a rotating star or planet
• Surface tide on a rapidly rotating body