Dynamical tides in rotating planets and stars

J. Goodman, C. Lackner

Research output: Contribution to journalArticlepeer-review

74 Scopus citations

Abstract

Tidal dissipation may be important for the internal evolution as well as the orbits of short-period massive planets - hot Jupiters. We revisit a mechanism proposed by Ogilvie and Lin for tidal forcing of inertial waves, which are short-wavelength, low-frequency disturbances restored primarily by Coriolis rather than buoyancy forces. This mechanism is of particular interest for hot Jupiters, because it relies upon a rocky core, and because these bodies are otherwise largely convective. Compared to waves excited at the base of the stratified, externally heated atmosphere, waves excited at the core are more likely to deposit heat in the convective region and thereby affect the planetary radius. However, Ogilvie and Lin's results were numerical, and the manner of the wave excitation was not clear. Using WKB methods, we demonstrate the production of short waves by scattering of the equilibrium tide off the core at critical latitudes. The tidal dissipation rate associated with these waves scales as the fifth power of the core radius, and the implied tidal Q is of order ten million for nominal values of the planet's mass, radius, orbital period, and core size. We comment upon an alternative proposal by Wu for exciting inertial waves in an unstratified fluid body by means of compressibility rather than a core. We also find that even a core of rock is unlikely to be rigid. But Ogilvie and Lin's mechanism should still operate if the core is substantially denser than its immediate surroundings.

Original languageEnglish (US)
Pages (from-to)2054-2067
Number of pages14
JournalAstrophysical Journal
Volume696
Issue number2
DOIs
StatePublished - May 10 2009

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • binaries: close
  • hydrodynamics
  • planetary systems
  • stars: oscillations
  • stars: rotation
  • waves

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