Published November 19, 2018 | Version v1

A Model of Rotating Convection in Stellar Interiors

  • 1. CEA/DRF/IRFU/DAp

Description

 A simplified monomodal model for stellar and planetary convection is derived for the magnitude of the rms velocity,
  degree of superadiabaticity, and characteristic length scale as a function of rotation rate as well as with thermal
  and viscous diffusivities, utilizing a heat-flux maximization principle and a spectrally-local turbulence closure. The
  convection model is used as a boundary condition for a linearization of the equations of motion in the transition
  region between convectively unstable and stably-stratified regions, such as the region at the base of the solar
  convection zone.  The equations of motion may be integrated to yield the depth to which convection penetrates into the
  stable region, establishing a relationship between that depth and the local Rossby number, diffusivity, and pressure
  scale height of those flows.  Upward and downward penetrative convection have a similar scaling with rotation rate and
  diffusivities, but they depend differently upon the pressure scale height due to the differing energetic processes
  occurring in convective cores of early-type stars versus convective envelopes of late-type stars. Convectively-driven
  gravito-inertial waves can be excited at the interface of convective and radiative regions. The magnitude of their
  energy flux will therefore vary with the properties of the convection. In the context of this convective model, that
  flux decreases with increasing angular velocity for a given wave frequency, implying that gravito-inertial modes may
  be increasingly difficult to detect and that they may transport less angular momentum in rapidly rotating stars.

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Additional details

Funding

European Commission
SPIRE - Stars: dynamical Processes driving tidal Interactions, Rotation and Evolution 647383