Three-Dimensional Simulations of Massive Stars: I. Wave Generation and Propagation. (arXiv:1903.09392v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Edelmann_P/0/1/0/all/0/1">P. V. F. Edelmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ratnasingam_R/0/1/0/all/0/1">R. P. Ratnasingam</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pedersen_M/0/1/0/all/0/1">M. G. Pedersen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bowman_D/0/1/0/all/0/1">D. M. Bowman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prat_V/0/1/0/all/0/1">V. Prat</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rogers_T/0/1/0/all/0/1">T. M. Rogers</a>
We present the first three-dimensional (3D), hydrodynamic simulations of the
core convection zone (CZ) and extended radiative zone spanning from 1% to 90%
of the stellar radius of an intermediate mass (3 $mathrm{M}_odot$) star. This
allows us to self-consistently follow the generation of internal gravity waves
(IGWs) at the convective boundary and their propagation to the surface. We find
that convection in the core is dominated by plumes. The frequency spectrum in
the CZ and that of IGW generation is a double power law as seen in previous
two-dimensional (2D) simulations. The spectrum is significantly flatter than
theoretical predictions using excitation through Reynolds stresses induced by
convective eddies alone. It is compatible with excitation through plume
penetration. An empirically determined distribution of plume frequencies
generally matches the one necessary to explain a large part of the observed
spectrum. We observe waves propagating in the radiation zone and excited
standing modes, which can be identified as gravity and fundamental modes. They
show similar frequencies and node patterns to those predicted by the stellar
oscillation code GYRE. The continuous part of the spectrum fulfills the IGW
dispersion relation. A spectrum of tangential velocity and temperature
fluctuations close to the surface is extracted, which are directly related to
observable brightness variations in stars. Unlike 2D simulations we do not see
the high frequencies associated with wave breaking, likely because these 3D
simulations are more heavily damped.
We present the first three-dimensional (3D), hydrodynamic simulations of the
core convection zone (CZ) and extended radiative zone spanning from 1% to 90%
of the stellar radius of an intermediate mass (3 $mathrm{M}_odot$) star. This
allows us to self-consistently follow the generation of internal gravity waves
(IGWs) at the convective boundary and their propagation to the surface. We find
that convection in the core is dominated by plumes. The frequency spectrum in
the CZ and that of IGW generation is a double power law as seen in previous
two-dimensional (2D) simulations. The spectrum is significantly flatter than
theoretical predictions using excitation through Reynolds stresses induced by
convective eddies alone. It is compatible with excitation through plume
penetration. An empirically determined distribution of plume frequencies
generally matches the one necessary to explain a large part of the observed
spectrum. We observe waves propagating in the radiation zone and excited
standing modes, which can be identified as gravity and fundamental modes. They
show similar frequencies and node patterns to those predicted by the stellar
oscillation code GYRE. The continuous part of the spectrum fulfills the IGW
dispersion relation. A spectrum of tangential velocity and temperature
fluctuations close to the surface is extracted, which are directly related to
observable brightness variations in stars. Unlike 2D simulations we do not see
the high frequencies associated with wave breaking, likely because these 3D
simulations are more heavily damped.
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