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Paper: Calibration of the Mixing-Length Free Parameter for White Dwarf Structures
Volume: 493, 19th European Workshop on White Dwarfs
Page: 89
Authors: Tremblay, P.-E.; Ludwig, H.-G.; Freytag, B.; Fontaine, G.; Steffen, M.; Brassard, P.
Abstract: We present a comparison of our grid of 3D radiation-hydrodynamical simulations for 70 pure-hydrogen DA white dwarfs, in the surface gravity range 7.0 ≤log g≤ 9.0, with 1D envelope models based on the mixing-length theory (MLT) for convection. We perform a calibration of the mixing-length parameter for the lower part of the convection zone. The 3D simulations are often restricted to the upper convective layers, and in those cases, we rely on the asymptotic entropy value of the adiabatic 3D upflows to calibrate 1D envelopes. Our results can be applied to 1D structure calculations, and in particular for pulsation and convective mixing studies. We demonstrate that while the 1D MLT only provides a bottom boundary of the convection zone based on the Schwarzschild criterion, the 3D stratifications are more complex. There is a large overshoot region below the convective layers that is likely critical for chemical diffusion applications.
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