Stellar models with calibrated convection and temperature stratification from 3D hydrodynamics simulations

Abstract

Stellar evolution codes play a major role in present-day astrophysics, yet they share common simplifications related to the outer layers of stars. We seek to improve on this by the use of results from realistic and highly detailed 3D hydrodynamics simulations of stellar convection. We implement a temperature stratification extracted directly from the 3D simulations into two stellar evolution codes to replace the simplified atmosphere normally used. Our implementation also contains a non-constant mixing-length parameter, which varies as a function of the stellar surface gravity and temperature -also derived from the 3D simulations. We give a detailed account of our fully consistent implementation and compare to earlier works, and also provide a freely available -module. The evolution of low-mass stars with different masses is investigated, and we present for the first time an asteroseismic analysis of a standard solar model utilising calibrated convection and temperature stratification from 3D simulations. We show that the inclusion of 3D results have an almost insignificant impact on the evolution and structure of stellar models -the largest effect are changes in effective temperature of order 30 K seen in the pre-main sequence and in the red-giant branch. However, this work provides the first step for producing self-consistent evolutionary calculations using fully incorporated 3D atmospheres from on-the-fly interpolation in grids of simulations.

Calibration of mixing-length parameterαfor MLT and FST models by matching with CO5BOLD models

“…3.4.4. Mosumgaard et al (2018) also found that a T eff shift from a solar-α track with the Eddington T (τ) to a varying-α track with the 3D T (τ) relation (Trampedach et al 2013) is not substantial, ∼ +30 K at log g = 3.2 for 1M ⊙ . We find it similar to the T eff shift from our solar-α to varying-α track for MLT, which is ∼ +24 K at the same log g. This similarity also can be explained by the closeness between Trampedach et al (2014b)'s α values and our 3D-calibrated α values for MLT(BV) with the Eddington T (τ).…”

Coupling 1D stellar evolution with 3D-hydrodynamical simulations on-the-fly II: stellar evolution and asteroseismic applications

“…In this procedure -which also relies on interpolation in T eff and log gthe outer boundary conditions are supplied by T(τ) relations extracted from the 3D simulations by Trampedach et al (2014a), and the models include a variable 3D-calibrated α MLT from Trampedach et al (2014b). This specific solar model is taken from Mosumgaard et al (2018) and is denoted RT2014 in the following.…”

“…How stellar evolution is affected by employing this parametrisation was initially investigated by Salaris & Cassisi (2015) and Mosumgaard et al (2017). Recently, Mosumgaard et al (2018) published details on how to implement the results in a stellar evolution code, and presented an in-depth analysis of the structural and asteroseismic impact, which turns out to be quite limited.…”

Damping rates and frequency corrections of Kepler LEGACY stars

“…⋆ E-mail: hg@phys.au.dk (GH) Moreover, with the recent success of three-dimensional (3D) hydrodynamical simulations of outer stellar layers (e.g., Trampedach et al 2013;Magic et al 2013;Ludwig & Steffen 2016;Kupka et al 2018), it is now possible to use averaged simulation results for calibrating convection parameters of 1D stellar models (e.g. Ludwig et al 1999;Trampedach et al 2014b;Magic et al 2015;Houdek 2017;Aarslev et al 2018) or replacing the outer layers of 1D stellar models by averaged 3D simulations for seismic analysis (e.g., Rosenthal et al 1995Rosenthal et al , 1999Piau et al 2014;Sonoi et al 2015Sonoi et al , 2017Magic & Weiss 2016;Ball et al 2016;Houdek et al 2017;Trampedach et al 2017;Jørgensen et al 2018;Mosumgaard et al 2018).…”