Theoretical oscillation frequencies for solar-type dwarfs from stellar models with $\langle 3\mathrm{D} \rangle$-atmospheres

TL;DR

This paper introduces a new patching method replacing stellar outer layers with interpolated 3D atmospheres to improve eigenfrequency accuracy in solar-type stars, demonstrating its effectiveness through tests and applications to Kepler stars.

Contribution

It develops a novel interpolation scheme for 3D atmospheres and systematically assesses how patching criteria influence stellar oscillation frequencies.

Findings

Eigenfrequencies are unaffected by patching deep within the adiabatic region.

Frequency shifts can exceed 1 μHz depending on patching choices.

Correcting structural deficiencies reduces model-observation frequency discrepancies.

Abstract

We present a new method for replacing the outermost layers of stellar models with interpolated atmospheres based on results from 3D simulations, in order to correct for structural inadequacies of these layers. This replacement is known as patching. Tests, based on 3D atmospheres from three different codes and interior models with different input physics, are performed. Using solar models, we investigate how different patching criteria affect the eigenfrequencies. These criteria include the depth, at which the replacement is performed, the quantity, on which the replacement is based, and the mismatch in $T_\mathrm{eff}$ and $\log g$ between the un-patched model and patched 3D atmosphere. We find the eigenfrequencies to be unaltered by the patching depth deep within the adiabatic region, while changing the patching quantity or the employed atmosphere grid leads to frequency shifts that may exceed $1\,\mu\mathrm{Hz}$. Likewise, the eigenfrequencies are sensitive to mismatches in $T_\mathrm{eff}$ or $\log g$. A thorough investigation of the accuracy of a new scheme, for interpolating mean 3D stratifications within the atmosphere grids, is furthermore performed. Throughout large parts of the atmosphere grids, our interpolation scheme yields sufficiently accurate results for the purpose of asteroseismology. We apply our procedure in asteroseismic analyses of four \textit{Kepler} stars and draw the same conclusions as in the solar case: Correcting for structural deficiencies lowers the eigenfrequencies, this correction is slightly sensitive to the patching criteria, and the remaining frequency discrepancy between models and observations is less frequency-dependent. Our work shows the applicability and relevance of patching in asteroseismology.