Sensitivity of the g-mode frequencies to pulsation codes and their parameters

TL;DR

This paper assesses how different pulsation codes and their parameters influence the computed g-mode frequencies in stellar models, ensuring numerical accuracy aligns with observational precision.

Contribution

It compares various pulsation codes and numerical settings to establish the accuracy of g-mode frequency calculations in stellar models.

Findings

Numerical accuracy of about 0.01 μHz achieved with current models and methods.

Comparison between ADIPLS and GraCo codes shows consistent results within error margins.

Proper numerical resolution and equilibrium models are crucial for reliable frequency computations.

Abstract

From the recent work of the Evolution and Seismic Tools Activity (ESTA, Lebreton et al. 2006; Monteiro et al. 2008), whose Task 2 is devoted to compare pulsational frequencies computed using most of the pulsational codes available in the asteroseismic community, the dependence of the theoretical frequencies with non-physical choices is now quite well fixed. To ensure that the accuracy of the computed frequencies is of the same order of magnitude or better than the observational errors, some requirements in the equilibrium models and the numerical resolutions of the pulsational equations must be followed. In particular, we have verified the numerical accuracy obtained with the Saclay seismic model, which is used to study the solar g-mode region (60 to 140$\mu$Hz). We have compared the results coming from the Aarhus adiabatic pulsation code (ADIPLS), with the frequencies computed with the Granada Code (GraCo) taking into account several possible choices. We have concluded that the present equilibrium models and the use of the Richardson extrapolation ensure an accuracy of the order of $0.01 \mu Hz$ in the determination of the frequencies, which is quite enough for our purposes.