Exploring the small-scale magnetic fields of the solar analog KIC 8006161 using asteroseismology

TL;DR

This study uses asteroseismology to investigate small-scale magnetic fields in the solar analog KIC 8006161, revealing their influence on oscillation frequencies and constraining their strength and location in the star's outer atmosphere.

Contribution

It introduces a method to infer small-scale magnetic field strengths in a solar-like star by modeling their effect on asteroseismic surface terms, a novel approach in stellar magnetism studies.

Findings

Magnetic field strengths are approximately 89-96 G in KIC 8006161.

Magnetic-arch splicing layers are located around 510-522 km in the stellar atmosphere.

The presence of small-scale magnetic fields explains observed asteroseismic frequency offsets.

Abstract

The magnetic field is a significant and universal physical phenomenon in modern astrophysics. Small-scale magnetic fields are very important in the stellar atmosphere. They are ubiquitous, and strongly couple with the acoustic waves. Therefore, their presence affects the properties of acoustic waves in the stellar outer layer. In the present work, under the assumption that the small-scale magnetic features are the cause of the asteroseismic surface term (the frequency-dependent frequency offset between stars and their models), we explore the strength of such fields in the solar analog KIC 8006161. By considering the effect of small-scale magnetic fields in the stellar photosphere, we use the observed oscillation frequencies to constrain the inner structures and surface small-scale magnetic fields of solar-like star KIC 8006161. To agree with the existing observations, such as oscillation frequencies, and their frequency separation ratios, the theoretical model requires a small-scale magnetic field to form a magnetic-arch splicing layer in the stellar outer atmosphere. The small-scale magnetic field strengths for KIC 8006161 obtained from best-fit model with $Y_{\rm init} = 0.249+1.33Z_{\rm init}$ and $Y_{\rm init}$ as a free parameter, are approximately 96 G and 89 G, respectively. The corresponding locations of the magnetic-arch splicing layer are about $522$ km and 510 km, respectively.