Does Solar Structure Vary with Solar Magnetic Activity?

Abstract

We present evidence that solar structure changes with changes in solar activity. We find that the adiabatic index, Γ₁, changes near the second helium ionization, i.e., at a depth of about 0.98 R_solar. We believe that this change is a result of the change in the effective equation of state caused by magnetic fields. Inversions should be able to detect the changes in Γ₁ if mode sets with reliable and precise high-degree modes are available.