Global Parameter and Helioseismic Tests of Solar Variability Models

Abstract

We construct models of the structure and evolution of the Sun which include variable magnetic fields and turbulence. The magnetic effects are (1) magnetic pressure, (2) magnetic energy, and (3) magnetic modulation to turbulence. The effects of turbulence are (1) turbulent pressure, (2) turbulent kinetic energy, and (3) turbulent inhibition of the radiative energy loss of a convective eddy, and (4) turbulent generation of magnetic fields. Using these ingredients we construct five types of solar variability models (including the standard solar model) with magnetic effects. These models are in part based on three-dimensional numerical simulations of the superadiabatic layers near the surface of the Sun. The models are tested with several sets of observational data, namely, the changes of (1) the total solar irradiance, (2) the photospheric temperature, (3) radius, (4) the position of the convection zone base, and (5) low-and medium-degree solar oscillation frequencies. We find that turbulence plays a major role in solar variability, and only a model that includes a magnetically modulated turbulent mechanism can agree with all the current available observational data. We find that because of the somewhat poor quality of all observations (other than the helioseismological ones), we need all data sets in order to restrict the range of models.

Stellar parameters and seismological analysis of the star 18 Scorpii

“…Details of the physics can be found in Guenther et al (1992), Chaboyer et al (1995), and Li et al (2003). We used the physical quantities of the OPAL equation-of-state tables EOS2005 (Rogers & Nayfonov 2002), the opacities GS98 (Grevesse & Sauval 1998) supplemented by the low-temperature opacities (Ferguson et al 2005), and the atmosphere following the Eddington T − τ relation.…”

Interpreting Helioseismic Structure Inversion Results of Solar Active Regions

“…How magnetic effects are incorporated in the models has been described in detail by Li and Sofia (2001) and Li et al, (2003). We give a brief overview here.…”

“…There are also changes in the properties of convection. The details of including the magnetic effects in models can be found in Lydon and Sofia (1995), Li and Sofia (2001) and Li et al (2003).…”

A Virial Theorem Investigation of Magnetic Variations in the Sun

“…On the other hand, if the convective efficiency is lowered because of an increasing (but not explicitly included) magnetic field, the photospheric radius shrinks (e.g., Balmforth et al 1996). The clear need to introduce an explicit physical interaction between turbulent convection and magnetic fields has been stressed by Li et al (2003). However, we would emphasize the still more important need to conserve the total energy of the star, which is a more fundamental constraint and does not require knowledge of how the various kinds of energy are exchanged with each other.…”