Effects of Opacity and Equation of State on Solar Structure and Oscillations
Abstract
The evolution and pmode oscillation frequencies of several solar models are presented, highlighting the effects of uncertainties in the opacity and equation of state. The Dappen, Mihalas, Hummer, and Mihalas ('MHD') equation of state tables are incorporated into the evolution and oscillation calculations, and the results are compared with those of models calculated using the analytical Iben equation of state. The nonadiabatic lowdegree pmode oscillation frequencies derived from models using either of these equations of state agree with observations to within a few microhertz. The MHD equation of state, with more detailed treatment of envelope ionization regions, improves agreement with observations for pmodes of degree l = 40300. For higher degree pmodes, observational uncertainties make it difficult to determine how much improvement the MHD equation of state provides over the analytical Iben procedure. Calculated pmode oscillation frequencies favor the higher RossAller opacities, which include molecular effects and more iron lines, over the older CoxTabor opacities in the solar envelope at temperatures below 9000 K. Thus, solar oscillations can be effectively used to constrain opacities at the solar surface and below the convection zone.
 Publication:

The Astrophysical Journal
 Pub Date:
 November 1991
 DOI:
 10.1086/170655
 Bibcode:
 1991ApJ...381..333G
 Keywords:

 Solar Interior;
 Solar Oscillations;
 Stellar Structure;
 Computational Astrophysics;
 Equations Of State;
 Opacity;
 Solar Temperature;
 Stellar Models;
 Solar Physics;
 EQUATION OF STATE;
 OPACITIES;
 SUN: INTERIOR;
 SUN: OSCILLATIONS