Convective flux and nonadiabatic solar oscillation.

Abstract

In this work, the role of convective flux in the solar nonradial oscillation is investigated. Although the adiabatic treatment is a good first order approximation of some physical process in the solar nonradial oscillations, a nonadiabatic analysis is needed to explain or compute other important aspects, especially the excitation and damping mechanisms. Since the nonadiabatic effects may rise to a significant level in the region that ranges from the outer part of the convection zone to the photosphere, an accurate description of the convective flux is required. Due to a lack of accurate and reliable theory of time dependent convection, previous works on nonadiabatic analysis simply neglected the perturbation of convective flux, or adopted the mixing length theory (MLT). We find the theory of time dependent turbulent convection developed by Xiong has many of the desired properties. We tried and tested many alternative ways of mathematical formulation and numerical computation to find a practical and reliable way to incorporate Xiong's work with our nonadiabatic analysis. While the treatment in this work may not be completely satisfactory, some interesting results are obtained. The curves of intensity amplitude vs. frequency display unique patterns from which we may suggest that the long period modes can be detected. The positions of minima in plots of temperature amplitude vs. frequency for ℓ = 2, 3, 4 are consistent with the results of SCLERA observations. This agreement speaks to the credibility of both the low order g-mode observations obtained at SCLERA and the way we treat the nonadiabatic oscillations coupled with the convective flux. The curves of heat input vs. radius suggest that the hydrogen ionization zone does play an important role for the coupling of convective flux and the low order g-mode oscillations.