2-D Stellar Evolution Code Including Arbitrary Magnetic Fields. I. Mathematical Techniques and Test Cases

摘要

A high-precision two-dimensional stellar evolution code has been developedfor studying solar variability due to structural changes produced by varyinginternal magnetic fields of arbitrary configurations. Specifically, we areinterested in modeling the effects of a dynamo-type field on the detailedinternal structure and on the global parameters of the Sun. The high precisionis required both to model very small solar changes (of order of $10^{-4}$) andshort time scales (or order of one year). It is accomplished by using the masscoordinate to replace the radial coordinate, by using fixed and adjustable timesteps, a realistic stellar atmosphere, elements diffusion, and by adjusting thegrid points. We have also built into the code the potential to subsequentlyinclude rotation and turbulence. The current code has been tested for severalcases, including its ability to reproduce the 1-D results.