The influence of a chromospheric magnetic field on the solar p- and f-modes. II - Uniform chromospheric field

Abstract

A dispersion relation for the p- and f-modes is derived in a model atmosphere containing a uniform chromospheric field. Asymptotic solutions to this equation have been derived for the case of small horizontal wavenumber. Numerical solutions for larger horizontal wavenumbers indicate that, in all cases, the effect of the chromospheric field is to increase the frequency of the modes. The magnitude of the frequency shift increases monotonically with radial order n, degree l and field strength B(0). Comparison with observed frequencies is difficult; however, results suggest that the f-mode in particular may provide a useful indicator of whether or not chromospheric fields are important in determining mode frequencies. Solar cycle variations of high-degree modes and comparisons between active and quiet regions are also likely to reveal the effects of chromospheric magnetism. Only detailed high-resolution data sets of high-degree modes are likely to reveal the importance of chromospheric magnetism for helioseismology.