DO P-MODE FREQUENCY-SHIFTS SUGGEST A HOTTER CHROMOSPHERE AT SOLAR MAXIMUM

The frequencies of p-modes are calculated for a model atmosphere consisting of an isothermal gas, within which is embedded a uniform horizontal magnetic field, resting upon a field-free medium whose temperature increases linearly with depth. We compare our results with Libbrecht & Woodard's recent observations of frequency changes. It is found that if simultaneously the chromospheric magnetic field strength and chromospheric temperature are increased, then the frequencies of the p-modes are shifted in a qualitatively similar fashion to that found in the observations, i.e., the frequency shift increases with frequency until about 3.9 mHz, when the shift decreases dramatically. We suggest that the combined influence of an increase in magnetic field strength and an increase in chromospheric temperature plays an important role in determining the observed downturn in frequency shift. Although the resulting frequency shift curve resembles the observed shift, with both possessing a gradual rise phase followed by a turnover, the calculated shift fails to match the steep downturn. Refinements in our basic model and/or new physics are thus indicated.