Physical processes determining the chromospheric temperature distribution

Abstract

Calculations performed with several models of the solar chromosphere support Ulmschneider's conclusion that relatively short period acoustic waves heat the low chromosphere in the region just above the temperature minimum. However, these same short period waves (10⩽ period P⩽80 s) are not able to maintain chromospheric temperatures at heights where τ5000A(normal) < 10-6. The calculations also show that an earlier conjecture stating that the H2 population might influence the non-LTE chromospheric H- population is probably not correct, due to lower values of the ratio ne/nH inferred from more recent observations. Finally, the calculations support Athay's contention that the Cayrel mechanism alone cannot produce the observed temperature rise, because the magnitude of the radiative cooling in the lines is too great.