| From the sunspot record, we know the Sun underwent an extended period of extremely low activity from 1640--1710 A.D., known as the Maunder Minimum. Conversely, astronomers have observed "Sun-like" stars that exhibit much higher levels of activity. To explore the impact of such extreme solar input, we built a one-dimensional physical model of the coupled thermosphere and ionosphere. Results from this global average model were found to be in good agreement with other empirical models, as well as previous physical models. Extrapolating the solar irradiance to assumed Maunder Minimum levels, we found the ionosphere undergoes a dramatic change, in which NO+ comes to dominate over O+ in the F-region. Increasing the solar flux to exceptionally high levels revealed a plateau in the peak electron density, although the total electron content continued to rise. |
