Semiempirical models of solar and stellar active chromospheres

Semiempirical modeling of the solar chromosphere has been used successfully for decades now, to study the structure of different regions of the Sun, under different states of activity. Recently, these models have become more sophisticated, with the inclusion of the effects of velocity fields, line blanketing, ambipolar diffusion, etc., even if they do not arrive to the levels of complexity of the dynamic models.

I will review the use of semiempirical chromospheric models to study activity in the solar and stellar chromospheres, from solar active regions to active late-type stars, and from solar to stellar flares.