  Measurements of ultraviolet line fluxes from Space Telescope Imaging
Spectrograph and Far-Ultraviolet Spectroscopic Explorer spectra of the K2-dwarf
Epsilon Eri are reported. These are used to develop new emission measure
distributions and semi-empirical atmospheric models for the chromosphere and
lower transition region of the star. These models are the most detailed
constructed to date for a main-sequence star other than the Sun. New ionisation
balance calculations, which account for the effect of finite density on
dielectronic recombination rates, are presented for carbon, nitrogen, oxygen
and silicon. The results of these calculations are significantly different from
the standard Arnaud & Rothenflug ion balance, particularly for alkali-like
ions. The new atmospheric models are used to place constraints on possible
First Ionisation Potential (FIP) related abundance variations in the lower
atmosphere and to discuss limitations of single-component models for the
interpretation of certain optically thick line fluxes.
