The unusually strong coronal emission lines of SDSS J1055+5637
  Many Seyfert galaxies display weak 'coronal' emission features corresponding
to [Fe VII], [Fe XI] and [Fe XIV] in their optical spectra, whereas elsewhere
these lines seem to be entirely absent. These lines appear to highlight zones
in the nucleus irradiated by high-energy photons. The presence of these zones
and the conditions therein as determined by the relative line strengths and
profiles impose important constraints on the physical models of active galactic
nuclei, and Seyferts in particular. In 2009 the discovery was announced of the
highly unusual spectrum of SDSS J0952+2143, where the coronal lines are
exceptionally strong. This paper presents a second object with abnormally
strong coronal features, SDSS J1055+5637. The spectrum, line ratios and related
parameters are compared to those of SDSS J0952+2143, three AGN with moderate
coronal lines and one where the coronal lines are missing altogether. Possible
mechanisms are discussed that may account for the stronger than usual coronal
features.
