  We show that the rapid and large decrease in the intensity of high-ionization
emission lines from the Eta Carinae massive binary system can be explained by
the accretion model. These emission lines are emitted by material in the nebula
around the binary system that is being ionized by radiation from the hot
secondary star. The emission lines suffer three months long deep fading every
5.54 year, assumed to be the orbital period of the binary system. In the
accretion model, for ~70 day the less massive secondary star is accreting mass
from the primary wind instead of blowing its fast wind. The accretion event has
two effects that substantially reduce the high-energy ionizing radiation flux
from the secondary star. (1) The accreted mass absorbs a larger fraction of the
ionizing flux. (2) The accreted mass forms a temporarily blanked around the
secondary star that increases its effective radius, hence lowering its
effective temperature and the flux of high energy photons. This explanation is
compatible with the fading of the emission lines at the same time the X-ray is
declining to its minimum, and with the fading being less pronounced in the
polar directions.
