Having found that type 1 Seyfert nuclei have excess [ \ion Fe7 ] \lambda 6087 emission with respect to type 2s , Murayama & Taniguchi have proposed that the high-ionization nuclear emission-line region ( HINER ) traced by the [ \ion Fe7 ] \lambda 6087 emission resides in the inner wall of dusty tori .
The covering factor of the torus is usually large ( e.g. , \sim 0.9 ) .
Further , electron density in the tori ( e.g. , \sim 10 ^ { 7 \mbox { - - } 8 } cm ^ { -3 } ) is considered to be higher significantly than that ( e.g. , \sim 10 ^ { 3 \mbox { - - } 4 } cm ^ { -3 } ) in the narrow-line region ( NLR ) .
Therefore it is expected that the torus emission contributes to the majority of the higher-ionization emission lines .
Taking this HINER component into account , we have constructed new dual-component ( i.e. , a typical NLR with a HINER torus ) photoionization models .
Comparison of our model with the observations show that that if the torus emission contributes \sim 10 % of the NLR emission , our dual-component model can explain the observed high [ \ion Fe7 ] \lambda 6087/ [ \ion O3 ] \lambda 5007 intensity ratios of the Seyfert 1s without invoking any unusual assumptions ( e.g. , the overabundance of iron ) .