Effect of increasing temperature on the Ni VI/Fe VIII line blend at 1148.2 Å (T_eff = 100, 105, and 110 kK, from top to bottom). Blue graphs show spectra computed without Ni lines, that is to say, we only see the Fe VIII line profile. The nickel lines become weaker and the iron line becomes stronger. As a result, the line Fe+Ni blend stays almost constant. The models have abundances of Fe = 3.5 × 10⁻³ and Ni = 3.0 × 10⁻⁴ by mass.