Ratio of shock emissivity to total emissivity for model S30 from Fig. 1 with R_min= 1.2 R_∗. Solid line: emissivity ratio at the outer boundary, r ≈ 130R_∗; dash-dotted line: emissivity ratio at the lower boundary of X-ray emission, r ≈ 1.2R_∗. The box located between 300 and 320 Å highlights the strong shock emissivity leading to the corresponding emission feature present in Fig. 1.