Spatial distribution along the northwest‐southeast direction of continuum and emission‐line intensities, normalized to unity. While the continuum and He II λ4686 profiles coincide, profiles of other emission lines are shifted in the southeast direction and coincide with the youngest stellar cluster detected by Melnick et al. (1992) and Thuan et al. (1996b). Difference in the spatial distribution of He II λ4686 and other emission lines implies that ionization of He⁺ by hard photons with λ ≤ 228 Å is not caused by main‐sequence O stars.