Distribution of ¹²CO (white) and C¹⁸O (red) profilesover the 9′ × 9′ region. In the left-hand panel, the background image is the Herschel 250 μm emission for cloud L1157, on which we overlay contours of the N₂H⁺ (1–0) line in yellow. The positions of core C1 and clump C2 are marked in white. The extent of the outflow is marked by the cyan arrow. Contour levels start from 4σ in steps of 3σ, where σ ~ 0.05 K km s⁻¹. The small windows in the right-hand panel show the average spectra of the ¹²CO, C¹⁸ O, and N₂H⁺ (1–0) (isolated component) lines for C1 (top) and C2 (bottom). The average was taken over the half-maximum contour of the intensity map of the N₂H⁺ emission for C1 and C2. The dashed line indicates the velocity of N₂H⁺ obtained from the Gaussian hyperfine fitting of its seven hyperfine components.