Color image shows the ratio of c-C₃H₂ to CCH column densities as derived from 1 mm observations, assuming the rotational temperature of Fig. 6. Pixels without a detection of both CCH and c-C₃H₂ have been masked. The black contours represent the integrated intensity of the 262.004  GHz CCH line (from 15 to 25   K   km   s^-1 in steps of 2.5  K   km   s^-1), and white contours represent the Spitzer IRAC 8   μm emission.