Observed DCO⁺ radial profile (black continuous line). These profiles are obtained by averaging the values of concentric ellipsoids of the integrated intensity maps. The error bars of the observed DCO⁺ radial profilecorresponds to 3σ, where σ is the standard deviation of the values contained in the ellipsoid divided by the square root of the number of beams. The 50 AU bar corresponds to the semiminor axis of the synthesized beam and serves as a measure of the spatial resolution. The dashed lines show radial profiles of the emission from models with two different evaporation temperatures of CO T_CO = 19–20 K and a constant abundance X_in = 5.0 × 10⁻⁵.