Best fitting models for HD53138 in the UV region, focusing on the main P-Cygni profiles, namely N v λ21238-42, C II λ21335-36, S iiv λ1394-1403, C iv 21548-50 and Al III λ21855-63, depicted in each row. Each column of panels shows models with the same shock temperature. For each panel the red-dashed stands for f_∞ = 1.0, orange/full for f_∞, = 0.5, green-dash-dotted for f_∞ = 0.2 and blue-dotted for f_∞ = 0.1.