Characteristic X-ray temperature T_X versus bubble radius R₂ for the sequences WR100V05 (right, solid) and WR100V05x5.5 (left, dashed) and the bubbles of our sample (Table 3). Again, bubble evolution occurs from left to right, and maximum stellar temperatures are indicated by a vertical mark. Evaporating bubbles with inhomogeneous composition are connected by thick solid or dashed lines. The mean temperatures of the hydrogen-poor part, T_X(WR), and of the hydrogen-rich part, T_X(PN), are shown as crosses and triangles, respectively, for the WR100V05 bubbles. As in the previous figure, the arrow indicates the (estimated) shift of the WR100V05 bubbles if the evolutionary timescale is increased by a factor of 2.5. The symbol of NGC 40 (no. 4) is shown in grey because of the large uncertainty of the derived TX value. The top and bottom panel displays the NEI and the CIE case, respectively.