Spatial variation of the X‐ray colors of two example galaxies are shown in the C21‐C32 plane. The data points give the colors, while the arrows connecting them show the direction of increasing radius. The galaxies are labeled. NGC 4649 is an X‐ray–bright, group 3 galaxy, while NGC 4697 is an X‐ray–faint, group 1 galaxy. The model tracks are the same as in Fig. 5.