Representative examples for each morphological group. From left to right: aligned bow shocks, unaligned bow shocks, and centered, unresolved, and not classified nebulae. All images are RGB images where red, green, and blue correspond to the WISE 22, 12, and 4.6 μm filters. The straight white lines show the proper motion corrected to the local standard of rest. Their length indicates the displacement of each star within 10 000 yr. The white bar at the bottom of each panel corresponds to 2^′.