Top: three-color 3.6 (blue), 5.8 (green), and 24 μm (red) image of Cepheus OB3b region. The extended pink emission is likely a mixture of emission from PAHs (particularly the 6.2 μm feature) mixed with thermal emission from dust grains in the 24 μm band. This emission defines the border of a cavity in the molecular cloud within which the young cluster is located. The extended red emission is due to warm dust at 24 μm in the H ii region. The massive stars in the region are labeled; the O7V star is HD 217086 and the early-B stars are HD 217061, BHJ 22, BHJ 24, BHJ 17br, and V454 Cep. Bottom: color composite Poss II image showing Cep OB3b in the visible. The nebulous green emission is the H ii region Sharpless 155. The regions imaged by Chandra for this study and from Getman et al. (2006) are outlined with the solid white line. The region imaged in the visible by Mayne et al. (2007) is outlined with the dashed white line.