W40 in the Aquila Rift as an example of StageIV: the formation of the W40 cluster in a hub has blown out the bipolar HII region (seen in blue-green; see Mallick et al. 2013, for details). The effects of radiation from OB stars “burning out” the hub-composing filaments can be seen as pillars. The ionising gas shock front sweeping up some filaments as it moves past it can also be seen. The colour composite uses Herschel SPIRE 500 μm image (tracing the filaments) as red, PACS 70 μm as green, and Spitzer MIPS 24 μm as blue.