The image shows most of the cloud associated with the Rosette nebula, located about 5,000 light-years from Earth in the constellation Monoceros, the Unicorn. The region contains a family of growing stars, with the oldest and most massive members in the center of the nebula, and younger and less massive generations located farther out in the associated cloud. The nebula's cluster of the most massive stars, located beyond the right edge of the picture, is responsible for hollowing out the cavity. There's enough dust and gas in the entire Rosette cloud to make about 10,000 suns.
The large, embryonic stars uncovered by Herschel are thought to be a younger generation. They are located inside the tips of pillars that appear to branch out from thicker cloud material. The pillars were, in fact, excavated by the nebula's massive star cluster. Winds and radiation from those stars pushed less dense material away from the pillars, and probably triggered the birth of the big stars inside the finger-like structures. In fact, the pillars point to the location of the massive nebula stars.
The intermediate-mass stellar embryos, each a couple of times as massive as the sun, are located in the redder regions of the image. The small spots near the center of the image are lower-mass embryonic stars, similar in mass to the sun.