To the human eye, the Rosette nebula appears as a vague ghost of a cloud around a bright star cluster in the constellation Monoceros, the Unicorn.
But to the infrared eye of the Herschel Space Observatory, this cosmic rose lights up with astonishing color:
—Image courtesy ESA/PACS & SPIRE Consortium/HOBYS Key Programme Consortia
More precisely, this epic picture was created by color-coding different infrared wavelengths based on the changing temperatures within the dust-and-gas cloud.
The bright regions are massive stars being born inside the nebula, each one shrouded by a dusty cocoon.
Herschel is offering astronomers some of the first views of these so-called protostars, which will grow up to become what are known collectively as OB class stars.
Once they reach adulthood, these very hot, very massive stars won’t live for long. But during their lifetimes, O and B stars emit some of the most energetic radiation that comes from living stars, usually in the form of ultraviolet light.
UV radiation from these stars can quickly ionize—or charge—the gases in the clouds around them, creating what are known as H II regions, such as the Rosette nebula.
H II regions in turn become nurseries for stars great and small, giving birth to thousands of stars over a few million years. Understanding how OB stars are born, live, and die can therefore help astronomers better understand the origins of less massive, longer-lived stars such as our own sun.
On the flip side, previous studies of the Rosette nebula also showed how O stars in particular can effectively halt planet formation around sunlike stars.
Some newborn stars are surrounded by swirling disks of dust and gas. Given enough time, gravity can pull clumps of matter together so that the disks coalesce into planets.
But O stars can create planetary “danger zones,” because the radiation streaming from the bright, massive monsters is so strong it can blow away any embryonic disks surrounding younger stars that formed too close by.