Via Wired, by Lisa Grossman; image from ESO:
This wispy blue cloud of gas and dust is a star-forming region surrounding the star R Coronae Australis, which is about 420 light-years away. The new portrait was taken with the Wide Field Imager at the La Silla Observatory in Chile. The image, a combination of 12 separate snapshots in three different colors, depicts a young family of stars still embedded in and interacting with the cloud of dust and gas from which they formed.
The image spans about 4 light-years, and focuses on a nascent star-forming region located in the small, tiara-shaped constellation Coronae Australis, the Southern Crown. The infant stars there give off hot, intense radiation, and the surrounding gas and dust either reflects or absorbs this radiation and re-emits it at a different wavelength.
While most nebulae glow with a characteristic red tint, the R Coronae Australis region takes an unusual blue hue. The stars are about the mass of the sun, and don’t emit enough ultraviolet light to strip the surrounding hydrogen gas of its electrons, which would produce the familiar red glow. The blue fog is mostly due to starlight reflecting off small dust particles.
In some regions, like the dark band that crosses the image from the bottom left, the starlight is completely absorbed by dust. Any stars hiding in this region would only be visible with an infrared telescope that can detect their heat.