Astronomy Picture of the Day: 10/22/13 - IC 5146

Resembling the blisteringly hot surface of a nuclear oven, this lovely celestial region, known as IC 5146 (or the Cocoon Nebula), is located at the front edge of a molecular cloud complex. (The image is kind of deceiving, as most of this nebula is very, very cold) Here, we can see not one, but three different types of nebulae. First, we have an emission nebula, made up of hydrogen gas. Then, we have a reflection nebula, where interstellar dust grains reflect starlight from embedded stars, bringing an otherwise invisible molecular cloud to life (at infrared wavelengths, which is the range of the electromagnetic spectrum we are looking at here)

Within the bright, bluish "cocoon" part of the nebula, we have an open cluster of stars, which have been dubbed Collinder 470. Whilst not pictured in this particular image, the stars that comprise the cluster are largely responsible for the shape, as the fierce winds that blow through the raw star formation material clear out several cavities, serving as a catalyst for ionization (the process that allows nebulae to glow)

Enclosed around the brightest portion of the emission nebula, we have a dark absorption nebula, known as Barnard 168. It separates the emission nebulae (and the filaments extending from the cluster) from the background surroundings. (Some of the individual filaments extend about 0.3 light-years across -- about 20,000 times the distance between the sun and Earth)

The stellar nursery can be found some 4,000 light-years from Earth in the Cygnus constellation. From top to bottom, the nebula stretches across more than 15 light-years in total. Beautiful, isn't it?

References, sources, and further reading can be found here: http://www.fromquarkstoquasars.com/astronomy-picture-of-the-day-102213-ic-5146/

Credit: ESA/Herschel/SPIRE/PACS/Gould Belt Survey/D. Arzoumanian (CEA Saclay)