Dense filaments of gas in the IC5146 interstellar cloud.


This colour-composite image of IC 5146 shows the extended filamentary structure of this star-forming cloud. A detailed study of this complex has shown a total of 27 filaments that all appear to have very similar widths, with a value of about 0.3 light years.

Over 350 compact starless cores have been detected embedded in the filaments in this region: about 45 of these are gravitationally bound, pre-stellar core candidates, the seeds of future stars. All pre-stellar cores are located in the densest, unstable filaments of the cloud - mostly along the main filamentary streamer visible in the central part of the image.

The glowing cavity on the left side of the image, also known as the Cocoon Nebula, is an HII region, where a young and bright B0 star illuminates the ionised hydrogen gas, causing it to shine. Some young stellar objects are visible as bright spots along the main filaments; many other young stellar objects are located in the Cocoon Nebula but are not visible in this image.

Located at a distance of about 1500 light years, the IC 5146 complex belongs to the Gould Belt, a giant ring of stars and star-forming clouds in the vicinity of the Sun.

ESA’s Herschel space observatory has revealed that nearby interstellar clouds contain networks of tangled gaseous filaments. Intriguingly, each filament is approximately the same width, hinting that they may result from interstellar sonic booms throughout our Galaxy.

The filaments are huge, stretching for tens of light years through space and Herschel has shown that newly-born stars are often found in the densest parts of them.

Such filaments in interstellar clouds have been glimpsed before by other infrared satellites, but they have never been seen clearly enough to have their widths measured. Now, Herschel has shown that, regardless of the length or density of a filament, the width is always roughly the same.

This image was taken by ESA’s Herschel space observatory at infrared wavelengths 70, 250 and 500 microns. Stars are forming along these filaments.

Credit: ESA/Herschel/SPIRE/PACS/D. Arzoumanian (CEA Saclay) for the “Gould Belt survey” Key Programme Consortium.


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