The constellation of Cygnus is one of the most recognisable in the northern hemisphere. During the summer months, the stars of its long neck stretch along the Milky Way and its wings sweep from side to side.
Switch to the invisible wavelengths of the far-infrared and the Milky Way’s river of stars disappears to reveal tendrils of cold dust. Shown here, in this image from Japan’s Akari space observatory, are the central regions of Cygnus, and it can be seen that the Milky Way displays a rich stock of dust.
This dust is part of the interstellar medium, which also contains gas. These infrared images reveal the detailed distribution of the interstellar medium, highlighting areas where bright, new stars are about to emerge in the Milky Way.
Far-infrared light is the key wavelength range for investigating stars and planet formation. When the interstellar medium gathers together under the attraction of its own gravity, it forms a giant molecular cloud. These can be hundreds of light-years across. Denser parts, just a few tenths of a light-year across, are known as molecular cloud cores. These are where stars and planets form.
Akari images, such as this one, are the only images in which scientists can closely examine the entire giant molecular cloud with the resolution of a molecular cloud core.
This false-colour image, spanning 20×15°, is constructed from three far-infrared bands: blue represents 65 micrometres, green shows 90 micrometres and red codes the 140 micrometre wavelength. The image is part of Akari’s recently released all-sky survey.
The mission observed more than 99% of the entire sky over a period of 16 months. The all-sky images have a resolution of 1–1.5 arcminutes, in four wavelengths: 65, 90, 140 and 160 micrometres.
Akari was a Japan Aerospace Exploration Agency (JAXA) project with ESA’s participation.