Massive stars forming in Cygnus X (annotated)
This image of the Cygnus X complex, taken with ESA's Herschel Space Observatory at far-infrared wavelengths, shows how young, massive stars are carving an intricate network of bubbles, filaments and pillars in this very rich stellar nursery. At a distance of about 4500 light years from us, Cygnus X is home to a large number of young, massive stars. With their powerful winds and copious amounts of ionising radiation released into their surroundings, these massive stars are responsible of forging most of the structure that can be seen across the image.
The OB association known as Cygnus OB2 is hosted in the complex, in the central-lower part of the image, as indicated by the white circle. This stellar group hosts thousands of stars, and although they are not visible in the Herschel image their remarkable effects on the nearby clouds stand out clearly: the blue glow in the centre of the image is an example of the powerful winds and radiation from stars in the OB association that have partly cleared out and heated up the surrounding material, making it shine.
The right part of the image displays an intricate network of filaments and pillars hosting intense star formation activity. One of the most notable features in this portion of the image is the DR21 region, an extremely dense filamentary structure that bifurcates towards the right, where very massive stars are being born. Several bubble-like structures are also visible in the right part of the image: DR20, DR22, DR17, W75N. They are all being carved by nearby massive young stars. The radiation released by these stars ionises the gas in their surroundings, causing the bubbles to shine brightly at the shortest of the wavelengths probed by Herschel (hence the blue-white glow that characterises these bubbles in the image).
In the left part of the image, the structure of clouds is more diffuse, with one prominent pillar-like feature, named DR15, whose shape resembles the neck of a swan. A highly symmetric bubble is visible, in blue, close to the edge of this pillar – likely a shell of material being ejected by the Luminous Blue Variable star G79.29+0.46, a supergiant star located at the centre of the shell but invisible at the wavelengths probed by Herschel. Throughout the image, several clumps are visible as compact red objects: these are dense concentrations of matter that will evolve into the next generation of massive stars.
The image combines data acquired with the PACS instrument at 70 micron (shown in blue) and 160 micron (shown in green) and with the SPIRE instrument at 250 micron (shown in red).