Cygnus X and the Horsehead: a farewell to Herschel

Image credits and text: The Herschel online showcase

This image shows the DR21 ridge, a very massive filamentary structure oriented north-south in the extremely active star-forming region Cygnus X. It resides at a distance of about 4500 light-years from Earth in the constellation of Cygnus, the Swan. A combination of three maps observed by ESA’s Herschel space observatory, the image reveals the finely detailed structure of the cold interstellar material in red colour. This cold material is organised into filaments, many of which converge towards the main ridge. Within the ridge, bright white compact sources trace the very young new stars that are caught in formation, including several high-mass stars. Due to its large mass reservoir, the DR21 ridge is expected to transform into the most massive young star cluster in the whole Cygnus X region. Herschel also shows the evolution of star formation along the DR21 ridge from the southern, brightest object – the HII region DR21 itself – to the more northern, fainter, less evolved young stars. High-mass stars are rare in number relative to stars like our Sun, but due to their much stronger radiation and their death as supernovae, they have a large influence on the evolution of the interstellar medium in our Galaxy. These new Herschel observations strongly suggest that the convergence of filaments in areas like the DR21 ridge is a way nature forms massive star clusters containing high-mass stars. The filaments play an important role in the process as they channel material towards the DR21 ridge to build up a large reservoir of mass.


The familiar Horsehead Nebula is at extreme right. The complete image spans some hundreds of light years. Violent star-formation processes are observed occurring throughout the region. Much more information can be found out at these European Space Agency pages.


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