Fireworks Galaxy (NGC 6946)

The face-on spiral galaxy NGC 6946 is a striking example of an actively star-forming galaxy. Located on the border of the constellations Cepheus and Cygnus, it displays a rich pattern of loosely wound spiral arms with small purple patches showing active regions of star formation.

NGC 6946 lies at a distance of about 8 megaparsecs (26 million light-years) just beyond the Local Group of galaxies. Spanning roughly 12 kiloparsecs (or 40000 light-years) in diameter, the galaxy is somewhat smaller than our own Milky Way but it has far more star forming regions. The high star formation activity also explains the galaxy’s remarkable history of supernova explosions. In the past ~100 years more than ten supernovae have been observed in NGC 6946, an unusually large number for a single galaxy and the reason for it to be named “Fireworks Galaxy.” These supernova explosions mark the deaths of massive stars which live fast and die young (astronomically speaking) and enrich the surrounding interstellar medium with heavier elements.

The image was captured from Leysin, Vaud (Switzerland) using a Celestron C14 Schmidt-Cassegrain reflector telescope with 356 mm apperture 3.9 m focal length. The final image is based on broadband RGB data supplemented with narrowband Hydrogen-alpha exposures. The additional Hydrogen-alpha signal enhances the visibility of ionised hydrogen in the galaxy’s star-forming regions, causing them to appear more prominently as reddish-purple patches along the spiral arms.
 
Aurel Schneider 2025