Veil Nebula with WFPC2 inset
This image shows the west end of the Veil Nebula known as the Witch's Broom Nebula or NGC 6960. The central bright star is 52 Cygni. The highlighted portion is an image taken with the Wide Field and Planetary Camera 2 (WFPC2) on board the NASA/ESA Hubble Space Telescope (see related images).
The colour in the WFPC2 image is produced by composite of three different images taken at three different wavelengths using narrow filters centred at 502 nm ([O III]), 656 nm (Hα) and 673 nm ([S II]). The different colours indicate emission from the different kinds of atoms excited by the shock: blue shows oxygen, green shows sulphur, and red shows hydrogen.