Bubble Nebula (NGC 7635)
The smallest of three bubbles surrounding the massive star
BD +60° 2522 in the constellation Cassiopeia
(R.A. 23h 20.7m Dec. +61° 12'), and part of the gigantic bubble network
S162, created with the help of other massive stars. As fast-moving gas spreads
out from BD +60° 2522, it pushes surrounding sparse gas into a shell.
The energetic starlight then ionizes the shell, causing it to glow. The
nebula is about 6 light-years across and visible even with a small telescope.
AND STAR CLUSTERS