The Bubble Nebula, NGC 7635

The Bubble Nebula is a shell of gas and dust carved out by the stellar wind of the massive central star (BD+602522, for the cognoscenti), and ionized by the same star's high-energy light. The Bubble Nebula is in the constellation Cassiopeia, and is bright enough to be seen with a small telescope. It is about 10 light-years across, and is part of a much larger complex of stars and gaseous shells. This picture was created from several exposures in each of three filters made with the T1KA CCD camera at the Kitt Peak National Observatory's 2.1-meter telescope in August of 1999. See also the wide-angle view of the Bubble, including M52.