NGC 7635, also designated Sharpless 162 and refered to as the Bubble Nebula, is an emission nebula located in the constellation Cassiopeia.  It was discovered by Friedrich Wilhelm Herschel in 1787.  The "bubble" is created by the stellar wind from a very hot, massive, magnitude 8.7 central star, affecting a nearby large molecular cloud, which causes it to glow.

http://en.wikipedia.org/wiki/NGC_7635 

ABOUT THE IMAGE

DATE/TIME:  July, 2008

CAMERA:  Meade DSI Pro II

TELESCOPE:  Celestron 235mm SCT @ F/10

EXPOSURE LENGTH:  45min. luminence, 80min. Ha

TOTAL EXPOSURE LENGTH:  2hrs., 5min.