The Bubble Nebula, NGC7635, is an emission nebula in Cassiopeia. The bubble itself is actually a void created by the stellar wind of a hot, young star making it one of t he more distinctive nebulae in the sky.
The nebula is anywhere from 7,100 to 11,100 light years away according to Wikipedia.
I chose the SOH palette to help the bubble itself stand out making it appear like a jewel floating in the night in a crumpled purple blanket. Leaving the poetic imagery aside, I though it was a nice color combination.
You can find the technical details at astrobin.