NGC 7635, also called the Bubble Nebula, is a beautiful emission nebula in the constellation Cassiopeia. It's about 11,000 light-years away. The Bubble is created by the stellarwind from a massive hot 8.7 magnitude young central star . The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being exited by the hot central star , causing it to glow .
The Bubble Nebula is 7 light-years across about one-and-a-half times the distance from our sun to its nearest stellar neighbor, Alpha Centauri and resides 7,100 light-years from Earth . The seething star forming this nebula is 45 times more massive than our sun. Gas on the star gets so hot that it escapes away into space as a “stellar wind” moving at over 4 million miles per hour. This outflow sweeps up the cold, interstellar gas in front of it, forming the outer edge of the bubble much like a snowplow piles up snow in front of it as it moves forward. As the surface of the bubble’s shell expands outward, it slams into dense regions of cold gas on one side of the bubble.
Dense pillars of cool hydrogen gas laced with dust appear at the upper left of the picture, and more “fingers” can be seen nearly face-on, behind the translucent bubble. The gases heated to varying temperatures emit different colors: oxygen is hot enough to emit blue light in the bubble near the star, while the cooler pillars are yellow from the combined light of hydrogen and nitrogen. It was discovered in 1787 by William Herschel.