The Bubble Nebula, NGC 7635
Sketch and Details by Serge Vieillard, additional text by Frank McCabe
Serge wrote:
“It was a pleasure to discover the Bubble NGC 7635. A portion of the transparent sphere can be seen with the edge looking like a cat’s claw.”
This beautiful sketch of the portion of NGC 7635 that is known as the Bubble nebula of Cassiopeia was made using an 18 inch Obsession telescope while Serge was in Spain during September of 2007. You can see that the 9th magnitude, young hot O-type star that is shedding its outer surface (stellar wind) and creating this bubble arc is not centered. This is due to the resistance to expansion created by a portion of the surrounding molecular cloud that can be seen glowing in part to the left of the arc. The Bubble is known today to be a diffuse emission nebula and was discovered by Fredrich W. Herschel in 1787.