NGC 7635 - Bubble Nebula

Designations:	NGC 7635, Caldwell 11, H IV 52
Object Type:	Emission Nebula
Constellation:	Cassiopeia
RA:	23 hr 20 min 42.0 sec	Dec:	+61° 11 min 00 sec
Magnitude:	8.69 (central star)	Size:	15.0 X 8.0 arcminutes
Distance:	11,300 light years

Easy to star-hop to, easy to find but not easy to see! The open cluster M52 points the way, The bubble nebula is just one degree away in a south-westerly direction. Observing from my suburban skies with an 10 inch, the nebula was not seen. The nebula has a strong O-III emission, an O-III nebula filter should make observation easier. To find M52, and hence the Bubble Nebula, follow the line Alpha to Beta Cassiopeiae and on in a straight line for the same distance. Billed by the Hubble Heritage Team (Hester et al. 1992), as the "bubble versus the cloud" . The part we know as the Bubble Nebula is being forced out by a stellar wind of ionized gas from a massive central star. However next door is a giant molecular cloud ( a portion of which is visible in the image). The cloud, although able to contain the expansion of the bubble's gas, gets blasted with intense radiation from the central star. This radiation heats up denser regions, ionizing it and causing the shell to glow. This interpretation was confirmed by Buckalew et al. (1999) who, using observations with the Space Telescope Imaging Spectroscope (STIS), concluded that the characteristic rim was the edge of a shell of ionized gas that is being "snow ploughed" through the surrounding region by the supersonic wind from the star. The Bubble Nebula is actually the smallest part of three bubbles surrounding the central star and part of gigantic network known as s162, created by other massive stars. The Bubble Nebula's central star BD+602522, is 10 to 20 times more massive than the Sun and is classed as type O6.5iiif. The Nebula is about 10 light years across and 11,300 light years away

Telescope:	TMB 152 F8 APO refractor
Focal Length:	1200
Mount:	Takahashi NJP 160
Camera	SBIG ST10XME
Guider:	SBIG ST402ME
Exposures:	12 15-minute exposures through a hydrogen alpha filter and 5 8-minute exposures through each color filter (red, green and blue). (5 hours total)
Location:	Prairie Grass Observatory
Software:	CCDSoft for image acquisition, processed with CCDStack and Photoshop CS2