Astronomy:Bubble Nebula

Short description: Emission nebula in the constellation Cassiopeia

NGC 7635

Emission nebula
H II region
Wide field image of NGC 7635 as captured by the Hubble Space Telescope
Observation data: J2000 epoch
Right ascension	23h 20m 48.3s
Declination	+61° 12′ 06″
Distance	7100 to 11000 ly   (3,400 pc)
Apparent magnitude (V)	~10
Apparent dimensions (V)	15′ × 8′
Constellation	Cassiopeia
Physical characteristics
Radius	3 to 5 ly
Notable features	Shell around SAO 20575
Designations	Bubble Nebula Sharpless 162 (Sh2-162) Caldwell 11

NGC 7635, also known as the Bubble Nebula, Sharpless 162, or Caldwell 11, is an H II region emission nebula in the constellation Cassiopeia. It lies close to the open cluster Messier 52. The "bubble" is created by the stellar wind from a massive hot, 8.7 magnitude young central star, SAO 20575 (BD+60°2522). The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow. It was discovered in November 1787 by William Herschel. The star BD+60°2522 is thought to have a mass of about 44 M_☉.

Amateur observation

NGC 7635 and its environs imaged through an 8-inch amateur telescope

With an 8-or-10-inch (200 or 250 mm) telescope, the nebula is visible as an extremely faint and large shell around the star. The nearby 7th magnitude star on the west hinders observation, but one can view the nebula using averted vision. Using a 16-to-18-inch (410 to 460 mm) scope, one can see that the faint nebula is irregular, being elongated in the north south direction.

See also

• Lists of nebulae

References

• "Results for NGC 7635". SIMBAD, Centre de Données Astronomiques de Strasbourg. February 23, 2007. http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=NGC+7635. 
• Kepple, George Robert; Sanner, Glen W. (1998). The Night Sky Observer's Guide. 1. Willmann-Bell, Inc.. pp. 108–109. ISBN 978-0-943396-58-3. 
• "An Expanding Bubble in Space". 2000. http://hubblesite.org/newscenter/archive/releases/2000/04/image/a/. 
• Nemiroff, R.; Bonnell, J., eds (July 16, 2004). "The Bubble". Astronomy Picture of the Day. NASA. https://apod.nasa.gov/apod/ap040716.html. 
• Nemiroff, R.; Bonnell, J., eds (November 7, 2005). "NGC 7635: The Bubble Nebula". Astronomy Picture of the Day. NASA. https://apod.nasa.gov/apod/ap051107.html. 
• Nemiroff, R.; Bonnell, J., eds (October 18, 2006). "NGC 7635: The Bubble". Astronomy Picture of the Day. NASA. https://apod.nasa.gov/apod/ap061018.html. 

External links

• NGC7635 The Bubble Nebula
• Bubble Nebula on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
• Bubble Nebula at Constellation Guide
• NASA Astronomy Picture of the Day: NGC 7635: Bubble in a Cosmic Sea (November 23, 2016)