NGC 7635

From Wikipedia, the free encyclopedia
Jump to: navigation, search
NGC 7635
Emission nebula
Bubble Nebula.jpg
Observation data
(Epoch J2000)
Type Emission[2]
Right ascension 23h 20m 48.3s[1]
Declination +61° 12′ 06″[1]
Distance 11 kly (3.4 kpc)
(7100[3] to 11000[4][5] ly, sources differ)   
Apparent magnitude (V) ~10[6]
Apparent dimensions (V) 15′ × 8′[2]
Constellation Cassiopeia
Physical characteristics
Radius 5 ly (3[3] to 5,[5][7] sources differ)   
Absolute magnitude (V) Unknown
Notable features Shell around SAO 20575[1]
Designations Bubble Nebula[1]
Sharpless 162 (Sh2-162)
Caldwell 11
Lists of nebulae

NGC 7635, also called the Bubble Nebula, Sharpless 162, or Caldwell 11, is a H II region[1] emission nebula in the constellation Cassiopeia. It lies close to the direction of the open cluster Messier 52. The "bubble" is created by the stellar wind from a massive hot, 8.7[1] magnitude young central star, the 15 ± 5 M[4] SAO 20575 (BD+60 2522).[7] 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.[7] It was discovered in 1787 by William Herschel.[6] The star SAO 20575 or BD+602522 is thought to have a mass of 10-40 Solar masses.

Amateur observation[edit]

With an 8 or 10-inch (250 mm) telescope, the nebula is visible as an extremely faint and large shell around the star.[2][1] The nearby 7th magnitude star on the west hinders observation, but one can view the nebula using averted vision.[2] Using a 16 to 18-inch (460 mm) scope, one can see that the faint nebula is irregular, being elongated in the north south direction.[2]

Widefield image of NGC 7635 and M52 as captured by an amateur telescope


  1. ^ a b c d e f g SIMBAD 2007
  2. ^ a b c d e Kepple & Sanner 1998
  3. ^ a b Hubble Site, 2000. An Expanding Bubble in Space. "diameter of 6 light-years", "distance of 7,100 light-years".
  4. ^ a b APOD (July 16, 2004), Astronomy Picture of the Day: The Bubble, NASA 
  5. ^ a b APOD (October 18, 2006), Astronomy Picture of the Day: NGC 7635: The Bubble, NASA 
  6. ^ a b "NGC-IC Project Database". Retrieved 2008-12-15. 
  7. ^ a b c APOD (November 7, 2005), Astronomy Picture of the Day: NGC 7635: The Bubble Nebula, NASA 


  • Kepple, George Robert; Sanner, Glen W. (1998), The Night Sky Observer's Guide 1, Willmann-Bell, Inc., pp. 108–109, ISBN 0-943396-58-1 

External links[edit]