NGC 7635

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NGC 7635
Emission nebula Lists of nebulae
Observation data
(Epoch J2000)
Type Emission[1]
Right ascension 23h 20m 48.3s[2]
Declination +61° 12 06[2]
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[1]
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[2]
Other designations Bubble Nebula[2]
Sharpless 162 (Sh2-162)
Caldwell 11
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NGC 7635, also called the Bubble Nebula, Sharpless 162, or Caldwell 11, is a H II region[2] 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[2] 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

With an 8 or 10-inch (250 mm) telescope, the nebula is visible as an extremely faint and large shell around the star.[1][2] The nearby 7th magnitude star on the west hinders observation, but one can view the nebula using averted vision.[1] 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.[1]

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

Notes

  1. 1.0 1.1 1.2 1.3 1.4 Kepple & Sanner 1998
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 SIMBAD 2007
  3. 3.0 3.1 Hubble Site, 2000. An Expanding Bubble in Space. "diameter of 6 light-years", "distance of 7,100 light-years".
  4. 4.0 4.1 APOD (July 16, 2004), Astronomy Picture of the Day: The Bubble, NASA 
  5. 5.0 5.1 APOD (October 18, 2006), Astronomy Picture of the Day: NGC 7635: The Bubble, NASA 
  6. 6.0 6.1 "NGC-IC Project Database". Retrieved 2008-12-15. 
  7. 7.0 7.1 7.2 APOD (November 7, 2005), Astronomy Picture of the Day: NGC 7635: The Bubble Nebula, NASA 

References

  • 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

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