NGC 7635

For the Bubble Nebula in Barnard's Galaxy, see Bubble Nebula (NGC 6822).

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
	edit

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 Friedrich Wilhelm 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. ^ ^{a b c d e} Kepple & Sanner 1998
2. ^ ^{a b c d e f g} SIMBAD 2007
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, http://antwrp.gsfc.nasa.gov/apod/ap040716.html 
5. ^ ^{a b} APOD (October 18, 2006), Astronomy Picture of the Day: NGC 7635: The Bubble, NASA, http://antwrp.gsfc.nasa.gov/apod/ap061018.html 
6. ^ ^{a b} "NGC-IC Project Database". http://www.ngcic.org/ngcicdb.asp. Retrieved 2008-12-15. 
7. ^ ^{a b c} APOD (November 7, 2005), Astronomy Picture of the Day: NGC 7635: The Bubble Nebula, NASA, http://antwrp.gsfc.nasa.gov/apod/ap051107.html 

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

• SIMBAD (February 23, 2007), Results for NGC 7635, SIMBAD, Centre de Données Astronomiques de Strasbourg, http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=NGC+7635 
• NGC7635 The Bubble Nebula
• NGC 7635 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images