NGC 7635

NGC 7635

Emission nebula
H II region
Widefield image of NGC 7635 as captured by the Hubble telescope.
Observation data: J2000 epoch
Right ascension	23^h 20^m 48.3^s[1]
Declination	+61° 12′ 06″[1]
Distance	7100[2] to 11000[3][4] ly   (3,400 pc)
Apparent magnitude (V)	~10[5]
Apparent dimensions (V)	15′ × 8′[6]
Constellation	Cassiopeia
Physical characteristics
Radius	3[2] to 5[7][4] ly
Notable features	Shell around SAO 20575[1]
Designations	Bubble Nebula[1] Sharpless 162 (Sh2-162) Caldwell 11

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.^[5] 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.^[6][1] The nearby 7th magnitude star on the west hinders observation, but one can view the nebula using averted vision.^[6] 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.^[6]

Notes

1. SIMBAD 2007.
2. HubbleSite 2000.
3. APOD 2004.
4. APOD 2006.
5. "NGC-IC Project Database". Retrieved 2008-12-15.
6. Kepple & Sanner 1998.
7. APOD 2005.

References

• SIMBAD (February 23, 2007). "Results for NGC 7635". SIMBAD, Centre de Données Astronomiques de Strasbourg.
• 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.
• HubbleSite (2000). "An Expanding Bubble in Space".
• Nemiroff, R.; Bonnell, J., eds. (July 16, 2004). "The Bubble". Astronomy Picture of the Day. NASA.
• Nemiroff, R.; Bonnell, J., eds. (November 7, 2005). "NGC 7635: The Bubble Nebula". Astronomy Picture of the Day. NASA.
• Nemiroff, R.; Bonnell, J., eds. (October 18, 2006). "NGC 7635: The Bubble". Astronomy Picture of the Day. NASA.
• Nemiroff, R.; Bonnell, J., eds. (November 23, 2016). "NGC 7635: Bubble in a Cosmic Sea". Astronomy Picture of the Day. NASA.

| url= http://apod.nasa.gov/apod/ap161123.html

External links

• NGC7635 The Bubble Nebula
• NGC 7635 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
• Bubble Nebula at Constellation Guide