Ring Nebula
From Wikipedia, the free encyclopedia
| Planetary nebula | Lists of nebulae |
|---|---|
 
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| Observation data (Epoch J2000) |
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| Right ascension | 18h 53m 35.079s[1] |
| Declination | +33° 01′ 45.03″[1] |
| Distance | 2.3+1.5−0.7 kly (700+450−200 pc)[2] |
| Apparent magnitude (V) | 9[3] |
| Apparent dimensions (V) | 230″ × 230″[2] |
| Constellation | Lyra |
| Physical characteristics | |
| Radius | 1.3+0.8−0.4 ly[a] |
| Absolute magnitude (V) | -0.2+0.7−1.8[b] |
| Notable features | - |
| Other designations | M 57,[1] NGC 6720[1] |
The Ring Nebula (also known as the Messier 57 or NGC 6720) is located in the constellation Lyra. It is among the most well known and recognizable examples of a planetary nebula. The nebula is located at 0.7 kpc (2300 light-years) from Earth and was discovered by Antoine Darquier de Pellepoix in 1779. The nebula has a visual magnitude of 8.8, and a photographic magnitude of 9.7. It is expanding at a rate of approximately 1 arcsecond per century (corresponding to 20–30 km/s). Its mass is approximately 1.2 solar mass.
M57 is illuminated by a central white dwarf of 14.7 visual magnitude. This star was discovered in 1800 by Count Friedrich von Hahn.
M57 is best seen through at least an 8-inch telescope, but even a 3-inch telescope will show the ring. Larger instruments will show a few darker zones on the eastern and western edges of the ring, and some faint nebulosity inside the disk.
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[edit] Structure
M 57 is estimated to have been expanding for approximately 1,610 ± 240 years. It is bipolar, that is, it has thick equatorial rings with extended structure along its axis of symmetry. It appears to be a prolate spheroid with strong concentrations of material in its equator. Such a structure is a natural product of a bipolar model. From earth, it is viewed at about 30° from the symmetry axis. M 57 exhibits knots characterized by a developed sense of symmetry. However, they are only visible as a silhouette against the background emission from the nebula's equatorial ring. M 57 may include N II emission located at the tips of the knots facing the central star. However, most of the knots are neutral and appear only in extinction. However, the existence of some with possible N II emission shows that the knots are located closer to the ionization front than those found in IC 4406. Some of the knots exhibit well developed tails which are often of a detectable optical thickness in the visual spectrum.[4][2]
[edit] Trivia
Season 3, Episode 1 (entitled 'Spree') of the CBS television drama NUMB3RS made several references to the M57 Nebula, comparing the complexity of human beings to the complexity of the nebula.
An object similar to the Ring Nebula, "The Eye of Jupiter," appears in the third-season episode of the same name in the re-imagined television drama Battlestar Galactica (2004 TV series).
[edit] See also
[edit] External links
- SEDS: Messier Object 57
- Infrared Ring Nebula, APOD 2005 March 11
- NightSkyInfo.com - The Ring Nebula
- M57 The Ring Nebula in Lyra
- M57 at ESA/Hubble
[edit] Notes
[edit] References
- ^ a b c d SIMBAD Astronomical Database. Results for Messier 57. Retrieved on December 19, 2006.
- ^ a b c O'Dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; Burkert, A. (2002). "Knots in Nearby Planetary Nebulae". The Astronomical Journal 123 (6): 3329-3347.
- ^ Murdin, P. (2000). "Ring Nebula (M57, NGC 6720)". Encyclopedia of Astronomy and Astrophysics, Edited by Paul Murdin, article 5323. Bristol: Institute of Physics Publishing, 2001. http://eaa.iop.org/abstract/0333750888/5323.
- ^ O'dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; Burkert, A. (2003). "Knots in Planetary Nebulae". Winds, Bubbles, and Explosions: a conference to honor John Dyson, Pátzcuaro, Michoacán, México, September 9-13, 2002 (Eds. S. J. Arthur & W. J. Henney) Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias) (http://www.astroscu.unam.mx/~rmaa/) 15: 29-33.
