Ring Nebula
| Nebula | |
|---|---|
 
M57, The Ring Nebula. Upper image credits: NASA/ESA | |
| Observation data: J2000 epoch | |
| 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] ly |
| Apparent magnitude (V) | 9[3] |
| Apparent dimensions (V) | 230″ × 230″[2] |
| Constellation | Lyra |
| Physical characteristics | |
| Radius | 1.3+0.8 −0.4 ly[a] ly |
| Absolute magnitude (V) | -0.2+0.7 −1.8[b] |
| Notable features | - |
| 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.
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.
Observation history
This nebula was discovered by Antoine Darquier de Pellepoix in 1779. In 1800, Count Friedrich von Hahn discovered a faint central star at the center of the nebula.
Structure
The nebula is located at 0.7 kpc (2300 light-years) from Earth. 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.
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. The existence of some knots with possible N II emission shows that they 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]
Media
 | This article contains a list of miscellaneous information. (June 2007) |
The Ring Nebula has appeared in some media productions. 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. A diagram of the Ring Nebula is sown in the "Astrometrics Lab" onboard the USS Voyager in the TV series Star Trek: Voyager.
See also
Notes
References
- ^ a b c d "SIMBAD Astronomical Database". Results for Messier 57. Retrieved 2006-12-19.
- ^ 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.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ 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.
{{cite journal}}: External link in|journal= - ^ 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.
{{cite journal}}: External link in|journal=