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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.

Contents

Observation history

Structure

Media

See also

Notes

References

External links

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.^[1]

Media

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 shown in the "Astrometrics Lab" onboard the USS ''Voyager'' in the TV series ''.

See also

★ List of planetary nebulae

★ Messier object

★ New General Catalogue

Notes

1. Radius = distance × sin(angular size / 2) = 2.3 kly
   ★ sin(230″ / 2) = 1.3 ly


2. 9 apparent magnitude - 5
   ★ (log₁₀(700 pc distance) - 1) = -0.2 absolute magnitude

References

1. Knots in Planetary Nebulae, O'dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; Burkert, A., , , 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/), 2003

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