Dumbbell Nebula

The Dumbbell Nebula (also known as the Apple Core Nebula, Messier 27, and NGC 6853) is a planetary nebula (nebulosity surrounding a white dwarf) in the constellation Vulpecula, at a distance of about 1360 light-years. It was the first such nebula to be discovered, by Charles Messier in 1764. At its brightness of visual magnitude 7.5 and diameter of about 8 arcminutes, it is easily visible in binoculars and is a popular observing target in amateur telescopes.

The Dumbbell Nebula appears shaped like a prolate spheroid and is viewed from our perspective along the plane of its equator. In 1992, Moreno-Corral et al. computed that its rate of expansion angularly was, viewed from our distance, no more than Template:Val (″) per century. From this, an upper limit to the age of 14,600 years may be determined. In 1970, Bohuski, Smith, and Weedman found an expansion velocity of Template:Val. Given its semi-minor axis radius of Template:Val, this implies that the kinematic age of the nebula is 9,800 years.

Like many nearby planetary nebulae, the Dumbbell contains knots. Its central region is marked by a pattern of dark and bright cusped knots and their associated dark tails (see picture). The knots vary in appearance from symmetric objects with tails to rather irregular tail-less objects. Similarly to the Helix Nebula and the Eskimo Nebula, the heads of the knots have bright cusps which are local photoionization fronts.

The central star, a white dwarf progenitor, is estimated to have a radius which is Template:Val (0.13 light seconds) which gives it a size larger than most other known white dwarfs. Its mass was estimated in 1999 by Napiwotzki to be Template:Val.

Appearance

File:Vulpecula IAU.svg Constellation Vulpecula

File:Messier27-starmap.png Location map

The Dumbbell nebula is located in the faint constellation Vulpecula, within the Summer Triangle. It is located in the sky a few degrees north of γ Sagittae, near the star 14 Vulpeculae. It is bright enough to be seen in binoculars.

See also

• Messier object
• List of Messier objects
• List of planetary nebulae
• New General Catalogue

Notes

1. ^{^} Radius = distance × sin(angular size / 2) = Template:Val * sin(8′.0 / 2) = Template:Val ly
2. ^{^} Semi minor axis = distance × sin(minor axis size / 2) = Template:Val × sin(5′.6 / 2) = Template:Val ly
3. ^{^} Kinematic age = semi-minor axis / expansion rate = Template:Val^[b] ly / 31 km/s = Template:Val / 31 km/s = Template:Val s = Template:Val yr
4. ^{^} 7.5 apparent magnitude - 5 × (log₁₀(Template:Val distance) - 1) = Template:Val absolute magnitude

External links

• SEDS: Messier Object 27
• Template:WikiSky
• M27 on astro-pics.com
• M27

Template:Messier objects Template:Ngc70 Template:Vulpecula Template:Portal bar Template:Sky Template:Authority control