Dumbbell Nebula

Dumbbell Nebula
ESO image showing extended structure and central star
Observation data (Epoch J2000)
Right ascension	19h 59m 36.340s
Declination	+22° 43′ 16.09″
Distance	1360+160 −212 ly (417+49 −65 pc)
Apparent magnitude (V)	7.5
Apparent dimensions (V)	8′.0 × 5′.6
Constellation	Vulpecula
Physical characteristics
Radius	1.44+0.21 −0.16 ly
Absolute magnitude (V)	−0.6+0.4 −0.3
Notable features	Central star radius is largest known for a white dwarf.
Other designations	NGC 6853, M 27, Diabolo Nebula, Dumb-Bell Nebula,

The Dumbbell Nebula (also known as Apple Core Nebula, Messier 27, M 27, or NGC 6853) is a planetary nebula in the constellation Vulpecula, at a distance of about 1,360 light years.

This object was the first planetary nebula to be discovered; by Charles Messier in 1764. At its brightness of visual magnitude 7.5 and its diameter of about 8 arcminutes, it is easily visible in binoculars, and a popular observing target in amateur telescopes.

• Vulpecula constellation map.svg

  M27 in Vulpecula constellation.

• Weighing in on the Dumbbell Nebula.jpg

  Image from the Spitzer Space Telescope.

• Dumbbell Nebula from NA.jpg

  Image from a ground-based telescope at Westview Observatory in Cridersville, OH

File:M27 by Mohamad Abbas.jpg

M27. This picture was processed and combined using IRAF and MaxIm DL by Mohamad Abbas.

Structure

The Dumbbell Nebula appears to be shaped like an 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 in the plane of the sky was no more than 2.3" per century. From this, an upper limit to the age of 14,600 yr may be determined. In 1970, Bohuski, Smith, and Weedman found an expansion velocity of 31 km/s. Given its semi-minor axis radius of 1.01 ly, this implies that the kinematic age of the nebula is some 9,800 years.

Knots

File:M27 Knots.jpg

HST closeup of knots in M 27
Credit: C.R. O'Dell (Vanderbilt University)

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.

Central star

The central star, a white dwarf, is estimated to have a radius which is 0.055±0.02 R_☉ which gives it a size larger than any other known white dwarf. The central star mass was estimated in 1999 by Napiwotzki to be 0.56±0.01 M_☉.

See also

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

Notes

1. ^{^} Radius = distance × sin(angular size / 2) = 1240+180
   −140 * sin(8′.0 / 2) = 1.44+0.21
   −0.16 ly
2. ^{^} Semi minor axis = distance × sin(minor axis size / 2) = 1240+180
   −140 × sin(5′.6 / 2) = 1.01+0.15
   −0.11 ly
3. ^{^} Kinematic age = semi-minor axis / expansion rate = 1.01+0.15
   −0.11 ly / 31 km/s = 9.56+1.42
   −1.04×10¹² km / 31 km/s = 3.08+0.46
   −0.34×10¹¹ s = 9800+1500
   −1100 yr
4. ^{^} 7.5 apparent magnitude - 5 × (log₁₀(420+50
   −70 pc distance) - 1) = −0.6+0.4
   −0.3 absolute magnitude

External links

• SEDS: Messier Object 27
• The Dumbbell Nebula on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
• M27 on astro-pics.com
• M27
• Dumbbell Nebula (M27) at Constellation Guide