ESO image showing extended structure and central star
|Right ascension||19h 59m 36.340s|
|Declination||+22° 43′ 16.09″|
−2121360 ly (+49
−65 pc) 417
|Apparent magnitude (V)||7.5|
|Apparent dimensions (V)||8′.0 × 5′.6|
−0.16 ly[a] 1.44
|Absolute magnitude (V)||
Central star radius is largest
known for a white dwarf.
NGC 6853, M 27,
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.
Image from the Spitzer Space Telescope.
Image from a ground-based telescope at Westview Observatory in Cridersville, OH
- Knots 1.1
- Central star 1.2
- See also 2
- Notes 3
- References 4
- External links 5
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.
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, is estimated to have a radius which is ±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 0.055±0.01 M☉. 0.56
^ Radius = distance × sin(angular size / 2) = +180
−140 * sin(8′.0 / 2) = 1240+0.21
−0.16 ly 1.44
^ Semi minor axis = distance × sin(minor axis size / 2) = +180
−140 × sin(5′.6 / 2) = 1240+0.15
−0.11 ly 1.01
^ Kinematic age = semi-minor axis / expansion rate = +0.15
−0.11[b] ly / 31 km/s = 1.01+1.42
−1.04×1012 km / 31 km/s = 9.56+0.46
−0.34×1011 s = 3.08+1500
−1100 yr 9800
^ 7.5 apparent magnitude - 5 × (log10(+50
−70 pc distance) - 1) = 420+0.4
−0.3 absolute magnitude −0.6
- "SIMBAD Astronomical Database". Results for M 27. Retrieved 2007-01-03.
- Benedict, G. Fritz; McArthur, B. E.; Fredrick, L. W.; Harrison, T. E.; et al. (2003). "Astrometry with The Hubble Space Telescope: A Parallax of the Central Star of the Planetary Nebula NGC 6853".
- Harris, Hugh C.; Dahn, Conard C.; Canzian, Blaise; Guetter, Harry H.; et al. (2007). "Trigonometric Parallaxes of Central Stars of Planetary Nebulae".
- O'Dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; et al. (2002). "Knots in Nearby Planetary Nebulae".
- O'dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; et al. (2003). "Knots in Planetary Nebulae".
- 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
- Dumbbell Nebula (M27) at Constellation Guide