| Emission nebula | |
|---|---|
| Planetary nebula | |
 Dumbbell Nebula (Messier 27) in Vulpecula | |
| Observation data: J2000 epoch | |
| Right ascension | 19h 59m 36.319s[1] |
| Declination | +22° 43′ 16.312″[1] |
| Distance | 389+15 −6[1] pc |
| Apparent magnitude (V) | 7.4[2] |
| Apparent dimensions (V) | 8.0′ × 5.6′[3] |
| Constellation | Vulpecula |
| Physical characteristics | |
| Radius | 1.44+0.21 −0.16[a] ly |
| Absolute magnitude (V) | −0.6+0.4 −0.3[d] |
| Notable features | Central star radius is among the largest known for a white dwarf. |
| Designations | NGC 6853,[1] M 27,[1] Diabolo Nebula,[1] Dumb-Bell Nebula,[1] |
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.[1] 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[4] 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 2.3 arcseconds (″) 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 31 km/s. Given its semi-minor axis radius of 1.01 ly, this implies that the kinematic age of the nebula is 9,800 years.[3][5]
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.[5]
The central star, a white dwarf progenitor, is estimated to have a radius which is 0.055±0.02 R☉ (0.13 light seconds) which gives it a size larger than most other known white dwarfs.[6] Its mass was estimated in 1999 by Napiwotzki to be 0.56±0.01 M☉.[6]
- ^ a b c d e f g h "M 27". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-12-31.
- ^ "Messier 27". SEDS Messier Catalog. Retrieved 21 July 2024.
- ^ a b O'Dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; et al. (2002). "Knots in Nearby Planetary Nebulae". Astronomical Journal. 123 (6): 3329–3347. Bibcode:2002AJ....123.3329O. doi:10.1086/340726.
- ^ "M 27". 2016-10-15.
- ^ a b O'dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; et al. (2003). "Knots in Planetary Nebulae". Revista Mexicana de Astronomía y Astrofísica, Serie de Conferencias. 15: 29–33. Bibcode:2003RMxAC..15...29O.
- ^ a b 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". Astronomical Journal. 126 (5): 2549–2556. arXiv:astro-ph/0307449. Bibcode:2003AJ....126.2549B. doi:10.1086/378603. S2CID 8562211.