| 词条 | Dumbbell Nebula |
| 释义 |
| image = Dumbbell Nebula M27 Göran Nilsson & The Liverpool Telescope.jpg | caption = Visual light (HaRGB) image of the Dumbbell Nebula (Messier 27, M 27) by the Liverpool Telescope | name = Dumbbell Nebula | epoch = J2000 | ra = {{RA|19|59|36.340}}[1] | type = Planetary | dec = {{DEC|+22|43|16.09}}[1] | dist_ly = {{val|1360|+160|-212}} ly ({{val|417|+49|-65|ul=pc}})[3][4] | appmag_v = 7.5[1] | size_v = 8′.0 × 5′.6[6] | constellation = Vulpecula | radius_ly = {{val|1.44|+0.21|-0.16|u=ly}}{{Ref label|A|a|none}} | absmag_v = {{val|-0.6|+0.4|-0.3}}{{Ref label|D|d|none}} | notes = Central star radius is largest known for a white dwarf. | names = NGC 6853,[1] M 27,[1] Diabolo Nebula,[1] Dumb-Bell Nebula,[1] }} 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,[2] and a popular observing target in amateur telescopes. The Dumbbell Nebula appears to be 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 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.[3][4] 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.[4] The central star, a white dwarf, is estimated to have a radius which is {{val|0.055|0.02|ul=R_solar}} (0.13 light seconds) which gives it a size larger than most other known white dwarfs.[5] The central star mass was estimated in 1999 by Napiwotzki to be {{val|0.56|0.01|ul=M_solar}}.[5] See also{{commons category|Dumbbell Nebula}}
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References1. ^1 2 3 4 5 6 {{cite simbad | title=M 27 | access-date=2007-01-03}} 2. ^{{Cite web | url=https://messierobjects101.com/messier-object-m27-dumbbell-nebula/ | title=M 27| date=2016-10-15}} 3. ^1 2 {{cite journal | author=O'Dell, C. R. | display-authors=4 | author2=Balick, B. | author3=Hajian, A. R. | author4=Henney, W. J. | author5=Burkert, A. | date=2002 | title=Knots in Nearby Planetary Nebulae | journal=Astronomical Journal | volume=123 | issue=6 | pages=3329–3347 | bibcode=2002AJ....123.3329O | doi=10.1086/340726}} 4. ^1 {{cite journal | author=O'dell, C. R. | display-authors=4 | author2=Balick, B. | author3=Hajian, A. R. | author4=Henney, W. J. | author5=Burkert, A. | date=2003 | title=Knots in Planetary Nebulae | journal=Revista Mexicana de Astronomía y Astrofísica, Serie de Conferencias | volume=15 | pages=29–33 | bibcode=2003RMxAC..15...29O }} 5. ^1 2 {{cite journal | author=Benedict, G. Fritz | display-authors=4 | author2=McArthur, B. E. | author3=Fredrick, L. W. | author4=Harrison, T. E. | author5=Skrutskie, M. F. | author6=Slesnick, C. L. | author7=Rhee, J. | author8=Patterson, R. J. | author9=Nelan, E. | author10=Jefferys, W. H. | author11=van Altena, W. | author12=Montemayor, T. | author13=Shelus, P. J. | author14=Franz, O. G. | author15=Wasserman, L. H. | author16=Hemenway, P. D. | author17=Duncombe, R. L. | author18=Story, D. | author19=Whipple, A. L. | author20=Bradley, A. J. | date=2003 | title=Astrometry with The Hubble Space Telescope: A Parallax of the Central Star of the Planetary Nebula NGC 6853 | journal=Astronomical Journal | volume=126 | issue=5 | pages=2549–2556 | bibcode=2003AJ....126.2549B | doi=10.1086/378603|arxiv = astro-ph/0307449 }} 6. ^1 2 {{cite journal | author = Harris, Hugh C. | display-authors = 4 | author2 = Dahn, Conard C. | author3 = Canzian, Blaise | author4 = Guetter, Harry H. | author5 = Leggett, S. K. | author6 = Levine, Stephen E. | author7 = Luginbuhl, Christian B. | author8 = Monet, Alice K. B. | author9 = Monet, David G. | author10 = Pier, Jeffrey R. | author11 = Stone, Ronald C. | author12 = Tilleman, Trudy | author13 = Vrba, Frederick J. | author14 = Walker, Richard L. | title = Trigonometric Parallaxes of Central Stars of Planetary Nebulae | date = 2007 | journal = Astronomical Journal | volume = 133 | issue = 2 | pages = 631–638 | bibcode = 2007AJ....133..631H | doi = 10.1086/510348|arxiv = astro-ph/0611543 }} External links
6 : Planetary nebulae|Vulpecula|Messier objects|NGC objects|Orion–Cygnus Arm|Astronomical objects discovered in 1764 |
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