Messier Index/M27

Dumbbell Nebula Dumbbell Nebula 3a+2 w:J2000 19 59 36.340SIMBAD Astronomical Database Results for M 27 http://simbad.u-strasbg.fr/Simbad 2007-01-03 +22 43 16.09 1,360160 212 ly (41749 65 pc) http://adsabs.harvard.edu/abs/2007AJ....133..631H Trigonometric Parallaxes of Central Stars of Planetary Nebulae 2007 February 2007 The Astronomical Journal 133 2 631–638 10.1086/510348 Harris, Hugh C.; Dahn, Conard C.; Canzian, Blaise; Guetter, Harry H.; Leggett, S. K.; Levine, Stephen E.; Luginbuhl, Christian B.; Monet, Alice K. B.; Monet, David G.; Pier, Jeffrey R.; Stone, Ronald C.; Tilleman, Trudy; Vrba, Frederick J.; Walker, Richard L. 7.5 8′.0February 2007 × 5′.6O'Dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; Burkert, A. Knots in Nearby Planetary Nebulae The Astronomical Journal 2002 123 6 3329–3347 http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002AJ....123.3329O 10.1086/340726 w:Vulpecula 1.440.21 0.16 lyA a -0.60.4 0.3D d Central star radius is largestknown for a white dwarf. NGC 6853, M 27, Diabolo Nebula, Dumb-Bell Nebula, The Dumbbell Nebula (also known as Messier 27, M 27, or NGC 6853) is a w:planetary nebula (PN) in the w:constellation w:Vulpecula, at a distance of about 1,360 w:light years. This object was the first w:planetary nebula to be discovered; by w:Charles Messier in 1764. At its brightness of w:visual magnitude 7.5 and its diameter of about 8 w:arcminutes, it is easily visible in binoculars, and a popular observing target in amateur telescopes. Structure thumb|left|w:ESO image showing extended structure and central starCredit: ESO This PN appears to be shaped like an w:prolate spheroid and is viewed from our perspective along the plane of its w:equator. In 1992, Moreno-Corral et al. computed that the rate of expansion in the plane of the sky of this PN 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 w:semi-minor axis w:radius of 1.01 ly, this implies that the kinematic age of the nebula is some 9,800 years.O'dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; Burkert, A. Knots in Planetary Nebulae Winds, Bubbles, and Explosions: a conference to honor John Dyson, Pátzcuaro, Michoacán, México, September 9-13, 2002 (Eds. S. J. Arthur & W. J. Henney) Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias) (http://www.astroscu.unam.mx/~rmaa/) 2003 15 29–33 http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003RMxAC..15...29O Knots thumb|left|HST closeup of knots in M 27Credit: 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 w:Helix Nebula and the w:Eskimo Nebula, the heads of the knots have bright cusps which are local w:photoionization fronts. Central star The central star, a w: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.Benedict, G. Fritz; McArthur, B. E.; Fredrick, L. W.; Harrison, T. E.; Skrutskie, M. F.; Slesnick, C. L.; Rhee, J.; Patterson, R. J.; Nelan, E.; Jefferys, W. H.; van Altena, W.; Montemayor, T.; Shelus, P. J.; Franz, O. G.; Wasserman, L. H.; Hemenway, P. D.; Duncombe, R. L.; Story, D.; Whipple, A. L.; Bradley, A. J. Astrometry with The Hubble Space Telescope: A Parallax of the Central Star of the Planetary Nebula NGC 6853 The Astronomical Journal 2003 126 5 2549–2556 http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003AJ....126.2549B 10.1086/378603 The central star mass was estimated in 1999 by Napiwotzki to be 0.56 ± 0.01 M☉. Notes A aRadius = distance × sin(angular size / 2) = 1,240180 140 * sin(8′.0 / 2) = 1.440.21 0.16 ly B bSemi minor axis = distance × sin(minor axis size / 2) = 1,240180 140 * sin(5′.6 / 2) = 1.010.15 0.11 ly C cKinematic age = semi-minor axis / expansion rate = 1.010.15 0.11B b ly / 31 km/s = 9.561.42 1.0412 km / 31 km/s = 3.080.46 0.3411 s = 9,8001,500 1,100 yr D d7.5 apparent magnitude - 5 * (log10(42050 70 pc distance) - 1) = -0.60.4 0.3 absolute magnitude References 2 External links SEDS Messier page on M27 M27 Dumbbell Nebula M27 image taken by Stargazer Observatory M27