Messier Index/M57

The Ring Nebula 250px M57, The Ring Nebula. w:NASA/w:STScI/w:AURA w:J2000 18 53 35.079SIMBAD Astronomical Database Results for Messier 57 http://simbad.u-strasbg.fr/Simbad 2006-12-19 +33 01 45.03 2.31.5 0.7 kly (700450 200 pc)O'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 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. 1.30.8 0.4 lyA a 9Murdin, P. Ring Nebula (M57, NGC 6720) Encyclopedia of Astronomy and Astrophysics, Edited by Paul Murdin, article 5323. Bristol: Institute of Physics Publishing, 2001. Http://eaa.iop.org/abstract/0333750888/5323 2000 http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000eaa..bookE5323. 10.1888/0333750888/5323 230″ × 230″ w:Lyra 0.9 ly -0.20.7 1.8B b - M 57, NGC 6720 The famously named "Ring Nebula" is located in the northern w:constellation of w:Lyra, and also catalogued as Messier 57, M57 or NGC 6720. It is one of the most prominent examples of the deep-sky objects called w:planetary nebulae (singular, planetary nebula), often abbreviated by astronomers as simply planetaries or PN. Observation left|thumb|Location of M57 in the constellation Lyra. M57 is located in w:Lyra, south of its brightest star w:Vega. w:Vega is the northeastern vertex of the three stars of the w:Summer Triangle. M57 lies about 40% of the angular distance from β Lyrae to γ Lyrae.Craig Crossen Rhemann, Gerald Sky Vistas: Astronomy for Binoculars and Richest-Field Telescopes 2004 Springer 3211008519 52424007 M57 is best seen through at least a 20 cm (8-inch) w:telescope, but even a 7.5 cm (3-inch) telescope will show the ring. Larger instruments will show a few darker zones on the eastern and western edges of the ring, and some faint nebulosity inside the disk. This nebula was discovered by w:Antoine Darquier de Pellepoix in January, 1779, who reported that it was "...as large as Jupiter and resembles a planet which is fading." Later the same month, w:Charles Messier independently found the same nebula while searching for w:comets. It was then entered into his catalogue as the 57th object. Messier and w:William Herschel also speculated that the nebula was formed by multiple faint stars that were unable to resolve with his telescope.Robert A. Garfinkle 1997 Star-hopping: Your Visa to Viewing the Universe Cambridge University Press 0521598893 37355269 Charles Messier 1780 Catalogue des Nébuleuses & des amas d'Étoiles, Connoissance des Temps for 1783 225–249 In 1800, Count w:Friedrich von Hahn discovered the faint central star in the heart of the nebula. In 1864, w:William Huggins examined the spectra of multiple nebulae, discovering that some of these objects, including M57, displayed the spectra of bright w:emission lines characteristic of fluorescing glowing gases. Huggins concluded that most planetary nebulae were not composed of unresolved stars, as had been previously suspected, but were nebulosities.Frommert Hartmut Kronberg, Christine http://seds.org/messier/Xtra/Bios/huggins.html William Huggins (February 7, 1824 - May 12, 1910) Students for the Exploration and Development of Space 2008-04-11 http://web.archive.org/web/20080421100135/http://seds.org/messier/Xtra/Bios/huggins.html 2008-04-21Huggins W. Miller, W. A. On the Spectra of Some of the Nebulae. And On the Spectra of Some of the Fixed Stars. Proceedings of the Royal Society of London 1863–1864 13 491–493 http://www.jstor.org/pss/112077 2007-02-04 10.1098/rspl.1863.0094 Evolution of planetary nebulae Planetary nebulae are formed after medium or low mass stars, such as the Sun, exhaust their hydrogen fuel in the stellar core. At this point the structure of the star changes so it can achieve a new equilibrium condition in which it can continue to burn; the outer layers of the star expand and it becomes a w:red giant. Further internal temperature instabilities develop from the fusion reactions, causing the outer atmosphere to be expelled by hot superwinds either continuously or in several energetic pulses. This expanding gaseous shell forms the spherical nebula, brightly illuminated by w:ultraviolet energy from the central star.C. W. H. De Loore Doom, C. 1992 Structure and Evolution of Single and Binary Stars Springer 0792317688 25711985 Properties 250px|thumb|The Ring Nebula in infrared. The nebula is located at 0.7 kpc (2,300 w:light-years) from w:Earth. It has a visual magnitude of 8.8v and w:photographic magnitude of 9.7p. Photographically, over a period of 50 years, the rate of nebula expansion is roughly 1 w:arcsecond per w:century, which corresponds from spectroscopic observations to 20–30 km-1). M57 is illuminated by a central w:white dwarf or planetary nebula nucleus (PNN) of 15.75v visual magnitude, whose mass is approximately 1.2 MΘ (in w:solar masses.) All the interior parts of this nebula have a blue-green tinge that is caused by the doubly-ionized w:oxygen w:emission lines at 495.7 and 500.7 nm. These observed so-called "w:forbidden lines" occur only in conditions of very low density containing a few atoms per cubic w:centimeter. In the outer region of the ring, part of the reddish hue is caused by w:hydrogen emission at 656.3 nm, forming part of the w:Balmer series of lines. Forbidden lines of ionized w:nitrogen or [N II] contributes to the reddishness at 654.8 and 658.3 nm.Hannu Karttunen 2003 Fundamental Astronomy 314 Springer 3540001794 Nebula structure M57 is an example of the class of planetary nebulae known as bipolar nebulae, whose thick equatorial rings visibly extend the structure through its main axis of symmetry. It appears to be a w:prolate spheroid with strong concentrations of material along its w:equator. From Earth, the symmetrical axis is viewed at about 30°. Overall, the observed nebulosity has been currently estimated to be expanding for approximately 1,610±240 years. Structural studies find this planetary exhibits knots characterized by well developed symmetry. However, these are only silhouettes visible against the background emission of the nebula's equatorial ring. M57 may include internal w:N II emission lines located at the knots' tips that face the PNN; however, most of these knots are neutral and appear only in extinction lines. Their existence shows they are probably only located closer to the ionization front than those found in the Lupus planetary w:IC 4406. Some of the knots do exhibit well-developed tails which are often detectable in optical thickness from the visual spectrum.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 Planetary nebula nucleus (PNN) The central PNN was discovered by Hungarian astronomer Jenő Gothard on September 1, 1886 from images taken at his observatory in Herény, near Szombathely (now part of Szombathely). Within the last two thousand years, the central star of the Ring Nebula has left the w:asymptotic giant branch after exhausting its supply of w:hydrogen fuel. Thus it no longer produces its energy through w:nuclear fusion and, in evolutionary terms, it is now becoming a compact w:white dwarf star. The PNN now consists primarily of w:carbon and w:oxygen with a thin outer envelope composed of lighter elements. Its mass is about 0.61–0.62 w:solar mass, with a surface temperature of 125,000±5,000 K. Currently it is 200 times more luminous than the w:Sun, but its w:apparent magnitude is only +15.75.O'Dell C. R. Sabbadin, F.; Henney, W. J. The Three-Dimensional Ionization Structure and Evolution of NGC 6720, The Ring Nebula The Astronomical Journal 2007 134 4 1679–1692 http://adsabs.harvard.edu/abs/2007AJ....134.1679O 2008-03-31 10.1086/521823 Notes A aRadius = distance × sin(angular size / 2) = 2.31.5 0.7 kly * sin(230″ / 2) = 1.30.8 0.4 ly B b9 apparent magnitude - 5 * (log10(700450 200 pc distance) - 1) = -0.20.7 1.8 absolute magnitude References 2 External links SEDS: Messier Object 57 Infrared Ring Nebula, APOD 2005 March 11 NightSkyInfo.com - The Ring Nebula M57 The Ring Nebula in Lyra M57 at ESA/Hubble M57 imaged with a semiprofessional amateur-telescope