Messier 92

Messier 92 (also known as M92, M 92, or NGC 6341) is a globular cluster of stars in the northern constellation of Hercules. It was discovered by Johann Elert Bode in 1777, then published in the Jahrbuch during 1779.[8] The cluster was independently rediscovered by Charles Messier on March 18, 1781 and added as the 92nd entry in his catalogue.[9] M92 is at a distance of about 26,700 light-years away from Earth.

M92 is one of the brighter globular clusters in the northern hemisphere, but it is often overlooked by amateur astronomers because of its proximity to the even more spectacular Messier 13. It is visible to the naked eye under very good conditions.[10]

Among the Milky Way population of globular clusters, Messier 92 is among the brighter clusters in terms of absolute magnitude. It is also one of the oldest clusters. Messier 92 is located around 16×103 ly (4.9 kpc) above the galactic plane and 33×103 ly (10 kpc) from the Galactic Center.[11] The heliocentric distance of Messier 92 is 26.7×103 ly (8.2 kpc). The half-light radius, or radius containing half of the light emission from the cluster, is 1.09 arcminutes, while the tidal radius is 15.17 arcminutes. It appears only slightly flattened, with the minor axis being about 89% ± 3% as large as the major axis.[3]

Characteristic of other globulars, Messier 92 has a very low abundance of elements other than hydrogen and helium; what astronomers term its metallicity. Relative to the Sun, the abundance of iron in the cluster is given by [Fe/H] = –2.29 dex,[11] which equates to only 0.5% of the solar abundance.[12] This puts the estimated age range for the cluster at 14.2 ± 1.2 billion years, or roughly the age of the Universe.[7]

The cluster is not currently in a state of core collapse and the core radius is about 2 arcseconds.[11] It is an Oosterhoff type II (OoII) globular cluster, which means it belongs to the group of metal poor clusters with longer period RR Lyrae variable stars. The 1997 Catalogue of Variable Stars in Globular Clusters listed 28 candidate variable stars in the cluster, although only 20 have been confirmed. As of 2001, there are 17 known RR Lyrae variables in Messier 92.[13] 10 X-ray sources have been detected within the 1.02 arcminute half-mass radius of the cluster, of which half are candidate cataclysmic variable stars.[14]

Messier 92
M92 Hubble WikiSky
Center of M92 by HST; 1.44′ view
Observation data (J2000 epoch)
ClassIV[1]
ConstellationHercules
Right ascension 17h 17m 07.39s[2]
Declination+43° 08′ 09.4″[2]
Distance26.7×103 ly (8.2 kpc)[3]
Apparent magnitude (V)+6.3[4]
Apparent dimensions (V)14' arc minutes
Physical characteristics
Mass2.0×105[5] M
Metallicity = –2.16[6] dex
Estimated age14.2 ± 1.2 Gyr[7]
Other designationsM92, NGC 6341, GCl 59[4]

Image gallery

All that glitters HST

Messier 92 is one of the brightest globular clusters in the Milky Way, and is visible to the naked eye under good observing conditions.[15]

M92HunterWilson

Messier 92 as seen with an amateur telescope

M92 arp 750pix

Messier 92 from the Isaac Newton Group of Telescopes

M92map

Map showing the location of Messier 92

References

  1. ^ Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin, 849 (849): 11–14, Bibcode:1927BHarO.849...11S.
  2. ^ a b Goldsbury, Ryan; et al. (December 2010), "The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters [ Erratum: 2011AJ....142...66G ]", The Astronomical Journal, 140 (6): 1830–1837, arXiv:1008.2755, Bibcode:2010AJ....140.1830G, doi:10.1088/0004-6256/140/6/1830
  3. ^ a b Chen, C. W.; Chen, W. P. (October 2010), "Morphological Distortion of Galactic Globular Clusters", The Astrophysical Journal, 721 (2): 1790–1819, Bibcode:2010ApJ...721.1790C, doi:10.1088/0004-637X/721/2/1790
  4. ^ a b "M 92". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-11-17.
  5. ^ Marks, Michael; Kroupa, Pavel (August 2010), "Initial conditions for globular clusters and assembly of the old globular cluster population of the Milky Way", Monthly Notices of the Royal Astronomical Society, 406 (3): 2000–2012, arXiv:1004.2255, Bibcode:2010MNRAS.406.2000M, doi:10.1111/j.1365-2966.2010.16813.x. Mass is from MPD on Table 1.
  6. ^ Forbes, Duncan A.; Bridges, Terry (May 2010), "Accreted versus in situ Milky Way globular clusters", Monthly Notices of the Royal Astronomical Society, 404 (3): 1203–1214, arXiv:1001.4289, Bibcode:2010MNRAS.404.1203F, doi:10.1111/j.1365-2966.2010.16373.x.
  7. ^ a b Paust, Nathaniel E. Q.; Chaboyer, Brian; Sarajedini, Ata (June 2007), "BVI Photometry and the Luminosity Functions of the Globular Cluster M92", The Astronomical Journal, 133 (6): 2787–2798, arXiv:astro-ph/0703167, Bibcode:2007AJ....133.2787P, doi:10.1086/513511
  8. ^ Kanas, Nick (2007), Star maps: history, artistry, and cartography, Springer-Praxis books in popular astronomy, Springer, p. 180, ISBN 978-0387716688
  9. ^ Garfinkle, Robert A. (1997), Star-Hopping: Your Visa to Viewing the Universe, Cambridge University Press, p. 131, ISBN 978-0521598897
  10. ^ Frommert, Hartmut; Kronberg, Christine (September 2, 2007), "Messier 92", SEDS, The Munich Astro Archive, retrieved 2012-04-08
  11. ^ a b c Drukier, G. A.; et al. (March 2007), "The Global Kinematics of the Globular Cluster M92", The Astronomical Journal, 133 (3): 1041–1057, arXiv:astro-ph/0611246, Bibcode:2007AJ....133.1041D, doi:10.1086/510721
  12. ^ Since 10−2.29 = 0.00513.
  13. ^ Kopacki, G. (2003), "Variable stars in the globular cluster M 92", Astronomy and Astrophysics, 369 (3): 862–870, arXiv:astro-ph/0211042, Bibcode:2001A&A...369..862K, doi:10.1051/0004-6361:20010155
  14. ^ Lu, Ting-Ni; et al. (August 2011), "Chandra and HST Studies of the X-Ray Sources in Galactic Globular Cluster M92", The Astrophysical Journal, 736 (2): 158, Bibcode:2011ApJ...736..158L, doi:10.1088/0004-637X/736/2/158
  15. ^ "All that glitters". www.spacetelescope.org. ESA/Hubble. Retrieved 8 December 2014.

External links

Coordinates: Sky map 17h 17m 07.27s, +43° 08′ 11.5″

List of NGC objects (6001–7000)

This is a list of NGC objects 6001–7000 from the New General Catalogue (NGC). The astronomical catalogue is composed mainly of star clusters, nebulae, and galaxies. Other objects in the catalogue can be found in the other subpages of the list of NGC objects.

The constellation information in these tables is taken from The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer, which was accessed using the "VizieR Service". Galaxy types are identified using the NASA/IPAC Extragalactic Database. The other data of these tables are from the SIMBAD Astronomical Database unless otherwise stated.

M92

M92 or M-92 may refer to:

Messier 92, a globular cluster in the Hercules constellation

M-92 (Michigan highway), a state highway in Michigan

Beretta 92FS, a model of Beretta handgun

Beretta 92 Models, a list of Beretta 92 model handguns and their relatives

Zastava M92, a shortened assault rifle based on the AK-47

M92 (helmet)

Messier object

The Messier objects are a set of 110 astronomical objects cataloged by the French astronomer Charles Messier in his Catalogue des Nébuleuses et des Amas d'Étoiles ("Catalogue of Nebulae and Star Clusters").

Because Messier was interested in finding only comets, he created a list of non-comet objects that frustrated his hunt for them. The compilation of this list, in collaboration with his assistant Pierre Méchain, is known as the Messier catalogue. This catalogue of objects is one of the most famous lists of astronomical objects, and many Messier objects are still referenced by their Messier number.

The catalogue includes some astronomical objects that can be observed from Earth's Northern Hemisphere such as deep-sky objects, a characteristic which makes the Messier objects extremely popular targets for amateur astronomers.A preliminary version first appeared in the Memoirs of the French Academy of Sciences in 1771,

and the last item was added in 1966 by Kenneth Glyn Jones, based on Messier's observations.

The first version of Messier's catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, with only 17 of the 45 objects being Messier's.

By 1780 the catalogue had increased to 80 objects. The final version of the catalogue containing 103 objects was published in 1781 in the Connaissance des Temps for the year 1784.

However, due to what was thought for a long time to be the incorrect addition of Messier 102, the total number remained 102. Other astronomers, using side notes in Messier's texts, eventually filled out the list up to 110 objects.The catalogue consists of a diverse range of astronomical objects, ranging from star clusters and nebulae to galaxies. For example, Messier 1 is a supernova remnant, known as the Crab Nebula, and the great spiral Andromeda Galaxy is M31. Many further inclusions followed in the next century when the first addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding Messier's side note in his 1781 edition exemplar of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and M109 by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967.

Nik Szymanek

Nicholas Szymanek, better known as Nik Szymanek, is a British amateur astronomer and prolific astrophotographer, based in Essex, England.Originally a train driver in the London Underground, he started to be interested in astronomical CCD imaging shortly before 1991. His interest in this kind of observational astronomy rose in 1991, after he met Ian King, another amateur astronomer and a fellow from the local Havering Astronomical Society.Since that time he got most known for his deep sky CCD images and his contributions to education and public outreach. He collaborates with professional astronomers and works with big telescopes located at La Palma in the Canary Islands, and at Mauna Kea Observatories at the Hawaiian Islands. He publishes his pictures in astronomical magazines and has written a book on astrophotography called Infinity Rising.His imaging and image-processing abilities brought him the Amateur Achievement Award of the Astronomical Society of the Pacific in 2004.

Star cluster

Star clusters are very large groups of stars. Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds to millions of old stars which are gravitationally bound, while open clusters, more loosely clustered groups of stars, generally contain fewer than a few hundred members, and are often very young. Open clusters become disrupted over time by the gravitational influence of giant molecular clouds as they move through the galaxy, but cluster members will continue to move in broadly the same direction through space even though they are no longer gravitationally bound; they are then known as a stellar association, sometimes also referred to as a moving group.

Star clusters visible to the naked eye include the Pleiades (M45), Hyades, and the Beehive Cluster (M44).

List
See also

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.