Messier 93

Messier 93 or M93, also known as NGC 2447, is an open cluster in the constellation Puppis. It was discovered by Charles Messier then added to his catalogue of comet-like objects on March 20, 1781.[5] Caroline Herschel, the younger sister of William Herschel, independently discovered M93 in 1783, thinking it had not yet been catalogued by Messier.[6] Walter Scott Houston described its appearance as follows:[7]

Some observers mention the cluster as having the shape of a starfish. With a fair-sized telescope, this is its appearance on a dull night, but [a four-inch refractor] shows it as a typical star-studded galactic cluster.

It has a Trumpler class of I 3 r, indicating it is strongly concentrated (I) with a large range in brightness (3) and is rich in stars (r).[8]

M93 is at a distance of about 3,380[1] light years from Earth and has a spatial radius of some 5 light years,[2] a tidal radius of 13.1±2.3 ly,[3] and a core radius of 4.2 ly.[9] Its age is estimated at 387.3 million years.[1] The cluster is positioned nearly on the galactic plane and it is following an orbit that varies between 28–29 kly (8.5–8.9 kpc) from the Galactic Center over a period of 242.7±7.9 Myr.[1]

54 variable stars have been found in M93, including one slowly pulsating B-type star, one rotating ellipsoidal variable, seven Delta Scuti variables, six Gamma Doradus variables, and one hybrid δ Sct/γ Dor pulsator.[10] Four spectroscopic binary systems in M93 include a yellow straggler component.[11]

Messier 93
Messier object 093
Observation data (J2000.0 epoch)
Right ascension 07h 44m 30.0s[1]
Declination−23° 51′ 24″[1]
Distance3.38 kly (1.037 kpc)[1]
Apparent magnitude (V)6.2[2]
Apparent dimensions (V)10′[2]
Physical characteristics
Mass723[3] M
Estimated age387.3 Myr[1]
Other designationsCl 160, NGC 2447, OCl 649.0 [4]


  1. ^ a b c d e f g Wu, Zhen-Yu; et al. (November 2009), "The orbits of open clusters in the Galaxy", Monthly Notices of the Royal Astronomical Society, 399 (4): 2146–2164, arXiv:0909.3737, Bibcode:2009MNRAS.399.2146W, doi:10.1111/j.1365-2966.2009.15416.x.
  2. ^ a b c d Finlay, Warren H. (2014), Concise Catalog of Deep-Sky Objects: Astrophysical Information for 550 Galaxies, Clusters and Nebulae, The Patrick Moore Practical Astronomy Series (2nd ed.), Springer, p. 120, ISBN 978-3319031705
  3. ^ a b Piskunov, A. E.; et al. (January 2008), "Tidal radii and masses of open clusters", Astronomy and Astrophysics, 477 (1): 165–172, Bibcode:2008A&A...477..165P, doi:10.1051/0004-6361:20078525.
  4. ^ "NGC 2447". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-12-06.
  5. ^ Frommert, Hartmut; Kronberg, Christine (September 2, 2007), "Messier 93", SEDS Messier pages, Students for the Exploration and Development of Space (SEDS), retrieved 2018-12-07.
  6. ^ Hoskin, Michael (February 1, 2016), "Gazing at the starry heavens", Astronomy & Geophysics, 57 (1): 1.22–1.25, Bibcode:2016A&G....57a1.22H, doi:10.1093/astrogeo/atw038
  7. ^ Houston, Walter Scott (2005). Deep-Sky Wonders. Sky Publishing Corporation. ISBN 978-1-931559-23-2.
  8. ^ Maitzen, H. M. (November 1993), "Photoelectric Search for Peculiar Stars in Open Clusters - Part Fourteen - NGC1901 NGC2169 NGC2343 CR:132 NGC2423 and NGC2447", Astronomy and Astrophysics Supplement, 102 (1): 1, Bibcode:1993A&AS..102....1M.
  9. ^ Piskunov, A. E.; et al. (June 2007), "Towards absolute scales for the radii and masses of open clusters", Astronomy and Astrophysics, 468 (1): 151–161, arXiv:astro-ph/0702517, Bibcode:2007A&A...468..151P, doi:10.1051/0004-6361:20077073.
  10. ^ Eyer, L.; Eggenberger, P.; Greco, C.; Saesen, S.; Anderson, R. I.; Mowlavi, N. (September 2010), "Time resolved surveys of stellar clusters", JENAM 2010, Joint European and National Astronomy Meeting held 6-10 September, 2010 in Lisbon Portugal, p. 212, Bibcode:2010jena.confE.212E, 212.
  11. ^ da Silveira, M. D.; et al. (June 2018), "Red giants and yellow stragglers in the young open cluster NGC 2447", Monthly Notices of the Royal Astronomical Society, 476 (4): 4907–4931, Bibcode:2018MNRAS.476.4907D, doi:10.1093/mnras/sty265

External links

Coordinates: Sky map 07h 44.6m 00s, −23° 52′ 00″

List of NGC objects (2001–3000)

This is a list of NGC objects 2001–3000 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.

List of open clusters

This is a list of open clusters located in the Milky Way. An open cluster is a gravitationally bound association of up to a few thousand stars that all formed from the same giant molecular cloud. There are over 1,000 known open clusters in the Milky Way galaxy, but the actual total may be up to ten times higher. The estimated half lives of clusters, after which half the original cluster members will have been lost, range from 150 million to 800 million years, depending on the original density.


M93 or M-93 may refer to:

Messier 93, an open star cluster in the constellation Puppis

Beretta M93R, a selective-fire machine pistol made by the Beretta company

Zastava M93 Black Arrow, a 12.7 mm Anti-materiel rifle

M93 Fox, a Chemical, Biological, Radiological and Nuclear reconnaissance vehicle

M-93 (Michigan highway), a state highway in Michigan

M93 HORNET mine, an American anti tank mine

Mannlicher M93, a Romanian service rifle

Salvator-Dormus M93, early Austro-Hungarian heavy machine gun

Swiss Mannlicher M93, a Swiss service rifle

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.


Puppis is a constellation in the southern sky. Puppis, the Poop Deck, was originally part of an over-large constellation, the ship of Jason and the Argonauts, Argo Navis, which centuries after its initial description, was divided into three parts, the other two being Carina (the keel and hull), and Vela (the sails of the ship). Puppis is the largest of the three constellations in square degrees. It is one of the 88 modern constellations recognized by the International Astronomical Union.

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.