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Messier 2 or M2 (also designated NGC 7089) is a globular cluster in the constellation Aquarius, five degrees north of the star Beta Aquarii. It was discovered by Jean-Dominique Maraldi in 1746, and is one of the largest known globular clusters.

Messier 2
Messier 2 by Hubble Space Telescope; 2.5′ view
Observation data (J2000 epoch)
Class	II[1]
Constellation	Aquarius
Right ascension	21h 33m 27.02s[2]
Declination	–00° 49′ 23.7″[2]
Distance	55,000 ly (17 kpc)[3]
Apparent magnitude (V)	6.5[4]
Apparent dimensions (V)	16′.0
Physical characteristics
Mass	1.04×105[5] M☉
Radius	87.3 ly[6]
Metallicity	${\displaystyle {\begin{smallmatrix}\left[{\ce {Fe}}/{\ce {H}}\right]\end{smallmatrix}}}$ = –1.65[5] dex
Estimated age	13 Gyr
Other designations	NGC 7089.[7]
See also: Globular cluster, List of globular clusters

Discovery and visibility

M2 was discovered by the French astronomer Jean-Dominique Maraldi in 1746[8] while observing a comet with Jacques Cassini.^{[citation needed]} Charles Messier rediscovered it in 1760, but thought it a nebula without any stars associated with it. William Herschel, in 1783, was the first to resolve individual stars in the cluster.^{[citation needed]}

M2 is, under extremely good conditions, just visible to the naked eye. Binoculars or a small telescope will identify this cluster as non-stellar, while larger telescopes will resolve individual stars, of which the brightest are of apparent magnitude 13.1.^{[citation needed]}

Characteristics

M2 is about 55,000 light-years distant from Earth. At 175 light-years in diameter, it is one of the larger globular clusters known. The cluster is rich, compact, and significantly elliptical. It is 13 billion years old and one of the older globulars associated with the Milky Way galaxy.^{[citation needed]}

M2 contains about 150,000 stars, including 21 known variable stars. Its brightest stars are red and yellow giant stars. The overall spectral type is F4.[7] M2 is part of the Gaia Sausage, the hypothesised remains of a merged dwarf galaxy.[9]

Data from Gaia has led to the discovery of an extended tidal stellar stream, about 45 degrees long and 300 light-years (100 pc) wide, that is likely associated with M2. It was possibly perturbed due to the presence of the Large Magellanic Cloud.[10]

References

See also

• List of Messier objects

External links

• M2,SEDS Messier pages
• M2, Galactic Globular Clusters Database page
• Historic observations of M2
• M2 in the Staracle Messier catalog
• Messier 2 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

На других языках

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[de] Messier 2

Messier 2 (kurz M2, auch NGC 7089) ist ein galaktischer Kugelsternhaufen vom Typ II im Sternbild Wassermann auf der Ekliptik. Er liegt rund 50.000 Lichtjahre vom Sonnensystem entfernt im inneren Halo der Milchstraße und hat einen Durchmesser von etwa 150 Lichtjahren. Mit rund 100.000 Mitgliedern ist er einer der sternreicheren und kompakteren Kugelsternhaufen, sein Alter wird auf 12 Milliarden Jahre geschätzt. Die hellsten Sterne sind gelbe und rote Riesen mit einer absoluten Helligkeit von −3 mag. In ihnen sind die schweren Elemente etwa 100-mal seltener als in der mehr als sieben Milliarden Jahre später entstandenen Sonne.

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- [en] Messier 2

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[es] Cúmulo globular M2

El cúmulo globular M2 (también conocido como objeto Messier 2, Messier 2, M2 o NGC 7089), se encuentra en la constelación de Acuario. Fue descubierto por Jean-Dominique Maraldi en 1746. Tiene un diámetro de aproximadamente 175 años luz, y contiene unas 150 000 estrellas, además de ser uno de los cúmulos más compactos y ricos conocidos.

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[ru] M 2

Messier 2 (англ. M 2, NGC 7089, рус. Мессье 2) — шаровое звёздное скопление в созвездии Водолея. M 2 обладает диаметром около 175 св. лет, содержит около 150 000 звёзд и считается одним из самых насыщенных и компактных шаровых скоплений.

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