EntityQ1047748· pop 29· linked from 410 articles

Q1047748

globular cluster in the constellation Dorado

Key facts

Constellation: Dorado
Right ascension: 06 30 12.62
Declination: −64 ° 19 ′ 40.0 ″
Apparent dimensions v: 3.4′
Mass: 1.01 × 10 M ☉
Metallicity: [ Fe/H ] = −1.78 dex
Estimated age: 12.74 ± 2.00 Gyr
Other designations: KMHK 1756, [SL63] 895, ESO 87-24, LW 481

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Wikidata facts

Image: NGC 2257.jpg

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catalog code: [SL63] 895
Commons category: NGC 2257
time of discovery or invention: 1834-11-30
apparent magnitude: 13.24
right ascension: 97.5500
declination: -64.3267
radial velocity: 301.6
metallicity: -1.59

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Article

NGC 2257 is a globular cluster that lies on the outskirts of the Large Magellanic Cloud (LMC). It was discovered in 1834 by John Herschel. The compiler of the New General Catalogue, John Louis Emil Dreyer, described this cluster as "faint, considerably large, round, very gradually a little brighter middle, mottled but not resolved, 17.0 seconds of time diameter." At an aperture of 30.5 arcseconds, its apparent V-band magnitude is 12.62, but at this wavelength, it has 0.12 magnitudes of interstellar extinction.

NGC 2257 is quite old, at about 12.74 billion years old. Its estimated mass is 1.01×10 M☉, and its total luminosity is 5.1×10 L☉, leading to a mass-to-luminosity ratio of 2.00 M☉/L☉. All else equal, older star clusters have higher mass-to-luminosity ratios; that is, they have lower luminosities for the same mass.