NGC 6231

NGC 6231
Observation data (J2000.0 epoch)
Constellation	Scorpius
Right ascension	16h 54m
Declination	−41° 48′
Distance	5.9 kly
Apparent magnitude (V)	2.6
Apparent dimensions (V)	15.0′
Physical characteristics
Estimated age	3.2 million years
Other designations	NGC 6171, Ha. I.7, De Cheseaux 9, Lacaille II.13 Dunlop 499, Melotte 153, Collinder 315, Caldwell 76
See also: Open cluster, List of open clusters

NGC 6231 is an open cluster located near Zeta Scorpii. Zeta¹ (HR 6262) is a member of this star cluster. (Its brighter apparent partner, Zeta² (HR 6271), is only 150 ly from Earth and so is not a cluster member.)

This cluster is estimated about 3.2 million years old, and is approaching the Solar System at 22 km/s. Very young stars including it, belong to the Scorpius OB1 association. Zeta¹ Scorpii (spectral type O8 and magnitude 4.71.^[1]) is the hottest star in it.

It was discovered by Giovanni Batista Hodierna before 1654. Hodierna listed it as Luminosae^[2] in his catalogue of deep sky observations. This catalogue was included in his book De Admirandis Coeli Characteribuse published in 1654 at Palermo. It was independently observed by other astronomers after Hodierna.

• 1678　　　Edmond Halley
• 1745-46　de Chéseaux
• 1751-52　Lacaille

Note

1. ^ Sky Catalogue 2000.0
2. ^ Stars visible to the naked eye. It meanings "luminous" in Latin.

See also

• New General Catalogue

External links

• SEDS
• Some Southern Objects at Chris’s No-Frills Home Page
• NGC 6231 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Coordinates: 16^h 54^m 00^s, +41° 48′ 00″