NGC 5822

NGC 5822 is an open cluster of stars in the southern constellation of Lupus.^[7] It was discovered by English Astronomer John Herschel on July 3, 1836,^[2] and lies close to another cluster, NGC 5823, which suggests there may be a physical association.^[8][9]

NGC 5822
NGC 5822 (taken from Stellarium)
Observation data (J2000 epoch)
Right ascension	15h 4m 21.(2)s[1]
Declination	−54° 23′ 5(8)″[1]
Distance	2,682 ly (822.3 pc)[1]
Apparent magnitude (V)	6.5[2]
Physical characteristics
Mass	~1.7×103[3] M☉
Radius	26.1 ± 1.3 ly (8.0 ± 0.4 pc)[4]
Estimated age	900±100 Myr[5]
Other designations	NGC 5822, Cr 289, ESO 176-SC 009[6]
Associations
Constellation	Lupus
See also: Open cluster, List of open clusters

NGC 5822 is an intermediate age cluster, estimated at around 900 million years old, and it is located nearby^[3] at a distance of 2,700 light years.^[1] The Trumpler class of this cluster is III 2m.^[9] It is richly populated^[5] with half the cluster members lying within an angular radius of 22.1′.^[1] The cluster is considered low mass at ~1,700 times the mass of the Sun.^[3] It has a core radius of 1.1±0.1 pc and a limiting radius of 8.0±0.4 pc.^[4]

Measuring the abundances of a set of F-type stars that are probable members demonstrates the cluster metallicity is very similar to the Sun.^[5] It displays an extended main sequence turnoff on the Hertzsprung–Russell diagram, most likely due to differences in stellar rotation.^[3] Two barium stars have been identified in NGC 5822, making it only the second cluster shown to host these objects as of 2013.^[10]

Gallery

• 
  Map showing the location of NGC 5822