NGC 2439

NGC 2439
NGC 2439
	NGC 2439 (taken from Stellarium)
Observation data (J2000 epoch)
Right ascension	07h 40m 45.0s
Declination	−31° 41′ 36″
Distance	3.855 kpc (12.57 kly)
Apparent magnitude (V)	6.9
Apparent dimensions (V)	10″
Physical characteristics
Radius	82 ± 23 ly (tidal)
Other designations	Cr 158, C 0738-315
Associations
Constellation	Puppis
	See also: Open cluster, List of open clusters

NGC 2439 is a sparse^[5] open cluster of stars in the constellation Puppis. It has an apparent visual magnitude of 6.9, an angular size of 10 arcminutes, and is visible using a small telescope.^[4] This is a young cluster with age estimates in the range of 20–300 million years.^[6]^[7] It has a tidal radius of approximately 82 light years.^[2] No chemically peculiar stars have been found.^[6]

Distance estimates to this cluster vary widely.^[5] Piskunov and associates (2008) gave an estimate of 3,855 kpc.^[2] A value in the range 3–4 kpc means the cluster lies well below the Galactic Plane. It is positioned in a hole in the Milky Way's gas and dust, with the reduced absorption resulting in a lower than expected extinction of 1.27 in visual magnitude. This result raises the question of whether this cluster actually exists.^[5] It is positioned along the same line of sight as two groups of B-type supergiant stars. The nearer group is located at a distance of 1.03 kpc, while the second group is at 3.2 kpc.^[8]

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