NGC 5986

NGC 5986 is a globular cluster of stars in the southern constellation of Lupus, located at a distance of approximately 34 kilolight-years from the Sun.^[3] It was discovered by Scottish astronomer James Dunlop on May 10, 1826. John L. E. Dreyer described it as, "a remarkable object, a globular cluster, very bright, large, round, very gradually brighter middle, stars of 13th to 15th magnitude".^[8] Its prograde–retrograde orbit through the Milky Way galaxy is considered irregular and highly eccentric. It has a mean heliocentric radial velocity of +100 km/s.^[4] The galacto-centric distance is 17 kly (5.2 kpc), which puts it in the galaxy's inner halo.^[9]

NGC 5986
NGC 5986 by Hubble Space Telescope; 3.5′ view
Observation data (J2000 epoch)
Class	VII[1]
Constellation	Lupus
Right ascension	15h 46m 03.00s[2]
Declination	–37° 47′ 11.1″[2]
Distance	33.9 kly (10.4 kpc)[3]
Apparent magnitude (V)	8.0
Apparent dimensions (V)	5'
Physical characteristics
Absolute magnitude	−8.44[4]
Mass	5.99×105[3] M☉
Metallicity	[Fe/H] = −1.35[5] dex
Estimated age	12.16 Gyr[5]
Other designations	ESO 329-SC 018, NGC 5986[6][7]
See also: Globular cluster, List of globular clusters

This is relatively massive cluster has been poorly studied, at least as of 2017.^[4] It is moderately concentrated, with a core radius of 28.2″ and a projected half-light radius of 58.8″. The three dimensional half-mass radius is ~78.16″.^[10] The cluster has a higher metallicity – what astronomers term the abundance of elements with higher atomic number then helium – compared to most other objects of its type.^[11] It may have at least 4–5 different stellar populations with distinct elemental compositions, and there is evidence that it has lost ~60–80% of its original mass.^[4]

Further reading

• Alves, David R.; et al. (January 2001). "CCD Photometry of the Globular Cluster NGC 5986 and Its Post-Asymptotic Giant Branch and RR Lyrae Stars". The Astronomical Journal. 121 (1): 318–326. arXiv:astro-ph/0010095. Bibcode:2001AJ....121..318A. doi:10.1086/318030. S2CID 119093584.