NGC 3201

NGC 3201
NGC 3201 by Hubble Space Telescope; 3.5′ view
Observation data (J2000 epoch)
ClassX[1]
ConstellationVela
Right ascension10h 17m 36.82s[2]
Declination–46° 24′ 44.9″[2]
Distance21.8 kly (6.7 kpc)[3]
Apparent magnitude (V)+8.24[4]
Apparent dimensions (V)18.2′
Physical characteristics
Mass1.57×105[5] M☉
Radius40 ly[6]
VHB14.77
Metallicity = –1.24[7] dex
Estimated age12.2±0.5 Gyr[8]
Other designationsGCl 15,[4] GC 2068, h 3238, Dun 445, Bennett 44, Caldwell 79,[9] Melotte 99
See also: Globular cluster, List of globular clusters

NGC 3201 (also known as Caldwell 79) is a low galactic latitude globular cluster in the southern constellation of Vela. It has a very low central concentration of stars.[10] This cluster was discovered by James Dunlop on May 28, 1826 and listed in his 1827 catalogue. He described it as "a pretty large pretty bright round nebula, 4′ or 5′ diameter, very gradually condensed towards the centre, easily resolved into stars; the figure is rather irregular, and the stars are considerably scattered on the south".[11]

The radial velocity of this cluster is unusually high at 490 km/s, larger than any other cluster known. This corresponds to a peculiar velocity of 240 km/s. While high, this is lower than the escape velocity of the Milky Way galaxy.[11] It is located at a distance of 16,300 light years from the Sun and has an estimated mass of 157,000 times the mass of the Sun.[5] This cluster is about 10.24 billion years old.[7]

The stellar population of this cluster is inhomogeneous, varying with distance from the core. The effective temperature of the stars shows an increase with greater distance, with the redder and cooler stars tending to be located closer to the core. As of 2010, this is one of only two clusters (including Messier 4) that shows a definite inhomogeneous population.[12]

  1. ^ Cite error: The named reference hcob849_11 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference aj140_6_1830 was invoked but never defined (see the help page).
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  4. ^ a b Cite error: The named reference simbad was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Vitral+22 was invoked but never defined (see the help page).
  6. ^ distance × sin( diameter_angle / 2 ) = 40 ly. radius
  7. ^ a b Cite error: The named reference mnras404_3_1203 was invoked but never defined (see the help page).
  8. ^ Monty, Stephanie; Puzia, Thomas H.; Miller, Bryan W.; Carrasco, Eleazar R.; Simunovic, Mirko; Schirmer, Mischa; Stetson, Peter B.; Cassisi, Santi; Venn, Kim A.; Dotter, Aaron; Goudfrooij, Paul; Perina, Sibilla; Pessev, Peter; Sarajedini, Ata; Taylor, Matthew A. (2018), "The GeMS/GSAOI Galactic Globular Cluster Survey (G4CS). I. A Pilot Study of the Stellar Populations in NGC 2298 and NGC 3201", The Astrophysical Journal, 865 (2): 160, arXiv:1808.05271, Bibcode:2018ApJ...865..160M, doi:10.3847/1538-4357/aadb43, S2CID 119089142
  9. ^ Cite error: The named reference dsoc was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference xiv0509085 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference omeara2002 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference aaa512_L6 was invoked but never defined (see the help page).