Mayall II

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Mayall II
HST G1 (Mayall II).jpg
Hubble Telescope image of Mayall II, colour picture assembled from separate images taken in visible and near-infrared wavelengths in July 1994.
Credit: Michael Rich, Kenneth Mighell, and James D. Neill (Columbia University), and Wendy Freedman (Carnegie Observatories) and NASA
Observation data (J2000 epoch)
Constellation Andromeda
Right ascension 00h 32m 46.51s[1]
Declination +39° 34′ 39.7″[1]
Distance 2.52 ± 0.14 Mly (770 ± 40 kpc)
Apparent magnitude (V) +13.8[1]
Physical characteristics
Mass 1×107[2] M (2×1037 kg)
Radius 21.2 ± 1.0 ly (6.5 ± 0.3 pc) (Half light radius rh)[3]
Estimated age ~ 12 Gyr [2]
Other designations SKHB 1, HBK 0-1[1]
See also: Globular cluster, List of globular clusters

Mayall II (M31 G1) also known as NGC-224-G1, SKHB 1, GSC 2788:2139, HBK 0-1, M31GC J003247+393440 or Andromeda's Cluster is a globular cluster orbiting M31, the Andromeda Galaxy.

It is located 130,000 light-years (40 kpc)[3] from Andromeda's galactic core, and is the brightest[3] (absolute magnitude) globular cluster in the Local Group, having an apparent magnitude of 13.7. G1 is considered to have twice the mass of Omega Centauri. G1 may contain a central, intermediate-mass (∼ 2×104 M) black hole.[3]

It was first identified as a possible globular cluster by Nicholas Mayall & O.J. Eggen in 1953 using a Palomar 48-inch Schmidt plate exposed in 1948.[3]

Because of the widespread distribution of metallicity, indicating multiple star generations and a large stellar creation period, many contend that it is not a true globular cluster, but is actually the galactic core that remains of a dwarf galaxy consumed by Andromeda.[3][4]

Origin of names

See also

References

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External links