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)|
|Right ascension||00h 32m 46.51s|
|Declination||+39° 34′ 39.7″|
|Distance||2.52 ± 0.14 Mly (770 ± 40 kpc)|
|Apparent magnitude (V)||+13.81|
|Mass||1×107 M☉ (2×1037 kg)|
|Radius||21.2 ± 1.0 ly (6.5 ± 0.3 pc) (Half light radius rh) and tidal radius 263.2 ± 12.7 ly (80.7 ± 3.9 pc) |
|Estimated age||~ 12 Gyr |
|Other designations||SKHB 1, HBK 0-1|
It is located 130,000 light-years (40 kpc) from the Andromeda Galaxy's galactic core, and is the brightest (by absolute magnitude) globular cluster in the Local Group, having an apparent magnitude of 13.81 in V band. Mayall II is considered to have twice the mass of Omega Centauri, and may contain a central, intermediate-mass (∼ 2×104 M⊙) black hole.
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.
Origin of names
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- Mayall II is named after Nicholas U. Mayall, who, with Olin J. Eggen, discovered it in 1953.
- SKHB 1 is named for Wallace L. W. Sargent, Charles T. Kowal, F. D. A. Hartwick, and Sidney van den Bergh. They also named it G1 in 1977.
- HBK 0-1 is named for John Huchra, J. P. Brodie, and S. M. Kent in 1991.
- "NAME Mayall II". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2009-09-13.
- Ma, Jun; de Grijs, Richard; Fan, Zhou; Rey, Soo-Chang; Wu, Zhen-Yu; Zhou, Xu; Wu, Jiang-Hua; Jiang, Zhao-Ji; Chen, Jian-Sheng; Lee, Kyungsook; Sohn, Sangmo Tony (June 2009). "RESEARCH PAPER: Old stellar population synthesis: new age and mass estimates for Mayall II = G1". Research in Astronomy and Astrophysics. 9 (6): 641–652. arXiv: . Bibcode:2009RAA.....9..641M. doi:10.1088/1674-4527/9/6/003.
- Ma, J.; de Grijs, R.; Chen, D.; van den Bergh, S.; Fan, Z.; Wu, Z.; Wu, H.; Zhou, X.; Wu, J.; Jiang, Z.; Chen, J. (April 2007). "Structural parameters of Mayall II = G1 in M31". Monthly Notices of the Royal Astronomical Society. 376 (4): 1621–1629. arXiv: . Bibcode:2007MNRAS.376.1621M. doi:10.1111/j.1365-2966.2007.11573.x.
- Meylan, G.; Sarajedini, A.; Jablonka, P.; Djorgovski, S. G.; Bridges, T.; Rich, R. M. (August 2001). "Mayall II=G1 in M31: Giant Globular Cluster or Core of a Dwarf Elliptical Galaxy?". The Astronomical Journal. 122 (2): 830–841. arXiv: . Bibcode:2001AJ....122..830M. doi:10.1086/321166.