Mayall II, 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
from the Andromeda Galaxy's galactic core, and is the brightest
(by
absolute magnitude) globular cluster in the
Local Group, with an absolute visual magnitude of −10.94 and the luminosity of 2 million Suns.
It has an
apparent magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...
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
M⊙)
black hole
A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. Th ...
.
It was first identified as a possible globular cluster by American astronomers
Nicholas Mayall and
Olin J. Eggen in 1953 using a
Palomar Schmidt plate exposed in 1948.
Because of the widespread distribution of
metallicity, indicating multiple
star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...
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
* 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.
See also
*
Messier 54
*
Omega Centauri
*
Mayall's Object
References
External links
Astrophysical Journal, Vol. 370, p. 495–504Publications of the Astronomical Society of the Pacific, Vol. 65, No. 382, p. 24–29Astronomical Journal, vol. 82, p. 947–953NightSkyInfo.com: Mayall II
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Andromeda Galaxy
Globular clusters
Andromeda (constellation)