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 A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...

orbiting M31, the

Andromeda Galaxy The Andromeda Galaxy (IPA: ), also known as Messier 31, M31, or NGC 224 and originally the Andromeda Nebula, is a barred spiral galaxy with the diameter of about approximately from Earth and the nearest large galaxy to the Milky Way. The gala ...

. It is located from the Andromeda Galaxy's galactic core, and is the brightest (by

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

) globular cluster in the

Local Group The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a "dumbbell" shape: the Milky Way and its satellites form ...

, having an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of 13.81 in V band. Mayall II is considered to have twice the mass of

Omega Centauri Omega Centauri (ω Cen, NGC 5139, or Caldwell 80) is a globular cluster in the constellation of Centaurus that was first identified as a non-stellar object by Edmond Halley in 1677. Located at a distance of , it is the largest-known globular clust ...

, and may contain a central, intermediate-mass (∼ 2 M_⊙)

black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...

. It was first identified as a possible globular cluster by American astronomers

Nicholas Mayall Nicholas Ulrich Mayall (May 9, 1906 – January 5, 1993) was an American observational astronomer. After obtaining his doctorate from the University of California, Berkeley, Mayall worked at the Lick Observatory, where he remained from 1934 to 1 ...

and Olin J. Eggen in 1953 using a Palomar Schmidt plate exposed in 1948. Because of the widespread distribution of

metallicity In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...

, indicating multiple

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

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 A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is ...

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 Wallace Leslie William Sargent (February 15, 1935 – October 29, 2012) was a British-born American astronomer and the Ira S. Bowen Professor of Astronomy at California Institute of Technology. Education Sargent was born in Elsham, No ...

, Charles T. Kowal, F. D. A. Hartwick and

Sidney van den Bergh Sidney Van den Bergh, OC, FRS (born 20 May 1929 in Wassenaar) is a retired Dutch-Canadian astronomer. He showed an interest in science from an early age, learning to read with books on astronomy. In addition to being interested in astronomy. ...

. They also named it G1 in 1977. * HBK 0-1 is named for

John Huchra John Peter Huchra ( ; December 23, 1948 – October 8, 2010) was an American astronomer and professor. He was the Vice Provost for Research Policy at Harvard University and a Professor of Astronomy at the Center for Astrophysics Harvard & Sm ...

, J. P. Brodie and S. M. Kent in 1991.

References

External links

Astrophysical Journal, Vol. 370, p. 495–504

Publications of the Astronomical Society of the Pacific, Vol. 65, No. 382, p. 24–29

Astronomical Journal, vol. 82, p. 947–953

NightSkyInfo.com: Mayall II
Andromeda Galaxy Globular clusters Andromeda (constellation) {{Astronomy-stub

Origin of names

See also

References

External links