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 memb ...

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 gal ...

. 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 astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it we ...

) 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 clus ...

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

black hole A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can defo ...

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

Olin J. Eggen Olin Jeuck Eggen (July 9, 1919 – October 2, 1998) was an American astronomer. Biography Olin Jeuck Eggen was born to Olin Eggen and Bertha Clare Jeuck in the village of Orfordville in Rock County, Wisconsin. Both of his parents were of Norw ...

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 ...

, indicating multiple

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

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 s ...

consumed by Andromeda.

Origin of names

* Mayall II is named after Nicholas U. Mayall, who, with

, discovered it in 1953. * SKHB 1 is named for Wallace L. W. Sargent,

Charles T. Kowal Charles Thomas Kowal (November 8, 1940 – November 28, 2011) was an American astronomer known for his observations and discoveries in the Solar System. As a staff astronomer at Caltech's Mount Wilson and Palomar Mountain observatories between ...

, 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 ''J. The Jewish News of Northern California'', formerly known as ''Jweekly'', is a weekly print newspaper in Northern California, with its online edition updated daily. It is owned and operated by San Francisco Jewish Community Publications In ...

and

S. M. Kent S is the nineteenth letter of the English alphabet. S may also refer to: History * an Anglo-Saxon charter's number in Peter Sawyer's, catalogue Language and linguistics * Long s (ſ), a form of the lower-case letter s formerly used where "s ...

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