Please answer the following question: Information:  - A centaur ("Kéntauros"), or occasionally hippocentaur, is a mythological creature with the upper body of a human and the lower body of a horse.  - A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is derived from the Latin "globulus"a small sphere. A globular cluster is sometimes known more simply as a "globular".  - In physics, redshift happens when light or other electromagnetic radiation from an object is increased in wavelength, or shifted to the red end of the spectrum. In general, whether or not the radiation is within the visible spectrum, "redder" means an increase in wavelength  equivalent to a lower frequency and a lower photon energy, in accordance with, respectively, the wave and quantum theories of light.  - Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. In Greek mythology, Centaurus represents a centaur; a creature that is half human, half horse (another constellation named after a centaur is one from the zodiac: Sagittarius). Notable stars include Alpha Centauri, the nearest star system to the Solar System, its neighbour in the sky Beta Centauri, and V766 Centauri, one of the largest stars yet discovered. The constellation also contains Omega Centauri, the brightest globular cluster as visible from Earth and one of the largest known.  - George Ogden Abell (March 1, 1927  October 7, 1983) was an astronomer at UCLA. He worked as a research astronomer, teacher, administrator, popularizer of science and education, and skeptic. Abell received his B.S. (1951), M.S. (1952) and Ph.D. (1957) from the California Institute of Technology under Donald Osterbrock. He began his astronomical career as a tour guide at the Griffith Observatory in Los Angeles.  - The Solar System is the gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of those objects that orbit the Sun directly, the largest eight are the planets, with the remainder being significantly smaller objects, such as dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury.  - Alpha Centauri ( Centauri, abbreviated Alpha Cen,  Cen) is the closest star system to the Solar System at a distance of . It consists of three stars: the pair Alpha Centauri A (also named Rigil Kentaurus) and Alpha Centauri B together with a small and faint red dwarf, Alpha Centauri C (also named Proxima Centauri), that may be gravitationally bound to the other two. To the unaided eye, the two main components appear as a single point of light with an apparent visual magnitude of 0.27, forming the brightest star in the southern constellation of Centaurus and the third-brightest star in the night sky, outshone only by Sirius and Canopus.  - Beta Centauri ( Centauri, abbreviated Beta Cen,  Cen), also named Hadar, is a triple star system in the southern constellation of Centaurus. The system's combined apparent visual magnitude of 0.61 makes it the second-brightest star in Centaurus and one of the brightest stars in the night sky. According to parallax measurements from the astrometric Hipparcos satellite, the distance to this system is about .  - The Abell catalog of rich clusters of galaxies is an all-sky catalog of 4,073 rich galaxy clusters of nominal redshift   "z"  0.2. This catalog supplements a revision of George O. Abells original Northern Survey of 1958, which had only 2,712 clusters, with a further 1,361 clusters  the Southern Survey of 1989, published after Abell's death by co-authors Harold G. Corwin and Ronald P. Olowin from those parts of the south celestial hemisphere that had been omitted from the earlier survey.  - A constellation is formally defined as a region of the celestial sphere, with boundaries laid down by the International Astronomical Union (IAU). The constellation areas mostly had their origins in Western-traditional patterns of stars from which the constellations take their names.  - The zodiac is an area of the sky centered upon the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The paths of the Moon and visible planets also remain close to the ecliptic, within the belt of the zodiac, which extends 8-9° north or south of the ecliptic, as measured in celestial latitude. In western astrology and (formerly) astronomy, the zodiac is divided into twelve signs, each sign occupying 30° of celestial longitude. Because the signs are regular, they do not correspond exactly to the boundaries of the twelve constellations after which they are named.  - Claudius Ptolemy ("Klaúdios Ptolemaîos", ; ) was a Greek writer, known as a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in the city of Alexandria in the Roman province of Egypt, wrote in Koine Greek, and held Roman citizenship. Beyond that, few reliable details of his life are known. His birthplace has been given as Ptolemais Hermiou in the Thebaid in an uncorroborated statement by the 14th-century astronomer Theodore Meliteniotes. This is a very late attestation, however, and there is no other reason to suppose that he ever lived anywhere else than Alexandria, where he died around AD 168.  - Omega Centauri ( Cen), also known as NGC 5139 and 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 15,800 light-years (4,850 pc), it is the largest globular cluster in the Milky Way at a diameter of roughly 150 light-years. It is estimated to contain approximately 10 million stars and a total mass equivalent to 4 million solar masses.  - Greek mythology is the body of myths and teachings that belong to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. It was a part of the religion in ancient Greece. Modern scholars refer to and study the myths in an attempt to shed light on the religious and political institutions of Ancient Greece and its civilization, and to gain understanding of the nature of myth-making itself.  - The Abell S740 is a cluster of galaxies identified in the Abell catalogue of southern rich clusters of galaxies . It is over 450 Mly away in the constellation Centaurus . It has a redshift of 10,073 km / s.  - A galaxy cluster, or cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity with typical masses ranging from 1010 solar masses. They are the largest known gravitationally bound structures in the universe and were believed to be the largest known structures in the universe until the 1980s, when superclusters were discovered. One of the key features of clusters is the intracluster medium (ICM). The ICM consists of heated gas between the galaxies and has a peak temperature between 215 keV that is dependent on the total mass of the cluster. Galaxy clusters should not be confused with star clusters, such as open clusters, which are structures of stars "within" galaxies, or with globular clusters, which typically orbit galaxies. Small aggregates of galaxies are referred to as groups of galaxies rather than clusters of galaxies. The groups and clusters can themselves cluster together to form superclusters.    After reading the paragraphs above, we are interested in knowing the entity with which 'abell s740' exhibits the relationship of 'instance of'. Find the answer from the choices below.  Choices: - administrator  - anthology  - area  - catalog  - centaur  - centauri  - century  - city  - cluster  - constellation  - course  - cult  - dwarf  - education  - eight  - electromagnetic radiation  - energy  - frequency  - galaxy cluster  - globular cluster  - greek mythology  - horse  - institute  - key  - los angeles  - magnitude  - march  - myth  - object  - october  - orbit  - part  - path  - physics  - point  - province  - reason  - red dwarf  - religion in ancient greece  - research  - ritual  - roman province  - sign  - single  - sky  - sphere  - star cluster  - star system  - statement  - study  - system  - three  - triple star system  - two  - wave  - zodiac
Answer:
galaxy cluster