NGC 6752 (also known as Caldwell 93 and nicknamed the Great Peacock Globular) 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 ...
in the
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
Pavo.
[ It is the fourth-brightest globular cluster in the sky, after ]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 ...
, 47 Tucanae
47 Tucanae, or 47 Tuc (also designated NGC 104) is a globular cluster located in the constellation Tucana. It is about away from Earth, and 120 light years in diameter. 47 Tuc can be seen with the naked eye, with an apparent magnitude of 4.1. It ...
and Messier 22
Messier 22 or M22, also known as NGC 6656, is an elliptical globular cluster of stars in the constellation Sagittarius, near the Galactic bulge region. It is one of the brightest globulars visible in the night sky. The brightest stars are 11th ...
, respectively. It is best seen from June to October in the Southern Hemisphere.[
NGC 6752 was first identified by one ]James Dunlop
James Dunlop FRSE (31 October 1793 – 22 September 1848) was a Scottish astronomer, noted for his work in Australia. He was employed by Sir Thomas Brisbane to work as astronomer's assistant at his private observatory, once located at Paramat ...
of Parramatta on 30 June 1826, who described it as an irregular bright nebula which could be resolved into a cluster of many stars, highly compressed at the centre. This corresponds with a core region densely populated with stars around 1.3 light-year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s in diameter, which indicates it has undergone core collapse. The cluster lies around 13,000 light-years distant and is one of the closer globular clusters to Earth. It also lies 17,000 light-years away from the galactic centre.[ It belongs to ]Shapley–Sawyer Concentration Class The Shapley–Sawyer Concentration Class is a classification system on a scale of one to twelve using Roman numerals for globular clusters according to their concentration. The most highly concentrated clusters such as M75 are classified as Class I ...
VI, namely of intermediate density,[ and has been calculated to be 11.78 ]billion years
A billion years or giga-annum (109 years) is a unit of time on the petasecond scale, more precisely equal to seconds (or simply 1,000,000,000 years).
It is sometimes abbreviated Gy, Ga ("giga-annum"), Byr and variants. The abbreviations Gya or ...
old.[ There are many binary stars in the system, as well as ]blue straggler
A blue straggler is a main-sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams ...
s, which are likely to have been formed by collisions and mergers of smaller stars.
The apparent magnitude of the cluster is 5.4, so it can be seen with the unaided eye.[ However this depends on good viewing conditions with a minimum of light pollution.][ With binoculars it can be seen to cover an area three quarters the size of the full moon. It lies 1.5 degrees east of 5th-magnitude Omega Pavonis.][ The nearest bright star is ]Peacock
Peafowl is a common name for three bird species in the genera ''Pavo (genus), Pavo'' and ''Afropavo'' within the tribe Pavonini of the family Phasianidae, the pheasants and their allies. Male peafowl are referred to as peacocks, and female pea ...
, which lies 3.25 degrees north and 9.25 degrees east.[
Six ]X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
sources have been identified in the cluster's core by the Chandra X-Ray Observatory
The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the during STS-93 by NASA on July 23, 1999. Chandra is sensitive to X-ray sources 1 ...
.[
]
Gallery
File:The accidentally discovered galaxy Bedin I.tif, Galaxy nicknamed Bedin I is located behind the bright stars of the cluster.
File:Star cluster NGC 6752.jpg, NGC 6752 taken by the Wide Field Imager on the MPG/ESO 2.2-meter telescope.
References
External links
*
http://seds.org/
{{DEFAULTSORT:NGC 6752
Globular clusters
Pavo (constellation)
6752
093b