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 that is bound together by gravity, with a higher concentration of stars towards its center. It can contain anywhere from tens of thousands to many millions of member stars, all orbiting ...
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 first constellati ...
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 clus ...
, 47 Tucanae
47 Tucanae or 47 Tuc (also designated as NGC 104 and Caldwell 106) is a globular cluster located in the constellation Tucana. It is about from Earth, and 120 light years in diameter. 47 Tuc can be seen with the naked eye, with an apparent magni ...
and Messier 22
Messier 22 or M22, also known as NGC 6656 or the Great Sagittarius Cluster, 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 s ...
, respectively. It is best seen from June to October in the Southern Hemisphere.[ It is also known as NGC 6777, though this identification is uncertain.
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 Param ...
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 (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...
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 Messier 75, M75 are classified ...
VI, namely of intermediate density,[ and has been calculated to be 11.78 ]billion years
A year is a unit of time based on how long it takes the Earth to orbit the Sun. In scientific use, the tropical year (approximately 365 solar days, 5 hours, 48 minutes, 45 seconds) and the sidereal year (about 20 minutes longer) are more exa ...
old.[ There are many binary stars in the system, as well as ]blue straggler
A blue straggler is a type of star that is more luminous and bluer than expected. Typically identified in a stellar cluster, they have a higher effective temperature than the main sequence turnoff point for the cluster, where ordinary stars b ...
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
This is the list of notable stars in the constellation Pavo, sorted by decreasing brightness.
See also
*List of stars by constellation
All stars but one can be associated with an IAU (International Astronomical Union) constellation. IAU const ...
.[ The nearest bright star is ]Peacock
Peafowl is a common name for two bird species of the genus '' Pavo'' and one species of the closely related genus '' Afropavo'' within the tribe Pavonini of the family Phasianidae (the pheasants and their allies). Male peafowl are referred t ...
, which lies 3.25 degrees north and 9.25 degrees east.[
Six ]X-ray
An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...
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 ...
.[
]
Gallery
File:The accidentally discovered galaxy Bedin I.tif, Galaxy nicknamed Bedin I
Bedin I is a dwarf spheroidal galaxy located in the constellation Pavo. It is situated around 28.38 million light-years from Earth, behind the globular cluster NGC 6752. Bedin I is possibly one of the oldest galaxies known, having formed aro ...
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