Robert's Quartet
Encyclopedia
Robert's Quartet is a compact galaxy group approximately 160 million light-year
s away in the constellation
Phoenix
. It is a family of four very different galaxies in the process of colliding and merging. Its members are NGC 87
, NGC 88
, NGC 89
and NGC 92
, discovered by John Herschel
in the 1830s.
The quartet is one of the finest examples of compact groups of galaxies. Because such groups contain four to eight galaxies in a very small region, they are excellent laboratories for the study of galactic interactions and their effects, in particular on the formation of stars. The quartet has a total visual magnitude of almost 13. The brightest member of the group has a magnitude of about 14. On the sky, the four galaxies are all within a circle of radius of 1.6 arcmin, corresponding to about 75,000 light-years. It was named by Halton Arp
and Barry F. Madore, who compiled A Catalogue of Southern Peculiar Galaxies and Associations in 1987.
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Phoenix
Phoenix (constellation)
Phoenix is a minor constellation in the southern sky. It is named after the Phoenix, a mythical bird. It is faint: there are only two stars in the whole constellation which are brighter than magnitude 5.0...
. It is a family of four very different galaxies in the process of colliding and merging. Its members are NGC 87
NGC 87
-References:* * -External links:...
, NGC 88
NGC 88
NGC 88 is a spiral galaxy located about 160 million light years from the Earth in the Phoenix constellation, NGC 88 is interacting galaxies NGC 92, NGC 87 and NGC 89....
, NGC 89
NGC 89
-See also:* Robert's Quartet...
and NGC 92
NGC 92
NGC 92 is a galaxy in Robert's Quartet, it is interacting with three neighbouring galaxies.-External links:...
, discovered by John Herschel
John Herschel
Sir John Frederick William Herschel, 1st Baronet KH, FRS ,was an English mathematician, astronomer, chemist, and experimental photographer/inventor, who in some years also did valuable botanical work...
in the 1830s.
The quartet is one of the finest examples of compact groups of galaxies. Because such groups contain four to eight galaxies in a very small region, they are excellent laboratories for the study of galactic interactions and their effects, in particular on the formation of stars. The quartet has a total visual magnitude of almost 13. The brightest member of the group has a magnitude of about 14. On the sky, the four galaxies are all within a circle of radius of 1.6 arcmin, corresponding to about 75,000 light-years. It was named by Halton Arp
Halton Arp
Halton Christian Arp is an American astronomer. He is known for his 1966 Atlas of Peculiar Galaxies, which catalogues many examples of interacting and merging galaxies...
and Barry F. Madore, who compiled A Catalogue of Southern Peculiar Galaxies and Associations in 1987.
Members
| Name | Type | Distance from Sun Sun The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields... (million ly Light-year A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres... ) |
Magnitude Apparent magnitude The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere... |
|---|---|---|---|
| NGC 87 NGC 87 -References:* * -External links:... |
IBm pec. | ~160 | +14.5 |
| NGC 88 NGC 88 NGC 88 is a spiral galaxy located about 160 million light years from the Earth in the Phoenix constellation, NGC 88 is interacting galaxies NGC 92, NGC 87 and NGC 89.... |
SB(rs)a pec. | ~160 | +15.21 |
| NGC 89 NGC 89 -See also:* Robert's Quartet... |
SB0(s)a pec. | ~160 | +14.57 |
| NGC 92 NGC 92 NGC 92 is a galaxy in Robert's Quartet, it is interacting with three neighbouring galaxies.-External links:... |
SAa pec. | ~160 | +14.29 |