Norma cluster
Encyclopedia
The Norma Cluster is a rich cluster
of galaxies
located near the center of the Great Attractor
. Although it is both nearby and bright, it is difficult to observe because it is located in the Zone of Avoidance
, a region near the plane
of the Milky Way
. Consequently, the cluster is severely obscured
by interstellar dust at optical wavelengths. Its mass is estimated to be on the order of 1015 solar mass
es.
Galaxy groups and clusters
Galaxy groups and clusters are the largest known gravitationally bound objects to have arisen thus far in the process of cosmic structure formation. They form the densest part of the large scale structure of the universe...
of galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
located near the center of the Great Attractor
Great Attractor
The Great Attractor is a gravity anomaly in intergalactic space within the range of the Centaurus Supercluster that reveals the existence of a localised concentration of mass equivalent to tens of thousands of Milky Ways, observable by its effect on the motion of galaxies and their associated...
. Although it is both nearby and bright, it is difficult to observe because it is located in the Zone of Avoidance
Zone of Avoidance
The Zone of Avoidance is the area of the night sky that is obscured by our own galaxy, the Milky Way.-Term:The ZOA was originally called the "Zone of Few Nebulae" in an 1878 paper by English astronomer Richard Proctor that referred to the distribution of "nebulae" in Sir John Herschel's General...
, a region near the plane
Galactic plane
The galactic plane is the plane in which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles...
of the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
. Consequently, the cluster is severely obscured
Extinction (astronomy)
Extinction is a term used in astronomy to describe the absorption and scattering of electromagnetic radiation by matter between an emitting astronomical object and the observer. Interstellar extinction—also called Galactic extinction, when it occurs in the Milky Way—was first...
by interstellar dust at optical wavelengths. Its mass is estimated to be on the order of 1015 solar mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es.
External links
- ESO Press Photos 46a-j/99
- Galaxy Cluster Has Two 'Tails' to Tell. NASANASAThe National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
Image of the Day, January 22, 2010.