The Bautz–Morgan classification was developed in 1970 by
Laura P. Bautz and
William Wilson Morgan to categorize
galaxy cluster
A galaxy cluster, or a 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 1014 to 1015 solar masses. Clusters consist of galax ...
s based on their
morphology.
It defines three main types: I, II, and III. Intermediate types (I-II, II-III) are also allowed. A type IV was initially proposed, but later redacted before the final paper was published.
Classification
* A type I cluster is dominated by a bright, large, supermassive
cD galaxy; for example
Abell 2029 and
Abell 2199.
* A type II cluster contains
elliptical galaxies
An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the three main classes of galaxy described by Edwin Hubble in his Hubble sequence and 1936 work ''The Re ...
whose brightness relative to the cluster is intermediate to that of type I and type III. The
Coma Cluster is an example of a type II.
* A type III cluster has no remarkable members, such as the
Virgo Cluster
The Virgo Cluster is a cluster of galaxies whose center is 53.8 ± 0.3 Mly (16.5 ± 0.1 Mpc) away in the Virgo constellation. Comprising approximately 1,300 (and possibly up to 2,000) member galaxies, the cluster forms the heart of the larger ...
. Type III has two subdivisions, type IIIE and type IIIS
** Type IIIE clusters do not contain many giant spirals
** Type IIIS clusters contain many giant spirals
* The deprecated type IV was for clusters whose brightest members were predominantly spirals.
Examples
See also
*
Active galactic nucleus
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such e ...
*
Galaxy morphological classification
Galaxy morphological classification is a system used by astronomers to divide galaxies into groups based on their visual appearance. There are several schemes in use by which galaxies can be classified according to their morphologies, the most f ...
*
List of Abell clusters
*
Planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...
*
Stellar classification
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction gratin ...
References
{{DEFAULTSORT:Bautz-Morgan classification
Astronomical classification systems
*Bautz-Morgan