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Types of galaxies according to the Hubble classification scheme : an E indicates a type of elliptical galaxy; an S is a spiral; and SB is a barred spiral galaxy. Galaxies come in three main types: ellipticals, spirals, and irregulars. A slightly more extensive description of galaxy types based on their appearance is given by the Hubble sequence.
Rings. Galaxies are divided into those possessing ring-like structures (denoted ‘(r)’) and those without rings (denoted ‘(s)’). So-called ‘transition’ galaxies are given the symbol (rs). [16] Spiral arms. As in Hubble’s original scheme, spiral galaxies are assigned to a class based primarily on the tightness of their spiral arms.
In the 1980s, the Lyons Groups of Galaxies listed 485 galaxy groups with 3,933 member galaxies. Galaxy Zoo is a project aiming at a more comprehensive list: launched in July 2007, it has classified over one million galaxy images from The Sloan Digital Sky Survey, The Hubble Space Telescope and the Cosmic Assembly Near-Infrared Deep ...
Many galaxies are thought to have black holes at their active centers. The Milky Way's central black hole, known as Sagittarius A* , has a mass four million times greater than the Sun. As of March 2016, GN-z11 is the oldest and most distant observed galaxy with a comoving distance of 32 billion light-years from Earth, and observed as it existed ...
This is a list of known galaxies within 3.8 megaparsecs (12.4 million light-years) of the Solar System, in ascending order of heliocentric distance, or the distance to the Sun. This encompasses about 50 major Local Group galaxies, and some that are members of neighboring galaxy groups , the M81 Group and the Centaurus A/M83 Group , and some ...
The most common kinds of binary system are binary stars and binary asteroids, but brown dwarfs, planets, neutron stars, black holes and galaxies can also form binaries. A multiple system is similar but consists of three or more objects, for example triple stars and triple asteroids (a more common term than 'trinary').
Galaxies by type. List of spiral galaxies; List of ring galaxies; List of polar-ring galaxies; List of quasars; Galaxies by association. List of largest galaxies; List of nearest galaxies; Satellite galaxies of the Milky Way; Other characteristics. List of galaxies named after people; List of galaxies with richest globular cluster systems
The spread of velocities for the individual galaxies is about 150 km/s. However, this definition should be used as a guide only, as larger and more massive galaxy systems are sometimes classified as galaxy groups. [4] Groups are the most common structures of galaxies in the universe, comprising at least 50% of the galaxies in the local universe.