Local Group

(redirected from The Local Group of Galaxies)
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Local Group,

in astronomy, loose cluster of at least 40 nearby galaxiesgalaxy,
large aggregation of stars, gas, dust, and usually dark matter, typically containing billions of stars. Recognition that galaxies are independent star systems outside the Milky Way came from a study of the Andromeda Galaxy (1926–29) by Edwin P.
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, including our own Milky WayMilky Way,
the galaxy of which the sun and solar system are a part, seen as a broad band of light arching across the night sky from horizon to horizon; if not blocked by the horizon, it would be seen as a circle around the entire sky.
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 galaxy, the Andromeda GalaxyAndromeda Galaxy,
cataloged as M31 and NGC 224, the closest large galaxy to the Milky Way and the only one visible to the naked eye in the Northern Hemisphere. It is also known as the Great Nebula in Andromeda. It is 2.
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, and the Magellanic CloudsMagellanic Clouds
, two dwarf galaxies located in the far southern sky and visible to the unaided eye; they are classified as irregular because they show no definite symmetry or nucleus.
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. The Local Group is spread over an ellipsoidal region of space with a major axis of approximately 3 million light-years. The Milky Way galaxy, near one end of the major axis, and the Andromeda Galaxy, near the other end, are the largest members of the group; most of the galaxies are dwarf galaxies. Some of the galaxies in the group have been detected only by their infrared radiationinfrared radiation,
electromagnetic radiation having a wavelength in the range from c.75 × 10−6 cm to c.100,000 × 10−6 cm (0.000075–0.1 cm).
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; a dusty region in space obscures their visible light. There may be other galaxies in the Local Group that are as yet undetected. As shown by the work of G. de Vaucouleurs, the Local Group is part of a supercluster containing at least 50 separate clusters, each having from a few dozen to as many as a thousand galaxies. These groups appear to be concentrated in a plane, which indicates that the supercluster is rotating. Its center lies approximately 50 million light-years away in the direction of the constellation Virgo, and it is known as the Virgo Supercluster. It has since been determined that the Virgo Supercluster is part of the much larger Laniakea Supercluster, which spans some 500 million light-years.
Local Groupclick for a larger image
Local Group

Local Group

The cluster of galaxies of which our Galaxy is a member. It is a comparatively small cluster with around 40 known members and some other possible members, most of which are dwarf ellipticals or irregular galaxies (see table). The most massive members are the Galaxy and the Andromeda galaxy (M31). The other major members are the Triangulum spiral (M33) and the Large Magellanic Cloud. The group is irregular in shape with two notable subclusters: one around our Galaxy and the Magellanic Clouds, the other around M31 and M33.

Local Group

[′lō·kəl ′grüp]
(astronomy)
A group of at least 20 known galaxies in the vicinity of the sun; the Andromeda Spiral is the largest of the group, and the Milky Way Galaxy is the second largest.
References in periodicals archive ?
"In tracing the orbit backwards in time, it is clear that the universe just is not old enough for Andromeda XII to have been ejected from the Local Group of galaxies, gone out, and be on its way back in," notes Lewis.
This vast stellar association is one of the largest star-formation regions in the Local Group of galaxies. NGC 206 is youthful, astronomically speaking, at a mere 30 million years of age.
Lying adjacent to the Local Group of galaxies - a group that includes the Milky Way - is a vast region of space known as the Local Void.
The discovery appears to be "the most spectacular example of such a satellite disruption seen so far outside the Local Group of galaxies," comments Francois Schweizer of the Carnegie Observatories in Pasadena, Calif.
Excluding members of the Local Group of galaxies and the nearby Sculptor Group and limiting the selection to galaxies brighter than about magnitude 12 1/2 and to those residing in the slice of sky between [22.sup.h] and [4.sup.h] of right ascension yield a list of several dozen objects.
Many of these distant targets are associated with the Local Group of galaxies, several of which are well placed for viewing at this time of year.
Davies, Alan Dressler, Donald Lynden-Bell, Roberto Terlevich and Gary Wegner, from institutions ranging from California and Chile to England.) Previous surveys had compared the motions of the local group of galaxies, including the one in which we live, to farily large reference groups of spiral galaxies.
I showed them the Andromeda Galaxy, M31, explaining that it was a big spiral like our own, and that it and the Milky Way are the biggest members of the Local Group of galaxies. I pointed out that the "fuzzy star" nearby was actually M32, another smaller galaxy.
Might bursts come from the Local Group of galaxies? Clearly not, because events do not cluster in the direction' of these galaxies.
The whole assembly -- the Local Group of galaxies -- fits neatly inside a gymnasium.