Local Group, definition and study. A-Z index of Cognitio.

Local Group is the very name given to the group of galaxies that our Galaxy is the Milky Way.

Milky Way, definition and study. A-Z index of Cognitio.

Milky Way

The Local Group includes more than 70 galaxies, for the most part small, and its center of gravity lies at a point between the Milky Way and the Andromeda Galaxy.

Andromeda galaxy, definition and study. A-Z index of Cognitio.

Andromeda galaxy

The group has a diameter of about 10 million light years, divided mainly into two large centers with an equivalent shape to a handlebar. The Local Group is a typical example of a group of galaxies as there are so many in the universe. It is, with the other 5 groups closest to it: Sculptor Group, Maffei 1 Galaxy Group, M81 Group, Centaurus A / M83 Group and M94 Group and Amphora of the Virgin, large and massive group of distant galaxies only 50 million light years, is part of a larger and extended structure known as Local Super wash consisting of various clusters and groups of galaxies. The most massive members of the Group are the three great spirals present: the Andromeda Galaxy, followed by the Milky Way and the Galaxy of the Triangle. Each of them forms a subgroup formed by a system of “satellites” galaxies. The term Local Group was introduced in 1936 by Edwin Hubble in Chapter VI of his book “The Realm of the Nebulae“, where it describes it as a typical small group of isolated nebulae in the larger space.

The galaxies closest to ours seem to be distributed in a fairly flat area. In addition, twelve out of fourteen of these are spiral-type, each featuring heavily crushed disks where stellar formation areas are present. The remaining two galaxies are elliptical, spheroid and arranged in diametrically opposite points in the ring. The gas ejected by these two celestial objects in their early evolutionary phases could have been conveyed to the members of the Local Group, contributing also to the formation of the Milky Way and Andromeda disks. But this study allows astronomers to go further and in particular to rebuild the conditions that led to the formation of the Milky Way. In particular, it would appear that a small increase in the density of matter in the primordial universe would be enough to trigger the formation of the galaxies that make up the Local Group today. To get to the present configuration, the nearby galaxies would develop into an exquisite ‘sheet’ made up of dark matter.

Dark matter, definition and study. A-Z index of Cognitio.

Dark matter

Recent surveys of the distant universe have revealed that galaxies are located along planes and filaments surrounded by empty regions. We can think of these structures as a giant sponge, whose large-scale geometry seems to replicate in the same way even in the local universe.

Local Group, definition and study. A-Z index of Cognitio.

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Local Group, definition and study. A-Z index of Cognitio.

Local Group