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The Sculptor Galaxy (NGC 253) is a disk galaxy. A disc galaxy (or disk galaxy) is a galaxy characterized by a galactic disc. This is a flattened circular volume of stars that are mainly orbiting the galactic core in the same plane. [1] These galaxies may or may not include a central non-disc-like region (a galactic bulge). [2]
An accretion disk is a structure (often a circumstellar disk) formed by diffuse material [a] in orbital motion around a massive central body. The central body is most frequently a star . Friction , uneven irradiance, magnetohydrodynamic effects, and other forces induce instabilities causing orbiting material in the disk to spiral inward toward ...
The Sculptor Galaxy (NGC 253) is an example of a disc galaxy. A galactic disc (or galactic disk) is a component of disc galaxies, such as spiral galaxies like the Milky Way and lenticular galaxies. Galactic discs consist of a stellar component (composed of most of the galaxy's stars) and a gaseous component (mostly composed of cool gas and dust).
2013 – The galaxy Z8 GND 5296 is confirmed by spectroscopy to be one of the most distant galaxies found up to this time. Formed just 700 million years after the Big Bang , expansion of the universe has carried it to its current location, about 13 billion light years away from Earth (30 billion light years comoving distance ).
The reason is that these galaxy formation models predict a large number of mergers. If disk galaxies merge with another galaxy of comparable mass (at least 15 percent of its mass) the merger will likely destroy, or at a minimum greatly disrupt the disk, and the resulting galaxy is not expected to be a disk galaxy (see next section).
The thin disk of our galaxy began to form when the universe was about 5 billion years old or 9 ± 2 Gya. [15] The Solar System formed at about 9.2 billion years (4.6 Gya), [ 5 ] : 22.2.3 with the earliest evidence of life on Earth emerging by about 10 billion years (3.8 Gya).
The thin disk contributes about 85% of the stars in the Galactic plane [3] and 95% of the total disk stars. [2] It can be set apart from the thick disk of a galaxy since the latter is composed of older population stars created at an earlier stage of the galaxy formation and thus has fewer heavy elements. Stars in the thin disk, on the other ...
The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms galactic plane and galactic poles usually refer specifically to the plane and poles of the Milky Way, in which Planet Earth is located.