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A dark galaxy is a hypothesized galaxy with no (or very few) stars. They received their name because they have no visible stars but may be detectable if they contain significant amounts of gas. Astronomers have long theorized the existence of dark galaxies, but there are no confirmed examples to date. [1]
NGC 1052-DF2, an ultra diffuse galaxy. An ultra diffuse galaxy (UDG), or dark galaxy, [1] is an extremely low luminosity galaxy, the first example of which was discovered in the nearby Virgo Cluster by Allan Sandage and Bruno Binggeli in 1984. [a] These galaxies have been studied for many years prior to their renaming in 2015. Their lack of ...
Pages in category "Dark galaxies" The following 7 pages are in this category, out of 7 total. This list may not reflect recent changes. ...
Cosmic voids (also known as dark space) are vast spaces between filaments (the largest-scale structures in the universe), which contain very few or no galaxies. In spite of their size, most galaxies are not located in voids. This is because most galaxies are gravitationally bound together, creating huge cosmic structures known as galaxy filaments.
Deep-field observations show that galaxies formed first, followed by clusters and superclusters as galaxies clump together, [48] and therefore that most dark matter is cold. This is also the reason why neutrinos , which move at nearly the speed of light and therefore would fall under hot dark matter, cannot make up the bulk of dark matter.
A dark or "ultra diffuse" galaxy is an extremely-low-luminosity galaxy. It may be the same size as the Milky Way, but have a visible star count only one percent of the Milky Way's. Multiple mechanisms for producing this type of galaxy have been proposed, and it is possible that different dark galaxies formed by different means. [102]
A 2011 survey, the WiggleZ galaxy survey of more than 200,000 galaxies, provided further evidence towards the existence of dark energy, although the exact physics behind it remains unknown. [ 32 ] [ 33 ] The WiggleZ survey from the Australian Astronomical Observatory scanned the galaxies to determine their redshift.
The following outline is provided as an overview of and topical guide to galaxies: Galaxies – gravitationally bound systems of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way.