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Satellite galaxies not randomly arranged

2 February 2018 Astronomy Now

New observations indicate dwarf galaxies may not orbit their parent galaxies in random alignments as predicted by dark matter computer models. Instead, satellite galaxies orbiting in more ordered planes may be the rule, not the exception.

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Mystery of ultra-diffuse faint galaxies solved

29 November 2016 Astronomy Now

Over the last year, researchers have observed some very faint, diffuse galaxies. These so-called ultra-diffuse galaxies (UDGs) are as faint as dwarf galaxies but are distributed over an area just as large as the Milky Way. Now, a solution to the mystery of how such galaxies form has been found.

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Large number of dwarf galaxies discovered in the early universe

25 November 2016 Astronomy Now

Researchers have found a large population of distant dwarf galaxies that could reveal important details about a productive period of star formation in the universe billions of years ago. It is believed that dwarf galaxies played a significant role during the so-called reionisation era in transforming the dark early universe into one that is bright, ionised and transparent.

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Hubble captures a galactic cannibal

7 November 2016 Astronomy Now

This NASA/ESA Hubble Space Telescope image reveals NGC 1222, a galaxy with a rather eventful story to tell. NGC 1222 has been described as a peculiar example of a so-called lenticular galaxy, but one that exhibits very recent star formation on a huge scale — an event known as a starburst — due to having recently consumed two dwarf galaxies.

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Dark matter satellites trigger massive birth of stars

9 March 2016 Astronomy Now

Astronomers have used computer simulations based on theoretical models to explain massive star formation observed in dwarf galaxies. Researchers in the US and the Netherlands found that during a dark matter satellite’s closest approach to a dwarf galaxy, through gravity it compresses the gas in the dwarf, triggering significant episodes of starbursts.

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Hubble sees starburst in the maelstrom of a galactic merger

1 February 2016 Astronomy Now

This Hubble image is of the peculiar galaxy NGC 1487, lying about 30 million light-years away. We are witnessing the possible merger of several dwarf galaxies into a new single galaxy. Its appearance is dominated by large areas of bright blue stars, illuminating the patches of gas that gave them life. This burst of star formation may well have been triggered by the merger.

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Galactic merger reveals an unusual black hole that has shed its stars

5 January 2016 Astronomy Now

In this season of post-Christmas gym memberships, black holes have shown that they too can lose a lot of the weight of the stars that surround them. One unusually star-deprived black hole at the site of two merged galaxies could provide new insight into black hole evolution and behaviour, according to observations with the Hubble Space Telescope and Chandra X-ray Observatory.