Andromeda 'born in a collision'

BBC News - Andromeda 'born in a collision': "The researcher explained that his team's findings had 'the potential to revise all our knowledge about the Local Group - and this may have also an impact regarding the amount of dark matter in galaxies'.

Using a computer simulation, the astronomers were able to reproduce most of the peculiar properties of the Andromeda galaxy: the large thin disk including its giant ring of gas and dust, the massive central bulge, the gigantic thick galactic 'disc', and the giant stream of old stars."