The same effect can not, by itself, explain the high speed of stars orbiting in spiral galaxies. (newscientist.com)
In neutron star collisions, two neutron stars orbit around each other, eventually merging to form a star with approximately twice the mass of the individual stars. (sciencedaily.com)
This means that there is probably a previously unseen companion star orbiting the star [4]. (alma-telescope.jp)