Astronomers have always known about runaway stars ejected from their home galaxies. They have, however, found that even entire, massive galaxies can apparently become "homeless" and flung out of their galactic clusters into cosmic oblivion.

To date, 11 galaxies considered "runaways" have been observed by scientists. These runaways are apparently drifting alone in space between galaxy clusters.

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These galaxies will face a lonely journey into the future, forever exiled from galaxy clusters that used to be their homes, according to Igor Chilingarian from the Harvard-Smithsonian Center for Astrophysics and Moscow State University.

Stars and now galaxies can be hurled from their host clusters during an acceleration of gravitational disturbances that can reach speeds far greater than their galactic home location's escape velocity, according to researchers.

Scientists explain this phenomenon by comparing it to a star escaping from our Milky Way galaxy. To escape, a star would need to achieve a speed of 1.2 million miles per hour.

For an entire galaxy to escape the gravitational forces of its entire galactic home cluster, it will need to accelerate to over six million miles per hour depending on the mass of the cluster inside.

During this research, Chilingarian and co-author Ivan Zolotukhin were conducting studies of a new class of galaxies called compact ellipticals that are smaller groups of stars measuring just a few hundred light years across. Ellipticals are bigger than a star cluster but smaller than a galaxy.

Out of 200 compact ellipticals observed, 11 were discovered in completely remote locations far away from any larger galaxy or cluster.

This phenomenon of homeless galaxies is similar to the processes in which two stars in a binary system are in close proximity with a supermassive black hole. The black hole will devour one star while flinging the other one into the depths of the cosmos. 

This slingshot effect can also be a good thing as it can help a compact galaxy survive away from the center of the cluster where it can be torn apart by a black hole in about one billion years.

This study was published in the journal, Science.

TagsScientists Find 'Homeless' Galaxies Ejected by their Clusters, homeless galaxies, runaway galaxies, Harvard-Smithsonian Center for Astrophysics, compact elliptical galaxies, homeless runaway galaxies flung out ejected clusters