Exiled Supernovae Exploded in the Depths of Intergalactic Space Between Galaxies

Sharp images from the Hubble Space Telescope has revealed that three supernovae discovered several years ago exploded in the dark emptiness of intergalactic space. What's interesting is that these supernovae exploded after being flung from their home galaxies millions or billions of years earlier.

Most supernovae are found inside galaxies containing hundreds of billions of stars. Some supernovae, though, can be found between galaxies. In fact, the closest neighbors of these supernovae were probably 300 light-years away, which is nearly 100 times further than our sun's nearest stellar neighbor, Proxima Centauri.

These rare, solitary supernovae may reveal important clues as to what exists in the empty spaces between galaxies. In addition, it may allow astronomers to better understand how galaxy clusters formed and evolved through the history of the universe.

Galaxies situated in massive clusters experience gravitational forces that wrench away about 15 percent of the stars. The clusters have so much mass, though, the the displaced stars remain gravitationally bound within the sparsely populated intracluster regions.

Once these stars are dispersed, they're too faint to be seen individually unless they explode as supernovae.

"We have provided the best evidence yet that intracluster stars truly do explode as Type Ia supernovae," said Melissa Graham, one of the researchers, in a news release. "This might be the first confirmed case, and may indicate that the faction of stars that explode as supernovae is higher in either low-mass galaxies or globular clusters."

The findings reveal a bit more about these strange supernovae and hint at what exists between galaxies.

The findings are published in The Astrophysical Journal.

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