NASA's Hubble Space Telescope has picked up the faint, ghostly glow of stars ejected from ancient galaxies that were ripped apart several billion years ago, according to a NASA press release.
The mayhem took place 4 billion light-years away, inside an immense collection of nearly 500 galaxies nicknamed "Pandora's Cluster," also known as Abell 2744.
The stars aren't bound to any one galaxy, and drift between galaxies in the cluster as they wish. By observing the light from the orphaned stars, Hubble astronomers have assembled forensic evidence that suggests around six galaxies were torn to pieces the cluster over a stretch of 6 billion.
Computer modeling of the gravitational dynamics among galaxies in a clusters suggests that galaxies as big as our Milky Way Galaxy are likely the candidates as the source of the stars.
The galaxies would have been pulled apart like taffy if they plunged through the center of a galaxy cluster where gravitational tidal forces are strongest, according to NASA. Researchers have long speculated that the light from scattered stars should be detectable after such galaxies are disassembled.
"The Hubble data revealing the ghost light are important steps forward in understanding the evolution of galaxy clusters," said Ignacio Trujillo of The Instituto de Astrofísica de Canarias (IAC), Santa Cruz de Tenerife, Spain, according to the release. "It is also amazingly beautiful in that we found the telltale glow by utilizing Hubble's unique capabilities."
The team estimates that the combined light of about 200 billion outcast stars contributes approximately 10 percent of the cluster's brightness.
"The results are in good agreement with what has been predicted to happen inside massive galaxy clusters," said Mireia Montes of the IAC, lead author of the paper published in the Oct. 1 issue of the Astrophysical Journal.
The team emphasized that this type of observation could only happen with Hubble's infrared sensitivity to extraordinarily dim light since these faint stars are brightest at near-infrared wavelengths of light.
Abell 2744 is a target in the Frontier Fields program, a three-year-long mission that combines Hubble and NASA's other observatories to study massive galaxy clusters, according to NASA.
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