Researchers detected the ghostly glow of stars that were ejected from their home galaxy and brutally ripped apart several billion years ago.
The observations, made with NASA's Hubble Telescope, suggest as many as six galaxies were torn to pieces inside "Pandora's Cluster" about six billion years ago, the Space Telescope Science Institute (STSci) reported.
The galactic cluster, also known as Abell 2744, is located four billion light-years away and holds over 500 distinct galaxies. The researchers believe about 200 billion stars contribute to 10 percent of this cluster's brightness. Computer modeling suggests these galaxies were at least as large as our own Milky Way, and are most likely the source of these mysterious stars. The star parts no longer belong to a galaxy, and float freely in intergalactic space.
"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), La Laguna, Tenerife, Spain, one of the researchers involved in this study of Abell 2744. "It is also amazingly beautiful in that we found the telltale glow by utilizing Hubble's unique capabilities."
Researchers had hypothesized light from the stars within the doomed galaxies would be detectable, but since it is so faint this has proven difficult. Thanks to the Hubble, the team was able to observe the stars, and even determine they are rich in element such as oxygen, carbon, and nitrogen. This suggests the scattered stars were second or third-generation that were enriched with elements from ancestors that existed in the early universe.
"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.
