NASA | GSFC | STScI | HubbleSite | 2014 Oct 30
[c][attachment=0]hs-2014-43-a-large_web[1].jpg[/attachment][/c]NASA’s Hubble Space Telescope has picked up the faint, ghostly glow of stars ejected from ancient galaxies that were gravitationally ripped apart several billion years ago. The mayhem happened 4 billion light-years away, inside an immense collection of nearly 500 galaxies nicknamed “Pandora’s Cluster,” also known as Abell 2744.
The scattered stars are no longer bound to any one galaxy, and drift freely between galaxies in the cluster. By observing the light from the orphaned stars, Hubble astronomers have assembled forensic evidence that suggests as many as six galaxies were torn to pieces inside the cluster over a stretch of 6 billion years.
Computer modeling of the gravitational dynamics among galaxies in a cluster suggests that galaxies as big as our Milky Way Galaxy are the likely candidates as the source of the stars. The doomed galaxies would have been pulled apart like taffy if they plunged through the center of a galaxy cluster where gravitational tidal forces are strongest. Astronomers have long hypothesized that the light from scattered stars should be detectable after such galaxies are disassembled. However, the predicted “intracluster” glow of stars is very faint and was therefore a challenge to identify.
“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. “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. ...
“Ghost Light” from Dead Galaxies
Instituto de Astrofísica de Canarias (IAC) | 2014 Oct 30
Intra-Cluster Light at the Frontier: Abell 2744 - Mireia Montes, Ignacio Trujillo
- Astrophysical Journal 794(2) 137 (2014 Oct 20) DOI: 10.1088/0004-637X/794/2/137
arXiv.org > astro-ph > arXiv:1405.2070 > 08 May 2014 (v1), 26 Aug 2014 (v3)
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