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Spooky ghost light reveals dead galaxies torn apart over 6bn years

Hubble spots ejected, wandering stars

Pic Astro boffins have observed a faded, ghostly glow of stars belched from ancient galaxies that NASA said were gravitationally ripped apart several billion years ago.

The chaotic, straying stars were spotted by the US and European space agency's Hubble telescope – which is the only instrument capable of making such an observation, NASA said, due to its infra-red sensitivity to extraordinarily dim light.

A ghoulish Pandora's Cluster artificially coloured blue in Hubble's view.
Image credit: NASA/ESA/IAC/HFF Team, STScI

NASA said:

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 [which – fact fans – weighs in at more than 4 trillion solar masses].

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.

Researchers believe that the galaxies may have been as big as our Milky Way, based on computational modelling of the gravitational dynamics among galaxies in a cluster.

The boffins estimated that the combined light of about 200 billion banished stars contributes approximately 10 per cent of the cluster's brightness.

“The results are in good agreement with what has been predicted to happen inside massive galaxy clusters,” Mireia Montes of the The Instituto de Astrofísica de Canarias said. ®


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