Half of Stars Roam Between Galaxies

A 2014 study suggested that as many as half of all stars in the universe may lurk outside the bright, well-defined parts of galaxies, drifting through the space between galaxies in clusters. The team reached that estimate by measuring faint fluctuations in the extragalactic background light with NASA suborbital rocket experiments, then arguing the extra glow likely came from huge numbers of “intracluster” stars stripped out during galaxy interactions.

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