Big Dipper Cosmic Ray 'Hotspot' Mystery Solved?


A hotspot of powerful, ultrahigh-energy particles streams toward Earth from beneath the handle of the Big Dipper constellation. This collection of cosmic rays may help scientists nail down the origin point of the powerful particles, a century-old mystery.

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"This puts us closer to finding out the sources — but no cigar yet," Gordon Thomson, of the University of Utah, said in a statement. Thomson is the co-principle investigator for the Telescope Array cosmic ray observatory in southern Utah, which discovered the hotspot, and one of the 125 researchers on the project.

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"All we see is a blob in the sky, and inside this blob there is all sorts of stuff — various types of objects — that could be the source," he added. "Now we know where to look." [8 Baffling Astronomy Mysteries]

A Hundred-Year-Old Mystery

Gordon worked with an international team of scientists to capture 72 ultarhigh-energy cosmic rays with the Telescope Array over a period of five years. If powerful cosmic ray sources spread evenly across the sky, the resulting waves should also be evenly distributed. Instead, 19 of the detected signals came from a 40-degree circle that makes up only six percent of the sky. The hot spot lies in the constellation Ursa Major, home of the Big Dipper.

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"We have a quarter of our events in that circle instead of 6 percent," collaborator Charlie Jui, also from the University of Utah, said in the same statement.

Jui describes the hotspot's location as "a couple of hand widths below the Big Dipper's handle." The region would appear like any other region of the sky to regular optical telescopes.

According to the researchers, the odds that the hotspot is a statistical fluke rather than real are only 1.4 in 10,000.

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