Secrets of Shady Star System Revealed

Secrets of Shady Star System Revealed
Reconstructed images showing the progression of the 2009-2010 eclipse of epsilon Aurigae as imaged by the Center for High Angular Resolution interferometer with the Michigan Infrared beam Combiner.
(Image: © John D. Monnier, University of Michigan)

New images of two strange stars, where one passes in frontof the other to block its light periodically as seen from Earth, are beginningto give up the secrets of this puzzling stellar pair.

The star system, called Epsilon Aurigae, experiences theeclipse once every 27 years. For the first time, scientists have directlyimaged the dark companion that blocks its companion?s light.

Astronomers have been watching this pair of stars since the1800s. Over time, they noticed that the main star appears dimmer than it shouldbe, given its mass, and that its brightness dips even more for longer than ayear every few decades. The system lies about 2,000 light-years from Earth (a light-yearis the distance light can travel in one year).

Scientists had previously surmised that the bright star hasa hidden companion that was blocking its light, and the new observationsconfirm that.

"Seeing is believing," said study leader JohnMonnier, an astronomer at the University of Michigan.

Astronomers have also wondered why this starcompanion was so difficult to see.

Some researchers have suggested that it is a faint star witha thick cloud of dust orbiting it, obscuring some of its light. But the alignmentof the cloud, the star, its companion, and Earth would have to be just rightfor this to be the case.

And indeed, the new data support this idea.

"This really shows that the basic paradigm was right,despite the slim probability," Monnier said. "It kind of blows mymind that we could capture this. There's no other system like this known. Ontop of that, it seems to be in a rare phase of stellar life. And it happens tobe so close to us. It's extremely fortuitous."

The astronomers used the Michigan Infra-Red Combinerinstrument to combine the light entering four telescopes at the CHARA array atGeorgia State University. The effect is a virtual telescope that is much largerthan its four constituents.

The researchers detail their findings in the April 8 issueof the journal Nature.

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