Binary star system directly observed

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ANN ARBOR, Mich., April 7 (UPI) -- U.S. astronomers say they have, for the first time, observed the smaller companion of a binary star system and the disk of dust that partly obscures it.

University of Michigan Associate Professor John Monnier and University of Denver Professor Bob Stencel said they captured images of the binary star system Epsilon Aurigae in the constellation Auriga at a time when the companion was eclipsing the larger star -- an event that only occurs every 27 years.

A binary star consists of two stars orbiting a common center of mass. The brighter star is called the primary and the other is its companion star or secondary.

The researchers said the primary star was long known to appear dimmer than expected for its mass. To explain that, astronomers developed the unlikely theory that a thick disk of dust was orbiting the smaller star in the same plane as the smaller star's orbit of the larger star.

Monnier said the new images confirm that unlikely arrangement.

"This really shows that the basic paradigm was right, despite the slim probability," he said. "It kind of blows my mind that we could capture this. There's no other system like this known."

Monnier led the development of the Michigan Infra-Red Combiner instrument that produced the images by a process called "interferometry," amplifying and combining images from four telescopes at Georgia State University.

The study that included graduate students Xiao Che and Brian Kloppenborg appears in the journal Nature.