News from another star system: First photos of an eclipse trillions of miles away

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Images of an on-going stellar eclipse resolve a mystery nearly 200 years in the making from a star system 2,000 light years away, according to an article published in the current issue of Nature.

Scientists have noticed periodic eclipses of the star system Epsilon Aurigae in the Aurigae constellation since 1821 and have been unable to explain them until now.

An array of six telescopes in California captured high-resolution images that were synthesized by computer to explain the event.

mages of an eclipse in a star system trillions of miles away solve a two century old mystery. The images were compiled with cameras from six separate telescopes in California. John D. Monnier/ University of Michigan.Images of an eclipse in a star system trillions of miles away solve a two century old mystery. The images were compiled with cameras from six separate telescopes in California. John D. Monnier/ University of Michigan.New technology developed at the University of Michigan was used to mimic images that would require a single telescope over 300 feet wide, roughly the size of a football field.

The images show the eclipse is caused by a dark disk that "appears to be about earth's mass of small rocky debris scattered over a volume the size of our inner solar system," said research team member Robert Stencel, a University of Denver astronomer.  Stencel has been observing the star system since the 1980s when he was a graduate student.

The eclipse is on-going and happens only once every 27 years. It involves two stars trillions of  miles away and, when the two stars align, it lasts quite some time. This particular eclipse began in August 2009 and is predicted to last until May 2011.

“The orbit of the disk star around the bright star is huge, on the scale of Saturn's, and takes 27 years to complete,” said Professor Robert Stencel. “Because the disk star is so large, it takes nearly 2 years for it to cross over.”

This artist's concept of the Epsilon Aurigae eclipse shows the supergiant dual star  covered by a dark disk. NASA / JPL-CaltechThis artist's concept of the Epsilon Aurigae eclipse shows the supergiant dual star covered by a dark disk. NASA / JPL-CaltechThe connection with thousands of years of human interest in eclipses places these finding on a par with determining how solar and lunar eclipses occurred in our solar system, according to Ed Guinan, author of the Nature article.

To put the photographed eclipse in perspective, Professor Harold McAlister of Georgia State University, compared the size of Epsilon Aurigae in the images to seeing an 11-point font letter ‘o’ from more than 93 miles away.

Epsilon Aurigae is a binary star, meaning a system of two stars that rotate together around a common center of mass.  

The images confirm the theory proposed by Northwestern Astronomer Su-Shu Huang in The Astrophysical Journal in 1974 that a dark disk in space causes the stellar eclipses, which happen every 27 years, said Stencel.The findings bolster the process of the scientific method of hypothesis and test, he said.

“The nature of the eclipse has been theorized for over 190 years, but we have finally obtained the first images and proven one of the many theories is correct,” said University of Denver graduate student Brian Kloppenborg, who authored the paper.

The pictures were obtained using the Michigan Infrared Combiner (MIRC), developed by University of Michigan Professor John Monnier, a technology that is somewhat new to the astronomy field.

Atop Mount Wilson, in California, a combination of six telescopes called the CHARA (Center for High Angular Resolution Astronomy) Array was used to capture the details of the eclipse. Monnier’s team uses an interferometer, which synthesizes the images captured by each telescope, and builds one composite image, stitched together on a computer.

“The CHARA Array is uniquely capable of making images like this, which, like the old cliché says, are indeed worth a million words in confirming or refuting theoretical models,” said McAlister.

The images of the double star system are “the best and most complete images to date,” said Monnier.

The combination of six telescopes simulates the work of one giant telescope the size of a football field.  Since a telescope of that nature would cost hundreds of millions of dollars, Monnier’s method is the most efficient.

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