Mystery Disk at Epsilon AurigaeEpsilon Aurigae, a star 2,000 light-years away, is eclipsed by a dark, dusty disk in an artist's conception. Since the 1820s astronomers have seen Epsilon Aurigae get eclipsed by a mysterious companion for 18 months every 27 years. In fact, the yellow supergiant star was fully eclipsed on January 1, 2010.The nature of the eclipsing object has been a mystery, with theories suggesting everything from a black hole to a dusty nebula. Recent studies have suggested that the unseen object is a star surrounded by a massive, dusty disk—and that the two stars orbit each other, forming what's called a binary system.Now, new pictures of Epsilon Aurigae, to be published in the April 8 issue of the journal Nature, seem to confirm the binary-disk theory. The images show that the disk is "a much longer, thinner cigar than most artists tend to illustrate," said study co-author Robert Stencel, a University of Denver astronomer.—Anne Minard

Illustration by Brian Thieme and courtesy www.citizensky.org

First Pictures: Mystery Disk Eclipses Star

New pictures confirm that a dark disk is responsible for the star Epsilon Aurigae's regular, 18-month-long eclipses. Also: how to see it in the night sky.

April 8, 2010