Some of its mysteries are now cleared

Apr 8, 2010 09:01 GMT  ·  By

The Epsilon Aurigae star system is a peculiar stellar formation, astronomers say. For many years, scientists have been pointing their instruments at it, in hopes of gaining additional insight into how the structure actually looks like. Many have hypothesized that the system is a binary, but thus far pieces of evidence to support this have been scarce at best. Additionally, experts noticed that the structure of Epsilon Aurigae was not exactly consistent with that of a classic binary, such as one featuring two normal stars, or two white/brown dwarfs, as usual, Space reports.

What caught the eye of astronomers the first time around was the fact that the light from one star appeared to be periodically blocked by something. They hypothesized that its companion had to be passing right in front of it, therefore reducing its apparent brightness. However, if a full-blown star had moved in front of it, then the brightness shouldn't have dipped by so much. This peculiarity was what made astronomers assume that the companion of the first star had to be in fact another star, only surrounded by a large disk made of gas and dust.

The stellar pair has been under surveillance by astronomers since the 1800s. Over these two centuries, they noticed that an eclipse occurred once ever 27 years. It was only recently, however, that an astronomy team managed to conduct a series of observations to confirm the existence of the second star, the one enveloped in dust. “Seeing is believing,” University of Michigan astronomer John Monnier, who has also been the study leader, explains. He and his team were very curious to learn why the second star was so difficult to see. Epsilon Aurigae is located about 2,000 light-years away from the Earth, slightly below Capella, the brightest star in the constellation Auriga.

“This really shows that the basic paradigm was right, despite the slim probability. It kind of blows my mind that we could capture this. There's no other system like this known. On top of that, it seems to be in a rare phase of stellar life. And it happens to be so close to us. It's extremely fortuitous,” the expert adds. The catch here is that, in order for the previous hypothesis to test out, the alignment between the binary system, the Earth, and the plane of the dust ring enveloping the second star should have been just right. According to the new study, published online in the April 8 issue of Nature, it was.