Dimming star mystery artist concept

An artist’s conception of Epsilon Aurigae and its dusty companion. Credit: NASA/JPL Caltech

Epsilon Aurigae is one of the few stars that you can see with your own eyes, even in the washed out, big-city sky. It’s big and very bright — except when it isn’t. Sometimes, it’s just not there.

Epsilon Aurigae is what’s known as an eclipsing star. Every 27 years or so, it dims dramatically. In fact, you would have a hard time finding Epsilon Aurigae right now, because the star began dimming last August — and it won’t be fully visible again for more than a year. That’s one of the longest eclipses known to man.

Astronomers have been puzzling over these drawn-out eclipses ever since they were first recorded early in the 19th century. Now, using data from NASA’s Spitzer Space Telescope, they’ve come up with a model that sheds new light on this 200-year-old mystery.

Don Hoard led the researchers at the California Institute of Technology, who looked at all the new data. He tells NPR’s Guy Raz that Epsilon Aurigae is actually two stars spinning around each other.

“About two eclipses ago — so in the mid-1950s, early 1960s — astronomers started to develop a picture that there must be something in this system other than just two stars orbiting each other and eclipsing each other,” Hoard says.

“The idea was formed that there’s probably a disc formed of gas and dust that surrounds one of the stars, and the reason the eclipse lasts so long is because this disc is passing in front of the other star — the brighter star in the system — and it just takes a long time to go past.”

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