Longest-lasting solar eclipse discovered

Imagine living in a world where, every 69 years, the sun disappears in a near total eclipse that lasts for three and a half years. That is just what happens in an unnamed binary star system nearly 10,000 light years from the Earth.

Astronomers have discovered an unnamed pair of stars that sets a new record for both the longest duration stellar eclipse (3.5 years) and longest period between eclipses (69 years) in a binary system.

The newly discovered system known as TYC 2505-672-1 sets a new record for both the longest duration stellar eclipse and the longest period between eclipses in a binary system.

"It's the longest duration stellar eclipse and the longest orbit for an eclipsing binary ever found... by far," said doctoral student Joey Rodriguez from Tennessee-based Vanderbilt University.

The previous record holder was Epsilon Aurigae, a giant star that is eclipsed by its companion every 27 years for periods ranging from 640 to 730 days.

"Epsilon Aurigae is much closer -- about 2,200 light years from the Earth -- and brighter, which has allowed astronomers to study it extensively," said Rodriguez.

TYC-2505-672-1 is so distant that the amount of data the astronomers could extract from the images was limited.

However, they were able to estimate the surface temperature of the companion star and found that it is about 2,000 degrees celsius hotter than the surface of the sun.

In order to produce the 69-year interval between eclipses, the astronomers calculate that they must be orbiting at an extremely large distance -- about 20 astronomical units -- which is approximately the distance between the Sun and Uranus.

"Right now, even our most powerful telescopes can't independently resolve the two objects," said Rodriguez.

"Hopefully, technological advances will make that possible by 2080 when the next eclipse occurs," he added in a paper accepted for publication in the Astronomical Journal.

Discovery of the system's extraordinary properties was made by a team of astronomers from Vanderbilt and Harvard University with other colleagues.