Astronomers Discover Third-Closest Star System

A newly discovered binary brown dwarf is the third-closest star system to our Solar System, and the closest system discovered since 1916.

An artist's conception of the binary system WISE 1049-5319 with the Sun in the background (Janella Williams / Penn State University)

An artist’s conception of the binary system WISE 1049-5319 with the Sun in the background (Janella Williams / Penn State University)

“The distance to this brown dwarf pair is 6.5 light years – so close that Earth’s television transmissions from 2006 are now arriving there,” said Prof Kevin Luhman of Penn State University, author of a paper reporting the discovery accepted for publication in the Astrophysical Journal Letters (arXiv.org version).

The star system, labeled WISE 1049-5319, was discovered in a map obtained by NASA’s Wide-field Infrared Survey Explorer (WISE).

WISE 1049-5319 is only slightly farther away than the second-closest star, Barnard’s star, which was discovered 6.0 light years from the Sun in 1916. The closest star system consists of Alpha Centauri, found to be a neighbor of the Sun in 1839 at 4.4 light years, and the fainter Proxima Centauri, discovered to be a neighbor in 1917 at 4.2 light years.

“It will be an excellent hunting ground for planets because it is very close to Earth, which makes it a lot easier to see any planets orbiting either of the brown dwarfs,” Prof Luhman said.

“One major goal when proposing WISE was to find the closest stars to the Sun. WISE 1049-5319 is by far the closest star found to date using the WISE data, and the close-up views of this binary system we can get with big telescopes like Gemini and the future James Webb Space Telescope will tell us a lot about the low mass stars known as brown dwarfs,” said Dr Edward Wright, the principal investigator for the WISE satellite.

Astronomers have long speculated about the possible presence of a distant, dim object orbiting the Sun, which is sometimes called Nemesis.

However, Prof Luhman has concluded, “we can rule out that the new brown dwarf system is such an object because it is moving across the sky much too fast to be in orbit around the Sun.”

Left: WISE 1049-5319 is at the center of the larger image taken by WISE, the inset shows sharper image from Gemini Observatory (NASA / JPL / Gemini Observatory / AURA /NSF). Right: this diagram illustrates the locations of the star systems that are closest to the Sun (Janella Williams / Penn State University)

Left: WISE 1049-5319 is at the center of the larger image taken by WISE, the inset shows sharper image from Gemini Observatory (NASA / JPL / Gemini Observatory / AURA /NSF). Right: this diagram illustrates the locations of the star systems that are closest to the Sun (Janella Williams / Penn State University)

To discover the new star system, Prof Luhman studied the images of the sky that the WISE satellite had obtained during a 13-month period ending in 2011. During its mission, WISE observed each point in the sky 2 to 3 times.

“In these time-lapse images, I was able to tell that this system was moving very quickly across the sky – which was a big clue that it was probably very close to our Solar System,” Prof Luhman explained.

“It was a lot of detective work,” Prof Luhman added. “There are billions of infrared points of light across the sky, and the mystery is which one – if any of them – could be a star that is very close to our Solar System.”

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Bibliographic information: K. L. Luhman. 2013. Discovery of a Binary Brown Dwarf at 2 Parsecs from the Sun. Astrophysical Journal Letters, in press; arXiv: 1303.2401