Researchers haven't determined how such a system came into being, but believe the formation involved, "a filament of gas that pushed them together in the same direction."
Simon Murphy from the Australian National University also notes, "They must not have lived their lives in a very dense environment. They are so tenuously bound together that any nearby star would have disrupted their orbit completely."
In terms of age, the pair is relatively young, likely having formed between 10 and 45 million years ago.
See photos of the solar system:
Astronomers find incredibly large, record-breaking solar system
IN SPACE - JANUARY 14: The planet Mercury is shown from a distance of approximately 17,000 miles, taken by NASA's Messenger spacecraft January 14, 2008 at the spacecraft's closest approach to planet. The image shows features as small as six miles in width. Similar to previously mapped portions of Mercury, this hemisphere appears heavily cratered. On the upper right is the giant Caloris basin, including its western portions never before seen by spacecraft. Formed by the impact of a large asteroid or comet, Caloris is one of the largest, and perhaps one of the youngest basins in the solar system. (Photo by NASA via Getty Images)
The Moon close-up on a black night sky shot through a telescope. Picture taken from the Russia, Moscow, May 4, 2012
This true-color simulated view of Jupiter is composed of 4 images taken by NASA's Cassini spacecraft on December 7, 2000. (Photo by: Universal History Archive/UIG via Getty Images)
This composite includes the four largest moons of Jupiter which are known as the Galilean satellites. Shown from left to right in order of increasing distance from Jupiter, Io is closest, followed by Europa, Ganymede, and Callisto. Galileo. (Photo by: Universal History Archive/UIG via Getty Images)
A giant of a moon appears before a giant of a planet undergoing seasonal changes in this natural color view of Titan and Saturn from NASA's Cassini spacecraft. (Photo by: Universal History Archive/UIG via Getty Images)
The sponge-like surface of Saturn's moon Hyperion is highlighted in this Cassini portrait. (Photo by: Universal History Archive/UIG via Getty Images)
The Cassini spacecraft examines the rough dark-light dichotomy of the terrain on Saturn's moon Iapetus. (Photo by: Universal History Archive/UIG via Getty Images)
NASA's Cassini spacecraft chronicles the change of seasons as it captures clouds concentrated near the equator of Saturn's largest moon, Titan. (Photo by: Universal History Archive/UIG via Getty Images)
The Cassini spacecraft looks at a brightly illuminated Enceladus and examines the surface of the leading hemisphere of this Saturnian moon. (Photo by: Universal History Archive/UIG via Getty Images)