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)
This photo of Venus was taken by the Galileo spacecraft's Solid State Imaging System on February 14, 1990, at a range of almost 1.7 million miles from the planet. (AP PHOTO/NASA)
This image provided by NASA Data from six orbits of the Suomi-NPP spacecraft on April 9, 2015 have been assembled into this perspective composite of southern Africa and the surrounding oceans. Tropical Cyclone Joalane is seen over the Indian Ocean. The image was created by the Ocean Biology Processing Group at NASA's Goddard Space Flight Center in Greenbelt, Maryland. (NASA via AP)
The Moon close-up on a black night sky shot through a telescope. Picture taken from the Russia, Moscow, May 4, 2012
EMBARGOED: NOT FOR PUBLICATION BEFORE 1900GMT WEDNESDAY FEB. 16 2005: This undated photo made available in London Wednesday Feb. 16, 2005, was taken by the NASA Hubble Space Telescope of the planet Mars. Vittorio Formisano, of the Institute of Physics and Interplanetary Science in Rome, claims there is a lot more methane on Mars than previously thought which leads him to believe there must be life on the Red Planet.(AP Photo/NASA Hubble Space Telescope, ho)
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)
This image made available by NASA on Friday, July 24, 2015 shows Pluto made by combining several images from two cameras on the New Horizons spacecraft. The images were taken when the spacecraft was 280,000 miles (450,000 kilometers) away from Pluto. (NASA/JHUAPL/SwRI via AP)