A dwarf planet recently discovered at the far edge of our solar system adds evidence for the existence of a much larger body, possibly 10 times the size of Earth, orbiting far from the sun but still in our solar system.
If astronomers can track it down, we could become a nine-planet solar system once again.
The planet is theoretical for now, inferred from the influence it seems to have on this new dwarf planet and others in its vicinity.
Its discovery is good news for the Tucson-based National Optical Astronomy Observatory, whose newly retrofitted 4-meter Blanco Telescope in Chile was used to find the newest member of our solar system.
NOAO astronomers did not take part in the discovery, which was published in the journal Nature Wednesday by astronomers Scott Sheppard of the Carnegie Institution for Science and Chad Trujillo of Gemini Observatory.
They report the detection and verification of a dwarf planet about 280 miles in diameter provisionally named 2012VP113 and jokingly called “Biden” because of its “VP” initials.
It is the farthest orbiting object ever detected, beating out Sedna, found in 2003 by a team led by Mike Brown of Caltech, which included Trujillo.
“Biden” was located in a region known as the inner Oort Cloud, far from the sun — this object is 80 times farther from the sun than the Earth is — and that’s at its closest point.
It then goes on a long, elliptical orbit out to 266 times Earth’s distance from the sun.
Sheppard called the orbit of “Biden” “very stable, but eccentric.”
What’s most interesting to the astronomers is that previously found objects and some they have since discovered are equally eccentric.
They point to the influence of a giant planet that perturbed the orbits of the objects being found and then either flew off into space — or is still hiding out there somewhere.
“The evidence for it is circumstantial,” Sheppard said in a phone interview from Chile, where he is observing again on the Blanco DECam at the Cerro Tololo International Observatory.
“We’re continuing the story,” he said. “We have several new candidates that we’re following up.”
The objects are very far away and very faint, he said, which is why they are so difficult to detect.
The DECam instrument was built by a collaboration of universities and national laboratories in the United States, United Kingdom and Spain, known as the Dark Energy Survey.
Light falling on the telescope’s 4-meter (13-foot) mirror is captured on a 570-megapixel camera with a 3-square degree field of view, equivalent to an area of the sky 20 times the size of the moon as seen from Earth.
It was built to survey the cosmos for the secrets of dark energy, but two-thirds of its time is allocated by NOAO to proposals from the astronomical community.
Astronomers have suspected, since Sedna was detected in 2003, that other objects orbit the sun at that great distance, but few survey cameras have the resolving power or wide field of DECam.
Astronomer Dave Jewitt, who made early discoveries of objects in the much closer Kuiper Belt where Pluto is located, said the failure to previously detect this and other objects reflects slow progress on building large survey telescopes.
Jewitt, who was a mentor to both Trujillo and Sheppard, said he is most intrigued by what the orbits suggest.
It could mean a massive planet, or it could mean we have to rethink our notions of planet formation, he said.