A dwarf planet discovered in a “no-man’s land” in deep space may have been tossed there when the solar system was born, according to scientists who say the finding may help them reconstruct an event that occured 4 billion years ago.
The object, whose diameter is one-eighth that of the moon, was observed by researchers beyond the Kuiper belt, a region of space formed by floating, icy chunks that lies past Neptune, still considered the furthest large planet from the sun.
Scientists used to believe the region was empty, a “no-man’s land,” said Scott Sheppard, a researcher at the Carnegie Institution for Science in Washington and a study author. The discovery in 2003 of a dwarf planet scientists named Sedna started a hunt for other objects. The latest finding, published yesterday in the journal Nature, hints more may exist there.
“Effectively frozen in place and untouched as the solar system evolved to its present state,” the dwarf planets “preserve the dynamical signature of whatever event scattered these bodies to such distances,” wrote Megan Schwamb, at the Institute of Astronomy and Astrophysics at Academia Sinica in Taipei, in an accompanying editorial.
In doing so, she said, they act as “fingerprints at a crime scene,” allowing scientists to test their theories on the formation of the sun and planets.
The new dwarf planet has been nicknamed “Biden” by its discoverers because its full name, 2012 VP113, is too much of a mouthful, Sheppard said. The rules of the International Astronomical Union prevent researchers from naming objects in space after politicians, so they are considering a name from Eskimo mythology because the planet is extremely cold, he said.
It has taken 10 years to find the latest dwarf planet because scientists need powerful telescopes to detect planets so far out. Sedna is 76 astronomical units from the sun, which means it’s 76 times the distance from the earth to the sun. VP113, which is smaller and dimmer, is even further out at 80 astronomical units.
Sheppard and lead author Chad Trujillo, a researcher at the Gemini Observatory in Hilo, Hawaii, used a new camera installed in 2012 at the Cerro Tololo Inter-American Observatory in La Serena, Chile, to make their discovery.
They are now scanning the skies for more objects in the inner Oort cloud, the region behind the Kuiper belt, and hope to find 10 or more, Trujillo said. Then, the scientists plan to use their findings to reconstruct the birth of the solar system, based on the objects’ orbits and movements.
If scientists can determine how the two dwarf planets got there, “we can trace back our sun’s formation history,” Sheppard said in a telephone interview. “They had to be tossed out there or brought out there.”
Current theories include a “rogue planet” being pushed out of the evolving solar system in its early days, pulling smaller pieces out with it, he said. Another theory proposes that a star passing close to our sun may have dragged the dwarf planets out into the inner Oort cloud.
Sheppard and Trujillo are not pausing too long to celebrate their finding of VP113. They are back at the telescope, looking for more objects. The more they find, the more evidence they will have to help them test their hypotheses. The team has already identified a few more potential object candidates, Sheppard said.
Michael Brown, a professor at the California Institute of Technology and the lead researcher who found Sedna in 2003, has also been searching for the past decade for other objects in the inner Oort cloud.
“I’m thrilled they finally found one of these things,” he said in a telephone interview, though he said he was disappointed his team didn’t get there first. “I’ve been working pretty hard for the past decade, and we’ve covered more sky than they have.”
Brown predicted that researchers will find a dozen more objects in the next two years, helped by the latest technology.
Sheppard had the same thought. “This is just the tip of the iceberg,” he said. “We’re going to find a lot more.”
The study added to recent discoveries that may help scientists reconstruct earlier events in the universe. On March 18, a team from institutions including Harvard-Smithsonian Center for Astrophysics and Stanford University said they found ripples in ancient light that provide evidence for the Big Bang.