For more than 70 years, scientists have predicted the existence of a certain type of object in the outer Solar System. Of small size, it is believed that these potential bodies constitute an important initial step in the process of formation of the planet.
Because these hypothetical objects are only 1 to 10 kilometers radius (0.6 to 6.2 miles), it is difficult to identify them from where we are. But now astronomers think they did it.
As they looked at the sky for hours, they obtained evidence of an object as small as a mile radius in the vicinity of Pluto's orbit. The find could finally be a representative of this proposed class of small objects of the Kuiper Belt.
Given their small size and obscurity, objects can not be seen directly. Then the astronomers of the National Astronomical Observatory of Japan tried another method – the concealment. This essentially means lurking and staring at a star, waiting for an object to pass in front of it and blocking out some of its light.
They chose 2,000 stars and spent a total of 60 hours observing them with the help of two small 11-inch (11-inch) telescopes.
The work was rewarded – the team found evidence of a tiny body called planetesimal orbiting the Sun at a distance of 32 astronomical units. This really puts it within the orbital range of Pluto, which is between 29 and 49 AU.
This is the first time that one of these planetesimals has been detected, the researchers said – and it is a wonderful feat considering the distances involved and the tools used.
"We have not even had enough money to build a second summit to protect our second telescope, but we have been able to make a discovery that is impossible for large projects, "said NAOJ astronomer Ko Arimatsu.
We do not know for sure how planetary formation works, but according to the current hypothesis it is a bit more or less.
After a star is born, it is surrounded by a disk of leftover dust and gas running in its orbit. Electrostatic forces begin to attach particles on this protoplanetary disk to each other, forming a cluster; As the clump becomes larger, its gravitational force increases as well, which collects more and more particles, further increasing the clump.
We have seen these disks around other stars using radio astronomy and even an image of what astronomers think is a forming planet.
Here, a little closer to home, in our Solar System, the Kuiper Belt – a large disk of rocky, icy bodies that are beyond the orbit of Neptune – is considered a remnant of our ancient Solar System. It contains larger bodies, including dwarf planets such as Pluto (2,377 kilometers or 1,477 miles) and 2014 MU69 (31 kilometers).
Because they are protected by ice and far from the radiation of the Sun, these bodies are considered capsules of time, preserving the conditions of the formation of the Solar System. And these objects between 1 and 10 kilometers are considered evidence of the point between the initial electrostatic dust aggregation and the gravitational growth of snowball.
This finding, using relatively inexpensive telescopes on a rooftop in Japan, means that these planetesimals are likely to be more abundant than previously thought – good evidence that our planetary training model is on track.
And the team is not ready yet. They are eyeing a prize far more distant.
"Now that we know our system works, we will investigate the Edgeworth-Kuiper Belt in more detail," said Arimatsu. "We are also eyeing the still undiscovered Oort Cloud in addition."
The team's research was published in the journal Astronomy of Nature.