Astronomers have spotted an intriguing cluster of objects in the Kuiper belt, the enormous, donut-shaped region of icy objects beyond the orbit of Neptune.
As New Scientist reports, it’s the second distant structure to have been observed in the far reaches of the solar system. In 2011, researchers discovered a “kernel” of well over 100 Kuiper belt objects at 44 astronomical units from the Sun, or 44 times the distance between the Sun and Earth.
This latest “inner kernel” was identified by a team led by Princeton University astrophysicist Amir Siraj, as detailed in a yet-to-be-peer-reviewed paper.
The team analyzed the orbital data of 1,650 Kuiper belt objects and trained an algorithm to identify any clustering.
“The kernel was never found alone — whenever the algorithm found the kernel, it found another group as well,” Siraj told New Scientist.
The inner kernel, as its name suggests, is only slightly closer to us than the originally identified kernel, at 43 astronomical units from the Sun.
“It is yet unclear whether the inner kernel is an extension of the kernel or a distinct structure,” the paper reads.
The inner kernel’s objects’ orbits are unusually in line with the solar system’s plane. Many objects found in the vicinity orbit our star at a more eccentric plane, at times tilted by tens of degrees.
“That kind of orbital calmness is a signal of a very old, undisturbed structure — the kind of structure that can provide clues to the evolution of the solar system, how the giant planets have moved in their orbits, what kind of interstellar environments the solar system has been through, all sorts of things about the early days of the solar system,” Siraj told New Scientist.
The discovery could allow us to better understand how Neptune migrated from the inner solar system to its current location billions of years ago. Experts believe the planet’s outward movement caused Kuiper belt objects to temporarily be caught by Neptune’s gravitational pull, causing them to clump together.
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