New research suggests that billions of years ago, Pluto captured its largest moon, Charon, with a very brief icy “kiss”. The theory could explain how a dwarf planet (yes, we wish Pluto was still a planet) could bind a moon about half its size.
The team behind this research believes that there are two frozen worlds Kuiper Belta ring of icy bodies located at the edge far from the sun solar systemthey collided together billions of years ago. Instead of canceling each other out, the two bodies came together as a spinning “cosmic snowman.” These bodies separated relatively quickly, but remained orbitally bound to form Pluto/Charon the system we see today.
This “kiss and capture” process represents a new theory of lunar capture and cosmic collision. It could also help scientists better investigate the structural strength of icy, icy worlds in the Kuiper Belt.
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“We found that if we assume that Pluto and Charon are bodies with material force, Pluto can capture Charon. huge impact“team leader and University of Arizona lunar and planetary researcher Adeene Denton told Space.com. “The process of this collision capture is called a ‘kiss and capture’ because Pluto and Charon briefly come together, the ‘kiss’ element, before separating. to form two independent bodies.”
most of planetary collision scenarios They are classified as “Hit and Run” or “graze and merge”, meaning this “kiss and catch” scenario is completely new.
“It was us without a doubt surprised by the ‘kiss’ part of the kiss-and-catch,” Denton continued. “There was no kind of impact where the two bodies temporarily join before separating again!”
The team’s research was published in the journal Monday (January 6). Nature Geoscience.
Pluto won over Charon with a 10-hour kiss
The reason Pluto’s relationship with Charon has been so challenging for scientists is because of the relatively small difference in size and mass between the two icy bodies.
“Charon is HUGE to Pluto until they’re actually a binary,” Denton explained. “It is half the size of Pluto and 12% its mass, making it more similar to Earth’s moon than any other moon in the Solar System.”
For comparison, our moon is only a quarter the size of Earth, while the largest moon in the solar system is Ganymedeis about 1/28 the size of its parent planet, Jupiter.
The University of Arizona researcher, who is also a NASA postdoctoral fellow, added that it is difficult to get such a relatively large moon in a “normal” way. (The gravitational capture of moons like “Normal”. Mars’ the moons Phobos and Deimos and the moons of the giant planets Jupiter and Saturn.)
This means that the prevailing theory about the formation of the Pluto and Charon systems is based on the idea of impact capture, where a massive body is thought to have crashed into Earth to throw material. our planet was captured to give birth to our moon.
“Something big hits Pluto, and you get Charon, but like Earth-moon systemwe don’t fully know how it works and under what conditions,” Denton said. “It’s a pretty big question because some large Kuiper Belt Objects also have large moons, so it looks like this is something. It happens with some frequency in the Kuiper Belt, but we don’t know how or why.’
A screenshot shows the Pluto/Charon system in its bound “snowman” phase.
Robert Melikyan and Adeene Denton
In a standard “collision capture”, a massive collision occurs, and both bodies are stretched and deformed in a fluid-like manner. This process well explains the formation of the Earth/moon system, because the intense heat generated by the collision and the greater mass of the bodies involved cause them to act fluidly.
When considering Pluto and Charon collisions in a capture process, there is an additional factor to consider: the structural strength of colder bodies of ice and rock. This is something that has been overlooked in the past when researchers considered the collisional formation of Charon.
To account for this in the simulations, the team played University of Arizona High Performance Computing Cluster. When Denton and colleagues considered the strength of these materials in their simulation, something completely unexpected emerged.
“Because both bodies have a material force, Charon did not penetrate deep enough to merge with Pluto, which is not true when the bodies are fluid,” Denton explained. “For the same impact conditions, if we assume that Pluto and Charon are unforced, they merge into a large body, and Charon is absorbed. With forces, however, Pluto and Charon remain structurally intact during their brief merger.”
Because Charon was unable to sink into Pluto in this scenario, it remained beyond the so-called “radius of co-rotation” of the two bodies. As a result, it could not rotate as fast as Pluto, which meant that the two bodies could not be joined. When this icy kiss and separation was over, the team believes that Pluto would have torqued Charon into a closer, higher circular orbit that would have pushed the moon out.
“In this kiss and capture ‘kiss’, the merger is very short, geologically speaking, lasting 10 to 15 hours before the two bodies separate again,” Denton said. “Charon then begins its slow outward migration toward its present position.”
The team believes that the initial collision occurred very early in the history of the solar system, probably tens of millions of years after the formation of the solar system, which would have been billions of years ago.
“The most common large collisions are direct mergers, where the bodies either combine or the two bodies remain independent,” Denton said. “So this was very new to us. It also raised a lot of interesting geological questions that we’d like to test, because the kiss-and-grab jobs depend on Pluto’s thermal state, which we can then relate to Pluto’s contemporary geology to test.
“I would really like to determine whether and how the initial impact of Pluto-Charon could affect Pluto and Charon develop the oceans”.
As Denton explains, the team can follow two paths to build on this development.
“The first is looking at how it applies to other large Kuiper Belt objects with large moons, like Eris and Dysnomia, Orcus and Vanth and others,” Denton explained. “Our initial analysis suggests that kiss-and-capture may also be the source of these other systems, but since they all differ in composition and mass, it is essential to know how kiss-and-capture may have worked throughout the Kuiper Belt.”
The second way the team wants to follow is to study the evolution of Charon’s long-term tides, in order to confirm its theory of formation.
“To be really sure that this is the process that formed Pluto and Charon, we need to make sure that Charon migrates to its current location 8 times the width of Pluto,” Denton said. “However, this is a process that occurs on much longer time scales than the initial collisions, so our models are not suitable for tracking.
“In the future we plan to study it much more deeply to determine the conditions that reproduce Pluto and Charon as bodies, as well as to put Charon in the right place, where it is today.”
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