How gas giants were formed and whether Planet Nine exists - trying to answer these questions
What is the new study about?
According to the authors, this study will helpunderstand how planets like Earth formed. And his findings also hint that there is a fifth gas giant, which is hidden at a distance of 80.5 billion km from our planet.
How do scientists explore planets?
Stars emerge from huge swirling cloudsspace gas and dust. After our Sun lit up, the early solar system was still filled with a primordial gaseous disk that played an important role in the formation and evolution of planets, including the gas giants.
At the end of the 20th century, scientists believed that the gas giants Jupiter and Saturn originally revolved around the Sun in smooth, small orbits. But it was not clear why the orbits had this particular shape.
In 2005, an international team of scientistsoffered an answer to this question: they developed the Nice model. According to her, there was instability between these planets - a chaotic set of gravitational interactions, as a result of which such orbits were formed.
The Nice model is still relevanttheory, but over the past 17 years, scientists have new questions. For example, the gas giant's instability was originally thought to have occurred hundreds of millions of years after the scattering of the primordial gaseous disk that gave birth to the solar system. But there is new evidence that it happened earlier. It also raises new questions about how the inner solar system, which contains the Earth, evolved.
What did the authors of the new work decide to do?
The authors of the new work previously suggested thatgas giants in the solar system have such smooth orbits because the primordial gas disk evaporated. This could explain why the planets spread out into orbits much sooner than the Nice model originally suggested, and perhaps even without the instability that pushed them there.
“We came up with the idea that giant planets,Perhaps they could move and spread due to the «rebound» effect. as the disk dissipates. They may never have been unstable,” said Sean Raymond of the University of Bordeaux in France. Next, the authors first proposed the idea of the “bounce” effect and created a simulation for it of all gaseous disks and large exoplanets.
“The situation in our solar system is a little different,because Jupiter, Saturn, Uranus and Neptune are located in wider orbits, said Beibei Liu, a researcher at Zhejiang University in China. “We realized that this phenomenon could be explained if the gas disk dispersed from the inside out.”
The team found that this inside-out dispersion was a natural cause of instability in the Nice model. As a result, the authors were convinced of the relevance of the Nice model.
How did the authors change the established model?
The situation that was at the beginning of instability, inThe authors' model looks the same. It still contains the nascent Sun, surrounded by a cloud of gas and dust. And several young gas giants that orbit the star in this cloud.
Researchers note that all solar systemsformed in a disk of gas and dust. This is a natural byproduct of how stars form. But when the Sun flared up, it began burning its nuclear fuel and generating sunlight, heating the disk and blowing it out from the inside.
This created a growing hole in the gas cloud aroundSun. As the hole grew, its edge passed through the orbits of each of the gas giants. According to the team's computer simulations, this transition with a very high probability led to the very instability of the giant planet. The process of moving these large planets into their current orbits is also earlier than the original Nice model timeline of hundreds of millions of years.
“Instability occurs earlier, when the Sun's gaseous disk dissipates. It should occur from a few million years to 10 million years after the birth of the solar system,” Liu said.
The new model also leads to mixingmaterial from the outer and inner solar systems. The geochemistry of the Earth suggests that such mixing must have occurred while our planet was still in the process of formation.
“This process will really stir up the innerthe solar system, and the Earth may come just from it, - said Jacobson - this is quite consistent with the observations. According to the team, their next goal is to study the connection between instability and the formation of the Earth.
How did the undiscovered planet come about?
Jacobson said their work addresses one of the most popular questions about our solar system: how many planets are there. Currently the answer is eight.
The authors note that the Nice model worked a littlebetter, given that there were five gas giants in the early solar system instead of four. This is a hint at Planet Nine, which scientists have been actively arguing about in recent years. According to the model, this extra planet was ejected from our solar system during instability.
But in 2015, researchers at the CaliforniaInstitute of Technology have found evidence that an undiscovered planet may still exist in the outskirts of the solar system, about 80.5 billion km from the Sun.
There is still no concrete evidence thatthis hypothetical planet—nicknamed Planet X or Planet Nine—or the additional planet from the Nice model actually exists. However, all of these objects may be the same thing.
Jacobson and colleagues weren't able to answer this question directly with their simulations, but they're going to test whether their model performs better for four or five gas giants.
In any case, humanity should soon receivethe answer to this question. The Vera Rubin Observatory, scheduled to be operational by the end of 2023, should detect Planet Nine if it exists. The instrument is planned to study weak microlensing in deep space, as well as small bodies in the Solar System.
Astronomers carried out calculations that showed thatThe telescope will be able to detect at least several such flares per year. In this case, scientists will be able to confirm that Planet Nine is a black hole, and further determine its orbital parameters.
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