2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Astronomers have hypothesized to explain the unusually large size and relatively low density of Jupiter's core. According to the new idea, this could happen in the case of a head-on collision of a large planetary embryo with a proto-Jupiter in the early solar system, the authors write in the journal Nature.
According to modern concepts, the planets are formed from a gas and dust disk. At the early stage of the formation of the system, many solid bodies of about a kilometer in size are formed - planetesimals. Their further unification leads to the gradual appearance of ever larger embryos of planets, some of which turn into protoplanets, and then into planets.
Models of planet formation show that large quantities of relatively heavy elements must lie in the centers of all planets, despite the fact that outside these bodies may be surrounded by extended shells of gas. Moreover, such nuclei should be formed at the earliest stages, and the subsequent growth occurs almost exclusively due to the gaseous substance, in connection with which there should be extremely few metals in the outer regions.
One of the results of the work of the automatic probe "Juno", located in the orbit of Jupiter, was an accurate measurement of the gravitational potential of the giant planet. This information, in turn, made it possible to assess the composition and structure of the interior of the body. In particular, it turned out that the concentration of heavy elements is inhomogeneous in the liquid layers of hydrogen and helium located above the solid core. In this case, the total mass of elements heavier than helium approximately corresponds to a couple of tens of Earth masses (from 5 to 15 percent of the mass of Jupiter), and these substances themselves are found up to about half the radius.
Several hypotheses have been proposed to explain these features, which contradict the predictions of the simplest models. First, there could be a gradual destruction of the core and the penetration of its material into the overlying layers; however, the effectiveness of such a process is not clear. The second option assumes that hydrogen and helium were present in the core from the very beginning, although such models usually fail to reproduce a rarefied core with the required parameters.
In the work of Shang-Fei Liu from Sun Yatsen University (China) and his colleagues from Japan, Switzerland, China and the United States, a new hypothesis is proposed, which assumes a head-on collision with a large embryo of the planet in the past. According to the computer simulation carried out, the fall of a body with a mass of about ten Earths would lead to the fusion of nuclei and a significant expansion of the region with a noticeable concentration of heavy elements.
The models showed that after the impact for only about 15 hours, the interior of the proto-Jupiter will change significantly. Subsequent mixing will cause the core to "swell" from an initial about 15 percent of the radius to about half, and this effect will be long-term. In the case of oblique collisions, the required distribution of elements was not achieved.
“Models of this scenario lead to an internal structure that is compatible with a rarefied core that has persisted for billions of years,” the authors write in the article. "We assume that collisions were common in the young solar system, and that a similar event could also have happened to Saturn, which affected the structural differences of the giant planets."
Previously, scientists found indications that the embryos of the planets slowed down the growth of Jupiter, scientists also found a water cloud on the planet. More recently, an amateur astronomer filmed the fall of an asteroid on a gas giant.
