New study suggests young Jupiter engulfed many planetesimals

(ORDO NEWS) — Jupiter is composed almost entirely of hydrogen and helium. The amount of each closely matches the theoretical amounts in the primordial solar nebula.

But it also contains other heavier elements that astronomers call metals. Even though metals make up a small fraction of Jupiter, their presence and distribution tell astronomers a lot.

Jupiter’s metal content and distribution means the planet ate a lot of rocky planetesimals when it was young, according to a new study. .

Since NASA’s Juno spacecraft reached Jupiter in July 2016 and began collecting detailed data, it has been reshaping our understanding of Jupiter’s formation and evolution.

One of the features of the mission is gravity. Scientific tool. It sends radio signals back and forth between Juno and the deep space network on Earth.

The process measures Jupiter’s gravitational field and tells researchers more about the planet’s composition.

When Jupiter formed, it started with a buildup of rocky material. This was followed by a period of rapid accretion of gas from the solar nebula, and many millions of years later Jupiter became the giant it is today.

But there is an important question regarding the initial period of rock accretion. Have large masses of rocks like planetesimals coalesced? Or did he build up material the size of pebbles? Depending on the answer, Jupiter formed on different time scales.

A new study aims to answer this question. It is titled “Jupiter’s Inhomogeneous Shell, Inhomogeneous Shell” and is published in the journal Astronomy and Astrophysics . The lead author is Yamila Miguel, Associate Professor of Astrophysics at the Leiden Observatory and the Netherlands Institute for Space Research.

We are getting used to great images of Jupiter thanks to the JunoCam camera of the Juno spacecraft. But what we see is only superficial. All these mesmerizing images of clouds and storms are just a thin 50 km (31 miles) outer layer of the planet’s atmosphere.

The key to Jupiter’s formation and evolution is buried deep in the planet’s atmosphere, which is tens of thousands of kilometers deep.

It is widely accepted that Jupiter is the oldest planet in the solar system. But scientists want to know how long it took to form. The authors of the article wanted to investigate metals in the planet’s atmosphere using the Juno’s Gravity Science experiment.

The presence and distribution of pebbles in the planet’s atmosphere is central to understanding Jupiter’s formation, and the Gravity Science experiment measured pebbles dissipating in the atmosphere.

Until Juno and her Gravity Science experiment, there was no accurate data on Jupiter’s gravitational harmonics.

The researchers found that Jupiter’s atmosphere is not as homogeneous as previously thought. There are more metals near the center of the planet than in other layers. In total, metals make up 11 to 30 Earth masses.

With the data in hand, the team built models of Jupiter’s internal dynamics. “In this article, we assemble the most comprehensive and diverse collection of Jupiter interior models to date and use it to study the distribution of heavy elements in the planet’s shell,” they write.

The team created two sets. models. The first set is the three-layer models, and the second is the dilute core models.

“A gas giant like Jupiter has two mechanisms for acquiring metals during its formation: by accretion of small pebbles or by larger planetesimals. said lead author Miguel.

“We know that once a small planet gets big enough, it starts throwing out pebbles. Such a wealth of metals inside Jupiter, which we see now, was impossible to achieve before.

We can exclude the scenario when only pebbles were used as solid bodies during the formation of Jupiter. The planetesimals are too big to block, so they must have played their part.”

The abundance of metals in the bowels of Jupiter decreases with distance from the center. This means that there was no convection in the deep atmosphere of the planet, which, according to scientists, was present.

“We used to think that there was convection on Jupiter, like boiling water, making it completely mixed,” Miguel said. “But our discovery shows otherwise.”

“We convincingly demonstrate that the abundance of heavy elements in the shell of Jupiter is not uniform,” the authors write in their paper.

“Our results indicate that Jupiter continued to accrete heavy elements in large quantities while its hydrogen-helium envelope grew, contrary to predictions based on the insulating mass of pebbles in its simplest incarnation, favoring instead planetosimal or more complex hybrid models.” .

The authors also concluded that Jupiter did not mix by convection after its formation, even when it was still young and hot.

The group’s results also extend to the study of gaseous exoplanets. and attempts to determine their metallicity. “Our result… represents a basic example for exoplanets: an inhomogeneous shell implies that the observed metallicity is the lower limit of the metallicity of the entire planet.”

In the case of Jupiter, it was not possible to determine its metallicity from a distance. It wasn’t until Juno arrived that scientists were able to indirectly measure the metallicity. “Therefore, metallicity derived from remote atmospheric observations of exoplanets may not reflect the overall metallicity of the planet.”

When the James Webb Space Telescope begins scientific work, one of its tasks is to measure the atmospheres of exoplanets and determine their composition. As this work shows, the data Webb provides may not reflect what is happening in the deeper layers of gas giant planets.


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