Jupiter may have grown up on a diet of infant planets, study suggests

Jupiter seen by NASA’s Voyager 1 spacecraft in 1979 (NASA)

In ancient mythology, it is Saturn that devours his children. But in reality, it turns out that Jupiter is the one eating baby planets.

In a new article published in the journal icaroresearchers analyzing data from NASA’s Juno mission realized that Jupiter’s core is more massive than some previous models of the gas giant’s formation would have predicted.

One possible explanation is that Jupiter consumed planetesimals – baby planets – at some point in the past, turning these potential planets into a center of mass that attracted the rest of the material that formed the large planet.

Jupiter is the largest planet in the Solar System, containing twice the mass of all other planets combined, having sucked in most of the hydrogen gas left over from the formation of the Sun.

This abundant hydrogen makes up most of the giant planet’s vast atmosphere and, at greater depths, is liquefied by pressure into a vast ocean of electrically conductive liquid metallic hydrogen, the source of Jupiter’s gigantic magnetic field.

Some theories of Jupiter’s formation hold that the planet condensed out of a vessel of gas cloud, with parts of the cloud rotating tighter and growing in mass until they collapsed in on themselves; somewhat of the way stars form, but without becoming massive enough to trigger a thermonuclear reaction and become a tiny star. Other theories hold that collisions of small icy space rocks may have formed a tiny seed of rock mass around which Jupiter as we know it coalesced.

But it is not known for sure whether a small rocky core is at the heart of Jupiter or has a more “diffuse” core of heavy elements diluted by hydrogen and helium. As the researchers write in the new paper, “There is no single solution to Jupiter’s internal structure, and more than one density profile can satisfy all observational constraints.”

Much of what scientists know about Jupiter’s interior comes from gravitational measurements made by NASA’s Juno spacecraft, which has been orbiting and studying the gas giant since 2016.

It was through analyzing Juno’s data that the researchers found an anomaly: Previous models suggested that Jupiter’s core, whatever it is, accounts for about 10% of the planet’s mass. But in their new models using Juno’s data, the researchers found that this region accounts for 30% or more of the planet’s mass, implying a greater-than-expected amount of elements heavier than hydrogen and helium.

Several scenarios could explain the new model, but the researchers decide which one they consider most likely: Instead of growing from the clumping of small space rocks, Jupiter’s initial growth could have been fueled by collisions between much larger planetesimals. This would explain the heavier elements found in Jupiter’s core, but could also have big implications for how we understand the formation of planets around our Sun and other stars.

Scientists know that Jupiter’s gravity has affected the formation and orbits of other planets, and that large, early-forming gas giants in other star systems can exert a similar influence.

But if the gas giants must also devour the planetesimals that could, if they survived, one day transform into rocky planets like Earth, these gas giants could have even more influence on the formation of other planets – and life as we know it – than than before. thought.

There are other, albeit less possible, explanations for Jupiter’s heavy center, the researchers note in the paper, including a giant impact from a large rocky body sometime during Jupiter’s early years.

Knowing for sure will require “future high-resolution observations of planet-forming regions around other stars, from the observed and modeled architectures of extrasolar systems with giant planets and future data from Juno obtained during its extended mission,” they write. they.

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