Jupiter has grown, devouring the embryos of the planets

In the new researchJupiter's inhomogeneous envelope / Astronomy and Astrophysics Dutch scientists were finally able to look beyond Jupiter's cloud cover using gravitational data from probes. This made it possible to map the rocky material in the planet's core, revealing a surprisingly high abundance of heavy elements. The chemistry suggests that Jupiter ate the embryonic planets (called planetesimals) to fuel its expansive growth.

The researchers built computer models of Jupiter's interior by combining data from Juno and its predecessor Galileo. The probes measured the planet's gravitational field at various points in its orbit. The data showed that the rocky material inside Jupiter has a high concentration of heavy elements, and made it possible to see exactly where it is located. The total mass of such elements is 3-9% of the mass of the planet, which is much more than previously thought.

All this points to the planetosimal origin of Jupiter: that is, it did not expand on its own, but absorbed planetesimals. If Jupiter formed naturally, the accretion (or, more simply, the accumulation) of the rocky layer would stop with the start of gas buildup, when the planet became large enough. This is because the growing layer of gas would create a pressure barrier preventing small, rocky objects from getting inside the planet.

Under such a scenario, the abundance of heavy metals on Jupiter would be significantly less than what scientists calculated. However, the planetesimals could have entered the core of Jupiter already during gas accretion: their gravitational attraction would be greater than the pressure exerted by the gas.

According to the researchers, the simultaneous accretion of gas and rocky material, which is possible due to absorption of planetesimals, is the only explanation for the high levels of heavy elements on Jupiter.