Research published in Astronomy and Astrophysics suggests that Jupiter isn’t all it's gassed up to be with heavy metals secreted inside its inner layer.
The planet was previously thought to have an even distribution of heavy metals in its layers due to convection – wherein the heat of the core pushes elements out to mix among the clouds over Jupiter’s lifetime.
NASA’s Juno probe, which has been in orbit since 2016, has been helping astronomers figure out what’s going on within Jupiter's interior with a suite of instruments.
One key to this research is high-precision gravity harmonics.
These advanced sensors can measure the pull of gravity that Jupiter exerts onto the Juno probe, and by using a wide range of fly-by configurations, the probe can collect data which astronomers use to piece together the particulars of Jupiter’s gravity field.
To discover the hidden source of heavy metals, the researchers used several sets of models to explain the potential structure of Jupiter and compared them to the readings from the Juno probe.
These models were as simple as a three-layer model to much more complex models containing details of outer and inner core characteristics.
On calculation, the researchers found most of the heavy metals were in the inner layer of Jupiter with much less found on the outer clouds, a non-uniform distribution that they call an ‘inhomogeneous envelope’.
The researchers also attempted to find out what the mass of the heavier elements were and tended to find variations between 11 to 30 Earth masses of heavier elements throughout their models, with Jupiter’s core thought to be made up of 7 earth masses.
Their conclusions also suggested that Jupiter, at 1 bar, could be as hot as 188K compared to previous measurements of 166K, suggesting a higher entropy closer to Jupiter’s core.
These results mean astronomers need to think twice when calculating the structure of Jupiter’s interior, and sets new expectations for any assessment of exoplanets – in particular, they may have more heavy metals in them than we think.
Findings shine new light on Jupiter’s origin
This research not only reveals some of the mystifying secrets of Jupiter’s interior, but it can also help us understand how it, and other planets like it, can form.
There have been a few theories to explain how Jupiter started ranging from the accretion of large rocky matter called the planetesimal-driven scenario and the much dustier and gassier pebble-driven scenario.
The planetesimal-driven scenario is where the space solids, from one to hundreds of kilometres in size, are drawn together due to gravity into one big clump, eventually solidifying into a planetary core.
This molten core attracts leftover gasses from the formation of the sun and, as it forms, mixes in its heavy metals.
The pebble-driven formation features tiny clumps of centimetre-large rocks that lose their speed due to a particularly dense field of gas.
The drag from the gas can help pull pebbles to a dense part of the gas cloud until it becomes its own planetesimal albeit with a much more even distribution of gas and heavier elements.
The findings from the study lend evidence to a mixed combination of these theories.
Due to the uneven distribution of heavy metals, it’s likely that Jupiter was probably formed in a planetesimal-driven scenario while it was already drawing gas.
