Decoding strange mysteries on Uranus and Neptune

One of the strangest things about Uranus and Neptune is their magnetic fields. Each of these planets has a highly active magnetosphere, eccentric and tilted off its axis of rotation in a way never seen on any other planet.

Until now, we did not fully understand why this was so. Now, a team of researchers from China and Russia helps us find a new piece of the puzzle: a truly strange, ionized form of water called aquodium that can exist deep inside at extremely high pressures. of the ice planet.

Aquodium consists of a normal water molecule with two extra protons, giving it a positive charge. When present in large enough numbers, they can create a planetary magnetic field similar to that of Uranus and Neptune.

Planetary magnetic fields extend into the space surrounding the planets that create them . However, they are created deep inside the planet by moving electrical charges, although the exact mechanism may vary.

Magnetic fields of Earth, Saturn, Jupiter, Uranus, Neptune.

On Earth, the iron-nickel alloy flows around the core, spinning, convection and conducting electricity, converting all that kinetic energy into a flow of electrons like in a giant underground generator. As for Jupiter and Saturn, scientists believe that hydrogen itself, under the enormous pressure of gravity, has become the metal that creates the magnetic field.

Earth, Jupiter and Saturn have relatively neat magnetic fields like the field of a giant bar magnet running along the planet's axis of rotation, its magnetic field lines shaped like a connected cage. north pole and south pole.

In contrast, the magnetic poles of Uranus and Neptune are tilted 59 and 47 degrees relative to their rotation axes, respectively, and the magnetic field lines are constantly varying and shifting. And they're not really focused on the planet's core like Earth and the two gas planets are.

One possible explanation is that the magnetic field could be generated by an ionic liquid , where the ions are the charge carriers rather than the liquid acting as a conduit for the electrons.

Physics and chemistry researcher Artem Oganov of the Skolkovo Institute of Science and Technology in Russia explains: 'The hydrogen surrounding Jupiter's rocky core under high pressure conditions is a form of liquid metal: It can flow, in the same way that molten iron in the bowels of the Earth flows, and its conductivity is due to the free electrons shared by all the hydrogen atoms being forced together. In Uranus, we think that itself Hydrogen ions or protons are free charge carriers'.

The question is which ion? Some, like ammonium, are obvious possibilities. But could planetary water molecules play a more important role in this process?

A team of researchers led by physicist Jingyu Hou of Nankai University (China), went back to first principles combined with models of how molecules can evolve, going deep into a concept called chemical hybridization.

This is when the orbital elements of an atom are mixed or combined to create an atom that can bond in new ways. There are many different types of hybridization, but the one relevant here is sp3 hybridization, in which the four orbitals form a tetrahedral arrangement around the central nucleus.

Show the structures of water, hydronium and aquodium molecules.

Each of the four points of the tetrahedron has a lone electron capable of bonding with another atom or a pair of electrons that cannot form bonds with other atoms.

Oxygen has two single electrons and two pairs of electrons in its outer shell. If you attach a hydrogen atom to each available valence electron, you get H ₂ O - water.

Sometimes hydrogen with no electrons – just a nucleus of 1 proton – will attach to one of the electron pairs to form a molecule called a hydronium ion.

Physicist Xiao Dong of Nankai University analyzed: 'The question is: Can you add another proton to the hydronium ion to fill the missing part? Such a configuration under normal conditions is energetically unfavorable, but our calculations show that there are two conditions that could cause it to happen.'

'First, very high pressures force matter to reduce its volume, and sharing a previously unused pair of oxygen electrons with a hydrogen ion (proton) is a neat way of doing it: just like a covalent bond with hydrogen, except that both electrons in the pair come from the oxygen atom. Second, you need a lot of available protons to create an acidic environment, because the effect of an acidic environment is to give protons."

The researchers did computational modeling and under conditions similar to those thought to exist inside Uranus and Neptune, this is what happened. At a temperature of about 3,000 degrees Celsius and a pressure of 1.5 million atmospheres, protons attach to hydronium to form H ₄ O – aquodium.

Of course, conjecture is still just theory. More detailed observations of the two outer Solar System planets will be needed to further investigate this possibility; But these findings give us a new way to understand the oddities of the blue planets Uranus and Neptune.