What magnetic fields can tell us about life on other planets?

The Earth has a magnetic field – this allows the compass to align north-south and allows us to navigate the oceans. It also protects the atmosphere, and therefore life, from the powerful wind of the sun.

Whatever the case may be, what about Earth-like planets in the galaxy? Do they also have magnetic fields to ensure life goes up?

Another investigation revealed a kind of exoplanet – the super-Earth up to five times the extent of our own planet – and presumes that they probably have a magnetic field, even created in an absolutely new way: by ocean magmas planets.

The incredible discovery that the melted rock, gradually striking the molten stones, produces a powerful magnetic field also suggests that in the early years of the Earth, it was a magnetic field created by the magma. This was despite his current field, which is created in the outer center of fluid iron.

The link between the inside of a planet and its magnetic field also offers astronomers a way to deepen their knowledge of the composition and age of exoplanets too far away to be visited.

Burkhard Militzer, professor of Earth Sciences and Planets at the University of Berkeley at the University of Berkeley, said: "It is a new regime for the generation of planetary magnetic fields. Our magnetic field on Earth is generated in the outer liquid iron core. On Jupiter, it comes from the convection of liquid metallic hydrogen. On Uranus and Neptune, it is supposed to be generated in layers of ice. We have now added molten rocks to this diverse list of field-generating materials. "

"It's very far into the future, but if someone observes an exoplanet and finds a magnetic field, it may indicate that there is an ocean of magma, even if it can not be." not see him directly. "

The results may suggest chances of survival on different planets. As the magma oceans cool from above, a near surface of life could appear as the melted mantle continues to disintegrate.

François Soubiran, a former postdoctoral fellow at UC Berkeley, today at the Ecole Normale Supérieure de Lyon, said: "A magnetic field can protect a planetary atmosphere of stellar breaths. Most super-Earths that we detect now are very close to their host stars and exposed to very strong stellar winds. Thus, the possibility of a magnetic field to exist is undoubtedly a key element of the evolution of the planet and its habitability.

Internal Dynamo of the Earth

The current terrestrial magnetic field is produced in the outer center of the liquid iron, where rising and falling masses of advanced fluid iron, connected to the spin of the planet, form a dynamo and an industrious magnetic field.

Anyway, the rough Earth was melted after its underlying arrangement 4.5 billion years ago and some layers can have melted water and convection – like boiling water, just more slowly – for many years after birth. Could the progressive convective ocean magma create a magnetic field very similar to that produced in the iron core today?

The same question arose after the discovery of super-Earths around other stars. The superlands are so massive that their interior, the mantle, should remain liquid and convective for a few billion years after its formation.

Scientists had access to computer models of minerals at the atomic scale, which allowed them to calculate the conductivity, in this case, quartz (silicon dioxide), magnesia (magnesium oxide), and carbon dioxide. 39, a silicon-magnesium oxide (post-perovskite). common in the rocks on the Earth, the Moon and probably all the planets of our solar system.

After performing long figurations for all three, they found that these silicates proved to be humbly predominant when they passed from strong to liquid at high temperatures and pressures. When they connected the conductivities to models of the interior of the Earth, they found that the stones were well oriented to support a dynamo and consequently a magnetic field.

Soubiran said, "Our calculations showed that the disorganized structure of the liquid helped the electrons to become drivers. Silicates liquid at 10,000 Celsius and 10 million pressure atmosphere have for example only about one hundredth of the conductivity of liquid iron. "

"Rotating planets with a period of two days or more would generate a magnetic field similar to the Earth: a dipolar field with a clear north and south. A slower rotation, however, could create a more disorganized field that would be harder to detect from afar. "

Bruce Buffett, a Berkeley expert on the dynamics of the Earth's interior who did not participate in the research, said planets could only generate magnetic fields if they had the right balance of Electrical conductivity and fluid velocity to create the return necessary to maintain a magnetic resistance. field.

"Many geophysicists expected that, at least in terrestrial conditions, the conductivity of liquid silicates would be more in the category of good, if you had very large fluid movements to compensate for low conductivity, you could have a magnetic field, "said Buffett, a professor of earth sciences and planets.

"This is the first detailed calculation for higher temperature and pressure conditions, and it shows that the conductivity seems to be a bit higher.The fluid movements that you would need to make this work are maybe a little less extreme. . "

Scientists published their findings on Sept. 24 in Nature Communications.