Melts metal in space

Magnetic induction melts planets

Supposedly Earth-like planets around dwarf stars like TRAPPIST-1 may be affected by extreme volcanism and form magma oceans on the surface. This is indicated by the analysis of a research team from Austria, Germany and Russia. According to this, the magnetic field of the central star could heat the planet by induction so that its mantle melts. Thus, despite its location in the star's friendly zone, such a planet would probably not be suitable for the creation of life, according to the scientists in the journal "Nature".

Rock planets of dwarf stars are particularly in the sights of astronomers in their search for life outside of our solar system. "Dwarf stars with small mass are particularly common in the cosmos and are often orbited by easily identifiable rock planets," write Kristina Kislyakova from the University of Vienna and her colleagues. Many of these rocky planets orbit within the life-friendly zone - defined as the area in which liquid water is possible on the surface. In addition, due to the low mass of the dwarf stars, the life-friendly zone is much closer to the star than to our sun, for example. However, dwarf stars often have strong magnetic fields that lead to violent bursts of radiation and thus affect the conditions for the creation of life on such planets as well as the bound rotation due to the narrow orbits. Because the planets often always assign the same side to their star, which would lead to extreme conditions in a possible atmosphere.

Kislyakova and her colleagues are now showing another effect that could affect the creation of life on such planets: magnetic induction. As an example, the researchers choose the planetary system around TRAPPIST-1. The central star, about forty light-years away, is orbited by at least seven planets, three of which may be in the livable zone. Analysis by Kislyakova and her team shows that magnetic induction could heat these planets to the point where their mantle melts. Extreme volcanism and the formation of magma oceans on the surface would be the result.

However, the prerequisite for this scenario is that the magnetic axis of the star is inclined to its axis of rotation. Only then does the magnetic field fluctuate in the area of ​​the planets, which induces heating currents. "There are a number of observations that indicate such a tilt of the magnetic field in dwarf stars," explains Kislyakova. However, so far these have only been measurements on a few objects. Even with TRAPPIST-1, the exact position of the magnetic field is not yet known. Only systematic studies of the magnetic fields of dwarf stars can show whether magnetic induction plays an important role for their planets.