The powerful magnetic field of the TRAPPIST-1 star heats the interiors of four of the seven planets in its system so much that complex life is impossible there - only three outer exoplanets can be inhabited.
Researchers from Europe and Russia have calculated the effect of the measured magnetic field of the TRAPPIST-1 star on its planets. They found that the four bodies closest to the luminary are either covered with oceans of lava, or are experiencing strong volcanic activity. This happens due to the heating of the planets by electromagnetic induction from their star - a mechanism that is absent in the solar system. A related article was published in Nature Astronomy.
On February 22, 2017, an international group of astronomers announced at a sensational press conference at NASA the discovery of a system of seven Earth-like planets near the ultracold red dwarf TRAPPIST-1, which lies only 39.5 light years away. According to scientists, all seven planets are close in size to Earth, and three of them lie in the habitable zone and may have oceans. These three planets receive from their luminary about the same amount of heat as our planet.
Schematic representation of the TRAPPIST-1 system.
The authors of the new work calculated the effect of the measured magnetic field TRAPPIST-1 (600 gauss) on the inner molten parts of the TRAPPIST-1b, c, d, and e planets. In doing so, they proceeded from the assumption that the composition of these planets is close to that of the Earth. And the deviation of the magnetic pole from the axis of rotation for a star in this system is close to 60 degrees.
It turned out that the four planets closest to the star must be seriously heated by electromagnetic induction, which works on the same principle as the earth's induction cooker. Due to changes in the magnetic field acting on the planets as they rotate relative to the star, an eddy current should arise in the mantle, heating them from the inside.
The level of heating should be such that these four bodies are either covered with oceans of lava, or are shaken by the most intense volcanic eruptions. In the latter case, their atmosphere can be oversaturated with carbon dioxide, which will lead to an increase in the greenhouse effect and overheating of the surface according to the Venus scenario. The planet TRAPPIST-1e is formally in the habitable zone, but if the authors' estimates are correct, it is practically unsuitable for complex life.
It should be noted that there are three more outer planets in the TRAPPIST-1 system, which are also in the habitable zone (the outer one - if there is a dense atmosphere). The influence of the magnetic field of the star (600 gauss) practically does not apply to these planets, since they are too far from the star. In the solar system, the magnetic field of the star is weaker, and the distance to the planets is greater than in TRAPPIST-1. Therefore, here such a mechanism plays a negligible role. Due to its absence in our system, astronomers did not even think about the fact that such a phenomenon exists and can somehow affect the planets near other stars.
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Comparison of the scales of the solar system and the TRAPPIST-1 system
The researchers note that if the planets in the TRAPPIST-1 system have normal plate tectonics, then their mantle can be cooled more efficiently than in the model they built. However, at the moment, most scientists believe that planets close to the star as much as TRAPPIST-1b, c, d and e should not have plate tectonics.
Plate tectonics is a typical surface renewal mechanism for the Earth. Light continental crust floats on the surface of a denser mantle until one plate hits another and begins to sink it with its weight. After immersion in the mantle, the old slab melts, and a new one forms over time from its lightest components rising upward. Plate tectonics is absent on other planets in the solar system, although the reasons for this are not entirely clear. There is no data yet on how common tectonics are for exoplanets. On Earth, it helps regulate the carbon dioxide in the atmosphere and thereby maintains a relatively stable climate on the planet.
IVAN ORTEGA