Four of the seven earth-like exoplanets in the system of TRAPPIST-1 proved unsuitable for life. Astronomers came to the conclusion that the activity of volcanoes on the surface is probably too large, and the upper layer of the mantle melted and is a ocean of magma, writes N+1 with reference to Nature Astronomy.
As previously reported, earlier in the year scientists have discovered four new planets in the system TRAPPIST-1. Its main star ultracold red dwarf with a temperature of 2550 K and a mass of about 0.08 mass of the Sun. It revolves around seven earth-like planets and at least three of them are in habitable zone — the region of space where the amount of heat from the star is sufficient for the existence of liquid water on the surface.
However, scientists have repeatedly subjected the suitability of the heavenly bodies for the life of the doubt because of the activity of the star. Previously, researchers have found that the Central star system of TRAPPIST-1 is often experiencing powerful flash. Because of this, the atmosphere surrounding the planets, likely unstable, which reduces the suitability of planets for life.
In a world… 40 light years away, seven Earth-size planets orbit a sun called #TRAPPIST1—three in its habitable zone https://t.co/rGdG4ZWTai pic.twitter.com/mLmr2jHvbD
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The creators of the work also concluded that conditions on the four planets of the system TRAPPIST-1 may be suitable for the emergence of organisms.
The fact that ultracold dwarfs of late spectral class M have a powerful magnetic field, the induction of which may reach values of several kilogauss. The length of the habitable zone around these stars is less, and that means that exoplanets are in it feel a strong influence of AC magnetic field. For comparison, induction of the basic magnetic field of the Sun, not counting the area of the dark spots or prominences, achieves the value of 1 Gauss. The average power of the dipole magnetic field TRAPPIST-1 is about 600 Gauss.
The researchers built a model in which the planets of the system TRAPPIST-1 have multiple internal layers with a homogeneous conductivity. Because scientists know little about these objects today, they suggested that the composition and conductivity of the heavenly bodies must be the same as that of the Earth. The simulation showed that near the planet will experience a strong influence of the alternating magnetic field provided that the magnetic dipole is tilted at an angle of 60 degrees relative to the axis of rotation of the star (the original assumption of the model). The changing magnetic flux will create eddy currents that will heat up the inner layers of planets.
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In particular, the mantle of two neighbor planets TRAPPIST-1b, -1c, in such circumstances, was quickly transformed into the ocean of magma. According to calculations, it may occupy the entire surface and reach the border with the kernel. Two other locations, TRAPPIST -1d and -1e, should be a strong volcanic activity and emissions of carbon dioxide (CO2). At the same TRAPPIST-1e is in the potential habitable zone.
Conditions at the three outer planets, TRAPPIST-1f, -1g, -1h, should be more favorable due to the fact that they are farther away from the main star and less influenced by its magnetic field. The authors note that the study of the influence of stellar magnetic fields is important to assess the suitability of planetary systems for the origin of life. Volcanic activity and emissions of carbon dioxide, which can cause a greenhouse effect like on Venus, playing a significant role in the formation of climate.
Previously, researchers have found that the Central star system of TRAPPIST-1 is often experiencing powerful flash. Because of this, the atmosphere surrounding the planets, likely unstable, which reduces the suitability of planets for life.