The TRAPPIST-1 system can contain life-friendly planets

The TRAPPIST-1 system is located 39 light years from Earth. Its star is a relatively cool red dwarf, whose weight is about 10% of the Sun's mass. This star produces about 12% of the light energy of the Sun. Probably this system contains at least seven rocky planets. Most of them are objects the size of the Earth. Scientists studied models of the Earth's climate and simulated what each planet of the TRAPPIST-1 system could be. It turns out that all seven planets of the system are similar to the planet Venus. This means that the oceans on these planets evaporated a long time ago. All seven planets of the TRAPPIST-1 system probably have a very dense atmosphere like Venus. Only one planet, called TRAPPIST-1e, can have liquid water on its surface. It is the water that can have life similar to the one that was created on Earth.

The TRAPPIST-1e planet is quite close to the star, making its surface warm enough to keep liquid water. This is the basic prerequisite for the creation of life that we know on Earth. TRAPPIST-1e can contain significant amounts of oxygen. When water evaporates from the planet's surface, hydrogen and oxygen molecules separate. Hydrogen is very light and can easily leave the planet's atmosphere regardless of gravity. Oxygen is heavier and probably is on the surface. Research indicates that the planet TRAPPIST-1e can have a dense atmosphere built up largely from oxygen. TRAPPIST-1e probably didn't lose all its water like the others. It may be a world full of water and even covered with a global ocean. The climate of this planet can therefore be very similar to the Earth. Apart from TRAPPIST-1e, two other planets of this system lie in the zone of appropriate temperature. These planets are TRAPPIST-1d and TRAPPIST-1h, which circulates farthest from the star.

Observation of the spectrum of gases in the atmosphere of these planets has allowed scientists to better predict where to look for life. Astronomers analyze the wavelengths in the spectra to determine which gases are present on the planet. The new James Webb Space Telescope, which is due to start research in 2021 will help in observations. Besides the best planet TRAPPIST-1e, where life can exist, research suggests that TRAPPIST-1b, the nearest planet of the system is very hot. Too hot for clouds to form there as on Venus. The planets TRAPPIST-1c and d receive a little more heat than Venus and the Earth from the Sun, so they have dense atmospheres. However, the farthest planets of the system such as TRAPPIST-1f, g and h are probably covered with ice. They receive too little energy to keep the water in liquid state.