Exoplanet Trappist-1e is destroying its own atmosphere։ Why is this bad news for humanity?

February 29, 2024  22:31

Scientists have discovered that the atmosphere of the potentially habitable planet Trappist-1e is disintegrating, a process that could eventually render Trappist-1e unsuitable for life. It has also been found that atmospheric decay is caused by electrical currents created as the planet orbits its red dwarf star. The study was published in the Astrophysical Journal.

This is a significant discovery because the Trappist-1 system, where this exoplanet orbits a small red dwarf star, has been one of the main targets for the search for life or the possible survival of life on other planets. At least three of the seven rocky Earth-like planets in this system are in the habitable zone, a region around a star that is neither too hot nor too cold; this would create favorable conditions for the preservation of liquid water, which is vital for the survival of life.

A planet without an atmosphere cannot sustain liquid water even if it is in the habitable zone. This suggests that while Trappist-1e may be a red dwarf in Trappist-1's habitable zone, which is 40 light-years away from Earth, its habitability may be transient. The same phenomenon affecting the atmosphere of Trappist-1e could also affect the atmospheres of other planets in this habitable zone, which is bad news for the possibility of finding life in this system.

Trappist-1e is about the size of Earth, but has a mass of about 0.7 times that of our planet. It makes one complete revolution around its star in 6.1 Earth days, and the distance between it and its star is only 0.028 times the distance between the large Earth and the Sun.

Because Trappist-1 is much smaller and cooler than the sun, its habitable zone is much closer to its surface compared to the sun's habitable zone. Therefore, it is not the radiation emitted by this red dwarf that destroys TRAPPIST-1e's atmosphere, but the wind of charged particles coming from the star, called the "stellar wind".

"We watched how the space weather changes around the planet's orbit as TRAPPIST-1e passes very quickly through very different conditions and pressures in the stellar wind, which causes a kind of pulsing compression and relaxation of the planet's magnetic field. This drives strong electrical currents in the upper atmosphere, the ionosphere, which heats the atmosphere like an electric heater,” astrophysicist Cecilia Garraffo of the Harvard & Smithsonian Center for Astrophysics told Space.com.  

Garraffo explained that Earth is also subject to fluctuations in the solar wind that cause similar heating of our planet's atmosphere. The difference is that the heating experienced by TRAPPIST-1e is up to 100,000 times stronger than what Earth experiences under the solar wind. It's just that Trappist-1e is moving much faster around its star, and the motion creates powerful ionospheric currents that dissipate and create extreme heating.

"It could be so strong for TRAPPIST-1e that the heat would essentially vaporize the upper atmosphere," Garraffo said. "Over millions of years, the planet could completely lose its atmosphere because of this phenomenon." 

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