Modeling has shown that the deadly outbursts of the TRAPPIST-1 star can sustain prolonged geological activity on its rocky planets, making them more suitable for life.
The appearance of our Earth and the very possibility of life on it are related to its high geological activity, which has persisted for billions of years. These processes are powered by the slow transfer of heat from the planet's core, where radioactive elements decay, to its surface. Other mechanisms are known that can create geological activity, but most of them cannot work for such a long time.
However, a new study by European astrophysicists has shown that planets in red dwarf systems can remain geologically "alive" for a long time due to the violent activity of their parent star. Article Alexander Grayver and his colleagues published in the Astrophysical Journal Letters.
The scientists turned to the famous TRAPPIST-1 system, located less than 40 light-years from the Sun. At its center is a red M-class dwarf only slightly larger than our Jupiter. At least seven rocky planets orbit the star, and in fairly tight orbits. Therefore, despite its weak brightness, some of them remain within the "habitability zone" of TRAPPIST-1 and could theoretically be suitable for life. However, this possibility also depends on how geologically active the planets are.
Another peculiarity of red dwarfs - their violent and unpredictable activity - may be of unexpected help. They now and then burst out with powerful bursts and mass ejections, which are thought to be able to destroy the atmospheres of nearby planets and sterilize their surfaces. But simulations by Graver et al. showed that the same outbursts stimulate the geological activity of the planets. Since red dwarfs are very long-lived stars, such processes can be sustained for billions of years.
Scientists attribute this to the same phenomenon that causes a conductor to heat when a current overcomes its resistance. In electronics, it is associated with ohmic energy loss, but on TRAPPIST-1 planets, this is what causes the crust to heat up.
Having calculated their "energy budget", astronomers have shown that it is enough to continuously maintain geological activity. Related volcanic activity and the influx of gases from the interior may compensate for the erosion of the atmosphere due to constant star outbursts. In addition, the same phenomena can create global magnetic fields, making the planets even more suitable for life in theory.
