The interiors of the planets of the TRAPPIST-1 system could be affected by solar flares

In a recent study published in the Astrophysical Journal LettersAn international team of researchers led by the University of Cologne in Germany examined how solar flares triggered by the star TRAPPIST-1 might affect the interior heating of its orbiting exoplanets.

This study has the potential to help us better understand how solar flares affect planetary evolution. The TRAPPIST-1 system is an exoplanetary system located approximately 39 light-years from Earth with at least seven potentially rocky exoplanets orbiting a star that is 12 times less massive than our own sun. From the mother star is much smaller than our own sun, so the planetary orbits within the TRAPPIST-1 system are also much smaller than our own solar system. So how can this study help us better understand the potential habitability of planets in the TRAPPIST-1 system?

“If we take Earth as the starting point, geological activity has shaped the entire surface of the planet, and geological activity is ultimately driven by planetary cooling,” said Dr. Dan Bower, a geophysicist at the Center for Space and Habitability at the University of Bern, and co-author of study it

“Earth has radioactive elements within it that generate heat and allow geological processes to persist beyond 4.5 Gyr. However, the question arises as to whether all planets require radioactive elements to drive geological processes that can establish a habitable surface environment that allows the evolution of life. Although some other processes can generate heat within a planet, they are often short-lived or require special circumstances, which would promote the hypothesis that geological activity (and habitable environments?) are possibly rare.”

What makes this study intriguing is that TRAPPIST-1 is known as an M-type star, which is much smaller than our sun and emits much less solar radiation.

“M (red dwarf) stars are the most common type of star in our stellar neighborhood, and TRAPPIST-1 has attracted significant attention since it was discovered to be orbited by seven Earth-size planets,” explained Dr. Bower.

“In our study, we investigated how TRAPPIST-1 stellar flares affected the interior heat budget of orbiting planets and found that, particularly for planets closest to the star, interior heating due to ohmic dissipation of the eruptions is significant and can drive geologic activity, and the process is long-lived and can persist over geologic timescales, potentially allowing the surface environment to evolve toward a habitable state or go through a series destructive, for example, by stripping away the protective atmosphere that envelops a planet. Our results present a different perspective, showing how flares may actually promote the establishment of a habitable environment near the surface.”

Ohmic dissipation, also known as ohmic loss, is defined as “a loss of electrical energy due to conversion to heat when a current flows through a resistance.” Essentially, it’s what scientists used to calculate the amount of heat a planet loses, also known as planetary cooling, that all terrestrial planetary bodies, including Earth, encounter.

The study’s findings indicate that the planetary cooling occurring on the TRAPPIST-1 planets is sufficient to drive geological activity, which would lead to thicker atmospheres. The researchers’ models also predict that the presence of a planetary magnetic field may enhance these warming outcomes.

NASA’s James Webb Space Telescope recently made its first observations of the TRAPPIST-1 system and found that one of the planets in its system has a low probability of possessing a hydrogen atmosphere like the gas planets in our own solar system. This could indicate that at least one of the TRAPPIST-1 planets could possess a more terrestrial atmosphere like Earth, Mars, and Venus. Since TRAPPIST-1 has potential for the field of astrobiology, what follow-up research is planned for this study?

“There are two obvious paths to take,” explains Dr. Bower. “First, our stellar neighborhood is dominated by M stars, so observing campaigns can assess the nature of the flares of many more M stars than TRAPPIST-1. Second, the improved characterization of the TRAPPIST planetary system through “This will allow us to refine our model in terms of whether the planets have an iron core and whether they have a large Earth-like mantle of silicate.”

“We plan to run more elaborate physical simulations to better understand the effect of intrinsic magnetic fields,” said Dr. Alexander Grayver, leader of Heisenberg’s junior research group at the University of Cologne and lead author of the study. “The long-term goal is to couple our model with models of formation and erosion of the atmosphere.”