in a recent study published in The letters of the astrophysical journal, an 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 in orbit around a star that is 12 times less massive than our own Sun. Since the parent star is much smaller than our own Sun , 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 our starting point, geologic activity has shaped the entire surface of the planet, and geologic activity is ultimately driven by planetary cooling,” said Dr. Dan Bower, a geophysicist at the Center for Space and Livability at the University of Bern, and co-author of the study. “The Earth has radioactive elements in its interior 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 life to evolve. 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 a M-type starwhich 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 balance of orbiting planets and found that, particularly for planets closest to the star, interior heating due to ohmic dissipation of eruptions is significant and may drive geological activity. . Furthermore, 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 of habitable states. Previously, the influence of stellar flares on habitability was seen as primarily destructive, for example, by stripping away the protective atmosphere that envelops a planet. Our results present a different perspective, showing how flares can 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, aka planetary coolingthat 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 researcher’s models also predict that the presence of a planetary magnetic field can enhance these warming outcomes.
Recently, NASA’s James Webb Space Telescope made its first observations of the TRAPPIST-1 system, finding that one of the planets in their 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 from many more M stars than TRAPPIST-1. Second, improved characterization of the TRAPPIST planetary system through observations and modeling will improve our understanding of planetary interiors. This will allow us to refine our model in terms of whether the planets have an iron core and whether they have a large silicate mantle similar to Earth’s.”
Do any of the TRAPPIST-1 planets contain the ingredients for life as we know it, or perhaps as we don’t know it? Only time will tell, and that is why we are scientists!
As always, keep up the science and keep looking up!