A study by astronomers at the University of Florida revealed that about one-third of the planets orbiting red dwarf stars could be in the habitable zone, where conditions could be conducive to the existence of liquid water on their surfaces, making them potential candidates for harboring life.
Red dwarfs, which account for about 70% of known stars, are small, cool stars with a maximum size equivalent to half that of the Sun. Billions of planets have been observed orbiting around them.
However, these planets would need to be close enough to their stars to receive the necessary heat to be habitable. But their proximity, similar to the distance between Mercury and the Sun, exposes them to a phenomenon known as “tidal heating.”
This phenomenon occurs because of the shape of the planetary orbits. The more oval the orbit, the more eccentric it will be, which implies that the planets will experience different gravitational attractions at different points along their trajectory. This will cause excessive friction that will evaporate the liquid water on these celestial bodies.
After examining the eccentricity of 150 planets around red dwarf stars using data from NASA’s Kepler and ESA’s Gaia telescopes, the researchers determined that two-thirds of these planets had orbits too eccentric to be habitable, but one-third of them could be in the habitable zone.
In addition, it was observed that star systems with multiple planets tend to have more circular orbits, allowing them to retain liquid water. On the other hand, it is believed that stars with a single planet are more likely to be affected by extreme tidal forces, resulting in the loss of water.
The results of this study are considered of great importance for future exoplanet research, as approaches are expected to focus on this population of red dwarf stars. These stars are considered promising targets for searching for small planets in orbits where liquid water may exist and, therefore, there is potential for habitability.