Astronomers from the University of California Irvine have discovered that exoplanets within a particular “terminator zone” area could potentially host extraterrestrial life. The terminator zone is a ring on a planet with one side that faces its star and one side that is always dark. Such planets are common around dimmer M-dwarf stars, making up about 70% of the stars in the night sky.
The key to habitability in the terminator zone is a “sweet spot” temperature that allows for liquid water, which scientists believe is essential for life. The dark side of terminator planets could be too cold for liquid water, while the side always facing the star could be too hot. However, the temperature could be just right for liquid water within the terminator zone.
The research team, led by Ana Lobo, modeled the climate of terminator planets using software typically used to model Earth’s climate, with adjustments for planetary rotation. They found that if a terminator planet is mainly covered in water, the water facing the star would likely evaporate and cover the entire planet in a thick layer of vapor. However, if there is land, this effect should not occur.
The study highlights that terminator planets are also viable refuges for life, increasing the options for life-hunting astronomers. Recognizing terminator zones as potential harbors for life also means that astronomers must adjust how they study exoplanet climates for signs of life.
The research will help inform future efforts by teams using telescopes such as the James Webb Space Telescope or the Large Ultraviolet Optical Infrared Surveyor telescope to search for planets that may host extraterrestrial life.
References
- Lobo, A. H., Shields, A. L., Palubski, I. Z., & Wolf, E. (2023). Terminator Habitability: The Case for Limited Water Availability on M-dwarf Planets. The Astrophysical Journal, 945(2), 161. https://doi.org/10.3847/1538-4357/aca970
- Van Wyk Joel, L. (2023, March 16). ‘Terminator zones’ on distant planets could harbor life, UC Irvine astronomers say. UCI News; University of California Irvine. https://news.uci.edu/2023/03/16/terminator-zones-on-distant-planets-could-harbor-life-uc-irvine-astronomers-say/
