Life Could Exists within “Terminator Zones”
According to a study by University of California, Irvine, and published in the Astrophysical Journal, life could exist on distant exoplanets that that have one side that always faces its star.
Ana Lobo, a postdoctoral researcher in the UCI Department of Physics & Astronomy who led the study, says that exoplanets that have a permanent daytime side and nighttime side have what scientists call a "terminator zone." This is where the light and dark sides meet.
As it turns out, these planets are quite common throughout the universe, and typically orbit M-class dwarf stars (which are cooler than our Sun). On these planets, the dark side sees perpetually sub-freezing temperatures, which would keep all water frozen solid. Conversely, the light side would feature searing temperatures where surface water would be nearly instantly evaporated.
However, Lobo and her cohorts believe that a "goldylocks" zone could exist in the periphery of these two extremes. The team modeled the climate of a terminator planet using software that is typically used to model our own planet's climate, although with some major adjustments, such as slowing down the planetary rotation to nothing.
The various models showed that the habitable zone could be large enough to sustain life. Critical to the experiment was determining what kind of terminator zone planet could retain liquid water. Speaking of liquid water, this study is unique among others in that scientists typically only study exoplanets which they believe to be covered in oceans, much like Earth, to hunt for habitable areas. This seems to be the first study of its kind showing that terminator zones could sustain life.
This study is also causing other astronomers to adjust the parameters of their study's to look for signs of life, as the byproducts life creates may only be present in specific parts of a planet's atmosphere. However, one would speculate that a tidal-locked planet, because of the extreme variations in temperature, would have planet-wide weather so severe that life would not be sustainable upon the surface.
This is just a brief summary of the extensive study released by Lobo and her teammates. For the full study, click here.