Some planets, due to their proximity to their star, end up synchronizing their rotation with their translation in such a way that they always have the same side exposed to the sun and another on which the sun never shines. That can lead to a big difference between the temperature on the day side and the night side. On the dayside, it may be too high to support life; and at night, too low. Could there, however, be life on the terminator, the ring where there is perpetual twilight or dawn? In recent research, this question has been examined.
Planets with eternal day and night are very abundant in the universe. And so are those of this type that orbit red dwarf stars, much cooler than our Sun, around which a planet can have freezing temperatures on the night side.
For life to exist on a planet as we understand it, the temperature must allow the existence of liquid water on the surface. Is it plausible that it could be on the terminator of one of those planets with permanent day and night orbiting a red dwarf?
Ana Lobo’s team, from the University of California at Irvine, in the United States, simulated the climate of planets with a stationary terminator using software commonly used to simulate the climate of our planet, but with some adjustments, including slowing down the planetary rotation. .
The results indicate that such planets can maintain habitable climates confined to their terminator.
Some exoplanets (planets outside our solar system) have one side permanently facing their star, while the other is in perpetual darkness. The ring-shaped border between the day and night regions is an immobile terminator. In the new study, it has been concluded that this ring-shaped area may be capable of supporting alien life. The image is an artist’s recreation of one such world. (Image: Ana Lobo/UCI)
Until now, planets of this class were considered highly unlikely for life, especially when compared to worlds that are covered by oceans, such as Earth. But now that Lobo’s team has shown that immobile terminator planets are also viable havens for life, the number of potentially habitable worlds astronomers can investigate increases.
Those worlds with an immobile terminator, despite having no seas in their habitable ring, could have lakes.
One of the keys to the finding was determining exactly what kind of planet with a stationary terminator can hold liquid water. The team found that if the planet is mostly covered in water, the water in the star-facing hemisphere would likely evaporate and cover the entire planet in a thick layer of steam.
But if there is enough dry land, this effect should not occur and the terminator zone would have a much better chance of being habitable.
Recognizing the terminator zones as possible havens for life also means that astronomers will have to adjust the way they study the climates of exoplanets (planets outside our solar system) for signs of life, because the biosignatures it creates life can be present only in specific parts of the planet’s atmosphere.
The study is titled “Terminator Habitability: The Case for Limited Water Availability on M-dwarf Planets.” And it has been published in the academic journal The Astrophysical Journal. (Fountain: NCYT by Amazings)