Life in the "Terminator Zone"

Explanits rotating around red dwarfs are considered one of the most promising and numerous goals to detect climate suitable for life. However, the planets in the potentially inhabited zone of red dwarfs, as the calculations show, most likely synchronized periods of rotation around their axis and circulation around the star. This means that the planet will be faced with one hemisphere all the time, and on this side of the planet there will be an eternal day and extremely hot temperatures, while on the opposite side - eternal night and the kingdom of the cold.

Previous studies considered the possible inhabitability of the daytime side of such planets, but in the new work of the astronomer Ana Lobo from the University of California in Irvain and its colleagues, the possibility of life in the “Terminator zone” - a narrow strip on the border of the day and night hemispheres. Using a global climatic model, the authors show that for exoplanets with a limited water supply, hot temperatures on the day and negative temperatures on the night hemisphere are possible while maintaining a temperate climate in the terminator area due to a decrease in atmospheric energy transfer.

“Such planets are especially common because they exist around stars that make up about 70 % of stars visible in the night sky - the so -called red dwarfs, which are relatively dull than our sun. The terminator is a dividing line between the day and night sides of the planet. Terminators can exist at a “correct” temperature between too hot and too cold. To search for a possible life, you need a planet that is at an optimal point with a temperature suitable for liquid water, because, as far as scientists are known, liquid water is an important component of life, ”says Ana Lobo.

Ana Lobo and her colleagues simulated the climate of planetary planets using the software usually used to model the Earth’s climate, but with some adjustments, including slowing down the planet rotation. “We are trying to draw attention to a larger number of planets with a limited water supply, which, despite the fact that they do not have extensive oceans, can have lakes or other smaller reservoirs with liquid water, and this climate can be very promising,” adds Ana Lobo. - One of the keys to the discovery was a definition of which planet could hold liquid water. If the planet is mainly covered with water, then, as we discovered, on the hemisphere facing the star, the water will most likely evaporate and cover the entire planet with a thick layer of steam. But if there is land on the planet, there should not be such an effect. ”

The results of the study were published by Astrophysical Journal.