In the quest to find habitable exoplanets like Earth, liquid water has played an important role in indicating the possibility of life. While scientists are searching for bodies of water similar to those found on Earth, one study suggests that liquid water could also exist on the surfaces of exoplanets for billions of years under other circumstances. Researchers from the University of Bern, the University of Zurich and the National Center for Competency in Planetary Research (NCCR) have explained why the search for habitable exoplanets may require an approach. different from the method currently being implemented.
According to Ravit Helling, Professor of Theoretical Astrophysics at the University of Zurich and co-author of research, “One of the reasons that water can be liquid on Earth is its atmosphere.” He said that the natural greenhouse effect on The earth traps the right amount of heat to create favorable conditions for oceans, rivers, and rain.
When the Earth was formed, its atmosphere consisted mainly of Hydrogen and Helium, known as the primordial atmosphere. While Earth loses this atmosphere over time, some larger planets may retain it indefinitely.
“Such huge primordial atmospheres can also cause the greenhouse effect – just like Earth’s atmosphere today. We therefore wanted to find out if these atmospheres could help create the necessary conditions for liquid water,” said Helt.
In their study, published in Natural Astronomy, the researchers modeled many planets and simulated their evolution over billions of years. They not only observed the properties of the atmosphere, but also observed the radiation intensity of the planetary stars and how much heat their interior radiated to the outside.
“What we found is that in many cases, the primordial atmosphere was lost due to intense radiation from stars, especially on planets close to their stars. But in the event that the atmosphere remains, the right conditions for liquid water can occur,” said Marit Mol Lous, PhD student and lead author of the study.
The researchers stress that their findings suggest that conditions can persist on planets for up to tens of billions of years. Yet another co-author, Christoph Mordasini, says that even if the planets have the right conditions, “it is still unclear how likely life is to emerge in such an exotic potential environment.”
