While finding habitable exoplanets that can bear life like Earth, liquid water has played an important role in illustrating the possibility of life. While scientists have looked for water bodies similar to that on Earth, a study indicates that liquid water could be found on the surface of exoplanets for billions of years under other circumstances. Experimenters from the University of Bern, the University of Zurich, and the National Centre of Competence in Research (NCCR) Planets have clarified why the search for habitable exoplanets might need a different strategy than the one currently taken.
According to Ravit Helled, Professor of Theoretical Astrophysics at the University of Zurich and co-author of the study, “One of the reasons that water can be liquid on Earth is its atmosphere.” He explained that” the natural greenhouse effect on Earth traps the right amount of heat to develop favorable conditions for oceans, rivers, and rain.”
When the Earth was created, its atmosphere primarily consisted of Hydrogen and Helium, known as a primordial atmosphere. Earth forfeited this atmosphere with time. However, some more giant planets can conserve it indefinitely.
“Such massive primordial atmospheres can also induce a greenhouse effect – much like Earth’s atmosphere today. We, therefore, wanted to find out if these atmospheres can help create the necessary conditions for liquid water,” explained Heller.
In their research, published in Nature Astronomy, the experimenters modeled several planets and simulated their development over billions of years.
“What we found is that in many cases, primordial atmospheres were lost due to intense radiation from stars, especially on planets that are close to their star. But in the cases where the atmospheres remain, the right conditions for liquid water can occur,” announced Marit Mol Lous, Ph.D. student and lead author of the study.