Astrophysicists from the University of Bordeaux and the University of Geneva Astronomical Observatory have disproved the generally accepted theory of planetary habitability, arguing that some exoplanets orbiting red dwarfs may be habitable. The work was published in the journal Nature.
The generally accepted theory states that most exoplanets orbiting red dwarfs and some other stars are unsuitable for maintaining water in liquid form on their surface, which is a prerequisite for the existence of life. However, the new theory completely turns our view of the above exoplanets upside down.
According to the new theory, some planets orbiting red dwarfs did not necessarily have to become as hot and arid as the conventional theory suggests. This means that water may have been preserved in the crust during their formation stage. Further, as the new theory suggests, water could have been ejected into the atmosphere as a result of volcanic activity, and this water did not escape into space, but later, as the planet cooled, condensed and formed oceans.
The reason why the planet may not become as hot as has been assumed so far is due to thermal radiation. This quantity has not been accounted for in previous theories. In addition, adding the effect of radiation effects into the calculations also reduces the time that an exoplanet can remain hot enough to literally melt rocks. Consequently, it increases the likelihood that the planetary crust will retain water, which could then appear on the surface in liquid form.
The research team notes that if its theory is confirmed in future studies, scientists will have to revise their views on the formation processes of some planets, such as the evolution of Venus. In addition, it returns to the list of planets potentially suitable for life, those objects that were previously excluded from it because of their proximity to the parent stars.
“The new theory of planetary habitability opens up new possibilities for the search for life in space,” said astrophysics professor James Kasting of Cornell University. “This is a very exciting and important study that could change our idea of what planets might be habitable. It may also help scientists better understand planet formation processes in general.”