A neighbouring exoplanet orbiting within the habitable zone of a star only 4.2 light-years away from Earth may have a large ocean, increasing its chances of harbouring life. Since its discovery, doubts regarding the circumstances on Proxima b’s surface have swirled; the planet’s mass is roughly 1.3 times that of Earth, and the red dwarf star it orbits is similar in age to our sun.
However, studies in recent years have both boosted and dashed hopes for its habitability. A recent study has increased the prospect that Proxima b could support life, implying that the exoplanet could survive liquid water under the correct conditions.
Updated version of the previous article.
“The major message from our simulations is that there’s a decent chance that the planet would be habitable,” Anthony Del Genio, a planetary scientist at the NASA Goddard Institute for Space Studies, told LiveScience.
The researchers conducted what are thought to be the first climate simulations of Proxima b with a dynamic ocean in the study, which was published this month in the journal Astrobiology. The planet is thought to be tidally locked with its star, Proxima Centauri, which means it has a constant ‘dayside’ and ‘nightside.’
While any water on the side left in the dark would be frozen, the opposite side would not necessarily be the case.
“Climate models with static oceans suggest that Proxima b could harbor a small dayside surface ocean despite its weak instellation,” the researchers explain in the new study. “With a dynamic (moving) ocean considered for the first time, the extent of this liquid water becomes much more significant, in some cases even dipping into parts of the nightside. The simulations showed that ‘with a dynamic ocean, a hypothetical ocean-covered Proxima Centauri b with an atmosphere similar to modern Earth’s can have a habitable climate with a broad region of open ocean, extending to the nightside at low latitudes.”
The researchers considered varied salinity levels as well as atmospheric greenhouse gas concentrations, all of which could influence the size of the watery zones. The study discovered that the exoplanet almost always had some kind of liquid ocean in more than a dozen simulations. But don’t get too thrilled about taking a dive just yet.
“We find that an ocean-covered Proxima b could have a much broader area of surface liquid water but at much colder temperatures than previously suggested, due to ocean heat transport and/or depression of the freezing point by salinity,” the researchers wrote.