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takyon writes:

Researchers have calculated that Proxima b may have liquid water oceans on its surface, or even be an "ocean planet" based on larger estimates of its radius:

A rocky planet discovered in the "habitable" zone of the star nearest our Sun may be covered with oceans, researchers at France's CNRS research institute said Thursday. A team including CNRS astrophysicists have calculated the size and surface properties of the planet dubbed Proxima b, and concluded it may be an "ocean planet" similar to Earth.

[...] They calculated the radius was between 0.94 and 1.4 times that of Earth, which is 6,371 kilometres on average. Assuming a minimum radius of 5,990 km, the planet would be very dense, with a metallic core making up two-thirds of the entire planet's mass, surrounded by a rocky mantle. If there is surface water, it would not contribute more than 0.05 percent to the planet's total mass, the team said—similar to Earth, where it is about 0.02 percent.

In the larger planet scenario, with a radius of 8,920 km, Proxima b's mass would be split 50-50 between a rocky centre and surrounding water. "In this case, Proxima b would be covered by a single, liquid ocean 200 km deep," said the CNRS. "In both cases, a thin, gassy atmosphere could surround the planet, like on Earth, rendering Proxima b potentially habitable," it concluded.

The exoplanet has not been seen transiting Proxima Centauri, so further data about its size and composition will require the James Webb Space Telescope or other observatories to directly observe it.

Original article in French.

Previously: "Earth-Like" Exoplanet Found in Habitable Zone of Proxima Centauri
ESO Confirms Reports of Proxima Centauri Exoplanet

Original Submission