Exoplanet Proxima B Orbiting Star Near Sun May Have Liquid Ocean


In August earlier this year, astronomers from the European Southern Observatory  and Harvard University announced the discovery of Proxima B, a rocky planet that orbits a neighboring star of the solar system's sun.

The exoplanet is in the so called "habitable" zone of its host star Proxima Centauri, which means that it lies in the region where the average temperature is just right for liquid water to exist — indicating possibility that it can support life.

Findings of a new study, which was published in The Astrophysical Journal Letters, suggest that the planet is also likely an ocean planet just like Earth. A team of scientists, including astronomers at French National Center for Scientific Research, calculated the size and surface properties of the planet. They found evidence suggesting that an ocean could be covering the planet's entire surface similar to some of the icy moons of Saturn and Jupiter.

The exoplanet appears to be a good candidate for finding alien life. It is estimated to be 1.3 times more massive than Earth and orbits its host star, a red dwarf, from a distance equivalent to about 10 percent of the distance between Mercury and the sun.

Because its host star is smaller and a thousand times weaker than the sun, Proxima B is located just at the right distance to support potentially habitable conditions.

Using computer simulations, researchers calculated that the radius of the planet is between 0.94 and 1.4 times than that of Earth, which spans 6,371 km on average.

If the radius is near the lower end of this estimate at 5,990 km, Proxima B would be very dense and would contain a metallic core that would account for two-thirds of its mass. If surface water is present on the planet, it would be responsible for about 0.05 percent of the total mass of the planet, which is comparable to that of Earth where the surface water accounts for 0.02 percent of the total planetary mass.

Given a radius of 8,920 km, its mass would be split by its rocky core and surrounding water, which could mean that the planet would be covered by a single, liquid ocean with a depth of about 200 km.

"Although this range of radii still allows very different planet compositions, it helps characterizing many aspects of Proxima Centauri b, such as the formation conditions of the system or the current amount of water on the planet," researchers wrote in their study.

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