Super-Earth in Habitable Zone

Astronomers discovered an exoplanet orbiting a red dwarf star 40 light-years from Earth that may be the new holder of the title 'best place to look for signs of life beyond the solar system'.

The newly discovered super-Earth LHS 1140b (artist concept). Image credit: tasnimnews.com (CC BY 4.0)

The newly discovered super-Earth LHS 1140b orbits in the habitable zone around a faint red dwarf star named LHS 1140, in the constellation of Cetus (The Sea Monster).

Red dwarfs are much smaller and cooler than the Sun and, although LHS 1140b is ten times closer to its star than the Earth is to the Sun, it only receives about half as much sunlight from its star as the Earth and lies in the middle of the habitable zone.

The orbit is seen almost edge-on from Earth and as the exoplanet passes in front of the star once per orbit it blocks a little of its light every 25 days.

For life as we know it to exist, a planet must have liquid surface water and retain an atmosphere.

When red dwarf stars are young, they are known to emit radiation that can be damaging for the atmospheres of the planets that orbit them.

In this case, the planet's large size means that a magma ocean could have existed on its surface for millions of years. This seething ocean of lava could feed steam into the atmosphere long after the star has calmed to its current, steady glow, replenishing the planet with water.

The astronomers estimate the age of the planet to be at least five billion years. They also deduced that it has a diameter 1.4 times larger than the Earth -- almost 18,000 kilometers.

But with a mass around seven times greater than the Earth, and hence a much higher density, it implies that the exoplanet is probably made of rock with a dense iron core. (Tasnim News Agency)

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