Super-Earth 40 light years away 'is rich in water with a thick, steamy atmosphere', confirm Japanese astronomers



GJ 1214b is 2.6 times Earth’s diameter and weighs seven times as much

It was first discovered as part of the g round-based MEarth Project in 2009

The observations by the Subaru telescope could help scientists f ind out more about the planet's birthplace and formation history

Blue light observations of a super-Earth 40 light years from our planet suggest that it is a world with a thick, steamy water-rich atmosphere.

Japanese astronomers used the Subaru telescope to observe planetary transits of the super-Earth, which is located at the centre of the Milky Way.

Astronomers had previously confirmed that this alien world has a thick atmosphere, but were unable to determine whether the atmosphere was primarily hydrogen or a steamy soup of water vapour.

Their findings confirm that the super-Earth has an atmosphere rich in water rather than hydrogen.

Artist's rendition of a transit of GJ 1214 b in blue light. The blue sphere represents the host star GJ 1214, and the black ball in front of it on the right is GJ 1214 b

SUPER-EARTH GJ 1214B

The water world, named GJ 1214b is one of the more well-known super-Earths and was discovered by the ground-based MEarth Project in 2009.

This super-Earth is about 2.6 times Earth’s diameter and weighs almost seven times as much. It orbits a red-dwarf star every 38 hours at a distance of 2 million kilometres, giving it an estimated temperature of 230 degrees Celsius. Astronomers had previously confirmed that this alien world has a thick atmosphere, but were unable to determine whether the atmosphere was primarily hydrogen or a steamy soup of water vapour.

Super-Earths are exoplanets orbiting a star outside of the solar system that are larger than Earth's but smaller than those of ice giants such as Uranus or Neptune.

Their planetary transits enable scientists to find changes in the wavelength in the brightness of the star, which indicate the planet's atmospheric composition.



If scientists can determine the major atmospheric component of a super-Earth, they can then find out the planet's birthplace and formation history.

The water world, named GJ 1214b is one of the more well-known super-Earths and was discovered by the ground-based MEarth Project in 2009.



This super-Earth is about 2.6 times Earth’s diameter and weighs almost seven times as much.



If the sky has a hydrogen-dominated atmosphere (as shown in the top image) Rayleigh scattering disperses blue light from the atmosphere of the host. The middle image shows how Rayleigh scattering is much weaker in water-rich atmospheres while the bottom image show what would happen if the sky had extensive clouds

It orbits a red-dwarf star every 38 hours at a distance of 2 million kilometres, giving it an estimated temperature of 230 degrees Celsius.

Last year, the Hubble space telescope examined GJ 1214b when it crossed in front of its host star.

During such a transit, the star’s light is filtered through the planet’s atmosphere, giving clues to the mix of gases.



They found the spectrum of GJ 1214b to be featureless over a wide range of wavelengths, or colours, also suggesting the planet had a dense atmosphere of water vapour.



The planet GJ 1214b, shown here in an artist's conception with two hypothetical moons, orbits a star 40 light-years from Earth. The super-Earth is about 2.6 times Earth's diameter and weighs seven times as much

Subaru found weak Rayleigh scattering in the optical wavelength which the team claim provided ‘powerful evidence’ for a water-dominated atmosphere.

Another possibility for the weak Rayleigh scattering is that the planet has a hydrogen-dominated atmosphere with extensive clouds.



Rayleigh scattering occurs when light particles scatter in a medium without a change in wavelength.

In a water-rich atmosphere, such as the one on GJ 1214b, the effect of the Rayleigh scattering is much weaker than in a hydrogen-dominated atmosphere.



Up until now, more than 800 exoplanets have been discovered and around so far and 12 are thought to have the environments that could be habitable.



More unusual discoveries include a planet that is as airy as Styrofoam, and another that rains glass.



Researchers claim there could be as many as 100 billion Earth-like planets in the Milky Way.

