Astronomers Discover Super-Earth has Water-Rich Atmosphere

The Subaru Telescope has made another amazing find. It's spotted the planetary transits of the super-Earth GJ 1214 b and has found that this planet has an atmosphere rich in water. The findings could tell us a little bit more about this large class of planets.

Super-Earths have emerged as a new type of exoplanet. With a mass and radius larger than Earth's but less than those of ice giants in our Solar System, super-Earths are a class all of their own. Currently, researchers are unsure whether these exoplanets are more like large Earths or small Uranuses, yet more information is being found every day about their properties.

In order to find out more about super-Earths, the researchers focused on GJ 1214 b, which is located about 40 light years from Earth in the constellation Ophiuchus. One of the most well-known super-Earths, it was first discovered in 2009. In this latest study, the researchers examined features of light scattering during its transit around its star. This revealed a little bit more about the large Earth's atmosphere.

Planetary transits allow scientists to investigate changes in the wavelength in the brightness of the star. This, in turn, indicates the planet's atmospheric composition. Strong Rayleigh scattering in the optical wavelength gives strong evidence for a hydrogen-dominated atmosphere, for example. In this case, though, the researchers did not see strong Rayleigh scattering. This implied that the planet has a water-rich or hydrogen-dominated atmosphere with extensive clouds.

The findings didn't completely discount the possibility that the planet has a hydrogen-dominated atmosphere. Yet new research seems to point more strongly toward a water-rich one. Currently, the scientists plan to conduct follow-up observations in order to reinforce the idea that the planet does indeed have water rather than hydrogen.

The findings are important for better understanding super-Earths. In addition, it shows the usefulness of observing transits to find out more about exoplanets.

The new study is published in The Astrophysical Journal.