Exoplanet With Water-Rich Atmosphere
September 6, 2013

Super-Earth Found With Water-Rich Atmosphere

John P. Millis, PhD for redOrbit.com - Your Universe Online

The search for a habitable planet beyond Earth is on. Scientists have been searching the heavens to find an exoplanet that is just the right distance from its host star to support liquid water, all the while targeting a surface gravity we would be familiar with and an atmosphere oozing with oxygen.

Such a planet has not yet been found, but progress has been made, and we continue to find smaller and smaller planets closer to the habitable zone. And with new techniques emerging, we are able to characterize the atmospheres of these planets more fully.

A new study by a team of Japanese researchers utilized the Suprime-Cam and Faint Object Camera Spectrograph (FOCAS) instruments aboard the Subaru Telescope to study the atmosphere of a super-Earth known as GJ 1214 B (Gilese 1214 b). Super-Earths are planets a few times more massive than Earth, but somewhat less massive than a Jupiter-type planet. It is still not known if these objects are really beefed-up Earths, or smaller Neptune-like orbs.

To gain insight into the atmospheric composition of the planet, located about 40 light-years from Earth in the constellation Ophiuchus, the team used a blue transmission filter to search for Rayleigh scattering in the atmosphere. The data revealed an unprecedented level of resolution to the bluest wavelengths of light scattering from the planetary atmosphere.

The results indicate that the atmosphere does not include significant amounts of Rayleigh scattering, meaning that the planet likely has a water-rich or hydrogen dominated atmosphere combined with significant cloud cover. More likely, though, Gelise 1214 b’s atmosphere is water-rich, based on the data combined with that from other wavelengths.

While this hardly constitutes definitive proof that Gelise 1214 b is a habitable, Earth-like planet, it's certainly a step in the right direction.