Hubble Telescope reveals cloudy weather on Exoplanet GJ 1214b

This image shows an artist's view of exoplanet GJ 1214b. Credit: NASA, ESA, & G. Bacon/STScI, STScI-PRC14-06

Weather forecasters on exoplanet GJ 1214b would have an easy job.

Today's forecast: cloudy. Tomorrow: overcast. Extended outlook: more clouds.

A team of scientists led by researchers in the Department of Astronomy and Astrophysics at the University of Chicago report they have definitively characterized the atmosphere of a super-Earth class planet orbiting another star for the first time.

The planet under scrutiny is known as GJ1214b. It is classified as a super-Earth type planet because its mass is intermediate between those of Earth and Neptune.

Recent searches for planets around other stars ("exoplanets") have shown that super-Earths like GJ 1214b are among the most common type of planets in the Milky Way galaxy.

Because no such planets exist in our Solar System, the physical nature of super-Earths is largely unknown.

Laura Kreidberg

Previous studies of GJ 1214b yielded two possible interpretations of the planet's atmosphere.

Its atmosphere could consist entirely of water vapour or some other type of heavy molecule, or it could contain high-altitude clouds that prevent the observation of what lies underneath.

But now a team of astronomers led by UChicago's Laura Kreidberg and Jacob Bean have detected clear evidence of clouds in the atmosphere of GJ 1214b from data collected with the Hubble Space Telescope.

Jacob Bean

The Hubble observations used 96 hours of telescope time spread over 11 months. This was the largest Hubble program ever devoted to studying a single exoplanet.

The researchers describe their work as an important milestone on the road to identifying potentially habitable, Earth-like planets beyond our Solar System.

The results appear in the Jan. 2 issue of the journal Nature.

This rendering shows the size of GJ 1214b and another, larger exoplanet compared to Earth and Neptune. 

Credit: NASA & ESA, STScI-PRC14-06b

"We really pushed the limits of what is possible with Hubble to make this measurement," said Kreidberg, a third-year graduate student and first author of the new paper.

"This advance lays the foundation for characterizing other Earths with similar techniques."

"I think it's very exciting that we can use a telescope like Hubble that was never designed with this in mind, do these kinds of observations with such exquisite precision, and really nail down some property of a small planet orbiting a distant star," explained Bean, an assistant professor and the project's principal investigator.

More information: "Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b," by Laura Kreidberg, Jacob L. Bean, Jean-Michel Désert, Björn Benneke, Drake Deming, Kevin B. Stevenson, Sara Seager, Zachory Berta-Thompson, Andreas Seifahrt, & Derek Homeier. dx.doi.org/10.1038/nature12888

Related paper: dx.doi.org/10.1038/nature12887