Researchers Piece Together Exoplanet's Atmosphere with Help from Hubble

Researchers from the University of Chicago have used the Hubble Space Telescope to piece together the atmosphere of a super-Earth class planet orbiting another star. Known as GJ 1214b, the planet with a mass between that of Earth's and Neptune's has perpetually cloudy weather, according to the study published in the journal Nature.

Previous studies of GJ 1214b, located just 40 light years from Earth, revealed that the planet could either consist all of water vapor or some other kind of heavy molecule, or high-altitude clouds preventing the scientists from determining what is going on beneath.

Led by UChicago's Laura Kreidberg and Jacob Bean, the researchers have gathered new data indicating the presence of clouds in the planet's atmosphere. The study used 96 hours of telescope time spread over 11 months, making it the largest Hubble program ever focused on one exoplanet.

"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.

"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."

Kreidberg and Bean teamed up with their colleagues to measure the planet's spectrum in near-infrared light. In doing so, they discovered evidence of high clouds smothering it and hiding any more information about the atmosphere or surface beneath.

Importantly, the researchers did not detect any chemical fingerprints in the planet's atmosphere, allowing them to rule out the possibility of cloud-free atmospheres made of water vapor, methane, nitrogen, carbon monoxide or carbon dioxide.

According to the researchers, this likely means there are high-altitude clouds of unknown composition, although models of super-Earth atmospheres predict clouds made of potassium chloride or zinc sulfide boasting temperatures of 450 degrees Fahrenheit.

"You would expect very different kinds of clouds to form than you would expect, say, on Earth," Kreidberg said.