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UMD Astronomer, Team Use James Webb Space Telescope to Study Elusive Exoplanet’s Atmosphere

By Emily C. Nunez

For more than a decade, astronomers have been trying to get a closer look at a planet known as GJ 1214b that orbits a star 40 light years from Earth, but a thick layer of haze stymied their efforts to study its atmosphere.

The infrared technology built into NASA’s new James Webb Space Telescope (JWST) solved that issue, and now a team of researchers including University of Maryland Associate Professor of Astronomy Eliza Kempton has used the revolutionary tool to observe GJ 1214b’s atmosphere by measuring the heat it emits while orbiting its host star.

Their results, published today in the journal Nature, represent the first time scientists have directly detected the light emitted by a sub-Neptune exoplanet—a category of planets that are larger than Earth but smaller than Neptune.

Though the planet is far too hot to be habitable, researchers discovered that its atmosphere is primarily composed of molecules heavier than hydrogen, including traces of water, methane or a mix of the two. These substances match a subtle absorption of light seen in the wavelength range observed by JWST. Further studies will be needed to determine the exact makeup of the planet’s atmosphere, but Kempton said the evidence remains consistent with the possibility of large amounts of water.

“GJ 1214b, based on our observations, could be a water world,” said Kempton, lead author of the study. “We think we detect water vapor, but it’s challenging because water vapor absorption overlaps with methane absorption, so we can’t say 100% that we detected water vapor and not methane. However, we see this evidence on both hemispheres of the planet, which heightens our confidence that there really is water there.”

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