Tucson Standard

NASA's James Webb Space Telescope has provided astronomers with new insights into the composition of a common type of exoplanet, revealing what researchers are calling a "new class of planet." Everett Schlawin, an assistant research professor at the University of Arizona's Steward Observatory, described this discovery as uncovering answers about planets unlike those found in our solar system.

Exoplanets come in various forms, many differing significantly from Earth and other familiar solar system bodies. One prevalent type falls between Earth and Neptune in size. These planets have been debated to be either rocky like Earth or icy like Neptune. A notable example is GJ 1214 b, located 48 light years away, which Schlawin describes as an "archetype representing an entire population of planets that is unlike anything we have in the solar system."

An international team led by Schlawin and Kazumasa Ohno from the National Astronomical Observatory of Japan used the James Webb Space Telescope to analyze GJ 1214 b's atmosphere for the first time. Their findings were published in The Astrophysical Journal Letters.

GJ 1214 b was discovered in 2009 and initially thought to be an ocean planet. In 2023, it was named Enaiposha by the International Astronomical Union. However, past studies on its atmosphere were inconclusive. Matthew Murphy, a graduate student at U of A and co-author on both studies, stated that understanding this planet had been a significant challenge for over a decade.

Using transmission spectroscopy with JWST's Near-Infrared Spectrograph (NIRSpec), Schlawin's team detected carbon dioxide rather than water vapor in GJ 1214 b's atmosphere. "The detected CO2 signal from the first study is tiny," Ohno said. He added that careful statistical analysis was necessary to confirm its presence.

Ohno utilized theoretical models to explore various scenarios about GJ 1214 b’s atmosphere. His work suggested that it is likely carbon-dominated, resembling a "super-Venus" and representing "an entirely new class of planet," according to Schlawin.

Schlawin compared detecting this atmospheric signature to finding one altered sentence within two copies of Leo Tolstoy’s "War and Peace." The team called for further studies to validate their findings on these enigmatic exoplanets.

Murphy emphasized humanity's pioneering role in studying distant worlds: "It's amazing what you can do when you have a team from all over the globe."

These results highlight JWST’s advanced capabilities alongside sophisticated modeling techniques developed by Ohno’s team known as "atmospheric retrieval." This research could lead astronomers closer to understanding smaller rocky planets potentially capable of supporting life – raising fundamental questions about our place in the universe.