The James Webb Space Telescope (JWST or Webb) has detected carbon dioxide in an exoplanet’s atmosphere, a breakthrough discovery that will usher in a new era of exploration of worlds beyond our solar system.
The discovery came during the James Webb Space Telescope’s first exoplanet campaign, meaning planets orbiting other stars. The observations were aimed at a hot gas giant called WASP-39 b, located about 700 light-years from Earth in the constellation Virgo.
The planet, about as massive as Saturn but larger than Jupiter, has previously been observed by the Hubble Space Telescope at optical wavelengths and by the Spitzer Space Telescope, which, like Webb, has observed heat-carrying infrared waves. Previous observations revealed the presence of water vapor, sodium and potassium in the planet’s atmosphere, but only when Webb detected the presence of carbon dioxide.
“As soon as the data appeared on my screen, I was captivated by the colossal signature of carbon dioxide,” said Zafar Rustamkulov, a graduate student at Johns Hopkins University in Baltimore, USA and a member of the transiting exoplanet team that conducted the study. statement (will open in a new tab). “It was a special moment when we crossed an important threshold in exoplanet sciences.”
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Carbon dioxide has never been detected on any exoplanet before. But astronomers hope the compound will help them better understand the formation history and evolution of the planets it has been found on.
“This unequivocal detection of carbon dioxide is a milestone in describing the atmosphere of an exoplanet,” said Laura Kreidberg, director of the Max Planck Institute for Astronomy in Germany and co-author of the paper describing the discovery. (will open in a new tab). “Carbon dioxide helps us measure the total amount of carbon and oxygen in the atmosphere, which is very sensitive to conditions in the disk where the planet formed.”
Such measurements could help determine how far away a planet formed from its star and determine how much solid and gaseous material it accumulated as it migrated to its current location.
The discovery was made using the Webb NIRSpec instrument, a highly sensitive spectrograph that separates incoming light into barcode-like spectra that show how observed objects absorb light. Neither Webb nor any other existing telescope can take direct pictures of an exoplanet or its atmosphere; instead, the researchers compare observations of typical starlight to light seen through the atmosphere as the planet passes in front of it.
The WASP-39 b measurements were collected on July 10, two days before the first official release of the Webb images.
The researchers believe the telescope will be able to detect carbon dioxide in the atmospheres of other types of planets, including Earth-like rocky bodies scattered throughout the galaxy.
“The exoplanet community has been searching for the carbon dioxide signature for decades,” Kreidberg said. “Thanks to the extraordinary new capabilities of JWST, it will be possible to regularly detect carbon dioxide on hot Jupiters, as well as on smaller and colder planets more like our Earth.”
WASP-39 b orbits very close to its parent star, WASP-39, less than 1/20 of the distance between the Earth and the Sun), making one rotation approximately every four Earth days. The planet was discovered in 2011 and can only be observed through the transits it makes around WASP-39, which causes short-term dips in the star’s brightness.
The article describing the study was accepted for publication by the journal Nature; article preprint available at arXiv.org (will open in a new tab).
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