Carbon Dioxide Detected Around Alien World by JWST For First Time@TheCosmosNews
#thecosmosnews Astronomers have found carbon dioxide (CO2) in the atmosphere of a Saturn-size planet 700 light-years away—the first unambiguous detection of the gas in a planet beyond the Solar System. The discovery, made by the James Webb Space Telescope, provides clues to how the planet formed. The result also shows just how quickly Webb may identify a spate of other gases, such as methane and ammonia, which could hint at a planet’s potential habitability for life. Webb is “ushering in this new era of the atmospheric science of exoplanets,” says Nikku Madhusudhan of the University of Cambridge, who was not involved in the study. The Webb telescope is sensitive to infrared wavelengths of light that are mostly blocked by Earth’s atmosphere. It has already dazzled astronomers with its ability to bring the universe’s most distant stars and galaxies into view. But the infrared sensitivity is also critical for researchers studying worlds much closer to home, in the Milky Way. When an exoplanet’s orbit takes it in front of its star, some of the starlight passes through the planet’s atmosphere and carries fingerprints of its composition. The atmospheric gases absorb specific wavelengths of light, which show up as dips in brightness when the starlight is spread out into a spectrum. For most gases of interest, the dips occur at infrared wavelengths. The Hubble Space Telescope and its infrared sibling, the Spitzer Space Telescope, have detected water vapor, methane, and carbon monoxide around a few hot, giant exoplanets, but little more. Webb promises to reveal many more gases in smaller Neptune-size planets and potentially even rocky planets similar in size to Earth, although it is unlikely to be able to confirm the existence of life. For its first exoplanet observations, astronomers targeted the hot gas giant WASP-39b, which orbits its star every 4 days in an orbit much tighter than Mercury’s. The first data were taken on 10 July and the team started work on them a few days later. Even in raw data based on a single transit across the star, the spectral dip of CO2 “sticks out like a sore thumb,” says Webb team member Jacob Bean of the University of Chicago. There have been some tentative detections of the gas before, he says, but none of them held up under scrutiny. Webb’s spectrum was “the right size, the right shape, and in the right position,” Bean says. “CO2 just popped out.”
