Submission + - Carbon dioxide detected around alien world for first time (science.org)
sciencehabit writes: 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.
Finding CO2 is valuable because it is a clue to a planet’s “metallicity”—the proportion of elements heavier than helium in its makeup. Hydrogen and helium produced in the big bang are the starting materials for all the visible matter in the universe, but anything heavier was forged later in stars. Researchers believe a good supply of heavy elements is crucial for creating giant planets. When planets form out of a disk of material around a new star, heavier elements form solid grains and pebbles that glom together into a solid core that eventually is massive enough to pull in gases with its own gravity and grow into a gas giant.
With Webb, finding “important chemicals will be the norm rather than the exception,” says one expert. He predicts that when Webb starts to study cooler planets closer in size to Earth, there will be some real surprises—perhaps some gases that could indicate whether the planets are amenable to life. “It’s anyone’s guess,” he says. “A whole zoo of chemicals is possible.”
Finding CO2 is valuable because it is a clue to a planet’s “metallicity”—the proportion of elements heavier than helium in its makeup. Hydrogen and helium produced in the big bang are the starting materials for all the visible matter in the universe, but anything heavier was forged later in stars. Researchers believe a good supply of heavy elements is crucial for creating giant planets. When planets form out of a disk of material around a new star, heavier elements form solid grains and pebbles that glom together into a solid core that eventually is massive enough to pull in gases with its own gravity and grow into a gas giant.
With Webb, finding “important chemicals will be the norm rather than the exception,” says one expert. He predicts that when Webb starts to study cooler planets closer in size to Earth, there will be some real surprises—perhaps some gases that could indicate whether the planets are amenable to life. “It’s anyone’s guess,” he says. “A whole zoo of chemicals is possible.”
