The James Webb Space Telescope has made the first clear detection of carbon dioxide in a distant world’s atmosphere, and there’s also an unexpected spike in the data.
25 Aug 2022
NASA’s James Webb Space Telescope (JWST) has detected carbon dioxide in the atmosphere of a planet 700 light-years away called WASP-39b. This is the first time the compound has been found on an exoplanet, and the observations also revealed hints of a mystery within the distant world.
WASP-39b is huge. It has a mass similar to that of Saturn and a diameter 1.3 times that of Jupiter. It orbits relatively close to its star, giving it an average temperature of around 900°C: the high temperature inflates the atmosphere, making it easier for JWST to see starlight shining through it.
When light from a star shines through a planet’s atmosphere, molecules in the atmosphere absorb some of the light in unique wavelength ranges. Carbon dioxide absorbs infrared light, and previous telescopes didn’t look at the right range or with the right method to detect its signature. JWST sees in the infrared and caught it right away.
Natalia Batalha at the University of California, Santa Cruz, and a team of more than 100 researchers examined the JWST observations, running them through four separate algorithms to make sure that no matter how they were processed, the results were the same. All four showed the clear signature of carbon dioxide. “The carbon dioxide firm was just yelling at us,” says Batalha. “Processing the data was not difficult: it was easy, straightforward, honestly beautiful.”
The result has a statistical significance of 26 sigma, which means that the probability of finding a signature as a statistical fluke is less than 1 in 10.149. “It’s just exquisite,” he says. eliza kempton at the University of Maryland, part of the research team. “I’ve never seen anything like 26 sigma in this field.”
The researchers found that WASP-39b has more carbon and oxygen than its host star, implying that it did not form when the gas around the star collapsed all at once, but rather that its rocky core formed first and then accreted. gas that forms its star. atmosphere. This is similar to how we think planets formed in our own solar system, and studying the exoplanet’s atmosphere in more detail could reveal more details about how and where it formed.
In addition to carbon dioxide, the researchers found another spike in their data, indicating that something unexpected in WASP-39b’s atmosphere was absorbing some of the starlight. “There’s something else there, some other molecule or some kind of cloud or haze, something that’s not predicted by the basic model” of exoplanet atmospheres, Kempton says. The researchers are not yet sure what this mystery molecule might be, but they are working to find it out with additional data from JWST and different models.
The fact that we could see carbon dioxide in the atmosphere of this gas giant is a good sign of our ability to eventually understand the atmospheres of rocky Earth-like worlds, one of the main goals of JWST, says Batalha. It can also be useful in the search for extraterrestrial life. “In the future, it may be an interesting biosignature when found in combination with other molecules like methane,” he says. Jessie Christiansen at NASA’s Exoplanet Science Institute in California.
“This planet is not a hospitable place, it’s like what you would get if you took Jupiter but brought it very close to the sun and baked it,” says Kempton. “It’s not a place you’d want to visit, but this is the first step toward characterizing the atmospheres of habitable planets.” And characterizing those atmospheres is perhaps our best bet for finding signs of extraterrestrial life.
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