Astronomers may be misinterpreting measurements of exoplanetary atmospheres from the James Webb Space Telescope, according to a new study.
The James Webb Space Telescopethe most complex space observatory ever built, captures stunning images from the farthest reaches of universe. Must also measurements of chemical compositions stars, galaxies and intriguing nebulae he sees. To interpret this data, scientists rely on complex models. But a new study by researchers at the Massachusetts Institute of Technology (MIT) found that these models aren’t precise enough to capture the nuances of Webb’s observations.
“There is a scientifically significant difference between a compound like water present at 5% vs. 25%, which current models cannot differentiate,” Julien de Wit, assistant professor in the Department of Earth, Atmospheric and Earth Sciences and Planets (EAPS) from MIT and a study co-lead said in the statement.
The models in question analyze the opacity of the material observed by Webb, a measure of how much light passes through it or is absorbed, and at what wavelengths this occurs. Since each chemical element absorbs light differently, astronomers can reconstruct the chemical compositions and ratios of these chemicals in great detail using these measurements.
Webb, although built to observe older stars and galaxies in the universe, has already proven itself in the study of planets orbiting the stars of our galaxy, the Milky Way. The telescope detected important molecules such as water and carbon dioxide in some planetary atmospheres, but has also taken a direct image of a gas giant exoplanet.
Astronomers are excited about Webb’s ability to study exoplanets in such detail, because the chemical compositions of planetary atmospheres they hope to find could offer clues to the possible presence of life on some of these distant worlds. But inaccurate readings of the data would mean that the information obtained would be quite unreliable.
“Our translation process will prevent us from capturing important subtleties, such as those that make the difference between a habitable planet or not,” de Wit said.
The researchers arrived at the conclusion by testing several versions of existing opacity models and providing them with synthetic light spectra simulating those obtained by the James Webb Space Telescope. They found that different versions of the model produced different values that demonstrated their limits of accuracy, they said.
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The models, the researchers said in the statement, “will not be sensitive enough to tell if a planet has an atmospheric temperature of 300 Kelvin. [80 degrees Fahrenheit/26 degrees Celsius] or 600 Kelvin [620 degrees Fahrenheit/326 degrees Celsius]or whether a certain gas occupies 5% or 25% of an atmospheric layer.”
“This difference is important for allowing us to constrain planetary formation mechanisms and reliably identify biosignatures,” Prajwal Niraula, a graduate student at EAPS and co-author of the new paper, said in the release. “Currently, the model we use to decipher spectral information is not up to the accuracy and quality of data we have from the James Webb Telescope. We need to up our game and solve the opacity problem. “
The researchers also proposed possible improvements such as taking more laboratory measurements to validate the light absorption behavior of various chemical compounds and improving theoretical calculations.
“There are so many things that could be done if we fully understood how light and matter interact,” Niraula said. “We know that pretty well around Earth conditions, but as we move into different types of atmospheres, things change, and that’s a lot of data, of increasing quality, that we risk misinterpreting.”
The study (opens in a new tab) was published in the journal Nature Astronomy on Thursday, September 15.