Webb can detect Earth-like atmosphere on exoplanets – 10/29/2023 – Sidereal Messenger

If there were a planet outside the Solar System with an atmosphere like Earth’s, marked by the presence of life, orbiting a nearby red dwarf star, would the James Webb Space Telescope be able to identify it as such? The answer is yes, according to a new study led by a quintet of scientists in the United States.

In the work, published in the Planetary Science Journal, researchers led by Jacob Lustig-Yaeger, from the Applied Physics Laboratory at Johns Hopkins University, present the validation of a model capable of, based on the transmission spectrum of an exoplanet, determining with reasonable accurately determine the composition of its atmosphere.

The transmission spectrum is a kind of signature that comes with the light that comes from the star and grazes the exoplanet’s atmosphere as it passes in front of it, interacting with the molecules present in the air of that world.

This signal is stronger the larger the size of the planet compared to its parent star, which makes worlds around red dwarfs (the most prevalent and smallest stars in existence, less than half the mass of the Sun) targets. within the range of Webb’s sensitivity.

As a first step, the researchers analyzed low- and high-resolution spectra of the Earth itself obtained by satellite using their computational model, to recover the atmospheric composition. In this process, they were successful in detecting even CFCs (chlorofluorocarbons), molecules that are present in low quantities and that serve as technosignatures – signs that there is intelligent life on our planet.

They then used this same Earth spectrum to generate simulated data from the James Webb Space Telescope’s NIRSpec and IRI instruments, as if they were observing the exoplanet Trappist-1e, which is in the habitable zone (a region that is neither too hot nor too cold). of a red dwarf 40 light years away.

The simulation represented the observation of 80 transits (passages of the planet in front of its star), which is equivalent to all the observable opportunities in the five years of Webb’s initial mission. By passing it through the computer model, the researchers obtained abundance estimates compatible with those on Earth (within the margin of error) for methane, carbon dioxide, ozone and water vapor.

In principle, the presence of these gases could be an indication of the existence of life (as is the case on Earth). Despite the positive identification, the researchers highlight that it would be difficult to say that there would be life there without a deeper study of the environment in question.

Since the beginning of its operations, Webb has been used to observe the atmospheres of exoplanets, and the seven worlds of the Trappist-1 system are among the main targets. But patience is needed: the need to observe multiple transits indicates that it will take time before we can say whether these planets have an atmosphere and whether any of them have traits potentially associated with habitability and life. The search, however, has already begun.

This column is published on Mondays in print, in Folha Corrida.

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