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  • Writer's pictureSam Orlando

James Webb Space Telescope Detects Hints of Water Vapor on Alien Planet

Written by: Sam Orlando

Staunton, VA - The James Webb Space Telescope has detected hints of water vapor on an alien planet, potentially representing a major breakthrough in exoplanet science.

Researchers used the telescope to study GJ 486 b, a rocky exoplanet orbiting a red dwarf star. While the water vapor could indicate the presence of an atmosphere, the team of scientists warns that it could also be originating from the star itself.

Red dwarf stars are the most common in the universe, and thus rocky exoplanets are most likely to be found orbiting these celestial bodies. However, these stars release ultraviolet and X-ray radiation that could destroy planetary atmospheres, raising questions about whether a rocky planet could maintain or reestablish an atmosphere in such an environment.

GJ 486 b is too close to its star to be within the habitable zone, with a surface temperature of about 800°F (430°C). Yet, observations from the James Webb Space Telescope's Near-Infrared Spectrograph (NIRSpec) suggest the presence of water vapor. If it is associated with the planet, this would indicate that GJ 486 b has an atmosphere despite its scorching temperature and close proximity to its star.

“We see a signal, and it’s almost certainly due to water. But we can't tell yet if that water is part of the planet's atmosphere, meaning the planet has an atmosphere, or if we’re just seeing a water signature coming from the star,” said Sarah Moran of the University of Arizona in Tucson, lead author of the study.

A water vapor atmosphere on GJ 486 b would be expected to erode gradually due to stellar heating and irradiation, meaning that if an atmosphere is present, it would likely have to be constantly replenished by volcanic activity.

The team observed two transits of the exoplanet, using transmission spectroscopy to decode its composition. Computer models suggested that the most likely source of the signal was water vapor, but an equally plausible explanation is that the water vapor originates from the star.

Future observations from the James Webb Space Telescope may help to differentiate between the planetary atmosphere and starspot scenarios. “It’s joining multiple instruments together that will really pin down whether or not this planet has an atmosphere,” said Kevin Stevenson of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, principal investigator on the program.

The discovery offers a tantalizing glimpse into the potential future of Webb-related discoveries, as the telescope continues to probe the mysteries of our universe and beyond.

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