The James Webb Space Telescope has found traces of water vapor within the atmosphere of a super-hot gas giant exoplanet that orbits its star in lower than one Earth day.
The exoplanet in query, WASP-18 b, is a gas giant 10 times more massive than the solar system‘s largest planet, Jupiter. The planet is kind of extreme, because it orbits the sun-like star WASP-18, which is positioned some 400 light-years away from Earth, at a median distance of just 1.9 million miles (3.1 million kilometers). For comparison, the solar system’s innermost planet, Mercury, circles the sun at a distance of 39.4 million miles (63.4 million km).
On account of such close proximity to the parent star, the temperatures in WASP-18 b’s atmosphere are so high that almost all water molecules break apart, NASA said in a press release. The incontrovertible fact that Webb managed to resolve signatures of the residual water is a testament to the telescope’s observing powers.
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“The spectrum of the planet’s atmosphere clearly shows multiple small but precisely measured water features, present despite the intense temperatures of just about 5,000 degrees Fahrenheit (2,700 degrees Celsius),” NASA wrote within the statement. “It’s so hot that it could tear most water molecules apart, so still seeing its presence speaks to Webb’s extraordinary sensitivity to detect remaining water.”
WASP-18 b, discovered in 2008, has been studied by other telescopes, including the Hubble Space Telescope, NASA’s X-ray space telescope Chandra, the exoplanet hunter TESS and the now-retired infrared Spitzer Space Telescope. None of those space telescopes, nonetheless, was sensitive enough to see the signatures of water within the planet’s atmosphere.
“Since the water features on this spectrum are so subtle, they were difficult to discover in previous observations,” Anjali Piette, a postdoctoral fellow on the Carnegie Institution for Science and one in all the authors of the brand new research, said within the statement. “That made it really exciting to finally see water features with these JWST observations.”
Along with being so massive, hot and shut to its parent star, WASP-18 b can also be tidally locked. Meaning one side of the planet consistently faces the star, identical to the moon‘s near side at all times faces Earth. In consequence of this tidal locking, considerable differences in temperature exist across the planet’s surface. The Webb measurements, for the primary time, enabled scientists to map these differences intimately.
The measurements found that probably the most intensely illuminated parts of the planet may be as much as 2,000 degrees F (1,100 degrees C) hotter than those within the twilight zone. The scientists didn’t expect such significant temperature differences and now think that there have to be some not yet understood mechanism in motion that forestalls the distribution of warmth across the planet’s globe.
“The brightness map of WASP-18 b shows an absence of east-west winds that’s best matched by models with atmospheric drag,” co-author Ryan Challener, of the University of Michigan, said within the statement. “One possible explanation is that this planet has a powerful magnetic field, which can be an exciting discovery!”
To create the temperature map, the researchers calculated the planet’s infrared glow by measuring the difference within the glow of the parent star in the course of the time the planet transited in front of the star’s disk after which when it disappeared behind it.
“JWST is giving us the sensitivity to make far more detailed maps of hot giant planets like WASP-18 b than ever before,” Megan Mansfield, a Sagan Fellow on the University of Arizona and one in all the authors of the paper describing the outcomes. said within the statement. “That is the primary time a planet has been mapped with JWST, and it’s really exciting to see that a few of what our models predicted, akin to a pointy drop in temperature away from the purpose on the planet directly facing the star, is definitely seen in the information.”
The recent study was published online Wednesday (May 31) within the journal Nature.