James Webb finds water in the atmosphere of a superheated exoplanet

The data collected by the James Webb Space Telescope served as the basis for an article published this Wednesday (31) in the online version of the scientific journal nature, which describes the detection of traces of water vapor in the atmosphere of a superheated exoplanet located 400 light-years from Earth.

With a mass 10 times that of Jupiter, the gas giant WASP-18 b takes less than an Earth day to orbit the star WASP-18, at a distance of just 3.1 million km, according to the study. For comparison, the innermost planet in the Solar System, Mercury, circles the Sun at 63.4 million km.

according to announcement released by NASA, due to proximity to the host star, temperatures in the atmosphere on that world are so high that most water molecules break apart.

“The spectrum of the planet’s atmosphere clearly shows several small but precisely measured features of water present despite extreme temperatures of nearly 2,700 degrees Celsius,” the agency reports. “It’s so hot that it would tear most water molecules apart, so even seeing its presence demonstrates Webb’s extraordinary sensitivity in detecting the remains of water.”

Since its discovery in 2008, WASP-18 b has been examined by various equipment, such as the Hubble Space Telescope, the Chandra X-ray Observatory, the exoplanet hunter TESS and the now retired Spitzer infrared telescope. None of them, however, were sensitive enough to pick up the signatures of water in the planet’s atmosphere.

In addition to being so massive, hot, and close to its parent star, this exoplanet is also tidally locked. This means that one side of it is constantly facing the star, just as the visible side of the Moon always faces the Earth.

As a result, there are significant temperature differences on its surface. Webb’s measurements allowed scientists to map these differences in detail for the first time.

To do this, the team calculated WASP-18 b’s infrared brightness by measuring the difference in light from its parent star during the time the planet passed in front of it.

They found that the brightest parts of the planet can be up to 1,100 degrees Celsius hotter than those in the twilight zone. Such significant temperature differences were not expected. The researchers believe that there must be an as-yet-ununderstood mechanism that prevents heat from being distributed around the globe.

“JWST is giving us the sensitivity to create more detailed maps than ever of hot giant planets like WASP-18b,” said Megan Mansfield, a researcher at the University of Arizona and one of the paper’s authors. “This is the first time a planet has been mapped with the JWST, and it’s really exciting to see that some of what our models predicted, such as a sharp drop in temperature away from the point on the planet directly facing the star, is actually seen in the data. ”.

The post James Webb finds water in the atmosphere of a superheated exoplanet first appeared on Olhar Digital.

Source: Olhar Digital