Exoplanet Wasp-18 B Has Strong Magnetic Field, Shows Signs of Water Vapor [Study]

New intriguing details about an exoplanet 400 light years away from us were unearthed thanks to the latest data from the Canadian NIRISS instrument on James Webb Space Telescope (JWST). Wasp-18 b is reportedly unique in our solar system.

Exoplanet Wasp-18 b Has Strong Magnetic Fields That Affect Wind Direction.

The exoplanet WASP-18 b is an ultra-hot gas giant ten times bigger than Jupiter. Its atmosphere has been found to contain water vapor. An international team of scientists has created a temperature map of the planet as it dipped behind and reemerged from its star in a secondary eclipse process. As the planet passes in front of the star, scientists may read the light coming from both the star and the planet together to fine-tune their initial readings, ScienceDaily reported.

WASP-18 b faces its star from the same side, known as the dayside, just as the Moon always faces Earth from the same side. The term for this is tidal locking.

The exoplanet's temperature map, also known as its brightness map, reveals a significant temperature variation of up to 1,000 degrees between the hotter point facing the star and the terminator, where the day and night sides of the tidally-locked planet come together in perpetual twilight.

JWST is providing researchers the sensitivity to map hot giant planets like WASP-18 b in greater detail. According to Megan Mansfield, a Sagan Fellow at the University of Arizona and one of the paper's authors, this is the first time a planet has been mapped with JWST. It's exciting to see that some of what their models predicted, such as a sharp drop in temperature away from the point on the planet directly facing the star, is seen in the data.

The researchers measured temperature gradients on the planet's dayside. There is probably something preventing winds from effectively dispersing heat to the night side, given how much cooler the globe is at the terminator. But it is still unclear what is influencing the winds.

The lack of east-west winds indicated by WASP-18 b's brightness map can best be replicated by models with atmospheric drag. The existence of a powerful magnetic field on this planet as one explanation would be a fascinating discovery, said Ryan Challener, a co-author from the University of Michigan.

One interpretation of the eclipse map is that magnetic forces cause the winds to blow East-West, as we would anticipate, from the planet's equator up over the North pole and down over the South pole.

Researchers observed temperature fluctuations at various elevations in the atmosphere's layers of the gas giant planet. They observed that temperatures varied by hundreds of degrees as altitude increased.

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Wasp-18 b Shows Signs of Water.

Despite the planet's extremely high temperatures of over 2,700 degrees Celsius, the spectrum of its atmosphere plainly reveals a number of microscopic but accurately observed water features. It is so hot that most water molecules would be torn apart. Thus, the fact that it is still detectable is a testament to Webb's exceptional sensitivity. The levels in the atmosphere of WASP-18 b show that water vapor exists at varying heights.

Louis-Philippe Coulombe, a Ph.D. candidate at the Université de Montréal, a member of the Trottier Institute for Research on Exoplanets (iREx), and the lead author of the WASP-18 b paper said it was a great feeling to look at WASP-18 b's JWST spectrum for the first time and see the subtle but precisely measured signature of water. Björn Benneke, a professor at UdeM and a member of iREx, who was also a co-author of this study, is optimistic that in the upcoming years, they will be able to find these compounds on a variety of planets using these kinds of measurements. Since 2016, Benneke has been spearheading international efforts to research WASP-18 b.