The James Webb Space Telescope has helped scientists discover the first asymmetric planet. The atmosphere of the gas giant WASP-107b is inflated differently in the eastern and western atmospheres.
Unique planet with asymmetric atmosphere
An international team of researchers, including astronomers at the University of Arizona, has been observing the atmosphere of a hot and uniquely inflated exoplanet using NASA’s James Webb Space Telescope. The exoplanet, which is the size of Jupiter but only a tenth of its mass, was found to have an east-west asymmetry in its atmosphere, meaning a difference between two edges of its atmosphere. The results of the study were published in the journal Nature Astronomy.
“This is the first time the east-west asymmetry of any exoplanet has ever been observed as it transits its star, from space,” said lead study author Matthew Murphy, a graduate student at Stewart University Observatory. A transit is when a planet passes in front of its star, like the Moon during a solar eclipse.
The east-west asymmetry of an exoplanet is the differences in atmospheric characteristics, such as temperature or cloud properties, observed between the eastern and western hemispheres of the planet. Determining whether this asymmetry exists is critical to understanding the climate, atmospheric dynamics, and weather patterns of exoplanets — planets that exist outside our Solar System.
Features of WASP-107b
Exoplanet WASP-107b is tidally locked. This means that it always faces the same side of the star around which it orbits. One hemisphere of a tidal exoplanet is always facing the star around which it orbits, while the other hemisphere is always facing away, causing the exoplanet to have a constant day side and a constant night side.
Murphy and his team used transmission spectroscopy with the James Webb Space Telescope. According to Murphy, it’s the primary tool astronomers use to understand what the atmospheres of other planets are made of. The telescope took a series of images as the planet passed by its star, encoding information about the planet’s atmosphere.
By taking advantage of new techniques and the unprecedented precision of the James Webb Space Telescope, researchers were able to separate signals from the east and west sides of the atmosphere and get a more focused picture of the specific processes taking place in the exoplanet’s atmosphere.
Exoplanet WASP-107b is unique due to its very low density and relatively low gravity, resulting in a more inflated atmosphere than other exoplanets of its mass. WASP-107b has a temperature of about 475°C, an intermediate temperature between the planets in our Solar System and the hottest known exoplanets.
Direct observation of the exoplanet
“Researchers have been looking at exoplanets for almost two decades, and many observations from both the ground and space have helped astronomers guess what the atmosphere of exoplanets would look like,” said Thomas Beatty, co-author of the study and an assistant professor of astronomy at the University.
“But this is really the first time that we’ve seen these types of asymmetries directly in the form of transmission spectroscopy from space, which is the primary way in which we understand what exoplanet atmospheres are made of—it’s actually amazing,” Beatty said.
Murphy and his team are working on the collected observational data and plan to study what is happening to the exoplanet more thoroughly, including additional observations, to understand the reason for this asymmetry.
“For almost all exoplanets, we can’t even look at them directly, let alone be able to know what’s going on one side versus the other,” Murphy said. “For the first time, we’re able to take a much more localized view of what’s going on in an exoplanet’s atmosphere.”
According to phys.org
