An international team of researchers has been able to successfully use NASA’s James Webb Space Telescope to map the weather on the hot gas-giant exoplanet WASP-43 b. The team utilized precise brightness measurements over a broad spectrum of mid-infrared light, combined with 3D climate models and previous observations, to determine the presence of thick, high clouds covering the nightside, clear skies on the dayside, and equatorial winds of up to 5,000 miles per hour mixing atmospheric gases. This investigation showcases the remarkable capabilities of Webb in measuring temperature variations and detecting atmospheric gases on exoplanets trillions of miles away.
WASP-43 b is a hot Jupiter type of exoplanet, similar in size to Jupiter, primarily made of hydrogen and helium, and much hotter than any giant planets in our solar system. The planet orbits at a distance of just 1.3 million miles from its star, being tidally locked with one side continuously illuminated and the other in permanent darkness. Strong eastward winds transport heat from the dayside to the nightside of the planet, despite the nightside never receiving any direct radiation from the star. Various telescopes, including NASA’s Hubble and now-retired Spitzer space telescopes, have observed WASP-43 b since its discovery in 2011.
The research led by Taylor Bell from the Bay Area Environmental Research Institute demonstrates the capability of Webb to provide more precise measurements for mapping the temperature, cloud cover, winds, and detailed atmospheric composition all around WASP-43 b. By utilizing Webb’s Mid-Infrared Instrument (MIRI) to measure light from the system every 10 seconds for over 24 hours, the team was able to calculate the planet’s temperature and construct a rough map of the temperature variations across the planet. The data revealed an average temperature of nearly 2,300 degrees Fahrenheit on the dayside and 1,100 degrees Fahrenheit on the cooler nightside. The team also located the hottest spot on the planet and identified eastward shifts due to supersonic winds.
Complex 3D atmospheric models were employed to interpret the temperature map and analyze the layers of thick clouds on the nightside of WASP-43 b, which affect its infrared brightness. The data also allowed the team to measure the amount of water vapor and methane present around the planet. Surprisingly, there was a lack of methane detected in the atmosphere, indicating wind speeds reaching up to 5,000 miles per hour on WASP-43 b. This high-speed mixing of gases prevents the expected production of methane on the nightside, leading to a consistent atmospheric chemistry around the planet. The findings highlight how Webb’s sensitivity and stability enable detailed studies of exoplanetary atmospheres.
The successful observation of WASP-43 b was part of the Webb Early Release Science programs, offering researchers a vast set of open-access data for studying cosmic phenomena. The team’s use of Webb’s capabilities to map the weather and infer the atmospheric composition of the exoplanet demonstrates the immense potential for further discoveries in exoplanet science. The findings also provide insights into the dynamics of hot Jupiter exoplanets, shedding light on the complexities of their atmospheres and weather patterns. Future studies using Webb and other telescopes will continue to enhance our understanding of exoplanets and their diverse characteristics.
