WASP-17b belongs to a class of planets known as 'hot Jupiters' -- enormous gas giants orbiting very close to their host stars and subjected to intense heating. The extreme conditions give rise to powerful winds and temperature contrasts that reshape the planet's atmosphere. The research was jointly led by Cornell University in the United States and the University of Bristol in the United Kingdom.
Lead author Dr. Lili Alderson, a Klarman Postdoctoral Fellow at Cornell who began the work while at Bristol, said: "This is proof of concept that planets are in fact 3D objects, and that consistently, as they go around their star, what we predict should be happening is happening. To move beyond computational exercises and see it for real is a different matter."
The observations relied on transmission strings, an innovative technique developed by Bristol astrophysicists Dr. David Grant and Dr. Hannah Wakeford. This method allowed the team to map the shape of the planet's transmitting limb as a function of angle across the poles for the first time, revealing that the atmosphere extends farther on the evening limb (where hot material is transported from the permanently irradiated dayside) than on the morning limb.
Co-author Dr. Hannah Wakeford, Associate Professor in Astrophysics at the University of Bristol, said: "Planets are temperamental, their atmospheres complex and chaotic. The fact that all of these numbers came to..."
The findings validate earlier theoretical models and provide one of the most detailed three-dimensional pictures of an exoplanet atmosphere yet produced. They establish a reference point for studying the more than 6,000 exoplanets confirmed so far, offering insight into atmospheric chemistry, temperature variations between equator and poles, and heat transport between permanently illuminated and dark hemispheres.