WASP-33 b and other hot Jupiters identified as prime targets for structural studies

Close-in giant planets often deform due to the intense gravity of their host stars. By measuring these physical distortions, researchers can gain insights into the interior density of these worlds. A new method identifies WASP-33 b, WASP-76 b, and HAT-P-32 b as the best candidates for future observations with the JWST and Ariel telescopes to map their internal structures using their orbital phase curves.

Star system: WASP-33 | Distance from the Sun: 378 light years

The physical shape of a giant planet orbiting close to its star offers a unique window into its internal composition. Intense gravitational pull from the host star stretches these planets, causing measurable deformations. These distortions are calculated using a value called the fluid Love number, which describes how a planet responds to external gravitational stress. By measuring this number, researchers can better understand how matter is distributed deep within a planet and test different models regarding their internal structure.

To identify the best targets for this research, a new measurement tool called the deformation metric has been developed. This tool combines the expected amount of physical stretching with the quality of light data that telescopes can capture during a full orbit. By applying this metric to a list of potential candidates, WASP-33 b, WASP-76 b, and HAT-P-32 b have been highlighted as the most promising targets for future study. These planets do not yet have known Love number measurements, making them ideal subjects for future telescope missions.

Simulations suggest that high-precision observations using the JWST or the upcoming Ariel telescope will provide enough data to accurately measure the Love number for these planets. These measurements will allow for the testing of various theories about planetary interiors, moving beyond simple external observations to probe the deep, hidden structures of gas giants.

Key findings
The deformation metric identifies WASP-33 b, WASP-76 b, and HAT-P-32 b as top targets for studying planetary shape.
Fluid Love numbers provide a direct link between a planet's visible shape and its internal density distribution.
JWST phase curve observations can measure these structural details with a precision of approximately 0.09.
Ariel mission visits are projected to achieve a precision of approximately 0.18 for these structural measurements.

Scientific study

Identifying deformed exoplanets with JWST and Ariel: A target selection metric for phase curve observations (external link)