TESS phase curve mapping confirms a cloud-free dayside for planet WASP-43 b

Star system: WASP-43 | Distance from the Sun: 284 light years

WASP-43 b is a hot Jupiter, a massive gas giant planet that orbits extremely close to its host star, causing it to have a very high surface temperature. By analyzing five sectors of observations from the TESS space telescope, researchers mapped the planet's phase curve—the change in brightness as the planet orbits its star—to study the composition of its atmosphere and determine if it possesses reflective clouds on its dayside.

To investigate the atmospheric properties, the TESS data were compared against previous multi-band analyses. The study measured the mid-eclipse depth, which is the dip in light when the planet passes behind its star, at 130 parts per million. This value is higher than predicted by thermal emission models, indicating that the planet reflects a small portion of light from its star.

By measuring the geometric albedo, or the planet's total reflectivity, at approximately 0.05 to 0.10, the study confirms the dayside of WASP-43b is largely cloud-free. Furthermore, the detected eastward shift of 44 degrees in the phase curve offset indicates that the telescope is detecting heat from deep within the planet's hot interior.

Key findings
- Mid-eclipse depth measured at 130 parts per million, indicating excess brightness.
- Geometric albedo estimated between 0.05 and 0.10, suggesting low reflectivity.
- Large eastward phase curve offset of 44 degrees indicates a cloud-free dayside.
- Excess emission in the TESS band provides evidence for a hot deep atmosphere.

Scientific study

WASP-43b TESS Phase Curve Mapping: Evidence for a Hot Interior (external link)