Atmospheric structure of WASP-94 A b revealed through new limb asymmetry method

A new analytical approach reveals distinct atmospheric differences between the leading and trailing edges of the exoplanet WASP-94 A b. By measuring small shifts in transit timing, researchers have successfully characterized the planet's temperature gradient and chemical composition, including the presence of water, carbon dioxide, carbon monoxide, and hydrogen sulfide on its evening side.

Star system: WASP 94 A | Distance from the Sun: 687 light years

A new method for analyzing light from distant planets allows for a detailed look at their atmospheres by comparing the leading and trailing edges of the planet. This technique addresses a common problem where previous methods created misleading data by treating these edges as linked. By focusing on the timing of when a planet crosses its star, the new framework provides a clearer picture of atmospheric composition and temperature without the biases found in older models. This approach significantly improves the precision of measurements regarding chemical elements within planetary atmospheres.

Researchers applied this method to the exoplanet WASP-94 A b using wide-ranging light data collected by space telescopes. The analysis shows that the planet has very different conditions on its two sides. The morning side of the planet is covered in a thick layer of aerosols, which are small particles suspended in the gas, making it difficult to see through. In contrast, the evening side is much clearer, allowing for the detection of water, carbon dioxide, carbon monoxide, and hydrogen sulfide. These findings provide a high-resolution map of the gas surrounding the planet.

Temperature measurements further highlight the differences between the two sides. At an atmospheric pressure of 1 millibar, the temperature difference between the morning and evening limbs is 415 Kelvin. Additionally, the study measured the metallicity and the ratio of carbon to oxygen in the atmosphere, both of which match the characteristics of the host star WASP-94 A. This consistency suggests a direct link between the composition of the star and the planet orbiting it.

Key findings
The morning side of WASP-94 A b is obscured by aerosols, while the evening side reveals signatures of water, carbon dioxide, carbon monoxide, and hydrogen sulfide.
A significant limb-to-limb temperature difference of 415 Kelvin exists at the 1 millibar pressure level.
The chemical composition of the atmosphere matches that of the host star WASP-94 A.
The new analytical framework improves the precision of atmospheric abundance measurements by up to 6 times.

Scientific study

A New Method for Constraining 3D Exoplanet Atmospheres: Application to WASP-94A b's Panchromatic Spectrum (external link)