New analysis technique reveals detailed atmospheric composition of planet WASP-39 b

Star system: WASP-39 | Distance from the Sun: 702 light years

WASP-39 b is a hot Jupiter, a large gas giant planet that orbits its host star at a very close distance, resulting in extremely high temperatures. Understanding the chemical makeup of its atmosphere provides insights into how the planet formed. A new analysis of data from the James Webb Space Telescope has now provided a precise inventory of the carbon and oxygen-bearing molecules in this planet's atmosphere using a single observation mode.

The research utilized an advanced technique called phase-resolved cross-correlation retrieval. This method, often used with ground-based telescopes, allows for high-resolution analysis of light passing through an atmosphere. By applying it to archival data of WASP-39 b, the team was able to distinguish chemical signatures that standard methods had previously missed.

This approach successfully detected water, carbon monoxide, carbon dioxide, and sulfur dioxide in the atmosphere of WASP-39 b. Specifically, it confirmed carbon monoxide as the primary carbon carrier, a molecule that standard retrieval methods struggled to identify in the same data. By measuring the concentrations of these molecules, researchers calculated a precise metallicity and a carbon-to-oxygen ratio for the planet.

These measurements match findings from previous studies that required combining multiple telescope observation modes. This success demonstrates that this high-resolution technique can maximize the scientific output of current and future space telescope observations, providing a more efficient way to study the atmospheres of distant worlds.

Key findings
- Identified major molecules including water, carbon monoxide, carbon dioxide, and sulfur dioxide.
- Confirmed carbon monoxide is the primary carbon carrier in the atmosphere of WASP-39 b.
- Derived a metallicity of 1.2 plus or minus 0.2 and a carbon-to-oxygen ratio of 0.68.
- Validated phase-resolved cross-correlation as a superior method for extracting data from single-mode observations.

Scientific study

Precise Determination of the Metallicity and C/O of WASP-39~b From a Single JWST Instrument Mode with Phase-Resolved Cross-Correlation Retrievals (external link)