Public PhD Defence Thomas Konings

Value of the Information & Strength of the Argument

The value of the information is high, as it presents original research that contributes to the understanding of exoplanet atmospheres, particularly the chemistry of warm gas giants. The argumentation is solid, built on a logical progression from basic concepts to specific findings. Konings clearly explains the reasoning behind each step, from the choice of target (WASP-107b) to the interpretation of spectral features. He acknowledges the limitations of 1D models and the complexity of the chemistry, which strengthens the credibility of his conclusions. The use of chemical network analysis to identify the dominant pathway for SO2 formation is a particularly strong point, as it provides mechanistic insight rather than just correlational evidence.

Scientific Rigor, Source Quality, Title Accuracy

The scientific rigor is high, with a clear methodology and reliance on established observational data from Hubble and JWST. The sources are primarily the observational datasets and the models themselves, which are standard in the field. The title accurately reflects the content, focusing on atmospheric chemistry and data-driven modeling. The presentation is well-structured and the conclusions are drawn from the evidence presented. However, as a thesis defense, the work has not yet undergone peer review, which is a minor caveat. No comments were provided, so no analysis of public reception is included.

The title accurately reflects the content, which focuses on atmospheric chemistry of gaseous exoplanets using data-driven modeling and statistical inference.

8/10

The defense presents original research with a clear methodology, using established observational data (Hubble, JWST) and numerical models. The scientific process is transparent, with limitations acknowledged. The presentation is rigorous and well-structured, though it is a thesis defense and not peer-reviewed in the traditional sense.

Markers derived by PSI from the transcript: the creator did not define chapters.

• 02:00Introduction: Thomas Konings begins his presentation, thanking the audience and outlining the structure of his talk.
• 05:00Definition of exoplanets and overview of the diversity of known exoplanets, with a mention of the first discovery in 1995.
• 10:00Explanation of detection methods, focusing on the transit method and how it provides planetary radii.
• 15:00Introduction to atmospheric characterization and transmission spectra, explaining how molecular features appear.
• 20:00Discussion of the building blocks of atmospheres (temperature, chemistry, clouds, climate) and their interdependencies.
• 25:00Focus on WASP-107b: its properties, previous Hubble observations showing muted water features, and the absence of methane.
• 30:00Presentation of JWST observations of WASP-107b, revealing a clear SO2 feature and still no methane.
• 35:00Numerical modeling of SO2 abundance as a function of metallicity, and the use of synthetic spectra to interpret observations.
• 40:00Chemical network analysis to identify the fastest pathway from H2S to SO2, highlighting the role of photochemistry.
• 45:00Investigation of methane absence: three regimes (equilibrium, vertical mixing, photochemistry) and the effect of C/O ratio.

• Hubble Space Telescope observations of WASP-107b (2018) — Mentioned as the source of the initial transit spectrum showing muted water features and no methane.
• James Webb Space Telescope MIRI observations of WASP-107b — Mentioned as the source of the new data revealing SO2 and confirming the absence of methane.

• Previous studies on WASP-107b — The findings are consistent with earlier work that suggested the presence of clouds and the absence of methane.

• Equilibrium chemistry models — Equilibrium models predicted a methane-dominated atmosphere, which is contradicted by the observed absence of methane.