In January 2024, I was contacted by a science writer about my PhD research on quantum chemistry, biosignatures, and exoplanet atmospheres. After multiple online meetings and back-and-forth emails, the story is now out in the August 2025 issue in Astronomy magazine!
Full story: The search for biosignatures in the Milky Way
In short
This feature explores one of the biggest questions in science: Are we alone in the universe? And for the first time, we’re starting to search for answers by looking not at distant stars themselves, but at the planets that orbit them, particularly, at the gases in their atmospheres.
Using the James Webb Space Telescope (JWST), astronomers can now detect the faint fingerprints of molecules in exoplanet atmospheres through transmission spectroscopy. As a planet passes in front of its host star, some of the starlight filters through the planet’s atmosphere. Molecules in that atmosphere absorb certain wavelengths of light, leaving behind distinct (though often subtle) signatures in the observed spectrum.
The story focuses on how scientists decode these signals, highlighting the detection of sulfur dioxide (SO2) in the atmosphere of the gas giant WASP-39b. This molecule hadn’t been predicted in earlier models. Only after incorporating high-energy photochemistry, where ultraviolet light breaks apart molecules like water and initiates a chain of chemical reactions, did researchers realise SO2 could form in large enough quantities to explain the observed signal.
To make such discoveries possible, astronomers rely on detailed laboratory measurements and computational models that simulate how molecules absorb light under different conditions. This collaboration between observatories and lab-based science is essential, especially as attention shifts toward rocky, potentially habitable worlds around M-dwarf stars.
The feature reminds us that interpreting exoplanet spectra isn’t just about pointing a telescope at the sky. It’s about combining physics, chemistry, and astronomy to understand what’s really going on in these atmospheres!
My contribution to the story: Approximate spectral data for biosignatures
One of the big challenges we face in exoplanet science today is that telescope data is revealing spectral features we can’t yet explain; signals that don’t match any known molecule in existing spectroscopic databases. This is becoming more and more common, especially with the James Webb Space Telescope now delivering some of the most detailed observations of exoplanet atmospheres to date.
Characterising the chemistry of these atmospheres is key to understanding how exoplanets evolve, how their climates behave, and whether they might support life. But to identify molecules in these atmospheres, we rely on reference spectra from high-resolution molecular spectroscopy. Unfortunately, generating this data is slow and time-expensive. It requires heavy-duty quantum chemistry calculations and precise lab measurements. As of the time of writing my PhD thesis (August 2023), only about 100 molecules had high-resolution infrared spectra available. That means our ability to detect new molecules is seriously limited: if we lack spectral data for a molecule, we simply can’t find it in a telescope spectrum.
To help address this, in my PhD I used computational quantum chemistry to predict approximate infrared spectra for over 2700 molecules that are considered potentially relevant in astrochemistry, but that previously had no spectral data available. While these spectra are not accurate enough for final identifications, they’re good enough to help narrow down the list of possible candidates behind those unidentified signals, and guide future lab work and high-accuracy calculations.
This work feeds directly into the bigger picture explored in the story. As we push towards detecting possible biosignatures in exoplanet atmospheres, having a wider library of candidate spectra becomes essential. Without it, we risk missing key molecules, or worse, misidentifying them!
Expanding our spectroscopic toolkit is one piece of the puzzle, and it’s exciting to see how contributions and collaborations like this can support the next generation of exoplanet science!