Measurements And Predictions Of H2 Pressure-broadening Coefficients Of CO2 Absorption Lines For Exoplanet Atmosphere Studies

Accurate and comprehensive H₂ pressure-induced broadening data for CO₂ infrared lines over a wide temperature range are essential for modeling atmospheric opacity of exoplanets. However, available data are currently limited, some of which are affected by large uncertainties.

In this work, H₂ induced pressure-broadening and pressure-shift coefficients were determined at room temperature for the entire nu3 band of CO₂ in the 4.3 micrometer spectral region using a high-resolution Fourier transform spectrometer. In addition, requantized molecular dynamics simulations of the CO₂-H₂ system were performed using an accurate intermolecular potential.

These simulations provide theoretical predictions of H₂-broadening coefficients for CO₂ lines over a temperature range of 200-1000 K and for rotational quantum number up to J=120. The predicted results show very good agreement with the experimental data, with difference of less than 3%, well below the precision required for exoplanet atmosphere studies.

This work provides the first accurate and comprehensive dataset of H₂2 broadening coefficients for CO₂ lines, suitable for modeling of H₂-rich exoplanetary atmospheres.

Faten Hendaoui, Pascale Chelin, Xavier Landsheere, Hassen Aroui, Ha Tran

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2605.11761 [astro-ph.EP] (or arXiv:2605.11761v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2605.11761
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Related DOI:
https://doi.org/10.1051/0004-6361/202659106
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Submission history
From: Ha Tran
[v1] Tue, 12 May 2026 08:33:17 UTC (6,264 KB)
https://arxiv.org/abs/2605.11761
Astrobiology,