NON-LTE SPECTROSCOPY OF ETHYLENE (C2H4) IN THE 1.6 μm SPECTRAL RANGE AT 3 DIFFERENT ROTATIONAL TEMPERATURES TO UNDERSTAND THE ATMOSPHERES OF THE HOT JUPITER EXOPLANETS - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2023

NON-LTE SPECTROSCOPY OF ETHYLENE (C2H4) IN THE 1.6 μm SPECTRAL RANGE AT 3 DIFFERENT ROTATIONAL TEMPERATURES TO UNDERSTAND THE ATMOSPHERES OF THE HOT JUPITER EXOPLANETS

Solène Perot
Michael M. Rey
Nicolas Suas-David
Julien Lecomte
Samir Kassi
Lucile Rutkowski
Robert Georges

Résumé

Accurate knowledge of the absorption fingerprint of the species expected in the atmospheres of the hot Jupiter exoplanets is required to allow their detection. Methane [1] and acetylene [2] were already detected in such environments, and the presence of other small hydrocarbons is expected. Therefore, it is necessary to provide unambiguous spectral assignment for ethylene (C2H4), which is not available beyond 3500 cm−1, partly due to its highly congested absorption spectrum at higher wavenumbers. We first focus on providing accurate assignments of the ethylene cold transitions. To do so, the jet-cooled gas is probed in the 1.65-1.68 nm spectral range using a cavity ring-down spectrometer. The low temperature is obtained by expanding the gas contained in a high pressure reservoir into a low-pressure chamber through a slit. This process leads to a simplification of the absorption spectrum by reducing drastically the rotational temperature and by narrowing the absorption line widths, which causes the sample to be in non-local thermodynamic equilibrium (non-LTE). Three spectra were recorded with a vibrational temperature of about 220K but different rotational temperatures: 5K, 35K and 75K. Unambiguous assignment of the observed lines was performed using the TheoReTS ab initio line list [3]. [1] M. R. Swain, G. Vasisht, G. Tinetti, Nature, 463 (7281), 637-639 (2008) [2] P. Giacobbe, et al., Nature, 592 (7853), 205-208 (2021) [3] M. Rey, A. V. Nikitin, Y. L. Babikov, and V. G. Tyuterev, J. Mol. Spectrosc., 327, 138–158 (2016)
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Dates et versions

hal-04185680 , version 1 (23-08-2023)

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  • HAL Id : hal-04185680 , version 1

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Solène Perot, Michael M. Rey, Nicolas Suas-David, Julien Lecomte, Samir Kassi, et al.. NON-LTE SPECTROSCOPY OF ETHYLENE (C2H4) IN THE 1.6 μm SPECTRAL RANGE AT 3 DIFFERENT ROTATIONAL TEMPERATURES TO UNDERSTAND THE ATMOSPHERES OF THE HOT JUPITER EXOPLANETS. 76th International Symposium on Molecular Spectroscopy (ISMS), Jun 2023, Urbana-Champaign, United States. ⟨hal-04185680⟩

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