The D/H ratio in Titan's acetylene from high spectral resolution IRTF/TEXES observations

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Auteurs principaux: Bézard, B., Nixon, C. A., Vinatier, S., Lellouch, E., Greathouse, T., Giles, R., Lombardo, N. A., Jolly, A.
Format: Preprint
Publié: 2024
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author Bézard, B.
Nixon, C. A.
Vinatier, S.
Lellouch, E.
Greathouse, T.
Giles, R.
Lombardo, N. A.
Jolly, A.
author_facet Bézard, B.
Nixon, C. A.
Vinatier, S.
Lellouch, E.
Greathouse, T.
Giles, R.
Lombardo, N. A.
Jolly, A.
contents We report observations of deuterated acetylene (C$_2$HD) at 19.3 $μ$m (519 cm$^{-1}$) with the Texas Echelon Cross Echelle Spectrograph on the NASA Infrared Telescope Facility in July 2017. Six individual lines from the Q-branch of the $ν_4$ band were clearly detected with a S/N ratio up to 10. Spectral intervals around 8.0 $μ$m (745 cm$^{-1}$) and 13.4 $μ$m (1247 cm$^{-1}$) containing acetylene (C$_2$H$_2$) and methane (CH$_4$) lines respectively, were observed during the same run to constrain the disk-averaged C$_2$H$_2$ abundance profile and temperature profile. Cassini observations with the Composite Infrared Spectrometer (CIRS) were used to improve the flux calibration and help to constrain the atmospheric model. The measured D/H ratio in acetylene, derived from the C$_2$HD/C$_2$H$_2$ abundance ratio, is (1.22$^{+0.27}_{-0.21})$ $\times$ 10$^{-4}$, consistent with that in methane obtained in previous studies. Possible sources of fractionation at different steps of the acetylene photochemistry are investigated.
format Preprint
id arxiv_https___arxiv_org_abs_2407_20882
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The D/H ratio in Titan's acetylene from high spectral resolution IRTF/TEXES observations
Bézard, B.
Nixon, C. A.
Vinatier, S.
Lellouch, E.
Greathouse, T.
Giles, R.
Lombardo, N. A.
Jolly, A.
Earth and Planetary Astrophysics
We report observations of deuterated acetylene (C$_2$HD) at 19.3 $μ$m (519 cm$^{-1}$) with the Texas Echelon Cross Echelle Spectrograph on the NASA Infrared Telescope Facility in July 2017. Six individual lines from the Q-branch of the $ν_4$ band were clearly detected with a S/N ratio up to 10. Spectral intervals around 8.0 $μ$m (745 cm$^{-1}$) and 13.4 $μ$m (1247 cm$^{-1}$) containing acetylene (C$_2$H$_2$) and methane (CH$_4$) lines respectively, were observed during the same run to constrain the disk-averaged C$_2$H$_2$ abundance profile and temperature profile. Cassini observations with the Composite Infrared Spectrometer (CIRS) were used to improve the flux calibration and help to constrain the atmospheric model. The measured D/H ratio in acetylene, derived from the C$_2$HD/C$_2$H$_2$ abundance ratio, is (1.22$^{+0.27}_{-0.21})$ $\times$ 10$^{-4}$, consistent with that in methane obtained in previous studies. Possible sources of fractionation at different steps of the acetylene photochemistry are investigated.
title The D/H ratio in Titan's acetylene from high spectral resolution IRTF/TEXES observations
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2407.20882