The D/H ratio in Titan's acetylene from high spectral resolution IRTF/Texes observations
- 1LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS, Meudon, France (bruno.bezard@obspm.fr)
- 2SwRI, San Antonio TX, USA
- 3NASA/GSFC, Greenbelt MD, USA
- 4Yale University, New Haven CT, USA
- 5LISA, Université Paris-Est, Créteil, France
In July 2017, we used the Texes high-resolution spectrometer at the NASA Infrared Telescope Facility to observe Titan in the 19.3-µm (519 cm-1) region where the ν4 band of deuterated acetylene (C2HD) is located. Six individual lines were clearly detected with a S/N ratio up to 10. Spectral intervals around 8.0 (745 cm-1) and 13.4 µm (1247 cm-1) were observed during the same run to constrain the disk-averaged temperature profile and acetylene (C2H2) abundance profile respectively. Telluric correction and flux calibration were obtained from observations of asteroid Hygiea. Constraints from Cassini/CIRS observations in 2017 around the sub-Earth latitude were also used to constrain the atmospheric model and check the flux calibration. The D/H ratio is derived from the C2HD/C2H2 abundance ratio. Preliminary results of this analysis indicate a D/H ratio in acetylene around 1.7×10-5 with an uncertainty of about 10%, in agreement with the previous, less precise, determination from Cassini/CIRS measurements. This ratio is slightly larger than that in methane (approximately 1.3×10-5), which suggests some fractionation at work in the photochemical production of acetylene from methane.
How to cite: Bézard, B., Vinatier, S., Greathouse, T., Giles, R., Nixon, C., Lombardo, N., Jolly, A., and Despan, D.: The D/H ratio in Titan's acetylene from high spectral resolution IRTF/Texes observations, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-363, https://doi.org/10.5194/epsc2022-363, 2022.
