Using SOFIA’s EXES To Search For C6H2 And C4N2 in Titan’s Atmosphere
In Titan’s atmosphere, the chemistry of small hydrocarbons and nitriles represent an important link from molecular species to the ubiquitous organic haze that gives Titan its characteristic yellow color.
Here we present a new search for two previously undetected molecules, triacetylene (C6H2) and the gas phase dicyanoacetylene (C4N2), using the Echelon-Cross-Echelle Spectrograph (EXES) instrument aboard the SOFIA (Stratospheric Observatory For Infrared Astronomy) aircraft. We do not detect these two molecules but determine upper limits for their mixing ratios and column abundances.
We find the 3σ upper limits on the uniform volume mixing ratio (VMR) above 100 km for C6H2 to be 4.3×10−11 which is lower than the photochemical model predictions. This new upper limit suggests that the growth of linear molecules is inhibited.
We also put a strict upper limit on the uniform VMR for gas phase C4N2 above 125 km to be 1.0×10−10. This upper limit is well below the saturation mixing ratio at this altitude for C4N2 and greatly limits the feasibility of C4N2) forming ice from condensation.
Zachary C. McQueen, Conor A. Nixon, Curtis de Witt, Véronique Vuitton, Panayotis Lavvas, Juan Alday, Nicholas A. Teanby, Joseph Penn, Antoine Jolly, Patrick G. J. Irwin
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2509.19127 [astro-ph.EP] (or arXiv:2509.19127v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2509.19127
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Submission history
From: Zachary McQueen
[v1] Tue, 23 Sep 2025 15:14:18 UTC (455 KB)
https://arxiv.org/abs/2509.19127
Astrobiology,
