P071-07
Aerosol-Organic Condensates-Lake Interactions on Titan

Tuesday, 15 December 2020: 07:24
Virtual
Yue Yu1, Julia Garver2, Xinting Yu1 and Xi Zhang3, (1)University of California Santa Cruz, Earth and Planetary Sciences, Santa Cruz, CA, United States, (2)University of California Santa Cruz, Physics, Santa Cruz, CA, United States, (3)UC Santa Cruz, Earth and Planetary Sciences, Santa Cruz, CA, United States
Recorded Presentation
Abstract:
Titan is a dynamic world with a unique N2-CH4 atmosphere where photochemistry actively converts nitrogen and methane into organic molecules such as C2H6, C2H2, C6H6, HCN, etc [1]. These simple organic molecules could further polymerize into more complex molecules and coagulate to form the refractory aerosols that make up Titan’s haze layers. Observations have detected layers of clouds made of the simple organic species in Titan’s atmosphere, such as CH4, C2H6, C6H6, HCN, etc [2]. The goal of this project is to provide a theoretical framework to better understand Titan’s cloud formation through wetting theories. Many of the cloud species would remain solid when they fall onto Titan’s surface, so we also aim to study the interactions between these species and the surface of Titan’s lakes.

We first determined the species that are condensable in Titan’s atmosphere by plotting their condensation curves over the temperature profile of Titan. We found that CH4, C2H6, C2H2, C3H4, C3H6, C4H2, C6H6, C2N2, C4N2, HCN, and HC3N form solid condensates and C3H8 form a liquid condensate. The refractory solid aerosols could act as cloud seeds for these potential cloud condensates. We used the previously determined surface energy of Titan’s aerosol analog “tholin” to estimate the liquid-solid/ice-solid contact angles between the potential condensates and Titan’s aerosol [3, 4]. We found that all contact angles between organic condensates and aerosols are relatively small (<35°). This indicates that Titan’s aerosols are easily wettable and thus are good cloud seeds for most hydrocarbon and nitrile clouds in Titan’s atmosphere. We also found small contact angles between the solid organic species and the Titan lakes (a mixture of CH4, C2H6, and N2), which means that these organics are unlikely to float on Titan’s lake surfaces.

  1. Hörst, S. M. 2017, JGR-Planets, 122, 432–482
  2. Anderson, C. M., et al., 2018, SSRv, 214, 125
  3. Yu, X., et al., 2017 JGR-Planets, 122, 2610
  4. Yu, X., et al. In revision
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