17:15 〜 18:30
[MIS14-P08] An experimental study on evaporite formation around the north pole of Titan
キーワード：タイタン、液体メタン、蒸発岩、有機物エアロゾル、ソリン
Through the Cassini-Huygens mission, 5μm-bright deposits are found at dried lakebeds and along paleo-shorelines of the north pole regions of Titan, which are inferred as organic evaporites (Barnes et al. 2009, 2011).
Evaporites on Titan can be formed when dissolved organic matter in liquid methane lakes is concentrated and precipitated upon drying (Barnes et al. 2009, 2011). Thus, they could be a proxy indicator of arid climates through effective evaporation of liquid methane. In addition, evaporative condensation promotes syntheses of complex organic molecules on Titan.
The previous study (Cordier et al. 2013) suggested that the main components of evaporites would be acetylene and butane solids based on results of photochemical calculation of precipitation rates of organic solids in Titan atmosphere (Lavvas et al. 2008).
However, spectral features of evaporites resembles to benzene and cyanoacetylene solids, rather than acetylene and butane solids (Clark et al. 2010).
Given that organic aerosols may be composed of PAHs, such as benzene, and nitriles, such as cyanoacetylene, dissolution of benzene and nitriles from organic aerosols by liquid methane could explain the enrichments of these molecules in evaporates on Titan. Nevertheless, there is no experimental study that investigates the solubility of organic aerosol analogs by liquid methane.
Here, we construct laboratory experimental system that can investigate interactions between organic aerosol analogues, called Titan tholin, and liquid methane. We developed a stainless-steel liquid methane generator that can keep liquid methane through controlling temperature inside the chamber. After immersing Titan tholin into liquid methane in the generator, dissolved species in liquid methane are analyzed with a gas chromatograph.
Evaporites on Titan can be formed when dissolved organic matter in liquid methane lakes is concentrated and precipitated upon drying (Barnes et al. 2009, 2011). Thus, they could be a proxy indicator of arid climates through effective evaporation of liquid methane. In addition, evaporative condensation promotes syntheses of complex organic molecules on Titan.
The previous study (Cordier et al. 2013) suggested that the main components of evaporites would be acetylene and butane solids based on results of photochemical calculation of precipitation rates of organic solids in Titan atmosphere (Lavvas et al. 2008).
However, spectral features of evaporites resembles to benzene and cyanoacetylene solids, rather than acetylene and butane solids (Clark et al. 2010).
Given that organic aerosols may be composed of PAHs, such as benzene, and nitriles, such as cyanoacetylene, dissolution of benzene and nitriles from organic aerosols by liquid methane could explain the enrichments of these molecules in evaporates on Titan. Nevertheless, there is no experimental study that investigates the solubility of organic aerosol analogs by liquid methane.
Here, we construct laboratory experimental system that can investigate interactions between organic aerosol analogues, called Titan tholin, and liquid methane. We developed a stainless-steel liquid methane generator that can keep liquid methane through controlling temperature inside the chamber. After immersing Titan tholin into liquid methane in the generator, dissolved species in liquid methane are analyzed with a gas chromatograph.