ALMA detection and astrobiological potential of vinyl cyanide on Titan

作者：Palmer Maureen Y^*; Cordiner Martin A; Nixon Conor A; Charnley Steven B; Teanby Nicholas A; Kisiel Zbigniew; Irwin Patrick G J; Mumma Michael J

来源：Science Advances, 2017, 3(7): e1700022.

DOI：10.1126/sciadv.1700022

Recent simulations have indicated that vinyl cyanide is the best candidate molecule for the formation of cell membranes/vesicle structures in Titan's hydrocarbon-rich lakes and seas. Although the existence of vinyl cyanide (C2H3CN) on Titan was previously inferred using Cassini mass spectrometry, a definitive detection has been lacking until now. We report the first spectroscopic detection of vinyl cyanide in Titan's atmosphere, obtained using archival data from the Atacama Large Millimeter/submillimeter Array ( ALMA), collected from February to May 2014. We detect the three strongest rotational lines of C2H3CN in the frequency range of 230 to 232 GHz, each with >4 sigma confidence. Radiative transfer modeling suggests that most of the C2H3CN emission originates at altitudes of greater than or similar to 200 km, in agreement with recent photochemical models. The vertical column densities implied by our best-fitting models lie in the range of 3.7 x 10(13) to 1.4 x 10(14) cm(-2). The corresponding production rate of vinyl cyanide and its saturation mole fraction imply the availability of sufficient dissolved material to form similar to 10(7) cell membranes/cm(3) in Titan's sea Ligeia Mare.

• 出版日期2017-7