JpGU-AGU Joint Meeting 2020

Presentation information

[J] Oral

P (Space and Planetary Sciences ) » P-CG Complex & General

[P-CG26] New Developments of Planetary Sciences with ALMA

convener:Tetsuo Hasegawa(National Astronomical Observatory of Japan, National Institutes of Natural Sciences), Takayuki Muto(Division of Liberal Arts, Kogakuin University), Takahiro IINO(Information Technology Center, the University of Tokyo), Masumi Shimojo(National Astronomical Observatory of Japan)

[PCG26-08] Effect of GCR on the atmospheric chemistry process of Titan: a new constraint by the determination of 14N/15N in CH3CN with ALMA

*Takahiro IINO1, Hideo Sagawa2, Takashi Tsukagoshi3 (1.Information Technology Center, the University of Tokyo, 2.Kyoto Sangyo University, 3.National Astronomical Observatory of Japan)

Keywords:Titan, ALMA

By analyzing archival data obtained by the Atacama Large Millimeter/submillimeter Array (ALMA), we have successfully detected rotational transitions of CH3C15N (J = 19--18) at the 338 GHz band in Titan's atmospheric spectra.
Using the radiative transfer analysis, comparing those observations with the simultaneously observed CH3CN (J = 19--18) lines at the 349 GHz band, which probe from 160 to ~400 km altitude, we then derived 14N/15N in CH3CN as 125 (+145/-44). The best-fit value suggests that 14N/15N for CH3CN is higher than values that have been previously observed and theoretically predicted for HCN and HC3N.
This may be explained by the different N2 dissociation sources according to the altitudes, as suggested by a recent photochemical model.