First results of Herschel-SPIRE observations of Titan

We investigate the composition of Titan’s stratosphere from high-resolution submillimetric observations performed with the SPIRE instrument on the Herschel satellite. From the flux density spectrum measured in the 20 − 52 cm-1 interval at an apodized resolution of 0.08 cm-1, we determine the stratospheric abundances of CH4, CO, HCN, as well as the isotopic ratios 12C/13C = 87 ± 6 in CO and 96 ± 13 in HCN, 14N/15N = 76 ± 6, and 16O/18O = 380 ± 60. The last of these results is the first documented measurement of Titan’s 16O/18O ratio in CO, with a value 24% lower than the terrestrial ratio.