Solar system

Abstract:

This Letter reports the first detection of the three ¹³C isotopologues of HC3N on Titan, from Cassini Composite Infrared Spectrometer (CIRS) infrared spectra. The data are limb spectra taken at latitudes N54°-N69° in 2006 and 2007 when HC3N was enhanced in the north. Using a new line list for the vs bands of all isotopologues, we have modeled the isolated emission of H¹³CCCN at 658.7 cm^-1 and both HC¹³CCN and HCC¹³CN at 663.0 cm^-1, which are blended with the Q-branch of HC3N at 663.3 cm^-1 at the resolution of CIRS (0.5 cm^-1) and detectable as an increase in the intensity of the low-frequency wing. Using the resolved pair H¹³CCCN /HC3N we find ¹²C/ ¹³C = 79 ± 17, in line with other measurements on Titan from Cassini and Huygens. © 2008, The American Astronomical Society, All rights reserved.