We present an observation of the very late thermal pulse object V4334 Sgr ( Sakurai ’ s Object ) with the Infrared Spectrometer ( IRS ) on the Spitzer Space Telescope .
The emission from 5-38 \mu m is dominated by the still-cooling dust shell .
A number of features are seen in absorption against the dust shell , which we attribute to HCN and polyyne molecules .
We use these features to determine the ^ { 12 } C/ ^ { 13 } C ratio for the absorbing gas to be \sim 3.2 ^ { +3.2 } _ { -1.6 } ; this implies that , despite the H-content of the molecules , the hydrocarbon-bearing gas must have originated in material produced in the very late thermal pulse .
We see no evidence of emission lines , despite the recently-reported optical and radio observations that suggest the effective temperature of the stellar remnant is rising .