Log-scaled ISO-SWS spectrum of Wd1-9 covering 2.4–20 μm. Rest wavelengths of the principal emission lines and interstellar features are indicated, with the arrowed features <6 microns being interstellar C2 and the PAH identifications from Boersma et al. (2010). An illustrative three-component black body fit comprising a stellar source (25 kK; not shown for clarity), hot (~1050 K) and cool (~260 K) dust (short dashed lines) and the summation of the contributions (long dashed line) is also shown.