Comment on “Comparison of the composition of the Tempel 1 ejecta to the dust in Comet C/Hale Bopp 1995 O1 and YSO HD 100546” by C.M. Lisse, K.E. Kraemer, J.A. Nuth III, A. Li, D. Joswiak [2007. Icarus 187, 69 86]

Abstract

Lisse et al. [Lisse, C.M., Kraemer, K.E., Nuth III, J.A., Li, A., Joswiak, D., 2007. Icarus 187, 69-86] recently presented a new analysis of an ISO spectrum of Comet C/1995 O1 (Hale-Bopp), from which they claimed the identification of many new dust species. Among them are PAHs, which were not found in our first analysis of the ISO spectra. We present here a re-examination of the ISO observations of Comet Hale-Bopp. From the absence of PAHs features in the 5.25-8.5 μm region, we infer that PAHs are at least twice less abundant than derived by Lisse et al. The carbonate feature at 7.00 μm is marginally present, but lower by a factor 2 to 3 than predicted by the model of Lisse et al.