The thermal infrared spectra of comets Hale-Bopp and 103P/Harley 2 observed with the Infrared Space Observatory

Abstract

The Infrared Space Observatory (ISO) offered us the opportunity to observe celestial bodies over the full infrared range from 2.4 to 196 micron. This spectral domain is of peculiar interest for comets. Cometary parent molecules, likely to have sublimated from the nucleus ices, can be investigated through their fundamental bands of vibration in the 2.5-12-micron region. With temperatures ranging between 100 and 400 K or more, cometary grains show thermal emission peaking in the 5-200-micron region, where spectral features related to their chemical nature may be expected.