The Infrared Spectrum Of Comet Hale-Bopp As Seen By The Infrared Space Observatory

Abstract

. Spectra of comet C/1995 O1 (Hale-Bopp) were obtained with the Infrared Space Observatory (ISO) at medium resolution with the grating spectrometer in the photometer (PHT-S) and/or at high resolution with the short wavelength spectrometer (SWS) and long wavelength spectrometer (LWS) in April 1996 (Crovisier et al., 1996), September--October 1996 (Crovisier et al., 1997a, 1997b) and December 1997, at distances from the Sun of 4.6, 2.9 and 3.9 AU, respectively. For the first time, high-resolution spectra of a comet covering the entire 2.4 to 200 ¯m spectral range were obtained. The vibrational bands of H2O, CO2 and CO are detected in emission with PHTS. Relative production rates of 100:22:70 are derived for H2O:CO2:CO at 3 AU pre-perihelion. H2O is observed at high spectral resolution in the 3 group of bands around 2.7 ¯m and the 2 group around 6 ¯m with SWS, and in several rotational lines in the 100--180 ¯m region with LWS. The high signal-to-noise ratio of the 3 band observed on Sep...