ISO LWS Observations of Cool Evolved Stars and Post-AGB Objects

Abstract

This review reports, on behalf of the LWS Consortium1, some of the spectroscopic results on dust and molecules around cool evolvd stars and postAGB objects that have been obtained at far-infrared wavelengths by the Infrared Space Observatory (ISO) since its launch in November 1995. The review will concentrate on oxygen-rich objects, while the companion review by J. Cernicharo will concentrate largely on carbon-rich objects. The results reported have been obtained mainly using ISO’s Long Wavelength Spectrometer (LWS; Clegg et al. 1996), but for some objects complementary spectra have also been obtained with the Short Wavelength Spectrometer (SWS; de Graauw et al. 1996). Highlights include the first detection of the far-infrared rotational lines of water vapour from cool star winds, showing them to be the dominant coolant in the winds; the detailed confirmation of the proposed radiative pump mechanism for circumstellar OH masers; and the detection of water ice emission bands and several new far-IR dust features in the LWS spectra of OH/IR stars, post-AGB objects and planetary nebulae.