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2.4-197 mu m spectroscopy of OH/IR stars: the IR characteristics of circumstellar dust in O-rich environments

Sylvester, RJ; Kemper, F; Barlow, MJ; de Jong, T; Waters, LBFM; Tielens, AGGM; Omont, A; (1999) 2.4-197 mu m spectroscopy of OH/IR stars: the IR characteristics of circumstellar dust in O-rich environments. Astronomy & Astrophysics , 352 (2) pp. 587-599. Green open access

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Abstract

Infrared spectra of a number of evolved O-rich stars have been obtained with the Short- and Long- Wavelength spectrometers on board the Infrared Space Observatory. The very broad wavelength coverage (2.4-197 mu m) obtained by combining observations made with the two spectrometers includes practically all of the flux emitted by the sources, and allows us to determine the emission and absorption features of the dense circumstellar dust shells. Agreement between the fluxes obtained by the two instruments is generally very good; the largest discrepancies are probably due to source variability. Our sample of oxygen-rich AGB stars exhibits a wealth of spectral features due to crystalline silicates and crystalline water ice in emission and absorption. In this study a qualitative overview of all features due to crystalline silicates and water ice in these high mass loss rate objects is presented. It seems that there is a certain onset value for the mass loss rate above which these features appear in the spectrum. Moreover, crystalline silicate emission features have been detected for the first time at wavelengths where the amorphous silicates are still in absorption, implying different spatial distributions for the two materials. A spherically symmetric and an axi-symmetric geometry are proposed. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) with the participation of ISAS and NASA.

Type: Article
Title: 2.4-197 mu m spectroscopy of OH/IR stars: the IR characteristics of circumstellar dust in O-rich environments
Open access status: An open access version is available from UCL Discovery
Publisher version: https://ui.adsabs.harvard.edu/abs/1999A%26A...352....
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Science & Technology, Physical Sciences, Astronomy & Astrophysics, stars : AGB and post-AGB, stars : circumstellar matter, stars : mass-loss, infrared : stars, LONG-WAVELENGTH SPECTROMETER, ABSORPTION FEATURES, INFRARED-EMISSION, BETA-PICTORIS, GRAIN-SIZE, WATER ICE, MASS-LOSS, H2O ICE, ISO, ENVELOPES
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10096063
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