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Astron. Astrophys. 346, 843-860 (1999)

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ISO observations of obscured Asymptotic Giant Branch stars in the Large Magellanic Cloud *

N.R. Trams 1, J.Th. van Loon 2, L.B.F.M. Waters 2,3, A.A. Zijlstra 4, C. Loup 5, P.A. Whitelock 6, M.A.T. Groenewegen 7, J.A.D.L. Blommaert 8, R. Siebenmorgen 8, A. Heske 8 and M.W. Feast 9

1 Integral Science Operations Centre, Astrophysics Div., Science Department, ESTEC, P.O.Box 299, 2200 AG Noordwijk, The Netherlands
2 Astronomical Institute, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
3 Space Research Organization Netherlands, Landleven 12, 9700 AV Groningen, The Netherlands
4 University of Manchester Institute of Science and Technology, P.O.Box 88, Manchester M60 1QD, UK
5 Institut d'Astrophysique de Paris, 98bis Boulevard Arago, F-75014 Paris, France
6 South African Astronomical Observatory, P.O. Box 9, 7935 Observatory, South Africa
7 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, D-85740 Garching bei München, Germany
8 ISO Data Centre, Astrophysics Division, Science Department of ESA, Villafranca del Castillo, P.O. Box 50727, E-28080 Madrid, Spain
9 Astronomy Department, University of Cape Town, 7700 Rondebosch, South Africa

Received 2 February 1999 / Accepted 9 April 1999


We present ISO photometric and spectroscopic observations of a sample of 57 bright Asymptotic Giant Branch stars and red supergiants in the Large Magellanic Cloud, selected on the basis of IRAS colours indicative of high mass-loss rates. PHOT-P and PHOT-C photometry at 12, 25 and 60 µm and CAM photometry at 12 µm are used in combination with quasi-simultaneous ground-based near-IR photometry to construct colour-colour diagrams for all stars in our sample. PHOT-S and CAM-CVF spectra in the 3 to 14 µm region are presented for 23 stars. From the colour-colour diagrams and the spectra, we establish the chemical types of the dust around 49 stars in this sample. Many stars have carbon-rich dust. The most luminous carbon star in the Magellanic Clouds has also a (minor) oxygen-rich component. OH/IR stars have silicate absorption with emission wings. The unique dataset presented here allows a detailed study of a representative sample of thermal-pulsing AGB stars with well-determined luminosities.

Key words: stars: carbon – stars: circumstellar matter – stars: mass-loss – stars: AGB and post-AGB – galaxies: Magellanic Clouds – infrared: stars

* This paper is based on observations with the Infrared Space Observatory (ISO). ISO is an ESA project with instruments funded by ESA member states (especially the PI countries: France, Germany, The Netherlands and the United Kingdom) and with the participation of ISAS and NASA.

Send offprint requests to: N.R. Trams (ntrams@astro.estec.esa.nl)

© European Southern Observatory (ESO) 1999

Online publication: June 17, 1999