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Astron. Astrophys. 315, L245-L248 (1996)

SWS observations of young main-sequence stars with dusty circumstellar disks *

C. Waelkens1, L.B.F.M. Waters2,3, M.S. de Graauw2, E. Huygen1, K. Malfait1, H. Plets1, B. Vandenbussche1,5, D.A. Beintema2,5, D.R. Boxhoorn2, H.J. Habing4, A.M. Heras5, D.J.M. Kester2, F. Lahuis5, P.W. Morris5,6, P.R. Roelfsema2,5, A. Salama5, R. Siebenmorgen5, N.R. Trams5, N.R. van der Bliek4, E.A. Valentijn2,5, and P.R. Wesselius2

1 Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200B, 3001 Heverlee, Belgium
2 SRON Space Research Laboratory, Groningen, The Netherlands
3 Astronomisch Instituut, Universiteit van Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
4 Sterrewacht Leiden, P.O. Box 9513, 2300 RA Leiden, The Netherlands
5 ISO Science Team, VILSPA, P.O. Box 50727, 28080 Madrid, Spain
6 SRON, Sorbonnelaan 2, 3584 CA Utrecht, the Netherlands

Received 16 July 1996 / Accepted 22 August 1996

Abstract. We present SWS full-scan observations of three objects that are thought to be in a stage of evolution between the youngest, embedded, Herbig Ae/Be stars and Beta Pictoris, a young main-sequence star with a circumstellar disk. The 8-12 img1.gifm spectra of all three stars cannot be understood in terms of purely amorphous silicates, but require the presence of crystalline silicates in different amounts. Around two objects both oxygen-rich and carbon-rich dust particles are present: the spectrum of HD 100546 displays the full set of UIR features; in the spectrum of HD 142527 both the 3.29 and 3.42 img1.gifm emission features are observed, as well as a strong 3.51  img1.gifm feature. The spectrum of HD 100546 is extremely rich in silicate features in the spectral range from 20 to 45 img1.gifm; some of these features strongly suggest the presence of appreciable amounts of crystalline silicates.

Key words: Circumstellar matter - Stars: Individual: HD100546 - Stars: Individual: HD142527 - Stars: Individual: 51 Oph - ISM: abundances - Infrared: ISM: lines and bands

* 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) and with the participation of ISAS and NASA

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Last change: December 16, 1996
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