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Astron. Astrophys. 315, L229-L232 (1996)

The ISO-SWS spectrum of P Cygni*

H.J.G.L.M. Lamers1,2, F. Najarro3, R.P.Kudritzki3,4, P.W. Morris5,2, R.H.M. Voors1,2, J.I. van Gent1,2, L.B.F.M. Waters6,7, Th. de Graauw7, D. Beintema5,7, E.A. Valentijn5,7, and D.J. Hillier8

1 Astronomical Institute, University of Utrecht, Princetonplein 5, 3584 CC Utrecht, The Netherlands
2 SRON Laboratory for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
3 Institut für Astronomie und Astrophysik der Universität München, Scheinerstr. 1, D-81679 München, Germany
4 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85740 Garching bei München, Germany
5 ISO Science Operations Center, Astrophysics Division of ESA, PO Box 50727, E-28080 Villafranca, Madrid, Spain
6 Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdan, The Netherlands
7 SRON Laboratory for Space Research, PO Box 800, 9700 AV Groningen, The Netherlands
8 Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA

Received 23 July 1996 / Accepted 13 August 1996

Abstract. The free-free IR excess and the IR emission lines of H and He I of the Luminous Blue Variable P Cygni are observed with the ISO-SWS instrument. The observed profiles and the free-free emission are compared with predictions from a non-LTE model atmosphere with a stellar wind. The observations agree very well with a model that has the following properties: Timg1.gif = 18100 K, Rimg2.gif = 76 Rimg3.gif , He/H=0.30 by number, img4.gif Mimg3.gif yr-1 and img7.gif =185 km s-1. We observed forbidden emission lines of [Fe II], [Fe III], [Ni II], [Ne II], [Ne III] and [Si II]. >From the study of the [Ne II] and [Ne III] lines we find that the Ne abundance is about three times higher than normal. This may be due to clumping in the CS envelope at img9.gif .

Key words: stars: early-type - stars: mass-loss - stars: atmospheres - stars: supergiants - stars: individual: P Cygni

* Based on observations made with ISO, an ESA project with instuments funded by the ESA member states (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) with the participation of ISAS and NASA

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Last change: December 16, 1996
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