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Astron. Astrophys. 315, L217-L220 (1996)

The ISO-SWS spectrum of NML Cyg*

K. Justtanont1, T. de Jong1,2, F.P. Helmich3, L.B.F.M. Waters2,1, Th. de Graauw1, C. Loup4, H. Izumiura5, I. Yamamura6,1, D.A. Beintema1, F. Lahuis1,7, P.R. Roelfsema1, and E.A. Valentijn1

1 SRON/Groningen, P.O.Box 800, 9700 AV Groningen, The Netherlands
2 Astronomical Institute `Anton Pannekoek', University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
3 Leiden Observatory, P.O. Box 9513, 2300 RA Leiden, The Netherlands
4 Institut d'Astrophysique, 98 bis Bd Arago, F-75014 Paris, France
5 Okayama Astrophysical Observatory, National Astronomical Observatory, Kamogata, Asaguchi, Okayama 719-02, Japan
6 Department of Astronomy, University of Tokyo, 2-11-16 Yayoi-cho, Bunkyo-ku, Tokyo 113, Japan
7 SIDT, ESA Villafranca, P.O. Box 50727, E-28080 Madrid, Spain

Received 16 July 1996 / Accepted 2 August 1996

Abstract. The high resolution spectrum of NML Cyg observed with the ISO-SWS in its slow-speed grating mode (2.4-45 img1.gifm) shows a wealth of features never seen before in previous observations. These include ro-vibrational lines of H2O at 2.7 and 6.2 img1.gifm, of OH between 3 and 3.5 img1.gifm and a deep absorption band of CO2 at 4.26 img1.gifm. We also report on the detection of pure rotational emission lines of H img2.gif O between 35 and 45 img1.gifm and of the 34.6 img1.gifm absorption line of OH which is thought to pump the well known 1612 MHz OH maser line. There are two, as yet, unidentified features at 33 and 40 img1.gifm which may be related to silicate dust.

Key words: stars: AGB and post-AGB - stars: circumstellar matter - stars: individual (NML Cyg) - stars: late-type - infrared: stars

* 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
© European Southern Observatory (ESO) 1996