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Astron. Astrophys. 327, 265-272 (1997)

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A spectral analysis of HDE 269445
from optical and infrared observations *

A. Pasquali 1, W. Schmutz 2, A. Nota ** 1 and L. Origlia 3

1 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
2 Institut für Astronomie, ETH-Zentrum, CH-8092 Zürich, Switzerland
3 Osservatorio Astronomico di Torino, Italy

Received 23 December 1996 / Accepted 9 May 1997

Abstract

We present new, near-IR spectroscopic observations of HDE 269445, which we combine with published HST and IUE ultraviolet data and optical high resolution spectra. We discuss the spectral morphology of the star from UV to near-IR wavelengths, concentrating on profile variations in the UV and optical H and He lines. From a spectroscopic analysis with non-LTE model atmospheres, we derive for HDE 269445: T [FORMULA] = 34000 K, R [FORMULA] = 43 R [FORMULA], log [FORMULA] (M [FORMULA] /yr) = -4.5 and He/H = 0.4/0.6 by number. These parameters are in good agreement with those previously derived by Pasquali et al. (1997) who used only ultraviolet and optical lines. Therefore, our analysis confirms that a combination of optical and infrared lines can be fruitfully used to determine stellar and wind properties when ultraviolet data are not available.

Our model calculations only fit the broad component underneath a strong core emission. We interpret the discrepancy between the observed and the model line profiles as the effect of a non-spherical wind which has a hot, fast polar component and a cold, slow equatorial component. The time-variability detected in some H and He lines indicates that the wind geometry may be variable and the star has undergone changes in Teff and [FORMULA]. These properties are similar to those observed for the galactic LBV AG Carinae by Leitherer et al. (1994) and we may suspect that HDE 269445 is also a Luminous Blue Variable. This could explain why HDE 269445 has defied easy spectral classification, and, although originally classified as a Ofpe/WN9, it has always represented a peculiarity for this spectral type.

Key words: stars: atmospheres - mass-loss - early-type - Wolf-Rayet - HDE 269445 (LMC)

* Based on observations obtained at the European Southern Observatory, La Silla
** Affiliated with the Astrophysics Division, Space Science Department of the European Space Agency

Send offprint requests to: A. Pasquali

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© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998
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