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A&A 400, 279-291 (2003)
DOI: 10.1051/0004-6361:20021908

Long-term spectroscopic monitoring of the Luminous Blue Variable HD 160529

O. Stahl¹, T. Gäng², C. Sterken³, A. Kaufer⁴, T. Rivinius^{1, 4}, T. Szeifert⁴ and B. Wolf<sup>1

1</sup>  Landessternwarte Königstuhl, 69117 Heidelberg, Germany
²  L-3 Communications, NASA/GSFC, Greenbelt, MD 20771, USA
³  Astronomy Group, Vrije Universiteit Brussel, Pleinlan 2, 1050 Brussels, Belgium
⁴  European Southern Observatory, 85748 Garching, Karl-Schwarzschild-Str. 2, Germany

(Received 7 November 2002 / Accepted 19 December 2002 )

Abstract
We have spectroscopically monitored the galactic Luminous Blue Variable HD 160529 and obtained an extensive high-resolution data set that covers the years 1991 to 2002. During this period, the star evolved from an extended photometric minimum phase towards a new visual maximum. In several observing seasons, we covered up to four months with almost daily spectra. Our spectra typically cover most of the visual spectral range with a high spectral resolution ( 20 000 or more). This allows us to investigate the variability in many lines and on many time scales from days to years. We find a correlation between the photospheric HeI lines and the brightness of the star, both on a time scale of months and on a time scale of years. The short-term variations are smaller and do not follow the long-term trend, strongly suggesting different physical mechanisms. Metal lines also show both short-term and long-term variations in strength and also a long-term trend in radial velocity. Most of the line-profile variations can be attributed to changing strengths of lines. Propagating features in the line profiles are rarely observed. We find that the mass-loss rate of HD 160529 is almost independent of temperature, i.e. visual brightness.

Key words: stars: individual: HD 160529 -- stars: early-type -- stars: emission-line, Be -- stars: variables: general -- stars: mass-loss

Offprint request: O. Stahl, O.Stahl@lsw.uni-heidelberg.de

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