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Session 19 - Hot Stars.
Display session, Monday, January 15
North Banquet Hall, Convention Center
We have observed the galactic Luminous Blue Variable (LBV) HD\,160529 with a spectral resolving power of R\approx\ 20\,000 in the wavelength range 3450\,Å\, < \lambda < 8650\,ÅThe observations were carried out with a fiber-linked echelle spectrograph at the ESO 50-cm telescope in La Silla from 1992 to 1995. In total over 200 spectra were obtained; each spectra with S/N\,\approx\,100 around 5500\,ÅP>We found that all spectral lines are variable. The lines with P Cygni-type profiles show variations in the emission as well as in the absorption components. Even pure absorption lines, forming deep in the atmosphere (e.g.\ He\,I\,\lambda5876 and Mg\,II\,\lambda4481), show signs of wind-influence, indicating that the observed variations are caused at the very base of the wind (e.g.\ by propagating density fluctuations starting at the photosphere).
The data is analyzed with the latest NLTE-codes of Hubeny et al (TLUSTY, SYNSPEC) to get reliable stellar parameters. The NLTE-results are compared with the output from other numerical codes in order to examine the significance and effects of the various parameters (LTE, spherical symmetry, wind,...) on the calculated synthetic atmospheres.
Finally we use the results from the previous (static) models as input for recently developed dynamical models (SEIDYNAMIC/Rivinius et al.\ 1995) to reconstruct the time-dependence of the observed line-profile variations.
Program listing for Monday