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Radiation-driven winds of hot luminous stars. XIII. A description of NLTE line blocking and blanketing towards realistic models for expanding atmospheres
Spectral analysis of hot luminous stars requires adequate modelatmospheres which take into account the effects of NLTE and radiationdriven winds properly. Here we present significant improvements of ourapproach in constructing detailed atmospheric models and syntheticspectra for hot luminous stars. Moreover, as we regard our solutionmethod in its present stage already as a standard procedure, we make ourprogram package WM-basic available to the community (download ispossible from the URL given below). The most important modelimprovements towards a realistic description of stationary wind modelsconcern: [(i)] A sophisticated and consistent description of lineblocking and blanketing. Our solution concept to this problem rendersthe line blocking influence on the ionizing fluxes emerging from theatmospheres of hot stars - mainly the spectral ranges of the EUV and theUV are affected - in identical quality as the synthetic high resolutionspectra representing the observable region. In addition, the lineblanketing effect is properly accounted for in the energy balance.[(ii)] The atomic data archive which has been improved and enhancedconsiderably, providing the basis for a detailed multilevel NLTEtreatment of the metal ions (from C to Zn) and an adequaterepresentation of line blocking and the radiative line acceleration.[(iii)] A revised inclusion of EUV and X-ray radiation produced bycooling zones which originate from the simulation of shock heatedmatter. This new tool not only provides an easy-to-use method for O-stardiagnostics, whereby physical constraints on the properties of stellarwinds, stellar parameters, and abundances can be obtained via acomparison of observed and synthetic spectra, but also allows theastrophysically important information about the ionizing fluxes of hotstars to be determined automatically. Results illustrating this arediscussed by means of a basic model grid calculated for O-stars withsolar metallicity. To further demonstrate the astrophysical potential ofour new method, we first provide a detailed spectral diagnosticdetermination of the stellar parameters, the wind parameters, and theabundances by an exemplary application to one of our grid-stars, theO9.5Ia O-supergiant alpha Cam. Our abundance determinations of the lightelements indicate that these deviate considerably from the solar values.
| SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
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