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Session 32 - Stellar Astrophysics II.
Oral session, Monday, January 15
La Condesa, Hilton

[32.02] Combined Stellar Structure and Atmosphere Models: Spectral and Interior Evolution of Massive Stars

D. Schaerer (STScI)

We present the first ``complete stellar models'' for massive stars, which consistently treat the stellar interior, the atmosphere, and the stellar winds. The non-LTE atmosphere models in particular also include line blanketing. This approach allows to simultaneously predict basic stellar parameters (luminosity, radii, temperatures), nucleosynthesis (abundances), as well as the detailed emergent spectrum through the relevant evolutionary phases (corresponding to OB, LBV and Wolf--Rayet stars). On the other hand, our modelling including the stellar winds also allows to study the influence of the outer layers on the stellar structure and evolution.

We here concentrate on the main sequence (MS) interior and spectral evolution of massive stars at solar metallicity. The main CoStar predictions presented and discussed for the MS are the following: 1) Ejected mass of the most important elements. Deposition of wind momentum and mechanical energy, 2) Estimates of mass loss rates due to radiation pressure including multiple scattering and line overlap, 3) Continuous spectral energy distribution (EUV to IR) and ionising fluxes, 4) UBVRIJHKLMN photometric evolution, 5) UV colours, 6) Detailed metal line blanketed UV spectra, 7) Non--LTE hydrogen and helium line spectra in the visible and IR, including theoretical K band spectra, and 8) Fit formulæ\ to derive mass loss rates from H\alpha, P\alpha and B\alpha equivalent width measurements.

We discuss the morphological evolution of the UV spectrum as well as the IR continuum and line spectrum. Particular importance is drawn on the H, He, and He^+ ionising spectrum of massive stars. The importance of non-LTE and wind effects on the predicted ionising fluxes is shown. We also discuss their implications on studies of massive star populations in HII regions, starbursts and related objects.

Program listing for Monday