Theory of extended stellar atmospheres. II - A grid of static spherical models for O stars and planetary nebula nuclei

Kunasz, P. B.; Hummer, D. G.; Mihalas, D.

doi:10.1086/153955

Cited by 26 publications

(16 citation statements)

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“…The METUJE spectrum is generally flatter; lower flux at high frequencies is accompanied with higher flux at visual frequencies. This trend has already been described for simple static spherically symmetric model atmospheres calculated without line blanketing (Kunasz et al 1975;Kubát 1996). Small differences at higher frequencies are also connected with more elaborate line blanketing in the TLUSTY models, and with simplified treatment of the line source function in the kinetic equilibrium equations using Sobolev approximation in our models.…”

Section: Comparison With Tlustysupporting

confidence: 78%

Comoving frame models of hot star winds

Krtička

Kubát

2017

A&A

101

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We calculate global (unified) wind models of main-sequence, giant, and supergiant O stars from our Galaxy. The models are calculated by solving hydrodynamic, kinetic equilibrium (also known as NLTE) and comoving frame (CMF) radiative transfer equations from the (nearly) hydrostatic photosphere to the supersonic wind. For given stellar parameters, our models predict the photosphere and wind structure and in particular the wind mass-loss rates without any free parameters. Our predicted mass-loss rates are by a factor of 2-5 lower than the commonly used predictions. A possible cause of the difference is abandoning of the Sobolev approximation for the calculation of the radiative force, because our models agree with predictions of CMF NLTE radiative transfer codes. Our predicted mass-loss rates agree nicely with the mass-loss rates derived from observed near-infrared and X-ray line profiles and are slightly lower than mass-loss rates derived from combined UV and Hα diagnostics. The empirical mass-loss rate estimates corrected for clumping may therefore be reconciled with theoretical predictions in such a way that the average ratio between individual massloss rate estimates is not higher than about 1.6. On the other hand, our predictions are by factor of 4.7 lower than pure Hα mass-loss rate estimates and can be reconciled with these values only assuming a microclumping factor of at least eight.

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Section: Comparison With Tlustysupporting

confidence: 78%

Comoving frame models of hot star winds

Krtička

Kubát

2017

A&A

101

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“…A second set of spherical non-LTE models has been constructed by Kunasz, Hummer, and Mihalas (1975). These, however, are completely static atmospheres in which the effects of radiation pressure have been taken into account rather artificially by a parameterized radiation force multiplier.…”

Section: Comparison With Theoretical Models and Discussionmentioning

confidence: 99%

Spectral energy distributions of O-type stars.

Kuan¹,

Kuhi²

1976

PASP

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Narrow-band photoelectric spectrum scanner observations of the spectral energy distributions of O and Of stars are presented. After the application of reasonable reddening corrections it is found that both Of and ordinary O stars present evidence for effects of atmospheric extension. These effects are seen primarily in the flatness of the energy distribution which is most extreme in the hottest Of stars. Model atmospheres (dynamic or static) which produce only minor observable effects of extension are therefore ruled out.

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“…As a consequence, there is more continuum radiation in a plane parallel geometry, which results in shallower line profiles. This has been well known for a long time (see, e.g., Kunasz et al 1975). This is why we plot another line profile, which also is obtained using the plane-parallel geometry, but in which the intensity incoming from directions with µ < 0.26 is set to zero.…”

Section: Stellar Windmentioning

confidence: 99%

“…A different profile from an axially symmetric code is in agreement with the fact the line profile obtained in spherical geometry is different from that obtained in a plane parallel geometry. The difference depends on the sphericity effects on the temperature structure (see, e.g., Kunasz et al 1975;Gruschinske & Kudritzki 1979;Kubát 1995Kubát , 1999.…”

Section: Stellar Windmentioning

confidence: 99%

Radiative transfer in moving media

Korčáková¹,

Kubát²

2005

A&A

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Abstract.A new method for the formal solution of the 2D radiative transfer equation in axial symmetry in the presence of arbitrary velocity fields is presented. The combination of long and short characteristics methods is used to solve the radiative transfer equation. We include the velocity field in detail using the Local Lorentz Transformation. This allows us to obtain a significantly better description of the photospheric region, where the gradient of the global velocity is too small for the Sobolev approximation to be valid. Sample test calculations for the case of a stellar wind and a rotating atmosphere are presented.

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Theory of extended stellar atmospheres. II - A grid of static spherical models for O stars and planetary nebula nuclei

Cited by 26 publications

References 0 publications

Comoving frame models of hot star winds

Comoving frame models of hot star winds

Spectral energy distributions of O-type stars.

Radiative transfer in moving media

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