Bright OB stars in the Galaxy

Маркова, Н.; Puls, J.; Repolust, T.; Markov, H.

doi:10.1051/0004-6361:20031463

Cited by 117 publications

(225 citation statements)

References 53 publications

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“…The stellar parameters (effective temperatures and radii) of an O star sample were derived using the model atmospheres with line blanketing Markova et al 2004;Martins et al 2005). Stellar masses were obtained using evolutionary tracks either by ourselves (using Schaller et al 1992 tracks) or by Martins et al (2005).…”

Section: Studied Model Starsmentioning

confidence: 99%

Comoving frame models of hot star winds

Krtička¹,

Kubát

2010

A&A

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We provide hot star wind models with radiative force calculated using the solution of comoving frame (CMF) radiative transfer equation. The wind models are calculated for the first stars, O stars, and the central stars of planetary nebulae. We show that without line overlaps and with solely thermal line broadening the pure Sobolev approximation provides a reliable estimate of the radiative force even close to the wind sonic point. Consequently, models with the Sobolev line force provide good approximations to solutions obtained with non-Sobolev transfer. Taking line overlaps into account, the radiative force becomes slightly lower, leading to a decrease in the wind mass-loss rate by roughly 40%. Below the sonic point, the CMF line force is significantly lower than the Sobolev one. In the case of pure thermal broadening, this does not influence the mass-loss rate, as the wind mass-loss rate is set in the supersonic part of the wind. However, when additional line broadening is present (e.g., the turbulent one) the region of low CMF line force may extend outwards to the regions where the mass-loss rate is set. This results in a decrease in the wind mass-loss rate. This effect can at least partly explain the low wind mass-loss rates derived from some observational analyses of luminous O stars.

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Section: Studied Model Starsmentioning

confidence: 99%

Comoving frame models of hot star winds

Krtička¹,

Kubát

2010

A&A

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“…Note that the parameters derived by Repolust et al (2004), Markova et al (2004), and Martins et al (2005) were obtained using blanketed model atmospheres, i.e., they should be more reliable than the older ones. Stellar masses were obtained using evolutionary tracks (Schaller et al 1992).…”

Section: Test Starsmentioning

confidence: 99%

X-ray emission from hydrodynamical simulations in non-LTE wind models

Krtička

Feldmeier

Oskinova

et al. 2009

A&A

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Hot stars are sources of X-ray emission originating in their winds. Although hydrodynamical simulations that are able to predict this X-ray emission are available, the inclusion of X-rays in stationary wind models is usually based on simplifying approximations. To improve this, we use results from time-dependent hydrodynamical simulations of the line-driven wind instability (seeded by the base perturbation) to derive the analytical approximation of X-ray emission in the stellar wind. We use this approximation in our non-LTE wind models and find that an improved inclusion of X-rays leads to a better agreement between model ionization fractions and those derived from observations. Furthermore, the slope of the L X − L relation is in better agreement with observations, however the X-ray luminosity is underestimated by a factor of three. We propose a possible solution for this discrepancy.

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“…However, recent observational studies Markova et al 2004) indicate that the situation is probably more complicated. They concluded that there are two different wind momentum-luminosity relationships for supergiants (or, probably more correctly, for stars with the Hα line in emission), and for other stars (mainly for giants and mainsequence stars).…”

Section: Wind Momentum Luminosity Relationshipmentioning

confidence: 99%

NLTE models of line-driven stellar winds

Krtička

Kubát

2004

A&A

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Abstract. New numerical models of line-driven stellar winds of late O stars are presented. Statistical equilibrium (NLTE) equations of the most abundant elements are solved. Properly obtained occupation numbers are used to calculate consistent radiative force and radiative heating terms. Wind density, velocity and temperature are calculated as a solution of model hydrodynamical equations. Contrary to other published models we account for a multicomponent wind nature and do not simplify the calculation of the radiative force (e.g. using force multipliers). We discuss the convergence behaviour of our models. The ability of our models to predict correct values of mass-loss rates and terminal velocities of selected late O stars (mainly giants and supergiants) is demonstrated. The systematic difference between predicted and observed terminal velocities reported in the literature has been removed. Moreover, we found good agreement between the theoretical wind momentum-luminosity relationship and the observed one for Cyg OB2 supergiants.

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Bright OB stars in the Galaxy

Cited by 117 publications

References 53 publications

Comoving frame models of hot star winds

Comoving frame models of hot star winds

X-ray emission from hydrodynamical simulations in non-LTE wind models

NLTE models of line-driven stellar winds

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