Absolute Magnitudes of Early-type Supergiants from <i>uvbyβ</i> Photometry and Parallax Data

Kaltcheva, N.; Paunzen, E.; Prišegen, Michal; Golev, Valeri; Watson, M. G.

doi:10.1088/1538-3873/ab8cce

Cited by 2 publications

(2 citation statements)

References 24 publications

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“…In Fig. 7 we plot these values for the stars for which we derived luminosities either from the literature (Kudritzki et al 1999;Crowther et al 2006;Lefever et al 2007;Haucke et al 2018) or determined using absolute magnitudes from Kaltcheva et al (2020) and bolometric corrections of Crowther et al (2006). The observational values are plotted relative to the predicted massloss rate Ṁ and compared to predicted ionization fractions.…”

Section: Comparison With Observations and Other Theoretical Modelsmentioning

confidence: 99%

New mass-loss rates of B supergiants from global wind models

Krtička

Kubát

Krtičková

2021

A&A

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Massive stars lose a significant fraction of mass during their evolution. However, the corresponding mass-loss rates are rather uncertain, especially for evolved stars. To improve this, we calculated global line-driven wind models for Galactic B supergiants. Our models predict radial wind structure and particularly the mass-loss rates and terminal velocities directly from basic stellar parameters. The hydrodynamic structure of the flow is consistently determined from the photosphere in nearly hydrostatic equilibrium to supersonically expanding wind. The radiative force is derived from the solution of the radiative transfer equation in the comoving frame. We provide a simple formula that predicts theoretical mass-loss rates as a function of stellar luminosity and effective temperature. The mass-loss rate of B supergiants slightly decreases with temperature down to about 22.5 kK, where the region of recombination of Fe IV to Fe III starts to appear. In this region, which is about 5 kK wide, the mass-loss rate gradually increases by a factor of about 6. The increase of the mass-loss rate is associated with a gradual decrease of terminal velocities by a factor of about 2. We compared the predicted wind parameters with observations. While the observed wind terminal velocities are reasonably reproduced by the models, the situation with mass-loss rates is less clear. The mass-loss rates derived from observations that are uncorrected for clumping are by a factor of 3 to 9 higher than our predictions on cool and hot sides of the studied sample, respectively. These observations can be reconciled with theory assuming a temperature-dependent clumping factor that is decreasing toward lower effective temperatures. On the other hand, the mass-loss rate estimates that are not sensitive to clumping agree with our predictions much better. Our predictions are by a factor of about 10 lower than the values currently used in evolutionary models appealing for reconsideration of the role of winds in the stellar evolution.

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Section: Comparison With Observations and Other Theoretical Modelsmentioning

confidence: 99%

New mass-loss rates of B supergiants from global wind models

Krtička

Kubát

Krtičková

2021

A&A

View full text Add to dashboard Cite

show abstract

“…In Fig. 7 we plot these values for the stars for which we derived luminosities either from the literature (Kudritzki et al 1999;Crowther et al 2006;Lefever et al 2007;Haucke et al 2018) or determined using absolute magnitudes from Kaltcheva et al (2020) and bolometric corrections of Crowther et al (2006). The observational values are plotted relative to the predicted mass-loss rate Ṁ and compared to predicted ionization fractions.…”

Section: Comparison With Observations and Other Theoretical Modelsmentioning

confidence: 99%

New mass-loss rates of B supergiants from global wind models

Krticka,

Kubat,

Krtickova

2021

Preprint

View full text Add to dashboard Cite

Massive stars lose a significant fraction of mass during their evolution. However, the corresponding mass-loss rates are rather uncertain, especially for evolved stars. To improve this, we calculated global line-driven wind models for Galactic B supergiants. Our models predict radial wind structure and particularly the mass-loss rates and terminal velocities directly from basic stellar parameters. The hydrodynamic structure of the flow is consistently determined from the photosphere in nearly hydrostatic equilibrium to supersonically expanding wind. The radiative force is derived from the solution of the radiative transfer equation in the comoving frame. We provide a simple formula that predicts theoretical mass-loss rates as a function of stellar luminosity and effective temperature. The mass-loss rate of B supergiants slightly decreases with temperature down to about 22.5 kK, where the region of recombination of Fe IV to Fe III starts to appear. In this region, which is about 5 kK wide, the mass-loss rate gradually increases by a factor of about 6. The increase of the mass-loss rate is associated with a gradual decrease of terminal velocities by a factor of about 2. We compared the predicted wind parameters with observations. While the observed wind terminal velocities are reasonably reproduced by the models, the situation with mass-loss rates is less clear. The mass-loss rates derived from observations that are uncorrected for clumping are by a factor of 3 to 9 higher than our predictions on cool and hot sides of the studied sample, respectively. These observations can be reconciled with theory assuming a temperature-dependent clumping factor that is decreasing toward lower effective temperatures. On the other hand, the mass-loss rate estimates that are not sensitive to clumping agree with our predictions much better. Our predictions are by a factor of about 10 lower than the values currently used in evolutionary models appealing for reconsideration of the role of winds in the stellar evolution.

show abstract

Absolute Magnitudes of Early-type Supergiants from uvbyβ Photometry and Parallax Data

Cited by 2 publications

References 24 publications

New mass-loss rates of B supergiants from global wind models

New mass-loss rates of B supergiants from global wind models

New mass-loss rates of B supergiants from global wind models

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