Selfconsistent Models of Winds from Rotating Early-Type Stars – Application to B[e] star winds

Petrenz, P.; Puls, J.

doi:10.1017/s0252921100056669

Cited by 24 publications

(31 citation statements)

References 6 publications

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“…However, with an initial rotation of 410 km s −1 the models predict that the star can reach high abundances while still keeping the high rotational velocity. This is therefore consistent with the above hypothesis that GHV-62024 is a fast rotator seen from a low inclination angle, whose velocity field properties would have been modified towards high β values without modifying the average WLR (in agreement with Maeder 2001 andPetrenz &.…”

Section: Discussionsupporting

confidence: 90%

A peculiar Of star in the Local Group galaxy IC 1613

Herrero¹,

García²,

Puls³

et al. 2012

A&A

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Context.Results from the theory of radiatively driven winds are nowadays incorporated in stellar evolutionary and population synthesis models, and are used in our interpretation of the observations of the deep Universe. Yet, the theory has been confirmed only until Small Magellanic Cloud metallicities. Observations and analyses of O-stars at lower metallicities are difficult, but much needed to prove the theory. Aims. We have observed GHV-62024, an O6.5 IIIf star in the low-metallicity galaxy IC 1613 (Z ≈ 0.15 Z ) to study its evolution and wind. According to a previous preliminary analysis that was subject to significant restrictions this star could challenge the radiatively driven wind theory at low metallicities. Here we present a complete analysis of this star. Methods. Our observations were obtained with VIMOS at VLT, at R ≈ 2000 and covered approximately between 4000 and 7000 Å. The observations were analysed using the latest version of the model atmosphere code FASTWIND, which includes the possibility of calculating the N iii spectrum. Results. We obtain the stellar parameters and conclude that the star follows the average wind momentum-luminosity relationship (WLR) expected for its metallicity, but with a high value for the exponent of the wind velocity law, β. Comparing this with values of other stars in the literature, we suggest that this high value may be reached because GHV-62024 could be a fast rotator seen at a low inclination angle. We also suggest that this could favour the appearance of the spectral "f"-characterictics. While the derived β value does not change by adopting a lower wind terminal velocity, we show that a wrong V ∞ has a clear impact on the position of the star in the WLR diagram. The N and He abundances are very high, consistent with strong CNO mixing that could have been caused by the fast rotation, although we cannot discard a different origin with present data. Stellar evolutionary model predictions are consistent with the star being still a fast rotator. We find again the well-known mass-discrepancy for this star. Conclusions. We conclude that the star follows the WLR expected for its metallicity. The results are consistent with GHV-62024 being a fast rotator seen close to pole-on, strongly contaminated at the surface with CNO products and with a wind structure altered by the fast rotation but without modifying the global WLR. We suggest that this could be a general property of fast rotators.

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Section: Discussionsupporting

confidence: 90%

A peculiar Of star in the Local Group galaxy IC 1613

Herrero¹,

García²,

Puls³

et al. 2012

A&A

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“…Feldmeier et al 1997;Runacres & Owocki 2002), and of effects of stellar rotation on the stellar wind (cf. Petrenz & Puls 2000) showed that basic wind parameters (i.e. terminal velocity and mass-loss rate) can be well reproduced by stationary and spherically symmetric wind models (for rotational velocities lower than the critical rotational velocity).…”

Section: Discussionmentioning

confidence: 96%

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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“…Such a method was used for the investigation of stellar wind structure, particularly in 2D, e.g. by Owocki et al (1994) and Petrenz & Puls (2000). Another method (integral method) was developed by Beutler (1979) and was applied to a solar wind problem by Bürgi (1992).…”

Section: Methodsmentioning

confidence: 99%

Multicomponent radiatively driven stellar winds

Krtička

Kubát

2001

A&A

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Abstract.We computed models of a three-component nonisothermal radiatively driven stellar wind for different spectral types of hot B stars. We showed that friction heats mainly the outer parts of the wind and the modified temperature stratification leads to a decrease of the outflow velocity. Contrary to the isothermal case, even the possibility of decoupling of radiatively absorbing ions and (major) nonabsorbing component is excluded for a realistic form of the driving force. Regardless of the actual form of the driving force, we derived general conditions under which decoupling of a stellar wind may occur. We demonstrated that the possibility of decoupling is closely related to the functional dependence of the driving force and to the ratio of the densities of individual components. We discuss several consequences of a multifluid phenomenon in hot star winds, particularly metallicity effects and the implications of possible helium decoupling on chemically peculiar stars. We propose an explanation of the low terminal velocity of τ Sco based on frictional heating.

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Selfconsistent Models of Winds from Rotating Early-Type Stars – Application to B[e] star winds

Cited by 24 publications

References 6 publications

A peculiar Of star in the Local Group galaxy IC 1613

A peculiar Of star in the Local Group galaxy IC 1613

NLTE models of line-driven stellar winds

Multicomponent radiatively driven stellar winds

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