Rotating massive O stars with non-spherical 2D winds

Müller, Patrick

doi:10.1051/0004-6361/201323031

Cited by 55 publications

(54 citation statements)

References 52 publications

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“…While the dependence of ¥ v on Ω and δ seems to follow the same trend, in agreement with the behavior described for the rest of the basic models, the slow solution obtained for T15 presents a relationship betweenṀ and δ with a negative slope. Hydrodynamical models for fast O-type rotators also showed decreases in the mass-loss rate toward the equator in response tothe computed line acceleration (Müller & Vink 2014). From our results we support that this peculiar behavior could be attained not only fordepen-dence ofṀ on δ but also forthe ratio T g log eff for a given set of k and α line-force parameters.…”

Section: Wind Properties Along the Spectral Sequence Of B Supergiantssupporting

confidence: 74%

The Wind of Rotating B Supergiants. I. Domains of Slow and Fast Solution Regimes

Venero

Curé

Cidale

et al. 2016

ApJ

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In the scenario of rotating radiation-driven wind theory for massive stars, three types of stationary hydrodynamic solutions are currently known: the classical ( fast) m-CAK solution, the Ω-slow solution that arises for fast rotators, and the so-called δ-slow solution if high values of the δ line-force parameter are allowed independently of the rotation speed. Compared to the fast solution, both "slow solutions" have lower terminal velocities. As the study of the parameter domain for the slow solution is still incomplete, we perform a comprehensive analysis of the distinctive flow regimes for B supergiants that emerge from a fine grid of rotation values, Ω, and various ionization conditions in the wind(δ) parameter. The wind ionization defines two domains: one for fast outflowing winds and the other for slow expanding flows. Both domains are clear-cut by a gap, where a kink/plateau structure of the velocity law could exist for a finite interval of δ. The location and width of the gap depend on T eff and Ω. There is a smooth and continuous transition between the Ω-slow and δ-slow regimes, a single Ω δ-slow regime. We discuss different situations where the slow solutions can be found and the possibility of a switch between fast and slow solutions in B supergiant winds. We compare the theoretical terminal velocity with observations of B and A supergiants and find that the fast regime prevails mostly for early B supergiants while the slow wind regime matches better for A and B mid-and late-type supergiants.

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Section: Wind Properties Along the Spectral Sequence Of B Supergiantssupporting

confidence: 74%

The Wind of Rotating B Supergiants. I. Domains of Slow and Fast Solution Regimes

Venero

Curé

Cidale

et al. 2016

ApJ

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“…It remains unclear whether rapid rotation per se leads to an increase in mass-loss (Müller & Vink 2014). However, as discussed in Müller & Vink (2014), it still appears reasonable to consider that the mass-loss rate does increase close to the Eddington limit (Langer 1997;Gräfener et al 2011).…”

Section: Mass-lossmentioning

confidence: 99%

“…This is why the surface rotational velocity at the TAMS of the fast rotators increases at low mass and does not follow the decreasing trend of the more massive stars which undergo CHE. Although rotating massive stars at breakup have gained some interest in the past (Decressin et al 2007), theoretical suggestions by Müller & Vink (2014) disfavour the concept of rotationallyenhanced stellar winds. Since the physical assumptions in these stellar models are currently under debate, we do not analyse this issue further at this point.…”

Section: Homogeneously-evolving Starsmentioning

confidence: 99%

Low-metallicity massive single stars with rotation

Szécsi

Langer

Yoon

et al. 2015

A&A

150

213

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Context. Low-metallicity environments such as the early Universe and compact star-forming dwarf galaxies contain many massive stars. These stars influence their surroundings through intense UV radiation, strong winds and explosive deaths. A good understanding of low-metallicity environments requires a detailed theoretical comprehension of the evolution of their massive stars. Aims. We aim to investigate the role of metallicity and rotation in shaping the evolutionary paths of massive stars and to provide theoretical predictions that can be tested by observations of metal-poor environments. Methods. Massive rotating single stars with an initial metal composition appropriate for the dwarf galaxy I Zw 18 ([Fe/H] = −1.7) are modelled during hydrogen burning for initial masses of 9−300 M and rotational velocities of 0−900 km s −1 . Internal mixing processes in these models were calibrated based on an observed sample of OB-type stars in the Magellanic Clouds. Results. Even moderately fast rotators, which may be abundant at this metallicity, are found to undergo efficient mixing induced by rotation resulting in quasi chemically-homogeneous evolution. These homogeneously-evolving models reach effective temperatures of up to 90 kK during core hydrogen burning. This, together with their moderate mass-loss rates, make them transparent wind ultraviolet intense stars (TWUIN star), and their expected numbers might explain the observed He II ionising photon flux in I Zw 18 and other low-metallicity He II galaxies. Our slowly rotating stars above ∼80 M evolve into late B-to M-type supergiants during core hydrogen burning, with visual magnitudes up to 19 m at the distance of I Zw 18. Both types of stars, TWUIN stars and luminous late-type supergiants, are only predicted at low metallicity. Conclusions. Massive star evolution at low metallicity is shown to differ qualitatively from that in metal-rich environments. Our grid can be used to interpret observations of local star-forming dwarf galaxies and high-redshift galaxies, as well as the metal-poor components of our Milky Way and its globular clusters.

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“…As the photon absorptions and scatterings depend on wind density and hence on the mass-loss rateṀ, we are able to obtain a consistent model where the momentum of the gas equals the transferred momentum by photons. Here we shall employ our local dynamical approach (Müller & Vink 2008, 2014Muijres et al 2012), in which we predictṀ, ∞ , and the wind structure parameter, β, simultaneously.…”

Section: Monte Carlo Modellingmentioning

confidence: 99%

Winds from stripped low-mass helium stars and Wolf-Rayet stars

Vink

2017

A&A

Self Cite

121

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We present mass-loss predictions from Monte Carlo radiative transfer models for helium (He) stars as a function of stellar mass, down to 2 M . Our study includes both massive Wolf-Rayet (WR) stars and low-mass He stars that have lost their envelope through interaction with a companion. For these low-mass He stars we predict mass-loss rates that are an order of magnitude smaller than by extrapolation of empirical WR mass-loss rates. Our lower mass-loss rates make it harder for these elusive stripped stars to be discovered via line emission, and we should attempt to find these stars through alternative methods instead. Moreover, lower massloss rates make it less likely that low-mass He stars provide stripped-envelope supernovae (SNe) of type Ibc. We express our mass-loss predictions as a function of L and Z and not as a function of the He abundance, as we do not consider this physically astute given our earlier work. The exponent of theṀ versus Z dependence is found to be 0.61, which is less steep than relationships derived from recent empirical atmospheric modelling. Our shallower exponent will make it more challenging to produce "heavy" black holes of order 40 M , as recently discovered in the gravitational wave event GW 150914, making low metallicity for these types of events even more necessary.

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Rotating massive O stars with non-spherical 2D winds

Cited by 55 publications

References 52 publications

The Wind of Rotating B Supergiants. I. Domains of Slow and Fast Solution Regimes

The Wind of Rotating B Supergiants. I. Domains of Slow and Fast Solution Regimes

Low-metallicity massive single stars with rotation

Winds from stripped low-mass helium stars and Wolf-Rayet stars

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