Coupling hydrodynamics with comoving frame radiative transfer

Sander, A. A. C.; Fürst, F.; Kretschmar, P.; Oskinova, L. M.; Todt, H.; Hainich, R.; Shenar, T.; Hamann, W. R.

doi:10.1051/0004-6361/201731575

Cited by 59 publications

(127 citation statements)

References 68 publications

(133 reference statements)

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“…In fact, we even see this in OB models, such as the HD calculations for ζ Pup (Sander et al 2017) and Vela X-1 (Sander et al 2018). It is also hinted in the slope of Γ rad shown in our demonstration model from Sander et al (2015).…”

Section: Discussionsupporting

confidence: 68%

“…Elements such as Si, P, or S, which are important to consider for O or B stars (e.g. Vink et al 1999;Noebauer & Sim 2015;Sander et al 2017Sander et al , 2018, provide only minor or even negligible contributions to the wind driving in a WNE. A full list of all considered elements and ions is listed in the appendix Table C2.…”

Section: The Radiative Accelerationmentioning

confidence: 99%

“…Until now, only one such model has been constructed for a WC5 star by Gräfener & Hamann (2005, highlighting the challenge in this task. In recent years, Sander et al (2015Sander et al ( , 2017Sander et al ( , 2018 developed a new hydrodynamical version of the PoWR stellar atmosphere code (Hamann & Koesterke 1998;Gräfener et al 2002) which is ideally suited for this task. One of the key advantages of this method is that it not only includes multi-line scatterings (as do Monte Carlo methods, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Driving classical Wolf-Rayet winds: A Γ- and Z-dependent mass-loss

Sander

Vink

Hamann

2019

Monthly Notices of the Royal Astronomical Society

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Classical Wolf-Rayet (WR) stars are at a crucial evolutionary stage for constraining the fates of massive stars. The feedback of these hot, hydrogen-depleted stars dominates their surrounding by tremendous injections of ionizing radiation and kinetic energy. The strength of a WR wind decides the eventual mass of its remnant, likely a massive black hole. However, despite their major influence and importance for gravitational wave detection statistics, WR winds are particularly poorly understood. In this paper, we introduce the first set of hydrodynamically consistent stellar atmosphere models for classical WR stars of both the carbon (C) and nitrogen (N) sequence, i.e. WC and WN stars, as a function of stellar luminosity-to-mass ratio (or Eddington Gamma), and metallicity. We demonstrate the inapplicability of the CAK wind theory for classical WR stars and confirm earlier findings that their winds are launched at the (hot) iron (Fe) opacity peak. For log Z/Z > −2, Fe is also the main accelerator throughout the wind. Contrasting previous claims of a sharp lower mass-loss limit for WR stars, we obtain a smooth transition to optically thin winds. Furthermore, we find a strong dependence of the mass-loss rates on Eddington Γ, both at solar and sub-solar metallicity. Increases in WC carbon and oxygen abundances turn out to slightly reduce the predicted mass-loss rates. Calculations at subsolar metallicities indicate that below the metallicity of the SMC, WR mass-loss rates decrease much faster than previously assumed, potentially allowing for high black hole masses even in the local universe.

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Section: Discussionsupporting

confidence: 68%

Section: The Radiative Accelerationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Driving classical Wolf-Rayet winds: A Γ- and Z-dependent mass-loss

Sander

Vink

Hamann

2019

Monthly Notices of the Royal Astronomical Society

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“…The acceleration starts very close from the photosphere around hot stars while it only starts at the dust condensation radius for winds of AGB stars. Depending on the stellar metallicity, the β exponent ranges between 0.5 and 2.5 for hot stars (Sander et al 2017) while it varies much more for AGB stars depending on the chemical content. C-rich AGB stars lead to dust grains of high opacity, strongly accelerated by the stellar radiative field.…”

Section: Presureless Test Casementioning

confidence: 99%

Wind morphology around cool evolved stars in binaries

Mellah

Bolte

Decin

et al. 2020

A&A

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Context. The late evolutionary phase of low and intermediate-mass stars is strongly constrained by their mass-loss rate, which is orders of magnitude higher than during the main sequence. The wind surrounding these cool expanded stars frequently shows non-spherical symmetry, thought to be due to an unseen companion orbiting the donor star. The imprints left in the outflow carry information on the companion but also on the launching mechanism of these dust-driven winds. Aims. We study the morphology of the circumbinary envelope and identify the conditions of formation of a wind-captured disk around the companion. Long-term orbital changes induced by mass-loss and mass transfer to the secondary are also investigated. We pay particular attention to oxygen-rich i.e. slowly accelerating outflows, in order to look for systematic differences between the dynamics of the wind around carbon and oxygen-rich asymptotic giant branch (AGB) stars. Methods. We present a model based on a reduced number of dimensionless parameters to connect the wind morphology to the properties of the underlying binary system. Thanks to the high performance code MPI-AMRVAC, we run an extensive set of 70 threedimensional hydrodynamics simulations of a progressively accelerating wind propagating in the Roche potential formed by a massloosing evolved star in orbit with a main sequence companion. The highly adaptive mesh refinement we use enables us to resolve the flow structure both in the immediate vicinity of the secondary, where bow shocks, outflows and wind-captured disks form, and up to 40 orbital separations, where spiral arms, arcs and equatorial density enhancements develop. Results. When the companion is deeply engulfed in the wind, the lower terminal wind speeds and more progressive wind acceleration around oxygen-rich AGB stars make them more prone than carbon-rich AGB stars to display more disturbed outflows, a disk-like structure around the companion and a wind concentrated in the orbital plane. In these configurations, a large fraction of the wind is captured by the companion which leads to a significant shrinking of the orbit over the mass-loss timescale, if the donor star is at least a few times more massive than its companion. In the other cases, an increase of the orbital separation is to be expected, though at a rate lower than the mass-loss rate of the donor star. Provided the companion has a mass of at least a tenth of the mass of the donor star, it can compress the wind in the orbital plane up to large distances. Conclusions. The grid of models we compute covers a wide scope of configurations in function of the dust chemical content, the terminal wind speed relative to the orbital speed, the extension of the dust condensation region around the cool evolved star and the mass ratio. It provides a convenient frame of reference to interpret high-resolution maps of the outflows surrounding cool evolved stars.

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“…This effect is thus unlikely to be critical in the case of the SFXTs, as their average X-ray luminosity is generally far below the critical level required to produce a systematic disruption of the stellar wind on scales that are as large as those expected for the CIRs (see, e.g., Ducci et al 2010, and references therein). However, this might not apply to bright persistent classical windfed SgXBs with average X-ray luminosities 10 36 −10 37 erg s −1 (e.g., Vela X-1; Watanabe et al 2006;Sander et al 2017), which we predict to not display super-orbital modulations. We note that all SgXBs discovered so far to display a super-orbital modulation are characterized by relatively low long-term luminosities, the brightest being IGR J16493-4348 with an estimated average X-ray luminosity of ∼1.5 × 10 36 erg s −1 when the largest allowed distance of 26 kpc is considered.…”

Section: The Cir-induced Super-orbital Modulation In Sgxbsmentioning

confidence: 71%

The super-orbital modulation of supergiant high-mass X-ray binaries

Bozzo

Oskinova

Lobel

et al. 2017

A&A

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The long-term X-ray light curves of classical supergiant X-ray binaries and supergiant fast X-ray transients show relatively similar super-orbital modulations, which are still lacking a sound interpretation. We propose that these modulations are related to the presence of corotating interaction regions (CIRs) known to thread the winds of OB supergiants. To test this hypothesis, we couple the outcomes of three-dimensional (3D) hydrodynamic models for the formation of CIRs in stellar winds with a simplified recipe for the accretion onto a neutron star. The results show that the synthetic X-ray light curves are indeed modulated by the presence of the CIRs. The exact period and amplitude of these modulations depend on a number of parameters governing the hydrodynamic wind models and on the binary orbital configuration. To compare our model predictions with the observations, we apply the 3D wind structure previously shown to well explain the appearance of discrete absorption components in the UV time series of a prototypical B0.5I-type supergiant. Using the orbital parameters of IGRJ 16493-4348, which has the same B0.5I donor spectral type, the period and modulations in the simulated X-ray light curve are similar to the observed ones, thus providing support to our scenario. We propose that the presence of CIRs in donor star winds should be considered in future theoretical and simulation efforts of wind-fed X-ray binaries.

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Coupling hydrodynamics with comoving frame radiative transfer

Cited by 59 publications

References 68 publications

Driving classical Wolf-Rayet winds: A Γ- and Z-dependent mass-loss

Driving classical Wolf-Rayet winds: A Γ- and Z-dependent mass-loss

Wind morphology around cool evolved stars in binaries

The super-orbital modulation of supergiant high-mass X-ray binaries

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