Accretion in massive colliding-wind binaries and the effect of the wind momentum ratio

Kashi, Amit; Michaelis, Amir; Kaminetsky, Yarden

doi:10.1093/mnras/stac1912

Cited by 5 publications

(3 citation statements)

References 67 publications

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“…As a consequence, the effect of a radially increasing velocity of the material in the rest frame of the companion is not accounted for, which, however reduces the momentum gradient introduced by the density stratification. Therefore, it is possible that the accretion rate does not fall very much below the BHL value, see also Kashi et al (2022) for a discussion in a different context.…”

Section: Simulations Of the Companion-envelope Interactionmentioning

confidence: 99%

Simulations of common-envelope evolution in binary stellar systems: physical models and numerical techniques

Roepke

Marco

2023

Living Rev Comput Astrophys

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When the primary star in a close binary system evolves into a giant and engulfs its companion, its core and the companion temporarily orbit each other inside a common envelope. Drag forces transfer orbital energy and angular momentum to the envelope material. Depending on the efficiency of this process, the envelope may be ejected leaving behind a tight remnant binary system of two stellar cores, or the cores merge retaining part of the envelope material. The exact outcome of common-envelope evolution is critical for in the formation of X-ray binaries, supernova progenitors, the progenitors of compact-object mergers that emit detectable gravitational waves, and many other objects of fundamental astrophysical relevance. The wide ranges of spatial and temporal timescales that characterize common-envelope interactions and the lack of spatial symmetries present a substantial challenge to generating consistent models. Therefore, these critical phases are one of the largest sources for uncertainty in classical treatments of binary stellar evolution. Three-dimensional hydrodynamic simulations of at least part of the common-envelope interaction are the key to gain predictive power in modeling common-envelope evolution. We review the development of theoretical concepts and numerical approaches for such three-dimensional hydrodynamic simulations. The inherent multi-physics, multi-scale challenges have resulted in a wide variety of approximations and numerical techniques to be exercised on the problem. We summarize the simulations published to date and their main results. Given the recent rapid progress, a sound understanding of the physics of common-envelope interactions is within reach and thus there is hope that one of the remaining fundamental problems of stellar astrophysics may be solved before long.

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Section: Simulations Of the Companion-envelope Interactionmentioning

confidence: 99%

Simulations of common-envelope evolution in binary stellar systems: physical models and numerical techniques

Roepke

Marco

2023

Living Rev Comput Astrophys

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“…The wind tunnel formalism that some studies employ leads to mass accretion rates that are much below the values according to the BHL accretion flow (e.g., MacLeod & Ramirez-Ruiz 2015a, 2015b; De et al 2020). On the other hand, full simulations of accretion from a wind, i.e., simulations that include the orbital motion in a binary system, derive the BHL accretion rate (Kashi et al 2022).…”

Section: The Sub-keplerian Accretion Flowmentioning

confidence: 99%

On the Nature of Jets from a Main Sequence Companion at the Onset of Common Envelope Evolution

Soker

2023

Res. Astron. Astrophys.

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I consider a flow structure by which main sequence companions that enter a common envelope evolution (CEE) with giant stars might launch jets even when the accreted gas has a sub-Keplerian specific angular momentum. I first show that after a main sequence star enters the envelope of a giant star the specific angular momentum of the accreted gas is sub-Keplerian but still sufficiently large for the accreted gas to avoid two conical-like openings along the two opposite polar directions. I suggest that the high-pressure zone that the accreted gas builds around the main sequence equatorial plane accelerates outflows along these polar opening. Most of the inflowing gas is deflected to the polar outflows, i.e., two oppositely-directed jets. The actual mass that the main sequence star accretes is only a small fraction, $\approx 0.1$, of the inflowing gas. However, the gravitational energy that this gas releases powers the inflow-outflow streaming of gas and adds energy to the common envelope ejection. This flow structure might take place during a grazing envelope evolution if it occurs, during the early CEE, and possibly in some post-CEE cases. This study increases the parameter space for main sequence stars to launch jets. Such jets might shape \add{ some morphological features in } planetary nebulae, add energy to mass removal in CEE, and power some intermediate luminosity optical transients.

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“…These applications vary in terms of their velocities, accretion radii, and adiabatic indices (γ), necessitating a general formulation for the accretion rate. In addition, other works examine accretion in a noncontinuous gaseous medium (Folini & Walder 2000;Kashi 2017;Kashi & Michaelis 2021;Kashi et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Morphology and Mach Number Dependence of Subsonic Bondi–Hoyle Accretion

Prust,

Glanz,

Bildsten

et al. 2024

ApJ

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We carry out three-dimensional computations of the accretion rate onto an object (of size R sink and mass m) as it moves through a uniform medium at a subsonic speed v ∞. The object is treated as a fully absorbing boundary (e.g., a black hole). In contrast to early conjectures, we show that for an accretor with R sink ≪ R A = 2 Gm / v ∞ 2 in a gaseous medium with adiabatic index γ = 5/3, the accretion rate is independent of Mach number and is determined only by m and the gas entropy. Our numerical simulations are conducted using two different numerical schemes via the Athena++ and Arepo hydrodynamics solvers, which reach nearly identical steady-state solutions. We find that pressure gradients generated by the isentropic compression of the flow near the accretor are sufficient to suspend much of the surrounding gas in a near-hydrostatic equilibrium, just as predicted from the spherical Bondi–Hoyle calculation. Indeed, the accretion rates for steady flow match the Bondi–Hoyle rate, and are indicative of isentropic flow for subsonic motion where no shocks occur. We also find that the accretion drag may be predicted using the Safronov number, Θ = R A /R sink, and is much less than the dynamical friction for sufficiently small accretors (R sink ≪ R A ).

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Accretion in massive colliding-wind binaries and the effect of the wind momentum ratio

Cited by 5 publications

References 67 publications

Simulations of common-envelope evolution in binary stellar systems: physical models and numerical techniques

Simulations of common-envelope evolution in binary stellar systems: physical models and numerical techniques

On the Nature of Jets from a Main Sequence Companion at the Onset of Common Envelope Evolution

Morphology and Mach Number Dependence of Subsonic Bondi–Hoyle Accretion

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