Formation of the Asymmetric Accretion Disk from Stellar Wind Accretion in an S-type Symbiotic Star

Abstract

The accretion process in a typical S-type symbiotic star, targeting~AG Draconis, is investigated through 3D hydrodynamical simulations using the FLASH code. Regardless of the wind velocity of the giant star, an accretion disk surrounding the white dwarf is always formed. In the wind models faster than the orbital velocity of the white dwarf, the disk size and accretion rate are consistent with the predictions under the Bondi-Hoyle-Lyttleton (BHL) condition. In slower wind models, unlike the BHL predictions, the disk size does not grow and the accretion rate increases to a considerably higher level, up to $>20\%$ of the mass-loss rate of the giant star. The accretion disk in our fiducial model is characterized by a flared disk with a radius of 0.16~au and a scale height of 0.03 au. The disk mass of $\sim 5\times 10^{-8}{M}_{\odot }$ is asymmetrically distributed with the density peak toward the giant star, being about $50\%$ higher than the density minimum in the disk. Two inflowing spiral features are clearly identified and their relevance to the azimuthal asymmetry of disk is pointed out. The flow in the accretion disk is found to be sub-Keplerian with about $90\%$ of the Keplerian speed, which indicates the caveat of overestimating the O VI emission region from spectroscopy of Raman-scattered O VI features at 6825 Å and 7082 Å.

arXiv comment26 pages, 10 figures, accepted for publication in ApJ

References in corpus (16)

• A catalogue of symbiotic stars
• A new radiative cooling curve based on an up to date plasma emission code
• Thermally Stable Nuclear Burning on Accreting White Dwarfs
• Disentangling the composite continuum of symbiotic binaries I. S-type systems
• A "Combination Nova" Outburst in Z Andromedae: Nuclear Shell Burning Triggered by a Disk Instability
• Mass Transfer and Disc Formation in AGB Binary Systems
• Slowly, slowly in the wind: 3D hydrodynamical simulations of wind mass transfer and angular-momentum loss in AGB binary systems
• The Formation and Evolution of Wind-Capture Disks In Binary Systems
• Roche-lobe filling factor of mass-transferring red giants - the PIONIER view
• Contemporaneous Observations of Direct and Raman Scattered O VI in Symbiotic Stars
• Three-dimensional hydrodynamical models of wind and outburst-related accretion in symbiotic systems
• First Resolved Images of the Mira AB Symbiotic Binary at Centimeter Wavelengths
• Raman Scattered O VI $\lambda$ 6825 and the Accretion Disk Emission Model in the Symbiotic Stars V1016 Cygni and HM Sagittae
• On the Profiles and Polarization of Raman Scattered Emission Lines in Symbiotic Stars:II. Numerical Simulations
• Numerical simulation of accretion discs in close binary systems and discovery of spiral shocks
• Stellar Wind Accretion and Raman Scattered O VI Features in the Symbiotic Star AG Draconis

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