Wind mass transfer in S-type symbiotic binaries I. Focusing by the wind compression model

Abstract

Context: Luminosities of hot components in symbiotic binaries require accretion rates that are higher than those that can be achieved via a standard Bondi-Hoyle accretion. This implies that the wind mass transfer in symbiotic binaries has to be more efficient. Aims: We suggest that the accretion rate onto the white dwarfs (WDs) in S-type symbiotic binaries can be enhanced sufficiently by focusing the wind from their slowly rotating normal giants towards the binary orbital plane. Methods: We applied the wind compression model to the stellar wind of slowly rotating red giants in S-type symbiotic binaries. Results: Our analysis reveals that for typical terminal velocities of the giant wind, 20 to 50 km/s, and measured rotational velocities between 6 and 10 km/s, the densities of the compressed wind at a typical distance of the accretor from its donor correspond to the mass-loss rate, which can be a factor of $\sim$10 higher than for the spherically symmetric wind. This allows the WD to accrete at rates of $10^{-8}-10^{-7}$ M(Sun)/year, and thus to power its luminosity. Conclusions: We show that the high wind-mass-transfer efficiency in S-type symbiotic stars can be caused by compression of the wind from their slowly rotating normal giants, whereas in D-type symbiotic stars, the high mass transfer ratio can be achieved via the gravitational focusing, which has recently been suggested for very slow winds in Mira-type binaries.

5 pages, 3 figures, 2 Tables, accepted for A&A

References in corpus (5)

• 3D simulations of RS Oph: from accretion to nova blast
• Numerical Simulations of Wind Accretion in Symbiotic Binaries
• Rotational velocities of the giants in symbiotic stars: II. Are S-type symbiotics synchronized?
• Rotational velocities of the giants in symbiotic stars: III. Evidence of fast rotation in S-type symbiotics
• The applicability of the wind compression model

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• Symbiotic Stars in the APOGEE Survey: The Case of LIN 358 and SMC N73 (LIN 445a)
• Multiwavelength modeling the SED of Luminous Supersoft X-ray Sources in Large Magellanic Cloud and Small Magellanic Cloud
• Wind-mass transfer in S-type symbiotic binaries IV. Indication of high wind-mass-transfer efficiency from active phases
• Entering the Wind Roche Lobe Overflow realm in Symbiotic Systems
• Density asymmetry and wind velocities in the orbital plane of the symbiotic binary EG Andromedae