Aims. We investigate the anisotropy of stellar winds in binaries to improve the models of accretion in high-mass X-ray binaries. Methods. We model numerically the stellar wind from a supergiant component of a binary in radial and three-dimensional radiation hydrodynamic approximation taking into account the Roche potential, Coriolis force, and radiative pressure in the continuum and spectral lines. Results. The Coriolis force influences substantially the mass loss and thus also the accretion rate. The focusing of the stellar wind by the gravitational field of the compact companion leads to the formation of a gaseous tail behind the companion.
Aims. We have developed a new code for the three-dimensional time-dependent raditation hydrodynamic simulation of the stellar wind in interacting binaries to improve models of accretion in high-mass X-ray binaries and to quantitatively clarify the observed variability of these objects. We used the code to test the influence of various parameters on the structure and properties of circumstellar matter. Methods. Our code takes into account acceleration of the wind due to the Roche effective potential, Coriolis force, gas pressure, and (CAK-) radiative pressure in the lines and continuum of the supergiant radiation field that is modulated by its gravity darkening and by the photo-ionization caused by X-ray radiation from the compact companion. The parameters of Cygnus X-1 were used to test the properties of our model. Results. Both two-and three-dimensional numerical simulations show that the Coriolis force substantially influences the mass loss and consequently the accretion rate onto the compact companion. The gravitational field of the compact companion focuses the stellar wind, which leads to the formation of a curved cone-like gaseous tail behind the companion. The changes of X-ray photo-ionization of the wind material during X-ray spectral-state transitions significantly influence the wind structure and offer an explanation of the variability of Cygnus X-1 in optical observations (the Hα emission).
We present a novel method for interpreting observations of high-mass X-ray binaries (HMXBs) based on a combination of spectroscopic data and numerical results from a radiation hydrodynamic model of stellar winds. We calculate synthetic Doppler tomograms of predicted emission in low/hard and high/soft X-ray states and compare them with Doppler tomograms produced using spectra of Cygnus X-1, a prototype of HMXBs. Emission from HMXBs is determined by local conditions within the circumstellar medium, namely density, temperature, and ionization state. These quantities depend strongly on the X-ray state of the systems. By increasing intensity of an X-ray emission produced by the compact companion in the HMXB model, we achieved a complete redistribution of the circumstellar medium in the vicinity of the modelled system. These changes (which simulate the transitions between two major spectral states) are also apparent in the synthetic Doppler tomograms which are in good agreement with the observations.
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