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Abstract: We investigate the morphology of the collision front between the stellarwinds of binary components in two long-period binary systems, one consisting ofa hydrogen rich Wolf-Rayet star WNL and an O-star and the other of a LuminousBlue Variable LBV and an O-star. Specifically, we follow the development andevolution of instabilities that form in such a shell, if it is sufficientlycompressed, due to both the wind interaction and the orbital motion. We useMPI-AMRVAC to time-integrate the equations of hydrodynamics, combined withoptically thin radiative cooling, on an adaptive mesh 3D grid. Using parametersfor generic binary systems, we simulate the interaction between the winds ofthe two stars. The WNL+O star binary shows a typical example of an adiabaticwind collision. The resulting shell is thick and smooth, showing noinstabilities. On the other hand, the shell created by the collision of the Ostar wind with the LBV wind, combined with the orbital motion of the binarycomponents, is susceptible to thin shell instabilities, which create a highlystructured morphology. We identify the nature of the instabilities as bothlinear and non-linear thin-shell instabilities, with distinct differencesbetween the leading and the trailing parts of the collision front. We also findthat for binaries containing a star with a relatively slow wind, the globalshape of the shell is determined more by the slow wind velocity and the orbitalmotion of the binary, than the ram pressure balance between the two winds. Theinteraction between massive binary winds needs further parametric exploration,to identify the role and dynamical importance of multiple instabilities at thecollision front, as shown here for an LBV+O star system.

Autor: Allard Jan van Marle, Rony Keppens, Zakaria Meliani



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