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Angular momentum loss from binary systems due to stellar winds
Hubová, Dominika ; Pejcha, Ondřej (advisor) ; Kurfürst, Petr (referee)
Massive binary evolution is crucial for our understanding of many pheno- mena in the Universe, such as high-mass X-ray binaries or the formation of compact systems emitting gravitational waves. In this work, we study the loss of angular momentum from binary systems caused by radiation driven stellar winds, which are characteristic for hot, massive stars. Calculating numerically ballistic trajectories of particles ejected from the binary surface, we establish the average specific angular momentum loss as a function of the system's mass ratio for binaries in semidetached and contact stages. We initiate the outflow on the Roche lobes or even on further equipotentials of the Roche potential in case of over-contact systems. Moreover, we implement two models of the radiation driven wind. Firstly, we eject particles from the surface of the binary with a non-zero initial velocity, but we then let them evolve only under the influence of the system's gravity. In the second model, we develop a simple method for computing the radiative acceleration due to the radiation pressure from the bi- nary surface. Our results can be used in further calculations of the evolution of massive binary systems.
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Mass loss from binary stars
Hubová, Dominika ; Pejcha, Ondřej (advisor) ; Kopáček, Ondřej (referee)
In this thesis we investigate the loss of mass from binary systems from the vicinity of the second Lagrange point L2. This phenomenon arises mainly in the common envelope evolutionary phase of close binary systems when the cores of the components orbit inside a shared gaseous envelope. It is a crucial but poorly understood stage in the system's development with two substantially different possible outcomes - stellar merger or formation of a close binary system with compact components. Modifying mass, energy and angular momentum of the binary, mass loss through the L2 point might significantly impact the system's evolution throughout the common envelope phase. Using numerical integration of equations of motion, we evaluate final states of test particles ejected from the proximity of the L2 point with arbitrary initial velocity with respect to the corotating reference frame. Furthermore, we compute the amount of energy and angular momentum these particles carry away from the system. Previously, only the particles ejected from the L2 point from initial corotation were studied; this work is therefore the first to address this problem with general initial conditions. Firstly, we initiate the particles at the L2 point with velocity pointing in the direction of x-axis and y-axis. Secondly, we eject the particles from...
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