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| Paper: |
Mass Transfer in Eccentric Binary Stars |
| Volume: |
293, 3D Stellar Evolution |
| Page: |
110 |
| Authors: |
Regos, E.; Bailey, V. C.; Mardling, R. |
| Abstract: |
The concept of Roche lobe overflow is fundamental to the theory of interacting binaries. If the mass losing star is asynchronous with the orbital motion or the orbit is eccentric no single frame of reference can be found in which all the relevant material is corotating. We use an analytic approximation whose predictions are largely justified by SPH simulations. We present smoothed-particle-hydrodynamics simulations of binary systems with the same semi-major axis a=5.55 Rsun, masses M1=1 Msun, M2=2 Msun and radius R1=0.89 Rsun for the primary star but with different eccentricities of e=0.4, 0.5, 0.6 and 0.7. In each case the secondary star is treated as a point mass. When e=0.4 no mass is lost from the primary while at e=0.7 catastrophic mass transfer, partly through the L2 point takes place near periastron. This would probably lead to common-envelope evolution if star 1 were a giant or to coalescence for a main-sequence star. In between, at e=>0.5, some mass is lost through the L1 point from the primary close to periastron. However, rather than being all accreted by the secondary some of the stream appears to leave the system. Our results indicate that the radius of the Roche lobe is similar to circular binaries when calculated for the separation and angular velocity at periastron. Part of the mass loss occurs through the L2 point. |
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