Welcome to the home of BINSTAR
BINSTAR is the detailed binary stellar evolution code developed at the Institut d'Astronomie et d'Astrophysique.
It is based on the highly successful STAREVOL single-star code. It incorporates STAREVOL's physics package, namely a nuclear network containing 185 reactions, OPAL and molecular opacity, the Pols. et al equation of state, convection by mixing length theory, overshooting, semi-convection, thermohaline and rotationally induced mixing, structural deformation due to rotation and mass loss/gain. The ultimate aim is to model low/intermediate-mass AGB stars in binary systems.
The BINSTAR project is currently developed by Lionel Siess, Philip Davis and Romain Deschamps in collaboration with our VUB colleagues.
BINSTAR allows the fully implicit computation of both stars of a binary system and its orbital motion simultaneously. The project started in 2008 with the impulse of the European Union (Marie Curie fellowship assigned to R. Izzard)
The main features include:
- A Henyey solver which calculates both stars and the orbital properties separation (a) and eccentricity (e) simultaneously.
- Wind accretion (Bondi-Hoyle)
- Tidal interaction using Hut (1981) and Zahn (1977, 1989) formalisms with self-consistent calculation of the E2 and k2 coefficients.
- Magnetic braking due to disc locking and enhanced magnetic winds (e.g. Dervisoglu et al. 2010)
- RLOF mass transfer following the de Ritter (1988) prescription supplemented by Kolb & Ritter (1990)
- Mass transfer in eccentric binaries with asynchronously rotating stars (Sepinsky 1997)
- In case of direct impact, the accreted angular momentum is estimated by calculating the ballistic trajectory of a test particle in the gainer's Roche potential (Flannery 1975)
- the physics of the hot spot is also accounted for (van Rensbergen et al 2008)
- the code also considers the possible storage of mass and angular momentum in a decretion disc