Mass Transfer in Binary Star Systems

mass ratio — the ratio of the masses of the mass-losing secondary star to the mass-gaining primary star

time — the number of elapsed orbits of the binary star system

initial velocity — The component is the component of the initial velocity of the particle in the direction of the mass-gaining primary star. The component is the component of the initial velocity of the particle in the direction of the orbit of the mass-losing star (in this simulation, the direction is up)

friction — the coefficient that governs the orbital decay of the transfer particle

In a binary system, the first Lagrange point (L1) is the point of gravitational equilibrium between the two stars. When the secondary star grows so large that L1 is on its surface, gas transfers from that point to the more massive primary star. This type of system is also known as a semi-detached binary star system. The path of a particle of gas depends on its initial velocity and the friction caused by other gas particles in the transfer.

Snapshot 1: This shows the trajectory of the mass transfer stream with low friction.

Snapshot 2: The masses of the stars are equal, so the center of mass is at the first Lagrange point.

Snapshot 3: With high friction, the trajectory steadily decays.