In a binary star system, two stars revolve about their combined center of mass. They are held together by the force of gravity. For a certain system, the force of gravity between the stars (masses M1 and M2) is F0.
In some binary systems, one star transfers material onto the other. If star 1 dumps half of its material onto star 2, which thus increases its mass by a factor of 5, how is the force affected if the distance between the stars' centers remains the same?