When m1(sun) is much greater than m2(planet), nothing will happen because the speed of orbit is determined by the semi-major axis of orbit. Kepler determined that the Period of orbit squared is proportional to the semi-major axis cube. (In the case of the sun and planets P^2=a^3 )
For objects of similar mass then Newton modified Keplers law to
P^2= [4pi^2 / G(m1+m2) ] a^3
Where G is the universal gravitational constant (still not accurately known
) and a is the semi-major axis of the orbit and P is the orbital Period.