Quick review for high school physics.
According to Newton's law of universal gravitation.
The force caused by other star is ${GMm\over r^2}$, and the gravity is $g = {GM\over r^2}$
$G$ is constant, $m$ is the mass of star itself, $M$ is the mass of the other star, and $r$ is the distance between stars.
If $r$ is large enough, the contribution to total force can be really small. Thus, we can approximate it by grouping its neighbors.
Quick review for high school physics. According to Newton's law of universal gravitation. The force caused by other star is ${GMm\over r^2}$, and the gravity is $g = {GM\over r^2}$ $G$ is constant, $m$ is the mass of star itself, $M$ is the mass of the other star, and $r$ is the distance between stars.
If $r$ is large enough, the contribution to total force can be really small. Thus, we can approximate it by grouping its neighbors.
For detail, see the wiki page
This comment was marked helpful 0 times.