Binary Star System and the Centre of Mass

Theory

Two bodies orbit their common centre of mass. With equal masses, each moves on a circle of radius $d/2$ with $v=\sqrt{\frac{GM}{2d}}$. A distant planet sees the pair almost as a single mass $2M$ (a circumbinary orbit, like Tatooine).

What to observe

• The circumbinary planet wobbles slightly because of the pair.

Try this

• Make one star heavier.

Also available in: Sistema binário e centro de massa (Português) · Sistema binario y centro de masa (Español)