Homework Help: Sun’s contribution to total orbital angular momentum of Sun-Jupiter orbit

1. Jan 11, 2010

From Carroll and Ostlie “An Introduction to Modern Astrophysics” prob 2.6 b

After determining angular momentum of sun-jupiter orbit system in part a, the question then asks you “What contribution does the sun make toward the total orbital angular momentum. It says assume jupiter is in a circular orbit, so r is constant and is easy to calculate from Keplers 2nd law. But it is asking what contribution does the sun make to the total orbital angular momentum of the sun-jupiter system. Obviously the sun is rotating so you can calculate angular momentum of sun about its rotational axis....but it doesnt ask you to do this until part e....so as for part b...is there some way to figure what the contribution of the sun is to the total orbital angular momentum (disregarding rotational angular momentum) Wouldnt it be zero since its not rotating around jupiter....??? I have mass of sun, jupiter, radius, period and velocity, and angular momentum of system (L). If L(sun)=M(sun)*r*v, well the velocity of sun is zero so is it that trivial? I somehow think it is not

Thanks
Chris

2. Jan 11, 2010

sylas

I believe in this problem you should assume that both the Sun and Jupiter are in circular orbits around the center of mass of the whole system.

3. Jan 11, 2010