Orbital periods

Oh my goodness, a lot has happened in the nearly two years since my last post. So much, in fact, that the thought of recapping it all is a total block on posting. So we're moving on.

I needed to check the orbital period of a companion to a 1.7 solar mass star, and the orbital separation is ~20 AU. I find myself having to do this sort of thing a lot, and I'm also supposed to be focusing on writing a paper, so instead I made a little figure that can serve as a handy reference if you need a ballpark feel for it. It shows the orbital period in years for a range of separations and primary masses. There is an implied assumption that the companion is much less massive than the primary.

The black dots are the Solar System planets (yes, including Pluto). The contour lines show constant orbital period. I like it but I think it would help a lot if I added the contour lines to the colorbar as well.