In a recent article appearing in the Astrophysical Journal, Vogt et al. (2005) published radial velocity data for six stars that appear to harbor multiple low-mass companions. The data for all six stars (HD 37124, HD 50499, HD 108874, HD 128311, HD 190360, and HD 217107) have been added to the system menu of the Systemic Console:

If you’ve worked through the console tutorials 1, 2, and 3, take a crack at using the console to fit these systems. HD 37124, in particular, is open to several different stable 3-planet configurations. In my current personal favorite fit, three very nearly equal-mass planets are caught up in an endless (or at least multi-billion year) cycle of rub-a-dub-dub. An .mpg animation of the long-term dynamical evolution of the orbits is here. Because the planets in this particular fit are fairly widely spaced, the motion is quite well described by second-order secular theory.