© Trent Dupuy
Multiple systems offer a unique perspective on various questions across star and planet formation and evolution. For one, there is a long tradition of binary systems providing model-independent "dynamical" masses, which continues today as we explore the substellar domain of brown dwarfs. Binary orbits also carry information about the conditions at their formation. For instance, a binary's semimajor axis and eccentricity limit the possible size of its protoplanetary disk. Measuring the orbits of all of the above systems typically requires very long-term monitoring, spanning decades. I will discuss recent progress on testing substellar evolutionary models (including giant planets) with dynamical mass measurements and on mapping the orbital architectures of planet-hosting binaries.