Program: GN-2019B-Q-224

Precise dynamical stellar masses can be measured for binary stars with both astrometric and radial velocity orbital solutions. In moving groups, dynamical masses can be translated into precise age measurements through stellar models, and provide a powerful (and unique) constraint on the moving group age. We propose here to monitor 35 moving group binaries with GPI NRM and the Zorro and 'Alopeke speckle cameras to characterize the orbits of these objects so that these stars may be used as calibrators for the ages of their host moving groups. Ages are vital for characterizing planet and brown dwarf companions, the majority of which are found around moving group stars, and so accurate ages for these groups strongly impact our understanding of directly imaged planets and brown dwarfs. We have recently demonstrated the viability of this method using two sets of binaries in the beta Pic moving group, and propose here to continue our program (approved in 2017A, 2017B, 2018A, and 2018B, with 14 stars observed to date) by monitoring stars in other groups and greatly reducing the uncertainties in quoted ages of nearby moving group stars and planets. After previous semesters allowed us to constrain multiple binary orbits, this semester we are focusing our GPI NRM time on characterizing the most interesting systems with well-defined orbits, but without resolved photometry: BS Ind, eta Hor, and CD-27 11535, while using the more efficient Zorro and 'Alopeke speckle imagers to better constrain the orbits of binaries with fewer observations to date.