Using Bayesian Statistics Software (BASE-9) to Analyze Binary Stars in Open Clusters M67 and M35

Binary systems offer insight into the evolution of open clusters as a result of collisions, gravitational interactions, energy transfers, and other dynamic activity. M35 (~150 Myr) and M67 (~4 Gyr) are open clusters of contrasting ages that are home to extensive binary populations. Using Gaia DR3, Pan-STARRS, and 2MASS photometry with the Bayesian statistical tool, BASE-9, we derive precise cluster parameters (including age, metallicity, distance, and reddening), identify binaries, and extract their mass ratios. We find agreement with previous literature values, where available. Importantly, we extend the binary demographics by many magnitudes faintward of previous (radial-velocity) studies in both clusters. We compare the binary parameters between M35 and M67. This study is a precursor for future work investigating trends across many clusters, with specific emphasis on how binary characteristics evolve over time as a result of the local stellar environment.