Constraining Binary Demographics in Open Clusters toTest Binary Formation and Evolution Theory

Binary stars are ubiquitous in our galaxy; yet important gaps remain in our understanding of their formation and evolution and consequently, in stellar evolution theory broadly. Using Gaia DR3, Pan-STARRS and 2MASS photometric data we self-consistently refine the cluster parameters and binary demographics for the open clusters (OCs) NGC 188, M35 (NGC 2168), M67 (NGC 2682), NGC 6819, and NGC 7789 and compare our results to previous work. These clusters span in age from ~150 Myr (M35) to ~7 Gyr (NGC 188). We make use of the Bayesian Analysis of Stellar Evolution code (BASE-9) to constrain the OC age, distance, reddening, metallicity, binary fraction, and binary mass ratio distribution. We use the results derived from BASE-9 for this set of OCs to investigate trends in binary parameters with cluster properties, testing current theoretical prediction of binary formation and evolution. While we present our methods and analysis for only five OCs here, we will extend our analysis to hundreds of OCs in future work and make the data open-source and easily accessible online in an effort to advance stellar evolution theory.