The 20th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun Edited by S. J. Wolk The SUPERWIDE Catalog of Wide Binaries Zachary Hartman,1,2 Sébastien Lépine1 1 Department of Physics & Astronomy, Georgia State University, Atlanta, Georgia 2 Lowell Observatory, Flagsta, Arizona Abstract We present the results of our search for wide binaries in the SUPERBLINK high proper motion catalog of 2.8 million stars with proper motions >40 mas/yr, which has been recently enhanced with data from the GAIA mission. In a rst step, we conduct a Bayesian analysis taking into account angular separations and proper motion dierences provided by the SUPERBLINK catalog, and identify all possible common proper motion (CPM) pairs with separations up to 60 arcminutes. In the second step we expand the analysis using parallaxes from the Gaia DR2 release, and calculate probabilities for each pair to be a gravitationally bound system. The result is a list of 18,000 pairs with probabilities of being real binaries greater than 99 percent. We show that the distribution of projected physical separations of these wide, eld binaries follows a decreasing power law, and shows no evidence of being bimodal, i.e. there is no evidence of a secondary population of pairs with separations > 104 AU. In addition, we nd clear evidence that at least 30 percent of these wide binaries are triples/multiples, based on one of the components being over-luminous. 1 Searching for Wide Binaries Using the SUPERBLINK high proper motion catalog and the Gaia DR2 data release (Gaia Collaboration et al. 2016, 2018b), we conducted two Bayesian analyzes tak- ing into account angular separations and proper motion dierences in the rst pass and distance dierences from the Gaia data in the second pass. Figure 1 shows the probability distributions for both passes, with the top gure showing the result for the rst pass and the bot- tom gure showing the result of the second pass. In the rst pass, we eliminated all pairs with probabilities below 10%, noting that the overwhelming majority of them are chance alignments on the sky. Those pairs with rst pass probabilities > 10% were then taken and passed through our second Bayesian analysis. Keeping pairs with nal probabilities greater than 95%, we obtain a sample of 22,175 high probability wide binaries. Figure 2 shows the sky positions of these pairs. 2 Distribution of Projected Physical Separations Figure 3 shows the distribution of projected physical separation, color coded for pairs that are de nitely physi- cal (purple), de nitely chance alignment (red), and unde- termined (yellow). Projected physical separation was cal- culated from the parallax of the primary and the angular separation to the secondary in the plane of the sky. SU- PERBLINK depends on 2MASS catalog identi cations, which have a 4 resolution. Therefore, our completeness limit depends on this times a distance limit, which was chosen to be 500 pc. This is marked on Figure 3 as a dotted line. Note that the distribution appears bimodal only when chance alignments are included; the distribu- tion of high probability, physical pairs falls o rapidly with physical separation, and does not show evidence of a distinct population of ultra-wide systems. Figure 4 shows multiple ts to the tail of the real pairs distribu- tion in log-log space. A Gaussian t based on the t from Duquennoy & Mayor (1991) and Raghavan et al. (2010) is shown in cyan, the model clearly overestimates the high-end tail of the distribution. Starting from around 104 AU, it appears that a single power law is a better t with a power = -2.2. This could indicate that very wide (>10,000AU) binary systems are disrupted over time. 3 Over-Luminous Stars We examined the possibility of triple systems by look- ing for over-luminous (O-L) stars in our sample of pairs with nal probabilities > 95%, with distances <250 pc and where the primary star is a K-dwarf to limit eects from evolved stars and metallicity. Figure 5