Comoving stars in Gaia DR1

Comoving stars include a range of objects from wide binaries and multiples to moving groups and open clusters. I will describe our recent work to find candidate comoving pairs using Gaia DR1. In order to select pairs of stars more likely to share the same space velocity, we build a probabilistic model and marginalize over unknown distances and velocities. We use the fully marginalized likelihood ratio to select comoving pairs. Of ~271k pairs that we examine with a maximum separation of 10pc and a maximum difference in tangential velocity of 10 km/s, we find 1.3k candidate comoving pairs among 10k stars. Some of these pairs form larger groups by sharing mutual comoving neighbors, many of which correspond to known open clusters in the Milky Way. We also find a large number of very wide separation (>3pc) candidate comoving pairs. I will discuss potential implications of the results and future directions.

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