Membership for open clusters with Gaia DR2

However, the utility of an open cluster can be limited by the accuracy and completeness of its known members. Here, we employ a "top-down" technique, Extreme Deconvolution Gaussian Mixture Models (XDGMMs), to extract and evaluate known open clusters from Gaia DR2 by fitting the distribution of stellar parallax and proper motion along a line of sight.

Extreme deconvolution techniques can recover the intrinsic distribution of astrometric quantities, accounting for the full covariance matrix of the errors; this allows open cluster members to be identified even when presented with relatively uncertain measurement data. To date, open cluster studies have only applied extreme deconvolution to specialized searches for individual systems. We use XDGMMs to characterize the open clusters reported by Ahumada & Lapasset (2007A&A...463..789A) and are able to recover 420 of the 426 open clusters therein (98.1%).