Extended stellar systems in the solar neighborhood

We present a novel view on the morphology and dynamical state of ten prominent, nearby (?500 pc), young (?30–300 Myr) open star clusters with Gaia DR2: ? Per, Blanco 1, IC 2602, 2391, Messier 39, NGC 2451A, 2516, 2547, Platais 9, Pleiades. introduce pioneering member-identification method that is informed by cluster bulk velocities deconvolves spatial distribution mixture Gaussians. Our approach enables inferring true effectively filtering field contaminants while at same time mitigating effect positional errors along line sight. This first application reveals vast stellar coronae extend for ?100 pc surround cores, which are comparatively tiny compact. The cores form intertwined, coeval, comoving extended populations, each encompassing tens thousands cubic parsec stretching across degrees sky. analysis shows gravitationally unbound but largely comprise mass populations. Most systems in highly dynamic state, showing evidence expansion sometimes simultaneous contraction different axes. velocity populations appears asymmetric aligned axis unique to cluster. overall kinematic signature consistent differential rotation pattern Milky Way. finding underlines important role global Galactic dynamics fate systems. results highlight complexity Way’s population call new perspective characterization clusters.