Identifying Milky Way Open Clusters With Extreme Kinematics using PRIM

Abstract

41 The recent (April 25, 2018) second data release (DR2) of the European Space Agency satellite Gaia provides a dramatic increase in the extent and precision of stellar attributes for an unprecedented number of sources in the Milky Way (MW). For instance, data on position in the sky and proper motion are available for more than 1.3 billion stars, with a subset of more than 7 million of the brightest stars having radial velocity measurements. (Definitions of proper motion, radial velocity, and other astronomical terms are provided in the glossary.) Investigation of kinematics— combined proper motion and radial velocity—is central to our exploratory analyses. The cartoon in Figure 1 illustrates how these components yield total stellar velocities. Subsequently, we describe how to transform from the depicted sun-centric viewpoint to a Galactic Center viewpoint. The systematic study of stellar velocities has been one of the primary applications of the Gaia DR2 resource, with particular interest in the identification of hypervelocity stars (HVS). Rewinding the paths of some of these stars has enabled speculation regarding mechanisms, often violent, about how the extreme speeds were attained. Two of these components— depicted in Figure 1 as transverse velocity—can be obtained from the Identifying Milky Way Open Clusters With Extreme Kinematics using PRIM