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Previous analyses of large databases of Milky Way stars have revealed thestellar disk of our Galaxy to be warped and that this imparts a strongsignature on the kinematics of stars beyond the solar neighborhood. However,due to the limitation of accurate distance estimates, many attempts to explorethe extent of these Galactic features have generally been restricted to avolume near the Sun. By combining Gaia DR2 astrometric solution, StarHorsedistance and stellar abundances from the APOGEE survey, we present the mostdetailed and radially expansive study yet of the vertical and radial motions ofstars in the Galactic disk. We map stellar velocity with respect to theirGalactocentric radius, angular momentum, and azimuthal angle and assess theirrelation to the warp. A decrease in vertical velocity is discovered atGalactocentric radius $R=13\ \text{kpc}$ and angular momentum $L_z=2800\\text{kpc}\ \text{km}\ \text{s}^{-1}$. Smaller ripples in vertical and radialvelocity are also discovered superposed on the main trend. We also discoveredthat trends in the vertical velocity with azimuthal angle are not symmetricabout the peak, suggesting the warp to be lopsided. To explain the global trendin vertical velocity, we built a simple analytical model of the Galactic warp.Our best fit yields a starting radius of $8.87^{+0.08}_{-0.09}\ \text{kpc}$ andprecession rate of $13.57^{+0.20}_{-0.18}\ \text{km}\ \text{s}^{-1}\\text{kpc}^{-1}$. These parameters remain consistent across stellar age groups,a result that supports the notion that the warp is the result of an external,gravitationally induced phenomenon.

Exploring the Galactic Warp Through Asymmetries in the Kinematics of the Galactic Disk