Analysis of galaxy kinematics based on Cepheids from the Gaia DR2 Catalogue

To construct the rotation curve of Galaxy, classical Cepheids with proper motions, parallaxes and line-of-sight velocities from Gaia DR2 Catalog are used in large part. The working sample formed literature data contains about 800 estimates their age. We determined that linear velocity Galaxy at a solar distance is $V_0=240\pm3$~km s$^{-1}$. In this case, Sun to axis found be $R_0=8.27\pm0.10$~kpc. A spectral analysis radial residual tangential younger than 120 Myr showed close parameters spiral density wave obtained both present time past. So, value wavelength $\lambda_{R,\theta}$ range [2.4--3.0] kpc, pitch angle $i_{R,\theta}$ [$-13^\circ$,$-10^\circ$] for four-arm pattern model, amplitudes perturbations $f_R\sim12$~km s$^{-1}$ $f_\theta\sim9$~km s$^{-1}$, respectively. Velocities older currently giving $\lambda_{R,\theta}\sim5$~kpc. This differs significantly one we samples young Cepheids. An positions old Cepheids, calculated by integrating orbits backward time, made it possible determine more reliable values wave: $\lambda_{R,\theta}=2.7$~kpc, $f_R=7.9$~km $f_\theta=5$~km