Dependence of Kinematics on the Age of Stars in the Solar Neighborhood

Abstract

The variations of kinematic parameters with age are considered for a sample of 15 402 thin-disk O--F stars with accurate $α$, $δ$, $μ$, and $π>3$ mas from the Hipparcos catalogue and radial velocities from the PCRV catalogue. The ages have been calculated from the positions of the stars on the Hertzsprung--Russell diagram relative to the isochrones from the Padova database by taking into account the extinction from the previously constructed 3D analytical model and extinction coefficient $R_V$ from the 3D map of its variations. Smooth, mutually reconciled variations of the velocity dispersions $σ(U)$, $σ(V)$, $σ(W)$, solar motion components $U_{\odot}$, $V_{\odot}$, $W_{\odot}$, Ogorodnikov--Milne model parameters, Oort constants, and vertex deviation $lxy$ consistent with all of the extraneous results for which the stellar ages were determined have been found. The velocity dispersion variations are well fitted by power laws the deviations from which are explained by the influence of predominantly radial stellar streams: Sirius, Hyades, $α$~Cet/Wolf~630, and Hercules. The accuracy of determining the solar motion relative to the local standard of rest is shown to be fundamentally limited due to these variations of stellar kinematics. The deviations of our results from those of Dehnen and Binney (1998), the Geneva--Copenhagen survey of dwarfs, and the Besancon model of the Galaxy are explained by the use of PCRV radial velocities with corrected systematic errors.