ИСТИНА

Statistical parallax technique is applied to classical Cepheids with pulsation periods greater than 9 days (this sample is expected to be almost free of first overtone pulsators). The sample includes 101 Cepheids with radial velocities, 99 Cepheids with proper motions (mostly from Hipparcos and Tycho-2) and 91 Cepheids with space velocities. Their heliocentric distances, calculated with Berdnikov et al. (1996) multi-colour `period- luminosity' relation (PL relation), do not exceed 6 kpc. Two approaches have been used: (1) The comparison of first derivatives of angular velocity law for the Galactic disc, calculated separately from radial velocities and proper motions; (2) The maximum likelihood estimation of all kinematical parameters (including the distance scale parameter) for three-dimensional velocity field. The first (robust) version of the statistical parallax method requires small (approximately 5%) reduction of distances, whereas the second version requires small (about the same 5%) expansion of all distances, both with large errors (15% and 10% respectively). We can conclude, that pre-Hipparcos Cepheids distances do not require an appreciable revision and are in general agreement with the short distance scale, with LMC distance modulus DMLMC < 18.4. The kinematical parameters, calculated from space velocities of 91 Cepheids, are: [U0, V0, W0] = (-8, -12, -6)±1 km s-1 , [sigmaVR, sigmaVtheta, sigmaVZ] = (15,10,11)±0.8 km s-1 , angular velocity Omega0 = (26.5±1.2) km s-1 kpc-1 and its first derivative Omega0' = (-4.45±0.3) km s-1 kpc-2 . The thick-disc and halo local populations of Galactic field RR Lyrae stars are analyzed by applying a bimodal version of the statistical parallax (maximum-likelihood) technique to a sample of 361 RR Lyraes with known periods, radial-velocities, metallicities, 2MASS K-band photometry, and absolute proper motions on the ICRS system. We inferred the following parameters: the thick-disc star fraction fdisc = 0.31±0.03, the velocitydistribution parameters [U0, V0, W0]halo = (-14±5; -239±8; -16±4) km s-1 , [?VR, ?V?, ?VZ]halo = (172±9; 82±5; 87±5) km s-1 and [U0, V0, W0]disc = (-14±5; -52±5; -16±4) km s-1 , [sigmaVR, sigmaVtheta, sigmaVZ]disc = (56±5; 44±4; 35±4) km s-1 and the infrared PL relation < MK >= -2.33 log PF -0.94 (± 0.06). A bimodal version of the 2D maximum-likelihood technique (without radial velocities) applied to a sample of 1204 bona fide type ab and c RR Lyraes with known periods, 2MASS K-band photometry, UCAC2 absolute proper motions, and heliocentric distances inferred using the above PL relation yielded the following results: fdisc = 0.42±0.02; [U0, V0, W0]halo = (-24±5; -255±7; -12±3) km s-1 , [sigmaVR, sigmaVtheta, sigmaVZ]halo = (189±8; 76±6; 114±8) km s-1 and [U0, V0, W0]disc = (-24±5; -52±6; -12±4) km s-1 , [sigmaVR, sigmaVtheta, sigmaVZ]disc = (48±6; 48±5; 22±4) km s-1 . Our zero point for the infrared PL relation for RR Lyrae variables implies a solar Galactocentric distance of R0 = 8.0±0.4 kpc and an LMC distance modulus of DMLMC = 18.32±0.08.