We use UCAC4 proper motions and WISE W 1-band apparent magnitudes intensitymean for almost 400 field RR Lyrae variables to determine the parameters of the velocity distribution of Galactic RR Lyrae population and constrain the zero points of the metallicity-< M V > relation and those of the period-metallicity-< M Ks >-band and period-metallicity-< M W 1 >-band luminosity relations via statistical parallax. We find the mean velocities of the halo-and thick-disc RR Lyrae populations in the solar neighbourhood to be (U 0 (Halo), V 0 (Halo), W 0 (Halo)) = (−7 ± 9, −214 ± 10, −10 ± 6) km s −1 and (U 0 (Disc), V 0 (Disc), W 0 (Disc)) = (−13 ± 7, −37 ± 6, −17 ±4) km s −1 , respectively, and the corresponding components of the velocity-dispersion ellipsoids, (σV R (Halo), σV φ (Halo), σV θ (Halo)) = (153 ± 9, 101 ± 6, 96 ± 5) km s −1 and (σV R (Disc), σV φ (Disc), σV θ (Disc)) = (46 ± 7, 37 ± 5, 27 ± 4) km s −1 , respectively. The fraction of thick-disc stars is estimated at 0.22 ± 0.03. The corrected IR periodmetallicity-luminosity relations are < M Ks > = -0.769 +0.088 · [Fe/H]-2.33 · log P F and < M W 1 > = -0.825 + 0.088· [Fe/H] -2.33 · log P F , and the optical metallicityluminosity relation, [Fe/H]-< M V >, is < M V > = +1.094 + 0.232· [Fe/H], with a standard error of ± 0.089, implying an LMC distance modulus of 18.32 ± 0.09, a solar Galactocentric distance of 7.73 ± 0.36 kpc, and the M31 and M33 distance moduli of DM M31 = 24.24 ± 0.09 (D = 705 ± 30 kpc) and DM M33 = 24.36 ± 0.09 (D = 745 ± 31 kpc), respectively. Extragalactic distances calibrated with our RR Lyrae star luminosity scale imply a Hubble constant of ∼80 km/s/Mpc. Our results suggest marginal prograde rotation for the population of halo RR Lyraes in the Milky Way. c 2013 RAS

Abstract. We report a new version of the catalogue of distances and light-curve parameters for Galactic classical Cepheids. The catalogue lists amplitudes, magnitudes at maximum light, and intensity means for 455 stars in BV RI filters of the Johnson system and (RI) C filters of the Cron-Cousins system. The distances are based on our new multicolour set of PL relations and on our Cepheidbased solution for interstellar extinction law parameters and are referred to an LMC distance modulus of 18.25.

The proper motions of OB-associations computed using the old (Hipparcos 1997) and new (van Leeuwen 2007) reductions of the Hipparcos data are in a good agreement with each other. The Galactic rotation curve derived from an analysis of lineof-sight velocities and proper motions of OB-associations is almost flat in the 3kpc neighborhood of the Sun. The angular rotation velocity at the solar distance is Ω 0 = 31 ± 1 km s −1 kpc −1 . The standard deviation of the velocities of OB-associations from the rotation curve is σ = 7.2 km s −1 . The distance scale for OB associations (Blaha & Humphreys 1989) should be shortened by 10-20%. The residual velocities of OB-associations calculated for the new and old reductions differ, on average, by 3.5 km s −1 . The mean residual velocities of OB-associations in the stellar-gas complexes depend only slightly on the data reduction employed.

Context. Significant progress has been made in recent years to understand the formation and evolution of our Galaxy, but we still lack a complete understanding of the Galaxy and its structure. Aims. Using an almost complete sample of Galactic open star clusters within 1.8 kpc, we aim to understand the general properties of the open cluster system in the Galaxy and probe the Galactic structure. Methods. We first extracted 1241 open clusters within 1.8 kpc of the Sun from the Milky Way Star Clusters (MWSC) catalog. Considering it an almost complete sample of clusters within this distance, we performed a comprehensive statistical analysis of various cluster parameters such as spatial position, age, size, mass, and extinction. Results. We find an average cluster scale height of z h = 60 ± 2 pc for clusters younger than 700 Myr, which increases to 64 ± 2 pc when we include all the clusters. The z h is found to be strongly dependent on R GC and age, and on an average, z h is more than twice as large as in the outer region than in the inner region of the solar circle, except for the youngest population of clusters. The solar offset is found to be 6.2 ± 1.1 pc above the formal Galactic plane. We derive a local mass density of ρ 0 = 0.090 ± 0.005 M ⊙ /pc 3 and estimate a negligibly small amount of dark matter in the solar neighborhood. The reddening in the direction of clusters suggests a strong correlation with their vertical distance from the Galactic plane with a respective slope of dE(B − V)/dz = 0.40±0.04 and 0.42±0.05 mag/kpc below and above the GP. We observe a linear mass-radius and mass-age relations in the open clusters and derive the slopes of dR/d(logM) = 2.08 ± 0.10 and d(logM)/d(logT ) = − 0.36 ± 0.05, respectively. Conclusions. The dependence of the spatial distribution of clusters on their age points to a complex interplay between cluster formation and survivability within the Galaxy. The geometrical characteristics of a significant number of clusters enabled us to understand large-scale spatial properties of the cluster systems within the Galaxy. The structural and physical parameters of clusters allowed us to check mutual correlations between the individual parameters.

Abstract-We analyze the space velocities of blue supergiants, long-period Cepheids, and young open star clusters (OSCs), as well as the H I and H II radial-velocity fields by the maximum-likelihood method. The distance scales of the objects are matched both by comparing the first derivatives of the angular velocity Ω determined separately from radial velocities and proper motions and by the statistical-parallax method. The former method yields a short distance scale (for R 0 = 7.5 kpc, the assumed distances should be increased by 4%), whereas the latter method yields a long distance scale (for R 0 = 8.5 kpc, the assumed distances should be increased by 16%). We cannot choose between these two methods. Similarly, the distance scale of blue supergiants should be shortened by 9% and lengthened by 3%, respectively. The H II distance scale is matched with the distance scale of Cepheids and OSCs by comparing the derivatives Ω determined for H II from radial velocities and for Cepheids and OSCs from space velocities. As a result, the distances to H II regions should be increased by 5% in the short distance scale. We constructed the Galactic rotation curve in the Galactocentric distance range 2-14 kpc from the radial velocities of all objects with allowance for the difference between the residual-velocity distributions. The axial ratio of the Cepheid+OSC velocity ellipsoid is well described by the Lindblad relation, while σ u ≈ σ ν for gas. The following rotation-curve parameters were obtained: Ω 0 = (27.5 ± 1.4) km s −1 kpc −1 and A = (17.1 ± 0.5) km s −1 kpc −1 for the short distance scale (R 0 = 7.5 kpc); and Ω 0 = (26.6 ± 1.4) km s −1 kpc −1 and A = (15.4 ± 0.5) km s −1 kpc −1 for the long distance scale (R 0 = 8.5 kpc). We propose a new method for determining the angular velocity Ω 0 from stellar radial velocities alone by using the Lindblad relation. Good agreement between the inferred Ω 0 and our calculations based on space velocities suggests that the Lindblad relation holds throughout the entire sample volume. Our analysis of the heliocentric velocities for samples of young objects reveals noticeable streaming motions (with a velocity lag of ∼7 km s −1 relative to the LSR), whereas a direct computation of the perturbation amplitudes in terms of the linear density-wave theory yields a small amplitude for the tangential perturbations. c 2002 MAIK "Nauka/Interperiodica".

We applied the currently most comprehensive version of the statistical-parallax technique to derive kinematical parameters of the maser sample with 136 sources. Our kinematic model comprises the overall rotation of the Galactic disk and the spiral density-wave effects. We take into account the variation of radial velocity dispersion with Galactocentric distance. The best description of the velocity field is provided by the model with constant radial and vertical velocity dispersions, (σU 0, σW 0) ≈ (9.4 ± 0.9 , 5.9 ± 0.8) km/s. We compute flat Galactic rotation curve over the Galactocentric distance interval from 3 to 15 kpc and find the local circular rotation velocity to be V 0 ≈ (235 − 238) km/s ±7 km/s. We also determine the parameters of the four-armed spiral pattern (pitch angle i ≈ (−10.4 ± 0.3) • and the phase of the Sun χ 0 ≈ (125 ± 10) • ). The radial and tangential spiral perturbations are about f R ≈ (−6.9 ± 1.4) km/s, f Θ ≈ (+2.8 ± 1.0) km/s. The kinematic data yield a solar Galactocentric distance of R 0 ≈ (8.24 ± 0.12) kpc. Based on rotation curve parameters and the asymmetric drift we Infer the exponential disk scale H D ≈ (2.7 ± 0.2) kpc under assumption of marginal stability of the intermediate-age disk, and finally we estimate the minimum local surface disk density, Σ(R 0 ) > (26 ± 3) M ⊙ pc −2 .

The kinematics and distribution of classical Cepheids within ∼ 3 kpc from the Sun suggest the existence of the outer ring R1R ′ 2 in the Galaxy. The optimum value of the solar position angle with respect to the major axis of the bar, θ b , providing the best agreement between the distribution of Cepheids and model particles is θ b = 37 ± 13• . The kinematical features obtained for Cepheids with negative Galactocentric radial velocity VR are consistent with the solar location near the descending segment of the outer ring R2. The sharp rise of extinction toward of the Galactic center can be explained by the presence of the outer ring R1 near the Sun.

We use the currently most complete collection of reliable Cepheid positions (565 stars) out to ∼ 5 kpc based mostly on our photometric data to outline the spiral pattern of our Galaxy. We find the pitch-angle to be equal to 9-10 o with the most accurate estimate (i =9.5 ±0.1 o ) obtained assuming that the spiral pattern has a four-armed structure, and the solar phase angle in the spiral pattern to be χ ⊙ = 121 o ± 3 o . The pattern speed is found to be Ω sp = 25.2 ± 0.5 km/s/kpc based on a comparison of the positions of the spiral arms delineated by Cepheids and maser sources and the age difference between these objects.