A sample of 477 solar-type binaries within 67 pc with projected separations larger than 50 AU is studied by a new statistical method. Speed and direction of the relative motion are determined from the short observed arcs or known orbits, and their joint distribution is compared to the numerical simulations. By inverting the observed distribution with the help of simulations, we find that average eccentricity of wide binaries is 0.59±0.02 and the eccentricity distribution can be modelled as f (e) ≈ 1.2e + 0.4. However, wide binaries containing inner subsystems, i.e. triple or higher-order multiples, have significantly smaller eccentricities with the average e = 0.52 ± 0.05 and the peak at e ∼ 0.5. We find that the catalog of visual orbits is strongly biased against large eccentricities. A marginal evidence of eccentricity increasing with separation (or period) is found for this sample. Comparison with spectroscopic binaries proves the reality of the controversial period-eccentricity relation. The average eccentricity does increase with binary period, being 0.39 for periods from 10 2 to 10 3 days and 0.59 for the binaries studied here (10 5 to 10 6 days).

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Abstract. We discovered a new component E in the nearby multiple system Gliese 225.2, making it quadruple. We derive a preliminary 24-yr astrometric orbit of this new sub-system C,E and a slightly improved orbit of the 68-yr pair A,B. The orientations of the A,B and C,E orbits indicate that they may be close to coplanarity. The orbit of AB,CE is rather wide and does not allow to determine its curvature reliably. Thus, the 390 yr orbit computed by Baize (1980, Inf. Circ. IAU Comm., 26(80)) was premature. The infrared colors and magnitudes of components A, B, and C match standard values for dwarfs of spectral types K5V, M0V, and K4V, respectively. The new component E, 3 magnitudes below the Main Sequence, has an anomalously blue color index. We estimate its mass as roughly 0.2 solar from the astrometric orbit, although there remains some inconsistency in the data hinting on a higher mass or on the existence of additional components in the system. Large space velocities indicate that Gliese 225.2 belongs to the thick Galactic disk and is not young. This quadruple system survived for a long time and should be dynamically stable.

Abstract. Complementing the Proper Motions of Fundamental Stars catalogue by Gontcharov et al. (CDS,) the photocentric orbits of some FK5/Hipparcos stars are calculated in a direct combination of the Hipparcos data with astrometric ground-based observational catalogues having epochs later than 1939. Some capabilities and limitations of this method are discussed in a comparison of our results with known orbits of Sirius, Procyon, Rasalhague, µ Cas and others. We conclude that this direct combination is an acceptable tool to discover and investigate photocentric orbits with periods from 10 to 55 years and the semi-major axis of apparent ellipses >0.08 arcsec. It is particularly suitable for pairs with large magnitude difference as well as for calculation of the preliminary orbits of new astrometric binaries which will be considered in forthcoming papers. In this paper new photocentric orbits and component masses are calculated for 4 pairs: α UMa, β LMi, δ And and ξ Aqr.