All Figures

Figure 1: Distribution of the surface density of open clusters versus their distance dxy from the Sun projected onto the Galactic plane. The dotted lines indicate the completeness limit, the dashed horizontal lines correspond to the average density of "field clusters'' (i.e., not contained in cluster complexes, s. Sect. 5). The bars are Poisson errors derived from cluster counts. Left panel: distribution of all clusters. Right panels: distributions of clusters with different ages. The panel designations from T1 to T4 are the identifiers of four subsamples of different ages as defined in the text.

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In the text

Figure 2: Open clusters and interstellar extinction. Distributions of the total extinction AV ( left panel), and of the extinction coefficient aV ( right panel) in the wider Solar neighbourhood. In both panels the contours show AV,aV-levels according to the grey-colour scales shown at the right upper corners of the panels. The circles represent open clusters. Their sizes (and colour) correspond to AV,aV of the clusters. The blank areas in the periphery of the plots are due to a lack of clusters in our sample at these locations.

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In the text

Figure 3: Distribution of clusters perpendicular to the Galactic plane. The distributions are constructed for clusters within the completeness limit of 850 pc. Panel A: all clusters, panels T1-T4: the 4 age samples (from T1 to T4) defined in Sect. 3.1. The thin black curves indicate smoothed spatial densities. The thin (magenta) curves in panels T1, T3 and A mark "field'' subsamples of the corresponding ages. The vertical solid lines give positions (Z0) of symmetry planes, and the dashed vertical lines show Z0 of "field'' subsamples. The thick solid curves correspond to Gaussian distributions computed with parameters listed in Table 1. Thick long-dashed lines give the barometric distributions fitted to observations.

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In the text

Figure 4: Distribution of open clusters in the XY-plane centered at the location of the Sun. Blue squares mark T1 clusters, black plusses - T2, red circles - T3, and black crosses - T4 clusters. Dots indicate the positions of clusters with known distances and ages from the DLAM catalogue (v2.0), which are not included in our sample. The youngest ( ) of these clusters are marked by triangles. Long dashed and solid thick curves are the grand design spiral arms with a pitch-angle of fitted to young clusters in the Perseus and Carina-Sagittarius regions. The large circle around the Sun indicates the completeness area of our sample.

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In the text

Figure 5: Observed kinematic data of open clusters versus Galactic longitude for four ranges of distances (as indicated at the top). The upper panels are for proper motions, the middle - for tangential velocities, and the bottom - for radial velocities. The parameters of individual clusters are marked by thin horizontal strokes together with the vertical error bars (in the RV panel the error bars are given only for clusters for which the rms-errors could be estimated). The crosses in the rightmost panels indicate clusters with d > 3.5 kpc. For a given distance range, the curves show systematic velocity components due to Solar motion and Galactic rotation computed with the parameters , A and B in Table 2. The thick dashed curves correspond to the contributions at the smallest distance of a given distance range, whereas the thin solid curves show this contribution at the largest distance. For example, in the upper left panel the dashed curve shows systematic variations versus longitude in proper motions expected for a cluster at 0.085 kpc from the Sun, whereas the solid curve shows this variations for a cluster at 0.5 kpc.

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In the text

Figure 6: Vector point diagrams of tangential velocities of open clusters in four age samples (from T1 to T4). The velocities are corrected for Solar motion and differential rotation of the Galaxy. Dots are clusters (independent of age) within the completeness area. The crosses mark clusters of a given age sample. The circles and squares are clusters located within the areas of the density excesses (samples T1 and T3). Their sizes indicate kinematic membership probability to belong to an OCC correspondingly, the largest symbols indicate  members, the intermediate circles are  members, and the smallest circles are  members. The squares (in T3) mark the members of the Perseus-Auriga group (see Sect. 5.3). The triangles (in T4) indicate possible members of the Hyades cluster group (see Sects. 4 and 5.4). The plusses in the bottom-left corners in each panel give the mean errors of tangential velocities of open clusters. The (green) cross-hair indicates the average tangential motion of each group, whereas the ellipses show the velocity ellipses of the complexes.

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In the text

Figure 7: Spatial distribution of the OCC 1 clusters in 3D-space. The proper coordinate system X',Y',Z of the OCC 1 is described in the text. The coordinate axes X and Y of the Galactic rectangular system are shown with dotted lines. Two circles centered at the origin of the Galactic coordinate system indicate the outer boundary of the area of the enhanced density at 0.5 kpc and the completeness area at 0.85 kpc. The solid ellipse outlines the OCC 1 members selected as described in the text. The dashed ellipse represents the Olano (1982) model of gas in Gould's Belt, given here for comparison. The small dots are all the clusters from our sample, the crosses mark T1 clusters, and the filled circles are for member candidates of the OCC 1. The small (cyan) circles are members, the dotted circles (green) of medium size show members, and the largest dotted circles (light yellow) with a (green) core indicate members. The grey colour contours give the projected density distribution of T1 clusters, derived separately in each panel. The density distribution was computed in windows of  pc2 and smoothed with a 5-point rectangular filter. The rules to the right indicate the corresponding density scales where the (X',Z) and (Z,Y')planes share the same grey colour scale. The straight line in the panel (Z,Y') is the regression line computed with  clusters. The resulting inclination i is given in the left upper corner of (Z,Y') plane.

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In the text

Figure 8: Spatial distribution of T3 clusters in 3D-space. The coordinates are given in the Galactic cartesian system. The larger circles indicate possible members of OCC2, the diamonds mark members of the Perseus-Auriga group (in order to avoid an overcrowding in the X,Z and Y,Z panels, they are shown together with the corresponding boundary circle only in the X,Y panel). The dashed circle gives the inner edge of the enhancement area. The other designations are the same as in Fig. 7.

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In the text

Figure 9: Tangential velocities of clusters versus Galactic longitude. The velocities are corrected for differential Galactic rotation and for Solar motion with respect to the cluster centroid. The points mark clusters of the corresponding sample. Panel  a) the T1 sample, circles are for the OCC 1 members. Panel  b) the T3 sample, circles and triangles indicate OCC 2 and Perseus-Auriga members, respectively. Panel  c) the T4 sample with candidates (circles) of a moving group. The Hyades and Praesepe are marked by squares. The distribution of tangential velocities of candidates is fitted by a sine function.

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In the text

Figure 10: The relative position of identified open cluster complexes and groups in the XY plane on a background of interstellar clouds revealed from data on our sample of clusters (Fig. 2). Large symbols mark candidate members for the Gould's Belt complex (triangles), OCC 2 (circles), the Perseus-Auriga group (diamonds), and the Hyades group (crosses). Small open circles mark field clusters. Large circles and the ellipse are apparent complex boundaries.

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In the text

Figure 11: Distribution of open clusters versus age. For an easier comparison, the distributions for the different samples are not normalised to unit area. Upper panel: our total sample is shown as the hatched histogram. The sample of field clusters within the completeness area is marked as the filled histogram, and the solid curve marks the fitted age distribution. The age step is 50 Myr. Lower panel: the same distributions as in the upper panel together with the age sample used by Wielen (1971). The data from Wielen (1971) are shown as the backhatched histogram in the foreground. The vertical bars correspond to Poissonian errors derived from cluster counts. The binning is chosen same as in Wielen (1971).

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In the text