|Proper Motions of Open Star Clusters and the Rotation Rate of the Galaxy|
The mean proper motions of 167 Galactic open clusters withradial-velocity measurements are computed from the data of the Tycho-2catalog using kinematic and photometric cluster membership criteria. Theresulting catalog is compared to the results of other studies. The newproper motions are used to infer the Galactic rotation rate at the solarcircle, which is found to be ω0=+24.6±0.8 km s-1 kpc-1.Analysis of the dependence of the dispersion of ω0 estimates onheliocentric velocity showed that even the proper motions of clusterswith distances r>3 kpc contain enough useful information to be usedin kinematic studies demonstrating that the determination of propermotions is quite justified even for very distant clusters.
|Post-Maximum Optical and Infrared Observations of Nova V1425 Aquilae 1995|
Abstract image available at:http://adsabs.harvard.edu/abs/1997AJ....114.2671K
|CCD Stromgren Photometry of Young Reddened Clusters|
The capabilities of CCD uvby photometry for the study of reddened youngclusters are investigated. Observations of four fields in the directionof the clusters Basel 1, Berkeley 86, NGC 6704, and NGC 6756, with atotal of 1665 stars measured in at least the y and b bands, produce newestimates for the clusters parameters. The results are compared to thosefrom previously published studies in different photometric systemsshowing good agreement in the values of color excess and distancemodulus, with the exception of NGC 6756, for which an essentially largerdistance is found. Furthermore, the ages estimated for this cluster,Basel 1, and NGC 6704 are found to be higher than previously assumed, inparticular for the last one. The presence of red giants as clustermembers is suggested in Basel 1, NGC 6704, and NGC 6756.
|Absolute proper motions of 181 young open clusters.|
|Estimates of geometric and dynamic parameters of star-gas complexes in the Galaxy|
Parameters of geometric models of 11 gas-star complexes (GSCs) wereobtained. We used information about GSC projections onto the celestialsphere and the Galactic plane and about GSC extension along the line ofsight. GSCs were represented as triaxial ellipsoids. To estimate thesemiminor axis of the GSC ellipsoidal model and GSC slope angle to theGalactic plane, we used data on spatial location of open stellarclusters (OSCs) entering GSCs. GSC slopes to the Galactic plane varybetween 2.5 and 20.5 deg. Their semiminor axes are between 11 and 164pc. GSC total masses are estimated from GSC tidal effect on OSCs thatare members of the corresponding GSCs. The effect manifests itself insmaller sizes of young OSCs as compared to their tidal sizes in theforce field of the Galaxy. We used studies of stability of an OSC movingin the joint force field of the Galaxy and spheroidal stationary GSC, aswell as studies of evolution of a virialized cluster located at thecenter of a nonstationary ellipsoidal GSC. Estimated total masses fordifferent GSCs lie between 0.65 x 10 exp 5 solar masses and 11.5 x 10exp 7 solar masses.
|Catalogue of blue stragglers in open clusters.|
An extensive survey of blue straggler candidates in galactic openclusters of both hemispheres is presented. The blue stragglers wereselected considering their positions in the cluster colour-magnitudediagrams.They were categorized according to the accuracy of thephotometric measurements and membership probabilities. An amount of 959blue straggler candidates in 390 open clusters of all ages wereidentified and classified. A set of basic data is given for everycluster and blue straggler. The information is arranged in the form of acatalogue. Blue stragglers are found in clusters of all ages. Thepercentage of clusters with blue stragglers generally grows with age andrichness of the clusters. The mean ratio of the number of bluestragglers to the number of cluster main sequence stars is approximatelyconstant up to a cluster age of about 10^8.6^ yr and rises for olderclusters. In general, the blue stragglers show a remarkable degree ofcentral concentration.
|Young stellar-gas complexes in the Galaxy|
It is found that about 90 percent of OB-associations and o-b2 clusterssituated within 3 kpc of the sun can be united into complexes withdiameters of 150-700 pc. Almost all of these clusters contain giantmolecular clouds with a mass greater than about 100,000 solar masses. Anumber of complexes are associated with giant H I clouds; a few of thesmall complexes are situated in the HI caverns. The concentration ofOB-associations and young clusters in star complexes attests to theircommon origin in the supergiant gaseous clouds.
|On Statistics of Star Complexes|
|A cluster analysis of open clusters|
The Galactic distribution of 361 open clusters is studied using acluster analysis method. It is shown that more than half of the clustersenter groups with characteristic dimensions of several hundred parsecs.To distinguish physical clusters from random condensations, criteriabased on age similarity, the color of the main-sequence blue end, andthe integrated color and radial velocity of the clusters are used. Theproximity of these values suggests a physical unity and common origin ofclusters in a group.
|Catalog of open clusters and associated interstellar matter.|
|Catalogue of UBV Photometry and MK Spectral Types in Open Clusters (Third Edition)|
|Spectral Types of Eclipsing Binaries in Optical Coincidence with Clusters and Associations|
|Catalogue of Eclipsing and Spectroscopic Binary Stars in the Regions of Open Clusters|
|Integrated Photometric Parameters of Open and Globular Clusters|
|Open clusters and galactic structure|
A total of 610 references to 434 clusters are employed in thecompilation of a catalog of open clusters with color-magnitude diagramson the UBV or RGU systems. Estimates of reddening, distance modulus, ageand number of cluster members are included. Although the sample isconsidered representative of the discoverable clusters in the galaxy,the observed distribution is nonuniform because of interstellarobscuration. Cluster distribution in the galactic plane is found to bedominated by the locations of dust clouds rather than by spiralstructure. The distributions of clusters as a function of age andrichness class show that the lifetimes of poor clusters are much shorterthan rich ones, and that clusters in the outer disk survive longer thanthose in the inner disk. An outer disk age which is only about 50% theage of the globular clusters is indicated by cluster statistics. Thethickening of the galactic disk with increasing galactocentric distancemay be due to either a younger dynamical age or a lower gravitationalpotential in the outer regions.
|UBV photometry of the open clusters NGC 6604 and NGC 6704|
Abstract image available at:http://adsabs.harvard.edu/abs/1978AJ.....83..266F
|A catalogue of galactic star clusters observed in three colours|
Abstract image available at:http://adsabs.harvard.edu/abs/1971A&AS....4..241B
|The ages of open clusters|
|Dreifarben-Photometrie von zwei offenen Sternhaufen in Richtung der Scutum-Wolke. Mit 4 Textabbildungen|
|Variable stars in open clusters.|