Proper motion determination of open clusters based on the UCAC2 catalogue
We present the kinematics of hundreds of open clusters, based on theUCAC2 Catalogue positions and proper motions. Membership probabilitieswere obtained for the stars in the cluster fields by applying astatistical method uses stellar proper motions. All open clusters withknown distance were investigated, and for 75 clusters this is the firstdetermination of the mean proper motion. The results, including the DSSimages of the cluster's fields with the kinematic members marked, areincorporated in the Open Clusters Catalogue supported on line by ourgroup.
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Astrophysical parameters of Galactic open clusters
We present a catalogue of astrophysical data for 520 Galactic openclusters. These are the clusters for which at least three most probablemembers (18 on average) could be identified in the ASCC-2.5, a catalogueof stars based on the Tycho-2 observations from the Hipparcos mission.We applied homogeneous methods and algorithms to determine angular sizesof cluster cores and coronae, heliocentric distances, mean propermotions, mean radial velocities, and ages. For the first time we derivedistances for 200 clusters, radial velocities for 94 clusters, and agesof 196 clusters. This homogeneous new parameter set is compared withearlier determinations, where we find, in particular, that the angularsizes were systematically underestimated in the literature.
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Metallicity distribution on the galactic disk
Depending mainly on UBVCCD data, the metallicities of 91 open starclusters nearby the galactic disk have been estimated using Cameron's[A&A 147 (1985b) 39] method. The metallicity radial gradient alongthe galactic plane is found to be -0.09 dex/kpc; which is in a very goodagreement with Panagia and Tosi [A&A 96 (1981) 306] and Carraro etal. [MNRAS 296 (1998) 1045]. Vertically on the galactic disk, withinabout 800 pc, the metallicity gradient is found to be so trivial. Anaverage age-metallicity relation has been examined, which confirms theprevious suggestion that the metallicity of a cluster depending mainlyon its position on the galactic disk more than its age.
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On the Galactic Disk Metallicity Distribution from Open Clusters. I. New Catalogs and Abundance Gradient
We have compiled two new open cluster catalogs. In the first one, thereare 119 objects with ages, distances, and metallicities available, whilein the second one, 144 objects have both absolute proper motion andradial velocity data, of which 45 clusters also have metallicity dataavailable. Taking advantage of the large number of objects included inour sample, we present an iron radial gradient of about -0.063+/-0.008dex kpc-1 from the first sample, which is quite consistentwith the most recent determination of the oxygen gradient from nebulaeand young stars, about -0.07 dex kpc-1. By dividing clustersinto age groups, we show that the iron gradient was steeper in the past,which is consistent with the recent result from Galactic planetarynebulae data, and also consistent with inside-out galactic diskformation scenarios. Based on the cluster sample, we also discuss themetallicity distribution, cluster kinematics, and space distribution. Adisk age-metallicity relation could be implied by those properties,although we cannot give conclusive result from the age- metallicitydiagram based on the current sample. More observations are needed formetal-poor clusters. From the second catalog, we have calculated thevelocity components in cylindrical coordinates with respect to theGalactic standard of rest for 144 open clusters. The velocitydispersions of the older clusters are larger than those of youngclusters, but they are all much smaller than that of the Galactic thickdisk stars.
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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.
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Morphological analysis of open clusters' propertiesII. Relationships projected onto the galactic plane
A morphological analysis study of open clusters' properties has beenachieved for a sample of 160 UBVCCD open star clusters of approximately128,000 stars near the galactic plane. The data was obtained and reducedfrom using the same reduction procedures, which makes this catalogue thelargest homogeneous source of open clusters' parameters.
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Integrated photometric characteristics of galactic open star clusters
Integrated UBVRI photometric parameters of 140 galactic open clustershave been computed. Integrated I(V-R)0 and I(V-I)0colours as well as integrated parameters for 71 star clusters have beenobtained for the first time. These, in combination with published data,altogether 352 objects, are used to study the integrated photometriccharacteristics of the galactic open clusters. The I(MV)values range from -9.0 to -1.0 mag corresponding to a range in totalmass of the star clusters from ~ 25 to 4*E4 Msun.The integrated colours have a relatively narrow range, e.g., I(B-V){_0}varies from -0.4 to 1.2 mag. The scatter in integrated colours at agiven integrated magnitude can be understood in terms of differences infraction of red giants/supergiants in the clusters. The observedintegrated magnitudes and colours agree with the synthetic ones, exceptthe dependences of I(V-R)0 and I(V-I)0 colours forclusters younger than ~ 100 Myrs and also of the integrated magnitudesof oldest clusters. The large sample provides the most accurate agedependence of integrated magnitudes and colours determined so far. Theluminosity function of the I(MV) has a peak around -3.5 magand its slope indicates that only ~ 1% of the open clusters in thegalactic disc are brighter than I(MV)=-11 mag. No variationhas been found of integrated magnitude with galactocentric distance andmetallicity.
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Proper motions of open clusters within 1 kpc based on the TYCHO2 Catalogue
We present mean absolute proper motions of 112 open clusters, determinedusing the data from the Tycho2 Catalogue. For 28 clusters, this is thefirst determination of proper motion. The measurements made use of alarge number of stars (usually several tens) for each cluster. The totalnumber of stars studied in the fields of the 164 open clusters is 5016,of which 4006 were considered members. The mean proper motions of theclusters and membership probability of individual stars were obtainedfrom the proper motion data by applying the statistical method proposedby Sanders (\cite{Sanders71}). Based on observations of the ESAHipparcos satellite. Tables 1, 2 and 5 to 117 are only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/376/441
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Morphological analysis of open clusters' propertiesI. Properties' estimations
A sample of 160 UBVCCD observations of open star clusters near thegalactic plane has been studied, and a catalogue of their propertiesobtained. The main photometrical properties have been re-estimated selfconsistently and the results have been compared with those of Lynga[Lynga, G., 1987. Catalog of Open Cluster Data, 5th Edition, StellarData Centers, Observatoire de Strasbourg, France].
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Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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Absolute proper motions of 181 young open clusters.
Not Available
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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.
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Redetermination of the characteristics of open clusters and the structure of the Galaxy
To obtain the most extensive set of characteristics of open clusters ofthe Galaxy by a uniform method, a computer program is designed toestimate interstellar reddening, distances and ages of clusters based onUBV-photometry data. Characteristics of 94 young clusters are estimated,and the distribution of clusters in the galactic plane is considered. Apronounced age gradient is found across the Sagittarius spiral arm.Several examples of triple and double clusters are considered.
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The open cluster NGC 6716
NGC 6716 is a young open star cluster in Sagittarius. Lindoff (1971)obtained photoelectric photometry for 12 stars and photographic UBVphotometry for 115 stars in the cluster field down to V = 13.8. Thiswork has been expanded to include more photoelectric standards and irisphotometry for 332 stars in the cluster field down to V = 16. Areddening E(B-V) = 0.17 mag, a distance modulus of 8.69 + or - 0.15 mag(d = 547 pc), and an age of around 100 million years for the cluster arederived. Of the stars studied, 75 were judged as likely cluster members,63 as possible members, and 194 as probable nonmembers.
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NGC6716: A Young Open Cluster in Sagittarius
Not Available
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The Guide Star Photometric Catalog.
This paper presents data and finding charts for the Guide StarPhotometric Catalog (GSPC), which is an all-sky set of 1477pohotoelectrically determined BV sequences covering the magnitude rangefrom 9 to 15. The GSPC was created to provide photometric calibratorsfor the Guide Star Catalog, which is a catalog of approximately 2 x 10to the 7th objects needed to support the pointing of the Hubble SpaceTelescope. For declinations greater than +3 deg, the sequences generallylie near the centers of the original (Palomar Observatory-NationalGeographic Society) Sky Atlas, while for smaller declinations they lienear the centers for the ESO/SERC Southern Sky Atlas. The sequencesnominally contain (at least) six stars, each with a photometricprecision of 0.05 mag. In practice, a small number of sequences containsfewer stars, and the precisions achieved for the faintest stars are morenearly 0.1 mag.
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Age distribution of open clusters as a function of their linear diameter and age-dependence of cluster masses
From the well-observed data of star clusters, the age distribution ofgalactic clusters is obtianed as a function of their linear diameter andit is concluded that the observed age distribution of clusters fordifferent linear diameter intervals within 1500 pc, is not seriouslyaffected by the selection effects. If we assume that the rate offormation of clusters is constant, the lifetimes r112 of the clustersfor different linear diameter intervals have been obtained and it isfound that the clusters with a linear diameter in the range 0-1.9 Pchave longer lifetimes than the clusters having linear diameters largerthan 2.0 Pc. Total masses of 57 clusters have been obtained using thecatalogues of Piskunov (1983) and Myakutin et al. (1984). A study ofage-dependence of cluster masses, based on the total masses of theclusters obtained in the present study and the cluster masses given byBruch and Sanders (1983) and Lynga (1983b), shows that there is adecreasing trend in the total mass with the age, however, there is anincreasing trend after the age of about 108 yr. It is also concludedthat the initial rate of formation of rich clusters was relativelyhigher than the present rate of formation
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Catalogue of UBV Photometry and MK Spectral Types in Open Clusters (Third Edition)
Not Available
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A photometric investigation of cluster membership for the Cepheid BB Sagittarii
Photoelectric UBV and VRI photometry is presented for the close pair ofopen clusters Cr 394 and NGC 6716 and for the 6.64 d classical CepheidBB Sgr. For Cr 394, E(B-V) = 0.25 + or - 0.01, V(0)-M(V) = 9.04 + or -0.08, d = 643 + or - 25 pc, age is about 60 million yr, nuclear radiusis 9 arcmin, and tidal radius is 27 arcmin. For NGC 6716, E(B-V) = 0.11+ or 0.01, V(0)-M(V) = 9.07 + or - 0.17, d = 650 + or - 52 pc, age isabout 60 million yr, nuclear radius 7 arcmin. The data combined withstar counts for the region of the cluster demonstrate that the Cepheidis a likely member of Cr 394.
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Metallicities and Distances of Galactic Clusters as Determined from UBV Data - Part Three - Ages and Abundance Gradients of Open Clusters
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&A...147...47C&db_key=AST
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Metallicities and distances of galactic clusters as determined from UBV-data. II - The metallicities and distances of 38 open clusters. III - Ages and abundance gradients of open clusters
After presenting a novel method for the simultaneous calculation of UVexcess and reddening in open clusters, the former is transformed into anFe/H abundance ratio value on the basis of the relation due to Cameron(1985), and the reddening is used to determine the distances of theclusters, incorporating a ratio of total-to-selective absorption that isboth a function of interstellar extinction and dependent on spectraltype. Metallicities and distances for 38 open clusters are therebyobtained and used to estimate the variation of metal abundance along thegalactic disk. The ages of the clusters are determined using the turnoffpoint method in the H-R diagram, and noted to cover a span of 5.1billion years. No firm relationship between cluster ages and theirmetallicity can be deduced; it is instead shown that, at a given age,there is a metallicity spread of up to + or - 0.3 dex.
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Integrated Photometric Parameters of Open and Globular Clusters
Not Available
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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.
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Catalogue of Masses and Ages of Stars in 68 Open Clusters
Not Available
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The present data situation for stars in open clusters. II
The present state of astrometric, spectroscopic, and photometric datafor stars in 63 open clusters nearer to the sun than 750 pc issummarized in tabular form. The limits of the available data arereported in terms of the apparent V magnitude. Information on theapparent V magnitude of the brightest main sequence star (Vbr) and onthe number of stars brighter than V equals 10 has been included. Thebluest spectral type on the main sequence has been used as an ageestimator.
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A catalogue of galactic clusters observed in three colours
This catalogue contains photometric data for 190 galactic clusters, allobserved in UBV or RGU. The distances of the young clusters (with spless than b3) have been calculated or recalculated according to method Aof Becker (1963). The galactic distribution of these clusters confirmstheir role of being good spiral tracers.
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First Supplement to the list of transit tables for star numberings in open clusters.
Not Available
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The open clusters NGC 6613 and NGC 6716
Abstract image available at:http://adsabs.harvard.edu/abs/1971A&A....15..439L
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Variable stars in open clusters.
Not Available
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