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New catalogue of blue stragglers in open clusters
We present a catalogue of blue-straggler candidates in galactic openclusters. It is based on the inspection of the colour-magnitude diagramsof the clusters, and it updates and supersedesthe first version(Ahumada & Lapasset 1995). A new bibliographical search was made foreach cluster, and the resulting information is organised into twotables. Some methodological aspects have been revised, in particularthose concerning the delimitation of the area in the diagrams where thestragglers are selected.A total of 1887 blue-straggler candidates have been found in 427 openclusters of all ages, doubling the original number. The catalogued starsare classified into two categories mainly according to membershipinformation.The whole catalogue (Tables 8, 9, notes, and references) is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/463/789
| On the current status of open-cluster parameters
We aim to characterize the current status of knowledge on the accuracyof open-cluster parameters such as the age, reddening and distance.These astrophysical quantities are often used to study the globalcharacteristics of the Milky Way down to the very local stellarphenomena. In general, the errors of these quantities are neglected orset to some kind of heuristic standard value. We attempt to give somerealistic estimates for the accuracy of available cluster parameters byusing the independently derived values published in the literature. Intotal, 6437 individual estimates for 395 open clusters were used in ourstatistical analysis. We discuss the error sources depending ontheoretical as well as observational methods and compare our resultswith those parameters listed in the widely used catalogue by Dias et al.In addition, we establish a list of 72 open clusters with the mostaccurate known parameters which should serve as a standard table in thefuture for testing isochrones and stellar models.
| 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.
| Analysing the database for stars in open clusters. I. General methods and description of the data
We present an overview and statistical analysis of the data included inWEBDA. This database includes valuable information such as coordinates,rectangular positions, proper motions, photometric as well asspectroscopic data, radial and rotational velocities for objects of openclusters in our Milky Way. It also contains miscellaneous types of datalike membership probabilities, orbital elements of spectroscopicbinaries and periods of variability for different kinds of variablestars. Our final goal is to derive astrophysical parameters (reddening,distance and age) of open clusters based on the major photometric systemwhich will be presented in a follow-up paper. For this purpose we havechosen the Johnson UBV, Cousins VRI and Strömgren uvbybetaphotometric systems for a statistical analysis of published data setsincluded in WEBDA. Our final list contains photographic, photoelectricand CCD data for 469 820 objects in 573 open clusters. We have checkedthe internal (data sets within one photometric system and the samedetector technique) and external (different detector technique) accuracyand conclude that more than 97% of all investigated data exhibit asufficient accuracy for our analysis. The way of weighting and averagingthe data is described. In addition, we have compiled a list of deviatingmeasurements which is available to the community through WEBDA.
| 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.
| 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.
| 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].
| Foreground and background dust in star cluster directions
This paper compares reddening values E(B-V) derived from the stellarcontent of 103 old open clusters and 147 globular clusters of the MilkyWay with those derived from DIRBE/IRAS 100 mu m dust emission in thesame directions. Star clusters at |b|> 20deg showcomparable reddening values between the two methods, in agreement withthe fact that most of them are located beyond the disk dust layer. Forvery low galactic latitude lines of sight, differences occur in thesense that DIRBE/IRAS reddening values can be substantially larger,suggesting effects due to the depth distribution of the dust. Thedifferences appear to arise from dust in the background of the clustersconsistent with a dust layer where important extinction occurs up todistances from the Plane of ~ 300 pc. For 3 % of the sample asignificant background dust contribution might be explained by higherdust clouds. We find evidence that the Milky Way dust lane and higherdust clouds are similar to those of several edge-on spiral galaxiesrecently studied in detail by means of CCD imaging.
| A Photometric and Spectroscopic Study of the Southern Open Clusters PISMIS 18, PISMIS 19, NGC 6005, and NGC 6253
CCD observations in the B, V, and I passbands have been used to generatecolor-magnitude diagrams (CMDs) for the southern open cluster candidatesPismis 18, Pismis 19, and NGC 6005, as well as for the old open clusterNGC 6253. The sample consists of about 1550 stars reaching down to V ~19 mag. From analysis of the CMDs, the physical reality of the threecluster candidates is confirmed and their reddening, distance, and ageare derived, as well as those of NGC 6253. In addition, integratedspectra for Pismis 18, Pismis 19, and NGC 6253 covering a range from3500 to 9200 Å were obtained. The reddening, age, and metallicityof these three clusters were derived from Balmer and Ca ii tripletequivalent widths by comparing the observed spectra with those oftemplate clusters. The photometric and spectroscopic results allow us toconclude that Pismis 18, Pismis 19, and NGC 6005 are intermediate-age (t~ 1 Gyr), genuine open clusters, while NGC 6253 has an age t ~ 5 Gyr.All these clusters are located approximately toward the Galactic center,between 1.5 and 2.7 kpc from the Sun. Their metallicities range overvalues that are typical of moderately metal-poor to moderatelymetal-rich open clusters.
| Catalogue of UBV Photometry and MK Spectral Types in Open Clusters (Third Edition)
Not Available
| 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.
| Southern open star clusters VI. UBV-Hbeta photometry of 18 clusters from Centaurus to Sagittarius.
Abstract image available at:http://adsabs.harvard.edu/abs/1975A&AS...20..155M
| Uniform survey of clusters in the southern Milky Way.
Abstract image available at:http://adsabs.harvard.edu/abs/1975AJ.....80...11V
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