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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
| Comparison of the Luminosity Functions of Open Clusters Based on USNO-A1 Data
The luminosity and mass functions of a group of Galactic open clustersare constructed by applying a statistical method to photometric datafrom the USNO-A1 catalog. Despite some limitations, this catalog can beused for statistical analyses in Galactic astronomy. Pairwisecomparisons of the derived cluster luminosity functions are performedfor five age intervals. The differences between the luminosity functionsof the open clusters are not statistically significant in most cases. Itis concluded that the luminosity functions are approximately universalthroughout a large volume in the solar neighborhood. Combined luminosityand mass functions are constructed for six age intervals. The slope ofthe mass spectrum may vary somewhat from cluster to cluster, and themean slope may be somewhat higher than the Salpetervalue.
| New variable stars in open clusters. I. Methods and results for 20 open clusters
We present high precision CCD photometry of 1791 objects in 20 openclusters with an age of 10 Myr to 1 Gyr. These observations wereperformed within the Δ a photometric system which is primarilyused to detect chemically peculiar stars of the upper main sequence.Time bases range from 30 min up to 60 days with data from severalnights. We describe the time series analysis reaching a detection limitof down to 0.006 mag for apparent variability. In total, we havedetected 35 variable objects of which four are not members of theircorresponding clusters. The variables cover the entireHertzsprung-Russell diagram, hence they are interesting targets forfollow-up observations.Based on observations obtained at Complejo Astronómico elLeoncito (CASLEO), operated under the agreement between the ConsejoNacional de Investigaciones Científicas y Técnicas de laRepública Argentina and the National Universities of La Plata,Córdoba y San Juan; ESO-La Silla and UTSO-Las Campanas.
| Theoretical isochrones for the Delta a photometric system
We have calculated theoretical isochrones for the photometric Delta asystem to derive astrophysical parameters such as the age, reddening anddistance modulus for open clusters. The Delta a system samples the fluxdepression at 520 nm which is highly efficient to detect chemicallypeculiar (CP) objects of the upper main sequence. The evolutionarystatus of CP stars is still a matter of debate and very important totest, for example, the dynamo and diffusion theories. In fact, thedynamo or fossil origin of the magnetic fields present in this kind ofstar is still not clear. Using the stellar evolutionary models by Claret(\cite{Cla95}), a grid of isochrones with different initial chemicalcompositions for the Delta a system was generated. The published dataof 23 open clusters were used to fit these isochrones with astrophysicalparameters (age, reddening and distance modulus) from the literature. Asan additional test, isochrones with the same parameters for Johnson UBVdata of these open clusters were also considered. The fits show a goodagreement between the observations and the theoretical grid. We findthat the accuracy of fitting isochrones to Delta a data without theknowledge of the cluster parameters is between 5 and 15%.
| 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.
| CCD Photometry of the Open Clusters NGC 2658, NGC 2849, and NGC 3247
We present CCD photometry of the galactic open clusters NGC 2658, NGC2849, and NGC 3247. By means of the comparison between the observedcluster sequences and the Padova theoretical isochrones, we derive thefollowing parameters: for NGC 2658, E(B-V)=0.35+0.05-0.10 , log(age) =8.50+0.25-0.05, and (m - M)0 =13.32+0.36-0.52; for NGC 2849, the reddening is inthe range 0.46 to 0.57 with an uncertainty of +/-0.12 mag, (m -M)0 = 14.02+0.38-0.40, and log(age) =8.8+0.1-0.05; finally, for NGC 3247 we obtainE(B-V)=0.39±0.07 , log(age) = 7.60+0.4-0.3, and(m - M)0 = 11.89+0.51-0.45. In thisstudy the isochrones have been renormalized to the solar values(B-V)ȯ =0.65 and M[V] = 4.84; the values ({V-R)ȯ =0.37 and (V-I)ȯ =0.70 areproposed as zero points in order to renormalize those colors as well.
| 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.
| 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].
| CCD photometric search for peculiar stars in open clusters. II. NGC 2489, NGC 2567, NGC 2658, NGC 5281 and NGC 6208
High accurate photometric data in the three filter, narrow-band Deltaa-system for five open clusters (NGC 2489, NGC 2567, NGC 2658, NGC 5281and NGC 6208) are presented permitting one to detect apparent chemicallypeculiar stars. The ages and distances are wide spread to improve thestatistics of peculiar stars in our Milky Way. A total of 235 starswithin these clusters have been observed. We have detected ten apparentpeculiar objects (six with significant positive and four with negativeDelta a-values) in four open clusters. Although three of them within theboundaries of NGC 2567 are probably not members of this cluster. Sinceno Strömgren uvbybeta data are available from the literature,Johnson UBV photometry was used to test and calibrate our photometricdata. The results from a comparison of both systems are excellent. Basedon observations at ESO-La Silla and UTSO-Las Campanas. Tables 4 to 8 areonly available 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/373/153 Figure 1 is onlyavailable in electronic form at http://www.edpsciences.org
| Upper main sequence and blue stragglers in galactic open clusters.
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| CCD observations in 7 open clusters - NGC2421, NGC2439, NGC2489, NGC2567, NGC2627, NGC2658 and NGC2910
Photometric UBVIc data are presented for the open clusters NGC2439,NGC2489, NGC2567, NGC2627, NGC2658, and NGC2910. From a combination ofthe new BVIc technique and the analysis of the CMDs, the color excessE(B-V), the distance modulus, and approximate age are given for theseclusters and NGC2421.
| Catalogue of Eclipsing and Spectroscopic Binary Stars in the Regions of Open Clusters
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| Uniform survey of clusters in the southern Milky Way.
Abstract image available at:http://adsabs.harvard.edu/abs/1975AJ.....80...11V
| A list of clusters that may be old.
Not Available
| Variable stars in open clusters.
Not Available
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