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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.
| BD +59°224: A New ζ Aurigae System
The star BD +59°224 has an interesting history of spectroscopicclassification, having been described in the literature variously as acomposite G- and F-type star with helium, a K5 star, an O-type star, andan emission-line object similar to a planetary nebula. We present newspectra of this object that clearly show the star to be a binary with aK4.5 Ib primary and a B3 V secondary. We also calculate a reddening anddistance [E(B-V)~0.75, d~2.1 kpc] and point out similarities betweenthis object and the class of ζ Aurigae stars.
| 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.
| 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].
| 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.
| Integrated photometric properties of open clusters
Galactic open clusters provide an abundant sample of stellar aggregatesof various sizes, ages and metal abundances, apt to constitute atemplate for comparison with star systems in other galaxies. In thispaper we present and discuss a standard methodology to synthesize U,B,Vfluxes and colours, and apply it to a set of 138 open clusters. Resultsare compared with previous ones available in the literature. We wereable to calibrate a mass-luminosity relation by which we evaluated themass of ~400 open clusters, leading to a well defined present-day massfunction. The number-complete sample of galactic open clusters presentedin Battinelli & Capuzzo-Dolcetta (1991) is enlarged of a 15%.
| Young open clusters as probes of the star formation process. 1: an atlas of open cluster photometry
We have obtained charge coupled device (CCD) photometry, in the UBVsystem, for 23 open clusters in order to explore the star formationhistory of the Cassiopeia region of the Perseus spiral arm of ourGalaxy. Magnitudes and colors of 35,788 stars were measured, making thisthe most comprehensive, homogeneous single study of open clusterproperties in one part of the Galaxy. This paper presents an atlas ofopen cluster photometry that serves as the database for an investigationof cluster properties such as their ages, distances, reddenings, sizes,and richnesses. This information provides insight into the spatial andtemporal formation sequence of the clusters and allows an investigationof the stellar content of the clusters to be undertaken.
| CCD photometric and spectroscopic observations of the young open cluster NGC 433
This paper presents the first CMD diagram and spectral types of stars inthe field of NGC 433. The cluster is rather poor, containing 12 starsdown to V = 16 in a radius of 106 arcsec around R.A. 1h 15m 07s, Dec. +60 deg 11 arcmin 11.7 arcsec (2000.0). The averaged reddening is (E(B -V)) = 0.8. The brightest stars are B5, corresponding to an age less than110 Myr. The derived cluster distance of 2.1 Kpc is compatible with aphysical association with an H I cloud detected in the clusterdirection, while the CO clouds observed in the same direction are verylikely in the foreground. Within the limits of the photometry, thecluster consists of a clump of B stars and is lacking of fainter stars.This work supports the idea that the population of disk stellar clusterscannot be sharply divided into 'true' bound open clusters and unboundstellar groups.
| A 21 centimeter line survey of a region around four outer galaxy open clusters
To investigate the role of atomic gas in the interaction of massivestars with the interstellar medium, a 21 cm survey was made of a regionsurrounding four young, outer Galaxy open clusters, NGC 281, 433, 436,and 457. A rectangular area ranging in Galactic longitude from 115 to133 deg, and in latitude from -10 to -1 deg, was observed with the NRAO140 foot telescope. Most of this region was fully sampled, resulting inspatial resolution equal to the telescope's 21 arcmin beamwidth. Thedata are presented as longitude-latitude and latitude-velocity contourmaps. A catalog of atomic gas features (e.g., clouds, filaments, andshells) is given.
| Young open clusters - CCD observations of NGC 433
Some of the results relying on CCD photometric and spectroscopicobservations of the young and poorly studied cluster NGC 433 arepresented. The cluster results to be rather poor and highly andirregularly reddened. The brightest stars are B5, corresponding to aMain Sequence age of 110 Myr. The derived cluster distance of 2.1 Kpc iscompatible with a physical association with an H I cloud detected in thecluster direction, while the CO clouds observed in the same directionare very likely in the foreground.
| Atomic and Molecular Gas Around 4 High Z Open Clusters
Not Available
| A CO survey of regions around 34 open clusters. II - Physical properties of cataloged molecular clouds
The physical properties of the 148 molecular clouds found in a CO surveyof regions around 34 young open clusters have been examined. Expressionsare given for the cloud size spectrum and the mass spectrum. Themass-radius relation implies that clouds of all size larger than a fewpc have about the same mean volume density. Power laws with slopes of0.6 and 3 describe, respectively, the relations of CO linewidth andcloud mass to cloud size. The clouds are distinctly nonspherical andappear to be randomly oriented with respect to the Galactic plane. Theobservations can be explained by a model for molecular clouds in whichclouds are ensembles of dense clumps of gas. Based on such a model, itis shown that molecular clouds are perturbed on a time scale shortcompared to the time required for them to reestablish virialequilibrium.
| A CO survey of regions around 34 open clusters
Results are presented from a systematic search for CO emission fromregions around 34 young open clusters in the outer Galaxy. The clustershave well-determined distances ranging from about 1 to 5 kpc and agesnot greater than about 100 Myr. It was found that some moderately youngclusters have no associated CO emission. All the surveyed clustersyounger than about 5 Myr have associated with them at least onemolecular cloud more massive than 10,000 solar mass, while the molecularclouds associated with clusters older than about 10 Myr are not moremassive than a few thousands solar masses. It was also found thatmolecular clouds are receding from young clusters at a rate of about 10km/sec, and that they seem to be destroyed by their interaction with thestars. Sites of ongoing star formation were identified in a number ofclouds associated with young clusters.
| Catalog of open clusters and associated interstellar matter.
Not Available
| A photographic survey of galactic clusters. V. NGC 189, I 1590, NGC 358, 366, 381, 433, 436, 457, 609, 637, I 166, NGC 743
Not Available
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