Upload your image
DSS Images Other Images
Submit a new article
|A Revised and Extended Catalog of Magellanic System Clusters, Associations, and Emission Nebulae. II. The Large Magellanic Cloud|
A survey of extended objects in the Large Magellanic Cloud was carriedout on the ESO/SERC R and J Sky Survey Atlases, checking entries inprevious catalogs and searching for new objects. The census provided6659 objects including star clusters, emission-free associations, andobjects related to emission nebulae. Each of these classes containsthree subclasses with intermediate properties, which are used to infertotal populations. The survey includes cross identifications amongcatalogs, and we present 3246 new objects. We provide accuratepositions, classification, and homogeneous measurements of sizes andposition angles, as well as information on cluster pairs andhierarchical relation for superimposed objects. This unification andenlargement of catalogs is important for future searches of fainter andsmaller new objects. We discuss the angular and size distributions ofthe objects of the different classes. The angular distributions show twooff-centered systems with different inclinations, suggesting that theLMC disk is warped. The present catalog together with its previouscounterpart for the SMC and the inter-Cloud region provide a totalpopulation of 7847 extended objects in the Magellanic System. Theangular distribution of the ensemble reveals important clues on theinteraction between the LMC and SMC.
|Integrated UBV Photometry of 624 Star Clusters and Associations in the Large Magellanic Cloud|
We present a catalog of integrated UBV photometry of 504 star clustersand 120 stellar associations in the LMC, part of them still embedded inemitting gas. We study age groups in terms of equivalent SWB typesderived from the (U-B) X (B-V) diagram. The size of the spatialdistributions increases steadily with age (SWB types), whereas adifference of axial ratio exists between the groups younger than 30 Myrand those older, which implies a nearly face-on orientation for theformer and a tilt of ~45^deg^ for the latter groups. Asymmetries arepresent in the spatial distributions, which, together with thenoncoincidence of the centroids for different age groups, suggest thatthe LMC disk was severely perturbed in the past.
|Spectroscopy of giants in LMC clusters. II - Kinematics of the cluster sample|
Velocities for 83 star clusters in the LMC are analyzed, based onindividual stellar velocities measured at the Calcium triplet. One-halfof the clusters are objects in the outer parts of the LMC which had noprevious velocity determinations. Published velocities for intermediateand old clusters are shown to have had systematic errors. These newvelocities with various rotation curve analyses of the LMC, and testaspects of the twisted disk model proposed by Freeman et al. (1983).When the transverse motion of the LMC is taken into account, a singlerotating disk solution fits the old and intermediate-aged clusters andother tracers (i.e., there is no need for an additional 'tilted disk'system).
|Spectroscopy of giants in LMC clusters. I - Velocities, abundances, and the age-metallicity relation|
Velocities and equivalent widths are presented for a large sample of LMCclusters. The calcium abundance is found to be a sensitive abundanceindicator over a very wide range of (Fe/H) between 0.0 and -2.2. Theage-metallicity relation is constructed for the inner and outer parts ofthe LMC. This relationsip can be characterized by a simple one-zoneenrichment model. The abundances for the inner and outer clusters at anage of 2 Gyr are nearly identical, so that little radial abundancegradient is evident in the cluster system.
|The cluster system of the Large Magellanic Cloud|
A new catalog of clusters in the Large Magellanic Cloud has beenconstructed from searches of the IIIa-J component of the ESO/SERCSouthern Sky Atlas. The catalog contains coordinate and diametermeasurements of 1762 clusters in a 25 deg x 25 deg area of sky centeredon the LMC, but excluding the very crowded 3.5 sq deg region around theBar. The distribution of these clusters appears as two superimposedelliptical systems. The higher density inner system extends over about 8deg; the lower density outer system can be represented by a 13 deg x 10deg disk inclined at 42 deg to the line of sight. There are suggestionsof two weak 'arms' in the latter.
|A case for H0 = 42 and Omega(0) = 1 using luminous spiral galaxies and the cosmological time scale test|
The two principal methods of finding the Hubble velocity-distance ratiosfor individual galaxies are compared, and it is shown that one route toH0 is flawed by selection effects when using flux-limited catalogs. Theproof is made by analyzing two sets of catalogs that reach differentapparent flux levels, so that selection effects are shown directly. Theoptical data on field spiral galaxies of the brightest van den Berghluminosity class are analyzed. Calibration using M31, M81, and M101which have Cepheid distances gives H0 = 42 + or - 11 km/s/Mpc. It isshown that all values of H0 derived by the method of assigning a fixedabsolute magnitude to any given distance indicator is subject tosystematic error, giving too large an H0 value if uncorrected for bias.The age of the globular clusters is adopted to be 13.5 + or - 1 Gyr, andthe age of the universe is put at 14.9 + or - 2 Gyr. A value of Omega(0)= 1.2 + 3 or - 0.9 with Lambda = 0 is obtained.
|A catalog of LMC star clusters outside the Hodge-Wright atlas|
The paper presents a catalog of 156 clusters outside the boundaries ofthe Hodge and Wright (1967) LMC atlas. The catalog contains coordinatesaccurate to 1-2 arcsec, offsets from the edge of the appropriate SRCJplates, cross references to previous identifications, and finding chartsof the brighter clusters. As defined by the clusters, the Hodge andWright atlas is found to represent the extent of the LMC to the west,and reasonably well to the east. To the north and the south, the clustersystem extends substantially beyond the boundaries of the atlas. Thesouthern clusters delineate a portion of the 'spiral arm' noted by deVaucouleurs (1955).
|Distribution of spectral types in the LMC clusters|
The distribution of spectral types in 42 LMC globular star clusterscovering all evolutionary ages was determined using objective prismspectra taken with the 1.2-m U.K. Schmidt Telescope in Australia. Thederived spectral type distributions show that the clusters can bedivided into five age categories from about 10 to the 7th to more than10 to the 9th yr. Several clusters were found to contain carbon starswith C/M ratios ranging from 0.07 to 0.4. These ratios were comparedwith those found for the SMC clusters and the Milky Way. It was foundthat the stars of the LMC exhibit a smaller range of C/M ratios than inthe SMC, but larger than in the Galaxy, thus providing an additionaltest of the theoretical models predicting a correlation between the C/Mratio and metal content. It was also found that the majority of youngclusters were embedded in older fields, while the intrmediate clusterswere embeded in younger fields, and the remote old clusters wereembedded in a stellar content of similar age.
|A Catalogue of Clusters in The LMC|
|A catalogue of clusters in the outer parts of the Large Magellanic Cloud|
Abstract image available at:http://adsabs.harvard.edu/abs/1963MNRAS.127...31L
Submit a new link
Member of following groups:
Observation and Astrometry data
Catalogs and designations: