תוכן
תמונות
הוסף תמונה שלך
DSS Images Other Images
מאמרים קשורים
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.
| A Search for Old Star Clusters in the Large Magellanic Cloud
Abstract image available at:http://adsabs.harvard.edu/abs/1997AJ....114.1920G
| 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.
| NGC 1978 in the LMC: the cluster and surrounding field.
We present deep BVRI CCD photometry of the Large Magellanic Cloudcluster NGC 1978 and of fields immediately to the west. From the studyof the colour-magnitude diagram and the luminosity function we derivefor NGC 1978 an age of slightly more than 2Gyr and a metallicity of[Fe/H]=-0.4. NGC 1978 is, for a globular cluster, rather ellipticalwhich had been explained by a merger origin. No age structure inside NGC1978 was found, which limits this possibility to a merger of roughlycoeval subunits. In the field indications for a higher star formationrate at 1x10^8^ and 6x10^8^yr exist 8' west of the cluster, while nosuch phases can be found near the cluster. At ages older than 2Gyr thestar formation rate appears to have been the same in all analysedfields. On a broader scale, NGC 1978 seems to be one of the oldest ofthe LMC intermediate age clusters. A coherent redetermination of theages of the oldest clusters of this age group underlines a suddenenhancement of the cluster formation rate in the LMC about 2 Gyr ago.
| 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.
| CMDs for the LMC clusters NGC 2249 and NGC 2241
Color-magnitude diagrams are derived for two LMC clusters, NGC-2249 andNGC 2241. A technique is introduced for 'subtracting' the field-starcontribution from the cluster CMDs using CMDs from nearby LMC fields.The possibility of a 'gap' in the main sequence of NGC 2249 isdiscussed, and, by identifying the gap as the point of core hydrogenexhaustion for stars with convective cores, the isochrones are found tobe well placed relative to the turnoff. Based on these isochrones, NGC2249 is thought to be 550 to 700 x 10 to the 6th years old, depending onthe reddening and distance modulus used. NGC 2241, by virtue of itssubgiant branch and giant clump and by comparison with NGC 2506, isthought to be between 3 and 4 x 10 to the 9th years old.
| Ages of Two LMC Clusters and an LMC Distance Determination Using Features of an LMC Field CMD
Not Available
| A Catalogue of Clusters in The LMC
Not Available
| 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
|
הכנס מאמר חדש
לינקים קשורים
הכנס לינק חדש
משמש של הקבוצה הבאה
|
תצפית ומידע אסטרומטרי
קטלוגים וכינוים:
|
