Tartalom
Képek
Kép feltöltése
DSS Images Other Images
Kapcsolódó cikkek
A UBVR CCD Survey of the Magellanic Clouds
We present photometry and a preliminary interpretation of a UBVR surveyof the Large and Small Magellanic Clouds, which covers 14.5deg2 and 7.2 deg2, respectively. This study isaimed at obtaining well-calibrated data on the brighter, massive stars,complementing recent, deeper CCD surveys. Our catalog contains 179,655LMC and 84,995 SMC stars brighter than V~18.0, and is photometricallycomplete to U~B~V~15.7 and R~15.2, although stars in crowded regions areselectively missed. We compare our photometry to that of others, anddescribe the need for gravity-dependent corrections to our CCD U-bandphotometry. We provide a preliminary cross-reference between our catalogstars and the stars with existing spectroscopy. We discuss thepopulation of stars seen toward the two Clouds, identifying the featuresin the color-magnitude diagram, and using existing spectroscopy to helpconstruct H-R diagrams. We derive improved values for the blue-to-redstar ratios in the two Clouds, emphasizing the uncertainties involved inthis before additional spectroscopy. We compare the relative number ofred supergiants and Wolf-Rayet stars in the LMC and SMC with that ofother galaxies in the Local Group, demonstrating a very strong, tighttrend with metallicity, with the ratio changing by a factor of 160 fromthe SMC to M31. We also reinvestigate the initial mass function of themassive stars found outside of the OB associations. With the newer data,we find that the initial mass function (IMF) slope of this fieldpopulation is very steep, with Γ~-4+/-0.5, in agreement with ourearlier work. This is in sharp contrast to the IMF slope found for themassive stars with OB associations (Γ~-1.3). Although much morespectroscopy is needed to make this result firm, incompleteness can nolonger be invoked as an explanation.
| The Optical Gravitational Lensing Experiment. Catalog of Star Clusters from the Large Magellanic Cloud
We present the catalog of star clusters found in the area of about 5.8square degree in the central regions of the Large Magellanic Cloud. Itcontains data for 745 clusters. 126 of them are new objects. For eachcluster equatorial coordinates, radius, approximate number of membersand cross-identification are provided. Photometric data for all clusterspresented in the catalog and Atlas consisting of finding charts andcolor-magnitude diagrams are available electronically from the OGLEInternet archive.
| 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.
| Clusters in the west side of the bar of the Large Magellanic Cloud: interacting pairs?
In this paper, we present the VI-CCD photometry of 11 unstudied clusterslocated in the bar of the Large Magellanic Cloud (LMC), as a part of aproject aimed to infer the star formation history of this galaxy. Wederive the ages of these clusters by means of isochrone fitting. Threeclose pairs of clusters are included in the sample, namely NGC 1903-SL357, SL 349-SL 353, SL 387-SL 385. We discuss the surface photometry ofthese objects: the distortion in the isophotal contours is regarded as asign of interactions between pairs of physically connected clusters.While the systems SL 349-SL 353 and SL 387-SL 385 are likely pairs ofnearly coeval clusters, NGC 1903-SL 357 is not because of the large agedifference between the two. Several possible mechanisms for theformation of this peculiar pair are examined in the context ofinteractions between the Large and Small Magellanic Cloud (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.
| Bar star clusters in the LMC - Formation history from UBV integrated photometry
The sample of star clusters in the LMC Bar region with integrated UBVphotometry was enlarged by approximately a factor four, totaling 129objects. The (B-V) histogram gap between blue and red clustersdisappears with this deeper sample. Age groups in terms of equivalentSWB types were derived and their spatial distribution studied. Clustersyounger than t about 200 Myr are not homogeneously distributed throughthe bar. In particular a strong star forming event at t about 100 Myrwas detected in the eastern part of the Bar, consisting of a compactgrouping of seven coeval clusters around NGC 2058 and NGC 2065. Also, 11close pairs and two trios are analyzed, and the colors indicate thatonly four pairs are clearly not coeval.
| Long-period variables in the Large Magellanic Cloud. I - Search and discovery
A search for long-period variables has been made in the bar and southernregions of the LMC using a series of I band UKST plates, resulting inthe discovery of 471 Mira variables and 572 SRa variables. By usingmainly automated methods of determining periods and amplitudes ofvariability, corrections for incompleteness have been estimated. TheMiras show a trend toward larger amplitudes and brighter luminositieswith period, both of which should contribute to increase mass-lossrates. The period distribution falls abruptly longward of about 420 daysand shortward of about 140 days, whereas the corresponding limits in thesolar neighborhood are about 450 and about 220 days, suggestingdifferent histories of star formation in the LMC and the Galaxy. Inparticular, there appear to be relatively more old stars in the LMC.
| Integrated UV magnitudes of the Large Magellanic Cloud associations
UV photographs (2600 A, 350 A passband) of the LMC have been obtained bythe S183 experiment during a Skylab mission. The background is estimatedand a method for deriving the integrated fluxes is presented. Theintegrated magnitudes of about 50 associations and isocontours of theirintensities are given, along with the B and V integrated magnitudes of13 associations.
| The Identifications of HDE Objects with Large Magellanic Cloud Clusters and Nebulae
Not Available
| Radial velocities from objective-prism plates in the direction of the Large Magellanic Cloud. List of 398 stars, LMC members. List of 1434 galactic stars, in the LMC direction
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...13..173F&db_key=AST
| Spectrographic and photometric observations of supergiants and foreground stars in the direction of the Large Magellanic Cloud
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....6..249A&db_key=AST
| Comparison of the Large Magellanic Cloud Catalogs of Sanduleak and Fehrenbach-Duflot
Abstract image available at:http://adsabs.harvard.edu/abs/1972A&A....17..326S
| Grand Nuage de Magellan. Liste des etoiles membres DU Grand Nuage de Magellan et liste d'etoiles galactiques
Not Available
| A Catalogue of Clusters in The LMC
Not Available
|
Új cikk hozzáadása
Kapcsolódó hivatkozások
- - (nincs kapcsolódó hivatkozás) -
Új link hozzáadása
Besorolás csoportokba:
|
Pozíciós és asztrometriai adatok
Katalógusok és elnevezések:
|
NEWS@SKY (Science&Space News)
