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|Photometric and spectroscopic study of low mass embedded star clusters in reflection nebulae|
An analysis of the candidate embedded stellar systems in the reflectionnebulae vdBH-RN 26, vdBH-RN} 38, vdBH-RN} 53a, GGD 20, ESO 95-RN 18 andNGC 6595 is presented. Optical spectroscopic data from CASLEO(Argentina) in conjunction with near infrared photometry from the 2MASSPoint Source Catalogue were employed. The analysis is based on sourcesurface density, colour-colour and colour-magnitude diagrams togetherwith theoretical pre-main sequence isochrones. We take into account thefield population affecting the analysis by carrying out a statisticalsubtraction. The fundamental parameters for the stellar systems werederived. The resulting ages are in the range 1-4 Myr and the objects aredominated by pre-main sequence stars. The observed masses locked in theclusters are less than 25 Mȯ. The studied systems haveno stars of spectral types earlier than B, indicating that star clustersdo not necessarily evolve through an HII region phase. The relativelysmall locked mass combined with the fact that they are not numerous incatalogues suggests that these low mass clusters are not importantdonors of stars to the field populations.Based on observations made at Complejo Astronómico El Leoncito,which is operated under agreement between the Consejo Nacional deInvestigaciones Científicas y Técnicas de laRepública Argentina and the National Universities of La Plata,Córdoba and San Juan, Argentina.
|A Catalogue of infrared star clusters and stellar groups|
We compiled a catalogue of infrared star clusters in the Galaxy, whichare most of them embedded. It condenses the growing literatureinformation. We also include in the sample infrared stellar groups whichare less dense than star clusters, such as those embedded in the darkclouds Taurus-Auriga and Chamaleon I. We provide galactic and equatorialcoordinates, angular dimensions, different designations and relatedobjects such as nebulae. A total of 189 infrared clusters and 87embedded stellar groups are included. A fraction of 25% of the embeddedclusters are projected close to each other in pair or triplet systems,indicating that multiplicity plays an important role in star clusterformation. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/397/177.
|Far-Ultraviolet Stellar Photometry: Fields Centered on rho Ophiuchi and the Galactic Center|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJS..104..101S&db_key=AST
|Far-ultraviolet stellar photometry: Fields in Sagittarius and Scorpius|
Far-ultraviolet photometry for 741 objects in a field in Sagittariuscentered near M8 and 541 objects in a field centered near sigma Scorpiiis presented. These data were extracted from electographic imagesobtained with two cameras during a shuttle flight in 1991 April/May. Thecameras provided band passes with lambdaeff = 1375 A andlambdaeff = 1781 A. Synthetic colors show that these bandsare sensitive to effective temperature for hot stars. Our measurementswere placed on a quantitative far-ultraviolet magnitude scale byconvolving the spectra of stars observed by IUE with our cameras'spectral response functions. Fifty-eight percent of the ultravioletobjects were identified with visible stars using the SIMBAD databasewhile another 40% of the objects are blends of early type stars tooclose together to separate with our resolution. Our photometry iscompared with that from the TD-1, OAO 2, and ANS satellites and the S201(Apollo 16) far-ultraviolet camera and found to agree at the level of afew tenths of a magnitude. Unlike previous studies, almost half of theidentified visual counterparts to the ultraviolet objects are early Bstars. A plot of distance modulus against ultraviolet color excessreveals a significant population of stars with strong ultravioletexcess.
|The Structure of Star Formation Regions - Part Three - Individual Regions - Spatial Extent Mass and Edge of the Star Formation Region SAGITTARIUS-1|
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