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The Carina Spiral Feature: Strömgren-Hβ photometry approach. I. The photometric data-base
A data-base collating all uvbybeta photometry available at present forO-B9 stars brighter than 10th visual magnitude in the field of theCarina Spiral Feature is presented. The completeness and homogeneity ofthe data-base are discussed.Based on CDS data.Table 1 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/410/523
| Strömgren and Hβ photometry of O and B type stars in star-forming regions. III. Carina Spiral Feature
Strömgren and Hβ photometry of O and B type stars, generallybrighter than 9.5 mag is reported for the field of the Carina SpiralFeature. The observations are based on the PPM catalogue identificationsand are designed to improve the completeness of the existing uvbybetadata for the bright early-type stars in the field. We present new uvbyphotometry for 283 stars and Hβ photometry for 225 of them. Theseobservations are part of an ongoing effort to study the structure ofselected star-forming regions in the Milky Way by means of uvbybetaphotometry. A comparison of the new data to other uvbybeta data sets forthis field is presented. Based on data from the Strömgren AutomaticTelescope of the Copenhagen University Observatory, La Silla. Tables 1and 2 are only available in electronic form at the CDS via anonymous ftpto 130.79.128.5 or via http://cdsweb.u-strasbg.fr/Abstract.html
| A Search for Star Clusters from the HIPPARCOS Data
We present results of a search for nearby star clusters and associationsusing Hipparcos Catalogue data, restricting the sample to stars withparallaxes above 2 mas (d <~ 500 pc). Two new OB associations havebeen identified in the Carina-Vela and Cepheus-Cygnus-Lyra-Vulpecularegions. A very probable new open cluster has been discovered in Carina.The cluster, a Car, named after its brightest member, is young (60 Myr)and nearby (d = 132 pc). However, only seven bona fide members can bedrawn from the Hipparcos data. We report a detection of nine opencluster candidates in the distance range of 150 to 400 pc, and sixpossible associations almost all located within the Gould belt, althoughslightly older than the known nearby associations. In all cases, wepresent Yale theoretical isochrone fits to the color-magnitude diagrams,which indicate a moderate spread of ages between 60 to 200 Myr.Evidently, these young open cluster and association candidates arerelated to the overall distribution of young OB and A-type stars in thesolar neighborhood.
| Experiments with CP stars
A method for fine-classification of stars is applied to a sample ofabout 100 stars within the approximate spectral type range B6-A5.Experiments have been performed to find a method for fine-classificationof A stars, both normal and chemically peculiar, within the MK system.It is found that, independent of the definition of the degree ofpeculiarity, no sharp border exists separating the CP stars from thenormal ones. It is also shown that spectral classification can, onaverage, be performed with almost the same accuracy for CP stars as forthe normal ones if cases of extreme peculiarity are avoided.
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