A Spectroscopic Search for λ Bootis and Other Peculiar A-Type Stars in Intermediate-Age Open Clusters
As part of our continuing search for peculiar A-type stars, especiallyλ Bootis stars, in open clusters of all ages, we have obtainedclassification spectra of 130 late B, A, and early F-type stars in 12intermediate-age open clusters, including NGC 1039, 2281, 2548, 6633,7039, 7063, 7092, and 7209, IC 4665, IC 4756, Stock 2, and Praesepe. Thespectra were obtained with resolutions of 1.8 and 3.6 Å on the 0.8m telescope of Appalachian State University and were classified on theMK system. Numerous classical Ap and Am stars were found among the 130,including two new Ap stars in NGC 7092. In addition, three emission-linestars and two candidate λ Bootis stars were found. Neither ofthese λ Bootis candidates turned out to be members of theirrespective clusters. Combined with 184 stars previously classified in 10other intermediate-age open clusters, also devoid of λ Bootisstars, a statistically significant null result is obtained. We discussthe implications of this null result for our understanding of theλ Bootis mechanism.
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Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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Mesures de vitesses radiales. VIII. Accompagnement AU sol DU programme d'observation DU satellite HIPPARCOS
We publish 1879 radial velocities of stars distributed in 105 fields of4^{\circ} \times 4^{\circ}. We continue the PPO series \cite[(Fehrenbachet al. 1987;]{Feh87} \cite[Duflot et al. 1990, 1992 and 1995),]{Du90}using the Fehrenbach objective prism method. Table 1 only available inelectronic form at CDS via to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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Membership in the Galactic open cluster NGC 1039 (M34)
Proper motions and membership probabilities for 354 stars in the regionof NGC 1039 (M34) are presented. A zero-age main-sequence fit thecolor-magnitude diagram of 89 probable members yields a distance modulusof 8.28. Comparing theoretical isochrones to the color-magnitude diagramof probable members yields in age of approximately 2.5 x 10 exp 8 years.Membership probabilities based on proper motions indicate that all sixof the visual binaries and three of the four known Ap stars are membersof the cluster. A possible giant member is identified. Evidence for masssegregation via dynamical relaxation is briefly discussed.
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Photometry of stars in the uvgr system
Photoelectric photometry is presented for over 400 stars using the uvgrsystem of Thuan and Gunn. Stars were selected to cover a wide range ofspectral type, luminosity class, and metallicity. A mean main sequenceis derived along with reddening curves and approximate transformationsto the UBVR system. The calibration of the standard-star sequence issignificantly improved.
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Stellar Content of Young Open Clusters - Part Two - Be-Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1982A&A...109...48M&db_key=AST
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Multicolor photometry of the galactic cluster NGC 1039 /M34/
Multicolor uvby and H-beta photometries have been obtained for 42 starsin the field of the galactic cluster NGC 1039 (M34). Analyses give amean cluster reddening of E(B-V) = 0.07 m and a distance modulus of 8.2m corresponds to a distance of 440 pc. The metallicity of NGC 1039 issimilar to the Pleiades cluster; its age is intermediate, older than thePleiades but younger than the Hyades cluster. The properties of itsthree Ap stars, two additional peculiar stars, membership criteria, andgaps in the UBV color-color relation are discussed
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Spectral types in the open cluster M 34.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977PASP...89..648A&db_key=AST
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Photoelectric photometry of the open cluster M34.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977A&AS...30..227C&db_key=AST
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Spectroscopy of Stars in the Galactic Cluster NGC 1039 (M34)
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970PASP...82..825I&db_key=AST
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Vermessung des offenen Sternhaufen Messier 34
Not Available
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Magnitudes and Colors in M34.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1954ApJ...119..185J&db_key=AST
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Spektral-Durchmusterung von Milchstrassenfeldern.
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Der offene Sternhaufen Messier 34
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