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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.
| 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
| A study of the open cluster NGC 7209 in the Vilnius photometric system
Photoelectric photometry in the Vilnius seven-colour system is presentedfor the open cluster NGC 7209. In total 96 probable cluster members havebeen measured down to V~14.0. For all stars their spectral types,absolute magnitudes, colour excesses, interstellar reddening anddistances are derived from the Vilnius photometry. The metallicity isestimated to be [Fe/H]=-0.07. In addition, a list of suspected binariesis provided. The reddening across the cluster shows a slight trend alongthe north-south direction. The mean reddening equals E(Y-V)=0.121 [inthe UBV system E(B-V)=0.171] which corresponds to A_V=0.54. The derivedmedian distance for NGC 7209 is 1026+/-30pc (equivalent to the distancemodulus V_0-M_V=10.06+/-0.06). Theoretical isochrone fits to thecolour-magnitude diagram yield an age estimate of 0.45Gyr.
| Uvby-beta photometry of open clusters. IV. NGC 1444, NGC 1662, NGC 2129, NGC 2169 and NGC 7209.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994RMxAA..28..139P&db_key=AST
| The studies of proper motions in the regions of open clusters. III - NGC 7209
Relative proper motions of 4290 stars in the region of the open clusterNGC 7209 have been determined from the PDS measurements of 12 Pulkovoand one Tashkent normal astrograph plates. In a 28-arcmin-diametercircle around the cluster 148 stars have membership probabilities Pgreater than 0 percent. The total number of cluster stars obtained byweighting them with membership probabilities reaches 109. The catalog ofproper motions is complete down to m(pg) = 15.1 mag; the limiting valueis 15.6 mag.
| Distance Moduli of Open Clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1965ApJS...12..215H&db_key=AST
| Spectral Classification in Nine Open Clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1962ApJ...136..788S&db_key=AST
| A catalogue of proper motions of stars in 13 open clusters and in their vicinity.
Not Available
| Untersuchungen der offenen Sternhaufen NGC 7092 (M 39), NGC 7209, und NCG [sic] 7243
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