Open Clusters as Galactic Disk Tracers. I. Project Motivation, Cluster Membership, and Bulk Three-Dimensional Kinematics
We have begun a survey of the chemical and dynamical properties of theMilky Way disk as traced by open star clusters. In this firstcontribution, the general goals of our survey are outlined and thestrengths and limitations of using star clusters as a Galactic disktracer sample are discussed. We also present medium-resolution (R ~ 15,0000) spectroscopy of open cluster stars obtained with the Hydramulti-object spectrographs on the Cerro Tololo Inter-AmericanObservatory 4 m and WIYN 3.5 m telescopes. Here we use these data todetermine the radial velocities of 3436 stars in the fields of openclusters within about 3 kpc, with specific attention to stars havingproper motions in the Tycho-2 catalog. Additional radial velocitymembers (without Tycho-2 proper motions) that can be used for futurestudies of these clusters were also identified. The radial velocities,proper motions, and the angular distance of the stars from clustercenter are used to derive cluster membership probabilities for stars ineach cluster field using a non-parametric approach, and the clustermembers so identified are used, in turn, to derive the reliable bulkthree-dimensional motion for 66 of 71 targeted open clusters. Thehigh-probability cluster members that we identify help to clarify thecolor-magnitude sequences for many of the clusters, and are primetargets for future echelle resolution spectroscopy as well asastrometric study with the Space Interferometry Mission (SIMPlanetquest).
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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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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Galactic clusters with associated Cepheid variables. II - NGC 129 and DL Cassiopeiae
The paper presents new photoelectric UBV photometry of 27 stars andspectroscopic observations of 12 stars for NGC 129, the clustercontaining the 8.00-d Cepheid DL Cas. The photometry is used torestandardize previously published photoelectric and photographicobservations of stars in NGC 129, including transformed Stromgren systemdata. A compilation of the best available photometric data for starswith V less than 15.3 is used in conjunction with published propermotion data and spectroscopic observations of the brighter stars for adetailed cluster analysis. The newly obtained distance modulus of NGC129 is 11.11 +/-0.02 s.e., and a value of 3.20 +/-0.30 s.e. is found todescribe the dust extinction in the field. A list of 94 candidatecluster members is presented, and a cluster radial velocity of -36.0+/-1.8 km/s is derived using the supergiants and bright B stars. Themembership status of the supergiants is discussed in connection withother available information for cluster stars.
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The binary Cepheid DL CAS and the open cluster NGC 129
The Cepheid DL Cas and the nonvariable supergiant Star A are confirmedas members of NGC 129, and both are found to be spectroscopic binarieswith orbital periods of a few years. Periods and orbits are determinedfor both stars. Star A is apparently rotating; tidal interaction withits companion is discussed and then rejected as the probable cause ofthe rotation. The membership of other stars and the velocity of thecluster are redetermined.
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Four-color and H-beta photometry of stars in the galactic cluster NGC 129
Four-color and H-beta photometry has been obtained for 22 stars in thefield of the open cluster NGC 129. Based on this photometry, themembership of these stars in the cluster is discussed and it is foundthat many are field stars. The color excesses for cluster membersobtained here range from E(b - y) = 0.207 to 0.513 and are larger thanthose found from previous UBV photometry. It has been suggested thatthis cluster contains a nonvariable Cepheid strip star. However, thepresent reddening places this star at the edge of the instability strip.A true distance modulus of 10.93 mag is found for this cluster, which isless than some previous values.
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Distance Moduli of Open Clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1965ApJS...12..215H&db_key=AST
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Astrometric investigations of galactic clusters. I. NGC 129.
Abstract image available at:http://adsabs.harvard.edu/abs/1961AJ.....66...16L
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Überriesen FO-K7 Ia-II in galaktischen Sterhaufen. I. Mittelung von: Leuchtkraft, Alter und Eigenfarben galaktischer Überriesen. Mit 3 Textabbildungen
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Dreifarben-Photometrie einer Sternhaufengruppe in der Cassiopeia (NGC 103, NGC 129, NGC 136, NGC 146, K 14, und K 16)
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Cepheids in Galactic Clusters.IV. DL CAS in NGC 129.
Abstract image available at:http://adsabs.harvard.edu/abs/1959ApJ...130...80A
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Cepheids in Galactic Clusters. II Radial Velcocities and Spectral Types in NGC 129, NGC 6664, and NGC 7790.
Abstract image available at:http://adsabs.harvard.edu/abs/1958ApJ...128..161K
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