The Keele-Exeter young cluster survey - I. Low-mass pre-main-sequence stars in NGC 2169
We have used RCIC CCD photometry from the IsaacNewton telescope and intermediate-resolution spectroscopy from theGemini North telescope to identify and characterize low-mass (0.15
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Internal Motions of Trapezium Systems
The separations of the various components of 44 trapezia as a functionof time are studied, taking advantage of many new, high precisionobservations for these objects. A previous study revealed that somesystems have components moving with velocities larger than the escapevelocity (Allen et al. 1974). The present work updates our previousstudy, extending the observations by about 30 years, and thus allowingan improved determination of the relative transverse motions of thecomponents. The analysis of the new data confirms the conclusions wereached in our previous work: most of the trapezia show the internalmotions expected for bound, virialized small clusters, but a few haveescaping components. The available observational material lends supportto the concept that trapezia are unstable systems with lifetimes of theorder of a few million years.
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CCD photometric search for peculiar stars in open clusters. I. NGC 2169, Melotte 105 and NGC 6250
The search for chemically peculiar (CP) stars in open clusters usingphotoelectric photometry sampling the presence of the characteristicflux depression feature at 5200 Å,via the Delta a-system (Maitzen\cite{M76}) has so far delivered data for objects usually no moredistant than 1000 pc from the Sun. A series of fourteen papers (first:Maitzen & Hensberge \cite{M81}; for the time being last: Maitzen\cite{M93}) were devoted to 1240 stars in 38 open cluster fields. If oneintends to study the presence of CP stars at larger distances from theSun, classical photometry has to be replaced by CCD photometry. We havetherefore initialized in 1995 a new survey in open clusters and theLarge Magellanic Cloud using the CCD technology. As a first step, wehave presented new Delta a-photometry of 22 CP2 stars in the galacticfield to prove the capability of CCD photometry for our aim (Maitzen etal. \cite{M97}). In the first paper of a new series devoted to CCDphotometry, we present data on NGC 2169 (13 stars investigated), Melotte105 (114 stars), and NGC 6250 (48 stars). NGC 2169 was used to test ourresults with those of classical photometry which yields excellentagreement. For NGC 6250 we find two new definite CP2 (according to thedefinition by Preston \cite{P74}) stars (Delta a = 0.065 and 0.026 mag)and two lambda Bootis candidates. Twelve objects with only marginallypeculiar Delta a-values for Melotte 105 were detected. Additionalspectroscopic and photometric evidence is needed to substantiate theirpeculiarity. Based on observations at ESO-La Silla, UTSO-Las Campanasand L.~Figl Observatory, Mt. Schöpfl, Austria.
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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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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
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Photoelectric Search for Peculiar Stars in Open Clusters - Part Fourteen - NGC1901 NGC2169 NGC2343 CR:132 NGC2423 and NGC2447
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..102....1M&db_key=AST
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Ubvy + H-beta photometry of the young open clusters NGC 1502 and NGC 2169
This study presents results of a ubvy + H-beta photometric investigationof 22 and 14 stars, in the fields of NGC 1502 and NGC 2169,respectively, including new H-beta measurements for the 22 stars in NGC1502. A comparison with the findings of Perry et al. (1978) and Reimannand Pfau (1987) is discussed, with particular attention to the presenceof systematic errors present in the sequences of instrumental andstandard values. The membership of the observed stars is discussed onthe basis of the available photometric and radial velocity data.
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Radial-velocity measurements in 20 young open clusters
The further results of a program to determine the radial velocities ofyoung open clusters are presented. Using the KPNO coude spectrographcoupled with the 1-m feed and 2.1-m telescopes, radial velocities havebeen measured for nearly one hundred stars, most of which are ofspectral type B and A, in 20 young clusters. The combination ofinstruments and the use of cross-correlation techniques show that radialvelocities of B and A type stars as faint as 10th magnitude can bedetermined with an internal precision of less than about 2 km/s. Asexpected, the uncertainties in the velocity determination for the youngclusters are dominated by spectroscopic binary stars in these clusters.A third of the stars in the sample are found to be spectroscopicbinaries, but with a large variation in the frequency of binaries fromcluster to cluster. Because the time coverage is still limited, thisshould be considered a lower limit to the binary frequency. Clustervelocities are determined after eliminating binaries and known nonmemberstars. The new velocities are compared with a model galactic rotationcurve, as well as with previous velocity determinations.
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Equatorial coordinates of double and multiple star components measured on GPO astrographic plates
Equatorial coordinates are given for some of the multiple starcomponents having incomplete or inconsistent information in the IndexCatalog of Visual Double Stars. Two photographic plates were taken foreach system with incomplete or inconsistent information using the GPOastrograph. The plate measurement and reduction techniques used aredescribed.
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A photometric and spectroscopic study of the open cluster NGC 2169.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978PASP...90...73P&db_key=AST
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Spectral Types in the Open cluster NGC 2169
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977PASP...89..646A&db_key=AST
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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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Polarization Measurements of the Open Clusters NGC 2169 and 7243
Not Available
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Stellar Spectra in Milky way Regions. VIII. a Region in Orion.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1959ApJS....4...23M&db_key=AST
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The Galactic Cluster NGC 2169.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956ApJ...123...59C&db_key=AST
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