The young open cluster NGC 663 and its Be stars
We present new BV(RI)CHα photometry of the young opencluster NGC 663. The Hα photometry is complete down to magnitudeRC = 15.4, corresponding to spectral type A5 for the clustermembers. This allows detection of mild and strong Hα emission inall B-type stars in the cluster. In addition to the 22 Be stars known inthe observed field of NGC 663, we discovered four new faint stars ofthis type. We find that Be stars in NGC 663 cover the whole range of theB spectral type. They are, however, most populous among stars withspectral types falling in the range between B0 and B3, where theirfraction amounts to 31 +/- 8%. Among B-type stars later than B3, Bestars are much less abundant: only 7 out of 101 observed stars, that is,7 +/- 3%, were detected. About 70% of the observed Be stars in NGC 663show detectable variations of light. In the time interval covered by ourobservations, the ranges of the largest variations reach 0.4 mag in theIC band. By means of the isochrone fitting, we derived thecluster distance of 2.1 kpc, age of 20-25 Myr, and the mean colourexcess E(R-I)C = 0.54 mag, with a ~ 0.1 mag scatter due todifferential reddening. Tables 2 and 3 are only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/376/144
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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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UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
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Near-infrared and Stromgren photometry of the open clusters NGC 663, NGC 1502 and NGC 1893
Observational data are presented regarding the three objects includingnear-IR JHK, Stromgren uvby, and H-beta photometry of the centralregions. The intrinsic photometric colors of average main-sequence starsare taken from previous studies to examine the data with m1 vs. b-y, c1vs. m1, beta vs. c1, J-H vs. H-K, and V-K vs. b-y diagrams. It isdetermined that the ages of and distance to NGC 663, NGC 1502, and NGC1893 are respectively 9 x 10 exp 6 yr and 2.5 kpc, 5 x 10 exp 6 yr and1.5 kpc, and 4 x 10 exp 6 yr and 4.3 kpc. The results indicate otherparameters, and considerable differental reddening is noted across NGC663. The total-to-selective extinction ratio is also examined showingthat it is smaller than the galactic value towards NGC 663 and 1893 andsignificantly lower than the average value for the ISM in NGC 1502. Itis concluded that the size distribution of the dust particles in thepresent line-of-sight has an inherent bias.
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More radial-velocity measurements in young open clusters
Further high resolution radial-velocity measurements are reported in 23young open clusters using the Kitt Peak CCD coude spectrograph on the0.9-m feed telescope. The radial velocities for the cluster stars arederived with the technique of cross correlation. The internal precisionof the velocity measurements is typically 2 km/s for early type stars.From these new data and previously published velocities, the observedstars in two clusters, NGC 663 and NGC 2287, were found to show arelatively small dispersion in the measured mean velocities. Furtherobservations of stars in young clusters will be useful in helping toestablish an early-type-star-velocity standard system.
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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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UBV Photometry of the Open Cluster NGC 663
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978AJ.....83.1075V&db_key=AST
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The space distribution and radial velocities of some early-type stars in the Perseus spiral arm
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..597M&db_key=AST
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Photographische UBV-Helligkeiten in 14 jungen Sternhaufen der nordlichen Milchstrasse.
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NGC 663.
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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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Galactic structure in Cassiopeia.
Abstract image available at:http://adsabs.harvard.edu/abs/1964AJ.....69..412M
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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
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Photometry of stars in galactic cluster fields.
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Der galaktische Sternhaufen NGC 663.
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A System of Three-Color Photometry, with applications to Galactic Structure in Cygnus
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1958AJ.....63..127T&db_key=AST
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Stellar Spectra and Colors in a Milky way Region in Cassiopeia.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1955ApJS....2..123F&db_key=AST
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Drei-Farben-Photometrie von 11 offenen Sternhaufen, insbesondere solchen mit O-und frühen B-Sternen. Mit 21 Text-abbildungen
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Kolorimetrische Untersuchungen an offenen Sternhaufen in den Standrd-Spektralbereichen der Integralphotometrie. Ngc 663
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An investigation of color excess in galactic star clusters
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A photometric research on two open clusters in Cassiopeia.
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A study of proper motions in the cluster NGC 663
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