CCD uvbyβ photometry of the young open cluster NGC 663
NGC 663 is a young, moderately rich open cluster, known to contain oneof the largest fractions of Be stars among all galactic clusters. Inthis work we present CCD uvbyβ photometry for stars in its centralarea. We have used these data to obtain the main cluster physicalparameters. We find that the reddening is highly variable, with valuesranging from E(b-y) = 0.639 +/- 0.032 in the central part to E(b-y) =0.555 +/- 0.038 in the south-east. The distance modulus is found to be11.6 +/- 0.1 mag (2.1 kpc) and the age logt= 7.4 +/- 0.1 yr(25+7-5 Myr). The age obtained is consistent withthe interpretation of the Be phenomenon as an evolutionary effect.
|
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
|
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
|
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.
|
Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
|
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.
|
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.
|
Large and kinematically unbiased samples of G- and K-type stars. IV - Evolved stars of the old disk population
Modified Stromgren and (R,I) photometry, along with DDO and Genevaphotometry, are presented for a complete sample of evolved old-disk Gand K giants in the Bright Star Catalogue. Stars with ages of between1.5 x 10 to the 9th and 10 to the 10th yr are found to have anear-normal distribution of heavy element abundances, centered on anFe/H abundance ratio of -0.1 dex. The old disk clusters NGC 3680 and IC4651 contain red-straggler young-disk giants that are probablycontemporaries of the blue stragglers in the clusters.
|
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.
|
Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJS...38..309H&db_key=AST
|
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
|
Noncircular motions in the Perseus spiral arm
An examination of the motions of the optical spiral tracers in thePerseus arm reveals a clear kinematic separation between the inner andouter sides of the arm. Those objects on the inner or near side have amean velocity residual of -10.7 km/s, while those on the outer or farside have a mean positive residual of +7.0 km/s. These velocityresiduals are interpreted in terms of the linear density-wave theory asstreaming motions between the sides of the arm. Plausible solutions forthe amplitudes of the noncircular motions yielded 10 to 20 km/s and 7 to15 km/s for the radial and tangential components, respectively. Theseresults are about twice the amplitudes suggested by the theory.
|
Photographische UBV-Helligkeiten in 14 jungen Sternhaufen der nordlichen Milchstrasse.
Not Available
|
Wavelength dependence of polarization. XXV. Rotation of the position angle by the interstellar medium.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..565C&db_key=AST
|
NGC 663.
Not Available
|
Photoelectric UBV photometry in Cygnus and Cassiopeia
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....6..117B&db_key=AST
|
The space distribution and kinematics of supergiants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..602H&db_key=AST
|
Messungen und Analyse der Polarisation des Sternlichtes in der Cassiopeia
Not Available
|
Catalogue d'etoiles O et B.
Not Available
|
Vitesses radiales dans 4 champs de petite latitude galactique.
Not Available
|
Distance Moduli of Open Clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1965ApJS...12..215H&db_key=AST
|
The galactic cluster NGC 4755 (κ Crucis)
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963MNRAS.126...11F&db_key=AST
|
Photoelectric measures of the 4430 A diffuse interstellar band
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963MNRAS.125..141W&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
|
Photometry of stars in galactic cluster fields.
Not Available
|
Turbulence and rotation in early-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1961MNRAS.123...81M&db_key=AST
|
Galactic clusters as indicators of stellar evolution and galactic structure
Not Available
|
Der galaktische Sternhaufen NGC 663.
Not Available
|
La mesure des vitesses radiales au prisme objectif. IX - 3e liste de vitesses radiales déterminées au prisme objectif à vision directe
Not Available
|
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
|
