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A CCD Search for Variable Stars of Spectral Type B in the Northern Hemisphere Open Clusters. VIII. NGC 6834
We present results of a CCD variability search in the field of the youngopen cluster NGC 6834. We discover 15 stars to be variable in light. Thebrightest, a multiperiodic ? Doradus-type variable is a foregroundstar. The eight fainter ones, including a ? Cassiopeiae-typevariable, two ? Eridani-type variables, an ellipsoidal variable,an EB-type eclipsing binary, and three variable stars we could notclassify, all have E(B-V) within proper range, thus fulfilling thenecessary condition to be members. One of the three unclassifiedvariables may be a non-member on account of its large angular distancefrom the center of the cluster. Four of the six faintest variable stars,which include two eclipsing binaries and two very red stars showingyear-to-year variations, are certain non-members. One of the remainingtwo faintest variable stars, an EA-type eclipsing binary may be amember, while the faintest one, a W Ursae Majoris-type variable, isprobably a non-member.For 6937 stars we provide the V magnitudes and V-IC colorindices on the standard system. Because of nonuniform reddening over thecluster's face, a direct comparison of these data with theoreticalisochrones is not possible. We therefore obtain E(B-V) from availableUBV photometry, determine the lower and upper bound of E(B-V) for NGC6834, and then fit properly reddened Padova isochrones to the data.Assuming HDE 332843, an early-F supergiant, to be a member we obtainlog(age/yr)=7.70, V0-MV=12.10 mag.For 103 brightest stars in our field we obtained the ? index, ameasure of the equivalent widths of the H? line. We find H?emission in five stars, including the ? Cas-type variable and thetwo ? Eri-type variables.
| Catalogue of stellar spectral classifications.
Not Available
| 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
| Catalogue of H-alpha emission stars in the Northern Milky Way
The ``Catalogue of Stars in the Northern Milky Way Having H-alpha inEmission" appears in Abhandlungen aus der Hamburger Sternwarte, Band XIin the year 1997. It contains 4174 stars, range {32degr <= l() II< 214degr , -10degr < b() II < +10degr } having the Hαline in emission. HBH stars and stars of further 99 lists taken from theliterature till the end of 1994 were included in the catalogue. We givethe cross-identification of stars from all lists used. The catalogue isalso available in the Centre de Données, Strasbourg ftp130.79.128.5 or http://cdsweb.u-strasbg.fr and at the HamburgObservatory via internet.
| Catalogue of stars in the northern Milky Way having H-alpha in emission
Not Available
| Photometric observations of emission B-stars in the southern Milky Way
In order to study the distribution of Be stars and their correlation tothe local spiral structure of the Galaxy photoelectric UBV photometrywas carried out for a total of 488 Be stars located in the southernMilky Way between galactic longitudes 315 and 45 deg. UBV magnitudes arepresented for these stars.
| A Survey for H-alpha emission objects in the Milky Way.
Not Available
| New determinations of R in open clusters
Variable-extinction analyses for 51 galactic clusters, using primarilyzero-age main-sequence-fitted data, are presented and discussed. Forthree of these clusters, spectroscopic data for the brighter stars arepresented. The weighted mean value of R, the ratio of total to selectiveextinction, for all 51 clusters is 3.08 plus or minus 0.03, in very goodagreement with the results of other determinations. Careful examinationof the data for individual clusters suggests that some evidence for adependence of R on intrinsic color and galactic longitude may bepresent.
| Observations of southern emission-line stars
A catalog of 1929 stars showing H-alpha emission on photographic platesis presented which covers the entire southern sky south of declination-25 deg to a red limiting magnitude of about 11.0. The catalog providesprevious designations of known emission-line stars equatorial (1900) andgalactic coordinates, visual and photographic magnitudes, H-alphaemission parameters, spectral types, and notes on unusual spectralfeatures. The objects listed include 16 M stars, 25 S stars, 37 carbonstars, 20 symbiotic stars, 40 confirmed or suspected T Tauri stars, 16novae, 14 planetary nebulae, 11 P Cygni stars, 9 Bep stars, 87 confirmedor suspected Wolf-Rayet stars, and 26 'peculiar' stars. Two new Tassociations are discovered, one in Lupus and one in Chamaeleon. Objectswith variations in continuum or H-alpha intensity are noted, and thedistribution by spectral type is analyzed. It is found that the skydistribution of these emission-line stars shows significantconcentrations in the region of the small Sagittarius cloud and in theCarina region.
| A survey for Halpha emission objects in the Milky Way. I. Vulpecula-Cygnus.
Not Available
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Osservazione e dati astrometrici
| Costellazione: | Cigno |
| Ascensione retta: | 19h52m01.39s |
| Declinazione: | +29°23'50.1" |
| Magnitudine apparente: | 11.621 |
| Moto proprio RA: | -12.8 |
| Moto proprio Dec: | 7.4 |
| B-T magnitude: | 12.017 |
| V-T magnitude: | 11.654 |
Cataloghi e designazioni:
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