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The Vienna-KPNO search for Doppler-imaging candidate stars. I. A catalog of stellar-activity indicators for 1058 late-type Hipparcos stars
We present the results from a spectroscopic Ca ii H&K survey of 1058late-type stars selected from a color-limited subsample of the Hipparcoscatalog. Out of these 1058 stars, 371 stars were found to showsignificant H&K emission, most of them previously unknown; 23% withstrong emission, 36% with moderate emission, and 41% with weak emission.These spectra are used to determine absolute H&K emission-linefluxes, radial velocities, and equivalent widths of theluminosity-sensitive Sr ii line at 4077 Ä. Red-wavelengthspectroscopic and Strömgren y photometric follow-up observations ofthe 371 stars with H&K emission are used to additionally determinethe absolute Hα -core flux, the lithium abundance from the Li i6708 Å equivalent width, the rotational velocity vsin i, theradial velocity, and the light variations and its periodicity. Thelatter is interpreted as the stellar rotation period due to aninhomogeneous surface brightness distribution. 156 stars were found withphotometric periods between 0.29 and 64 days, 11 additional systemsshowed quasi-periodic variations possibly in excess of ~50 days. Further54 stars had variations but no unique period was found, and four starswere essentially constant. Altogether, 170 new variable stars werediscovered. Additionally, we found 17 new SB1 (plus 16 new candidates)and 19 new SB2 systems, as well as one definite and two possible new SB3systems. Finally, we present a list of 21 stars that we think are mostsuitable candidates for a detailed study with the Doppler-imagingtechnique. Tables A1--A3 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
| A Photometric study of EB-type eclipsing binary GO Cyg.
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| The GO Cygni system: a near contact eclipsing binary
The GO Cygni system is a short period -0.7177 days- eclipsing binarywith a % beta Lyrae-type light curve. In this study our new BVphotoelectric observations of the system, made at the BucharestObservatory during 1993-94 are presented. These, and our old ones -madeat the Kryonerion Astronomical Station of the National Observatory ofAthens, Greece, in 1985- are analysed using Wood's program. Thegeometrical elements of the system -derived from the present analysis-correspond to a contact configuration suggesting that it belongs to theso-called near contact binaries. Moreover, its physical parameters leadto an unevolved system with both of its components located very close tothe ZAMS. Finally, its orbital period is examined and found to showcontinuous increased.
| Photometric Observations and Light Curves Analysis of GO Cygni
Photoelectric observations, in U, B and V, of the system GO Cygni wereobtained during 1995 at the Birouni Observatory, Shiraz, Iran, and thecorresponding light curves analysed with the use of Wilson-Devinney;'stechniques. New photoelectric and absolute elements for the system aregiven. The period of the system, a reverse Algol type semi-detachedbinary was found to continue its increasing.
| Close Binary System GO Cygnus: Standard UBV Observations and Light Curve Analysis
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| Study of the eclipsing binary GO Cygni based on observations of Bucharest and Athens observatories from 1985 to 1994
The principal aim of this work is to study the eclipsing binary systemGO Cygni for which a series of photoelectric observations have beencarried out for ten years, 1985-1994, either at Athens or at theBucharest Observatories. The unpublished data obtained from 1989 to 1992are given and the corresponding light curves of the system are presentedwhile a general discussion concerning some of their features is made. Ashift of the order of 0.082 found in the V light curves of 1989-90 &92 and those of 1993-94 can be due to the variability of the comparisonstar BD+35°4197, which has to be checked; while some peculiarfeatures of its light curves may be due to the activity of the system.Moreover, the observed variations in the period of GO Cygni arediscussed.
| UBV Photometry of GO Cyg
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| Fotometria fotoelettrica in due colori della binaria GO Cygni
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| Two-colour photoelectric photometry of GO Cygni
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1954MNRAS.114..569O&db_key=AST
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