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A catalogue of eclipsing variables
A new catalogue of 6330 eclipsing variable stars is presented. Thecatalogue was developed from the General Catalogue of Variable Stars(GCVS) and its textual remarks by including recently publishedinformation about classification of 843 systems and making correspondingcorrections of GCVS data. The catalogue1 represents thelargest list of eclipsing binaries classified from observations.
| Spectroscopy, Photometry and Micro-arcsec Astrometry of Binaries with the GAIA Space Mission and with the RAVE Experiment
The GAIA astrometric mission of ESA will be very efficient indiscovering binary and multiple stars with any orbital period, fromminutes to millions of years. The main parameters of the revised missiondesign are presented. Next we estimate the fraction of binary starsdiscovered by means of astrometry, photometry and on-board spectroscopy.Finally we summarize observations that confirm the ability to measurephysical parameters like masses, radii and spectroscopic distance fromGAIA data alone. GAIA will fly only in 2010, but the radial velocityexperiment (RAVE) has started this year. We show that its spectroscopicobservations have the capacity to discover a large fraction of so farunknown binary systems.
| An Assessment of Dynamical Mass Constraints on Pre-Main-Sequence Evolutionary Tracks
We have assembled a database of stars having both masses determined frommeasured orbital dynamics and sufficient spectral and photometricinformation for their placement on a theoretical H-R diagram. Our sampleconsists of 115 low-mass (M<2.0 Msolar) stars, 27pre-main-sequence and 88 main-sequence. We use a variety of availablepre-main-sequence evolutionary calculations to test the consistency ofpredicted stellar masses with dynamically determined masses. Despitesubstantial improvements in model physics over the past decade, largesystematic discrepancies still exist between empirical and theoreticallyderived masses. For main-sequence stars, all models considered predictmasses consistent with dynamical values above 1.2 Msolar andsome models predict consistent masses at solar or slightly lower masses,but no models predict consistent masses below 0.5 Msolar,with all models systematically underpredicting such low masses by5%-20%. The failure at low masses stems from the poor match of mostmodels to the empirical main sequence below temperatures of 3800 K, atwhich molecules become the dominant source of opacity and convection isthe dominant mode of energy transport. For the pre-main-sequence samplewe find similar trends. There is generally good agreement betweenpredicted and dynamical masses above 1.2 Msolar for allmodels. Below 1.2 Msolar and down to 0.3 Msolar(the lowest mass testable), most evolutionary models systematicallyunderpredict the dynamically determined masses by 10%-30%, on average,with the Lyon group models predicting marginally consistent masses inthe mean, although with large scatter. Over all mass ranges, theusefulness of dynamical mass constraints for pre-main-sequence stars isin many cases limited by the random errors caused by poorly determinedluminosities and especially temperatures of young stars. Adopting awarmer-than-dwarf temperature scale would help reconcile the systematicpre-main-sequence offset at the lowest masses, but the case for this isnot compelling, given the similar warm offset at older ages between mostsets of tracks and the empirical main sequence. Over all age ranges, thesystematic discrepancies between track-predicted and dynamicallydetermined masses appear to be dominated by inaccuracies in thetreatment of convection and in the adopted opacities.
| Evaluating GAIA performances on eclipsing binaries. I. Orbits and stellar parameters for V505 Persei, V570 Persei and OO Pegasi
The orbits and physical parameters of three detached, double-lined A-Feclipsing binaries have been derived combining HP,VT, BT photometry from the Hipparcos/Tycho missionwith 8500-8750 Å ground-based spectroscopy, mimicking thephotometric+spectroscopic observations that should be obtained by GAIA,the approved Cornerstone 6 mission by ESA. This study has two mainobjectives, namely (a) to derive reasonable orbits for a number of neweclipsing binaries and (b) to evaluate the expected performances by GAIAon eclipsing binaries and the accuracy achievable on the determinationof fundamental stellar parameters like masses and radii. It is shownthat a 1% precision in the basic stellar parameters can be achieved byGAIA on well observed detached eclipsing binaries provided that thespectroscopic observations are performed at high enough resolution.Other types of eclipsing binaries (including semi-detached and contacttypes) and different spectral types will be investigated in subseguentpapers in this series.
| Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| GAIA Spectroscopy: Proposing the 8500--8750 Angstroms Region and Evaluating the Performances
We propose the Gaia spectroscopic observations to be performed over thewavelength interval 8500--8750 Angstroms, with an optimal dispersion of0.25 Angstroms/pix (or 1000 pixels budget per spectrum) and a 2 pixelPSF. In this paper, on the base of extensive observations as well assynthetic spectra and simulations, we review the spectroscopicperformances expected for Gaia: radial and rotational velocities,spectral classification, detection of mass-loss and spectralpeculiarities, chemical abundance analysis and reddening estimates fromthe 8620 Angstroms diffuse interstellar band. Lower dispersion spectra(corresponding to smaller pixel budgets) are considered too.
| An astrometric catalogue of stars in the region of M15
We present positions and proper motions with respect to the PPMcatalogue of 863 stars in a field of 8 deg x 6 deg centered on theglobular cluster M15. The catalogue is based on measurements of 136plates from the Carte du Ciel telescope of Bordeaux, the CERGA Schmidttelescope, and the double refractor of Bonn. The modal accuracy of theproper motions is +/- 0 arcsec 15/100 a.
| UBV photometry of stars whose positions are accurately known.
Photometric indices V, B-V, and U-B were measured for about 560 stars ofthe AGK3R and NPZT catalogs between BD declinations 11 deg and 23 deg,using the 40-cm Cassegrain telescope of the Kvistaberg Observatory fromApril 1986 to May 1987. The observation procedure and the reductiontechnique were the same as in the earlier papers of this series by Oja(1984, 1985, 1986, and 1987). The mean errors were calculated from theinternal consistency of the data. The accuracy was found to be the sameas for the earlier parts of the survey.
| Meridian observations made in Brorfelde (Copenhagen University Observatory) 1975-76.
This catalogue presents positions for selected faint stars mainly fromAGK3 observed with the 7" transit circle at Brorfelde. The stars aredistributed in 43 selected areas around radio sources and are suitableas reference stars for measuring the optical counterparts to the radiosources. The obscr 'itioi cre carried out from 1975.16 to 1976.04, andevery star was observed at least two times giving a m.s.e. of "13 forthe catalogue positions given in the FK4 system. These positions usedtogether with AGK3 proper motions will in the period 1975 to 1980 have am.s.e. at the epoch ranging from `:13 to `:15, which is less than halfof what is expected when using AGK3 positions. Key words: transit circle- catalogue of positions
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| Takýmyýldýz: | Kanatli At |
| Sað Açýklýk: | 21h41m37.70s |
| Yükselim: | +14°39'30.8" |
| Görünürdeki Parlaklýk: | 8.328 |
| Uzaklýk: | 446.429 parsek |
| özdevim Sað Açýklýk: | -0.9 |
| özdevim Yükselim: | -13.6 |
| B-T magnitude: | 8.635 |
| V-T magnitude: | 8.354 |
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