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Pulkovo compilation of radial velocities for 35495 stars in a common system.
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| RXJ2130.6+4710 - an eclipsing white dwarf-M-dwarf binary star
We report the detection of eclipses in the close white-dwarf-M-dwarfbinary star RXJ2130.6+4710. We present light curves in the B, V and Ibands and fast photometry obtained with the three-channel CCD photometerUltracam of the eclipse in the u', g' and r' bands. The depth of theeclipse varies from 3.0 mag in the u' band to less than 0.1 mag in the Iband. The times of mid-eclipse are given by the ephemerisBJD(mid-eclipse) = 2452785.681876(2) + 0.521035625(3) E, where figuresin parentheses denote uncertainties in the final digit. We presentmedium-resolution spectroscopy from which we have measured thespectroscopic orbits of the M dwarf and white dwarf. We estimate thatthe spectral type of the M dwarf is M3.5Ve or M4Ve, although the data onwhich this is based are not ideal for spectral classification. We havecompared the spectra of the white dwarf with synthetic spectra from purehydrogen model atmospheres to estimate that the effective temperature ofthe white dwarf is Teff= 18000 +/- 1000 K. We have used thewidth of the primary eclipse and duration of totality measured preciselyfrom the Ultracam u' data combined with the amplitude of the ellipsoidaleffect in the I band and the semi-amplitudes of the spectroscopic orbitsto derive masses and radii for the M dwarf and white dwarf. The M dwarfhas a mass of 0.555 +/- 0.023 Msolar and a radius of 0.534+/- 0.053 Rsolar, which is a typical radius for stars of thismass. The mass of the white dwarf is 0.554 +/- 0.017 Msolarand its radius is 0.0137 +/- 0.0014 Rsolar, which is theradius expected for a carbon-oxygen white dwarf of this mass andeffective temperature. The light curves are affected by frequent flaresfrom the M dwarf and the associated dark spots on its surface can bedetected from the distortions to the light curves and radial velocities.RXJ2130.6+4710 is a rare example of a pre-cataclysmic variable star thatwill start mass transfer at a period above the period gap forcataclysmic variables.
| Broadband Photometry of Northern-Hemisphere Luminous Stars. VII. UBV Photometry for 38 Case-Hamburg Stars
CCD-based UBV photometry for 38 intrinsically luminous stars drawn fromvolumes II, III, and IV of the Luminous Stars in the Northern Milky Waycatalog is reported. Most were imaged three or four times. These objectsinclude a number of bright giants and supergiants of spectral types B,A, and F. All but two are previously unobserved photometrically.
| Initial Results of a Comprehensive Ultrasoft Survey of the Einstein IPC Database: Source List and Confirmation of the Selection Procedure
We have carried out a survey of the entire Einstein IPC database (atotal of 5934 sources) to select objects with strong components ofultrasoft X-ray emission (i.e., emission below 0.5 keV). The selectioncriteria are based on ratios of counts within three broad energy bands(i.e., X-ray ``colors''). A total of 516 objects have been selected,with 202 (39%) having been identified through correlations with otherdatabases. Of the currently identified objects, 45% are active galacticnuclei, 28% are stellar objects, 6% are ``normal'' galaxies and galaxyclusters, and the remaining 21% are ``nonstellar'' Galactic objects suchas cataclysmic variables, pulsars, and white dwarfs. We present adiscussion of the survey selection procedure, the list of selectedsources, and discussions of interesting objects from the aforementionedgroups. We discuss the remarkable success of our rather ``lowresolution'' method of estimating spectral shape and present plans forfollow-up studies of the as yet unidentified sources.
| The ROSAT galactic plane survey: analysis of a low latitude sample area in Cygnus.
We present the analysis of the point source content of a low galacticlatitude region selected from the ROSAT all-sky survey. The test fieldis centered at l=90deg, b=0deg and has an area of 64.5deg^2^. A total of128 soft X-ray sources are detected above a maximum likelihood of 8.Catalogue searches and optical follow-up observations show that in thisdirection of the galactic plane, 85% of the sources brighter than 0.03PSPC cts/s are identified with active coronae. F-K type stars represent67%(+/-13%) of the stellar identifications and M type stars account for19%(+/-6%). A small but significant number of X-ray sources areassociated with A type stars on the basis of positional coincidence.These results together with those of similar optical campaignsdemonstrate that the soft X-ray population of the Milky Way is largelydominated by active stars. We show that the density and distribution influx and spectral type of the active coronae detected in X-rays areconsistent with the picture drawn from current stellar population modelsand age dependent X-ray luminosity functions. The modelling of thispopulation suggests that most of the stars detected by ROSAT in thisdirection are younger than 1Gyr. This opens the possibility to extractin a novel way large samples of young stars from the ROSAT all-skysurvey. The small number of unidentified sources at low X-ray flux putrather strong constraints on the hypothetical X-ray emission from oldneutron stars accreting from the interstellar medium. Our observationsclearly rule out models which assume no dynamical heating for thispopulation and a total number of N_ns_=10^9^ neutron stars in theGalaxy. If accretion on polar caps is the dominant mode then our upperlimit may imply N_ns_=~10^8^. Among the non coronal identifications arethree white dwarfs, a Seyfert 1 active nucleus, two early type stars andone cataclysmic variable. We also report the discovery of a Me + WDclose binary system with P_orb_=~12h.
| The Tokyo PMC catalog 90-93: Catalog of positions of 6649 stars observed in 1990 through 1993 with Tokyo photoelectric meridian circle
The sixth annual catalog of the Tokyo Photoelectric Meridian Circle(PMC) is presented for 6649 stars which were observed at least two timesin January 1990 through March 1993. The mean positions of the starsobserved are given in the catalog at the corresponding mean epochs ofobservations of individual stars. The coordinates of the catalog arebased on the FK5 system, and referred to the equinox and equator ofJ2000.0. The mean local deviations of the observed positions from theFK5 catalog positions are constructed for the basic FK5 stars to comparewith those of the Tokyo PMC Catalog 89 and preliminary Hipparcos resultsof H30.
| Kinematics of Sandage-Fouts stars in three cardinal directions
V and (B - V) for 429, 442, and 427 stars are observed in the directionsof the anticenter, Cygnus, and the NGP, respectively, and DDO colors forthose stars G0 and later. The samples observed are ones for whichSandage and Fouts (1987) have published radial velocities. W, V, and Wcomponents of space velocity are derived from DDO distances withavailable proper motions. A clear correlation was found to exist betweenthe velocity dispersions and Fe/H with the dispersions decreasing asFe/H increases to about + 0.00, where V then becomes significantlynegative. The 'thick disk' component is clearly recognized, with sigma(W) approximately equal to 36 km/sec. In the 'old thin disk' and the'young thin disk', 43 percent and 42 percent of the stars have negativeV values, respectively.
| U, V, W velocity components for the old disk using radial velocities of 1295 stars in the three cardinal Galactic directions
New radial velocities are presented for 1295 stars chosen at random nearthe three cardinal Galactic directions of l = 180 deg, b = 0; l = 90deg, b = 0 deg; and b = 90 deg, giving the distribution in U, V, and W,respectively, from the radial velocities alone. The measurements weremade with the coude spectrograph of the Mount Wilson 100 in. Hookerreflector. The purpose of the program is to set limits on the densitynormalization in the solar neighborhood of the old thin disk, the oldthick disk, and the halo. Many more high-velocity stars are present inthe unbiased sample than expected from previous estimates of thenormalization. The data suggest the density ratios in the solarneighborhood to be about 90 percent, 10 percent, and about 0.5 percentfor the thin disk, thick disk, and halo populations, respectively.
| UBV photometry of stars whose positions are accurately known. III
UBV photometric observations of 417 stars at BD declination 35-49 degfrom the NPZT(74) catalog of Yasuda et al. (1982) and the AGK3R catalogof Corben (1978), obtained with the 40-cm Cassegrain reflector atKvistaberg Observatory during 1984-1985, are reported. The data arepresented in tables, and the mean errors per observation are given as0.016 mag in V, 0.011 mag in B-V, 0.012 mag in U-B for U less than 10,and 0.026 mag in U-B for U greater than 10.
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| קבוצת-כוכבים: | ברבור |
| התרוממות ימנית: | 21h30m18.05s |
| סירוב: | +47°10'19.0" |
| גודל גלוי: | 8.447 |
| מרחק: | 81.766 פארסק |
| תנועה נכונה: | -15.5 |
| תנועה נכונה: | -6 |
| B-T magnitude: | 9.059 |
| V-T magnitude: | 8.498 |
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