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The ROSAT all-sky survey catalogue of optically bright main-sequence stars and subgiant stars
We present X-ray data for all main-sequence and subgiant stars ofspectral types A, F, G, and K and luminosity classes IV and V listed inthe Bright Star Catalogue that have been detected as X-ray sources inthe ROSAT all-sky survey; several stars without luminosity class arealso included. The catalogue contains 980 entries yielding an averagedetection rate of 32 percent. In addition to count rates, sourcedetection parameters, hardness ratios, and X-ray fluxes we also listX-ray luminosities derived from Hipparcos parallaxes. The catalogue isalso available in electronic form via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Evolved GK stars near the Sun. 2: The young disk population
From a sample of nearly 2000 GK giants a group of young disk stars withwell determined space motions has been selected. The zero point of theluminosity calibrations, both from the ultraviolet flux (modifiedStroemgren system) and that in the region of 4200 to 4900 A (DDOsystem), show a discontinuity of about a half magnitude at the border ofthe young disk and old disk domains. The population separation is basedon the space velocity components, which are also an age discriminant,with the population interface near 2 x 109 yr, based onmodels with convective overshoot at the core. This age corresponds togiant masses near 1.7 solar mass, near the critical mass separating theyoung stars that do not burn helium in degenerate cores from older starsthat do. Ten percent of both populations show CN anomalies in that thederived value of P(Fe/H) from CN (Cm) and fromFe(M1) differ by more than 0.1 dex and the weak and strong CNstars occur equally in the old disk but the weak CN stars predominate inthe young disk. Peculiar stars, where flux distortions affect theluminosity calibrations, are of the CH+(Ba II) and CH-(weak G band)variety and represent less than 1% of the stars in both populations. Theyoung disk giants are restricted to ages greater than about109 yr, because younger stars are bright giants orsupergiants (luminosity class 2 or 1), and younger than about 2 x109 yr, because the old disk-young disk boundary occurs near1.7 solar mass. The distribution of heavy element abundances, P(Fe/H),for young disk giants is both more limited in range (+/- 0.4 dex) and isskewed toward higher abundances, compared with the nearly normaldistribution for old disk giants. The distribution of (U,V) velocityvectors gives (U,V,W) and their dispersions = (+17.6 +/- 18.4, -14.8 +/-8.4, -6.9 +/- 13.0) and (+3.6 +/- 38.4, -20.7 +/- 27.5, -6.7 +/-17.3)km/s for young and old disk giants, respectively.
| Large and Kinematically Unbiased Samples of G- and K-Type Stars. III. Evolved Young Disk Stars in the Bright Star Sample
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1989PASP..101...54E&db_key=AST
| Large and kinematically unbiased samples of G- and K-type stars. II - Observations of evolved stars in the Bright Star sample. III - Evolved young disk stars in the Bright Star sample
Four color and RI observations were obtained for a large sample ofG-type and K-type stars in the Bright Star Catalogue. Data are firstpresented for 110 evolved stars. Photometry of evolved young diskpopulation stars have then been calibrated for luminosity, reddening,and metallicity on the basis of results for members of the Hyades andSirius superclusters. New DDO results are given for 120 stars.
| The Einstein Galactic plane survey. II - Optical observations of Northern Hemisphere X-ray sources
Spectroscopic and photometric observations of 67 Northern-HemisphereX-ray sources from the Einstein Galactic Plane Survey (Hertz andGrindlay, 1984) (HG) are reported. Data obtained at 450-700 nm using the1.5-m telescope at Whipple Observatory and the MMT are combined withpublished observational data in tables, and the identificationalgorithms described by HG are applied. Identifications with opticalobjects are proposed for 45 sources, and it is inferred that most of theothers are noncoronal extragalactic objects. None of the objects can beassigned to the class of low-luminosity accretion sources proposed byHG.
| The Einstein galactic plane survey - Statistical analysis of the complete X-ray sample
A flux-limited survey of the galactic plane using the Einstein ImagingProportional Counter has been conducted, discovering 71 point-like X-raysources exceeding a five sigma threshold. These sources arestatistically analyzed, and it is concluded that the number-fluxrelation for low-flux galactic plane X-ray sources has a slope of -1.10,significantly steeper than the about -0.5 found for bright sources byUhuru and Ariel V. The sample contains about 46 percent coronal sources,about 31 percent extragalactic sources, and about 23 percent galacticaccretion sources. Thus, about 16 new galactic accretion sources havebeen discovered. The approximate number density of such sources isconsistent with their being cataclysmic variables and other accretingwhite dwarfs. Faint galactic plane sources are significantlyconcentrated toward the galactic bulge, and those near the bulge exhibita flatter number-flux relation than those at higher galactic latitudesand longitudes. This indicates a different source population with a lessisotropic distribution.
| Photoelectric radial velocities. V. 69 southern HR stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972MNRAS.155..449G&db_key=AST
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| Сазвежђа: | Једнорог |
| Ректацензија: | 06h52m22.90s |
| Deклинација: | -05°18'58.0" |
| Apparent магнитуда: | 6.3 |
| Даљина: | 146.199 parsecs |
| Proper motion RA: | -20 |
| Proper motion Dec: | -14.8 |
| B-T magnitude: | 7.517 |
| V-T magnitude: | 6.39 |
Каталог и designations:
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