A photometric-spectroscopic analysis and the evolutionary status of the Algol-type binary U Coronae Borealis
The prime purposes of this study are to obtain reliable orbitalparameters for the Algol-type binary U Coronae Borealis (U CrB) and toexplain the evolutionary status of this system. All observations of theprimary star's radial velocity are consistent with the valueK1= 58.6 +/- 2.0 km s-1. Measurements of theradial velocity of the secondary component give K2=185.2+/-5.0 km s-1. Using the photometrically determined inclinationof 78.7 +/- 0.3, the masses of the two stars are therefore deduced to be4.74 +/- 0.28 and 1.46 +/- 0.06 Msolar for the primary andsecondary components, respectively. Using all available observations, wediscuss the origin and evolution of the close binary system U CrB. Wederive the restrictions concerning masses and period from a generalnetwork of calculations of medium mass close binary evolution. Detailedmodels are calculated within the derived ranges, giving the most likelyinitial system parameters as and Pi= 1.4 d. It turns out thatthe interactive evolution up to the present stage has beennon-conservative. During its evolution, U CrB has lost about 14 per centof its initial total mass (ΔM~ 1 Msolar) and around 18per cent of its initial total angular momentum. We also examine thepossibility of probing dynamo action in the mass-losing component of UCrB. We point out that, in order to maintain the evolution of U CrB inits later stages, which is presumably driven by stellar `magneticbraking', an efficient mechanism for producing large-scale surfacemagnetic fields in the donor star is required. We suggest that observedX-ray activity in U CrB may be a good indicator of its evolutionarystatus and the internal structure of the mass-losing component.
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Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
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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.
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UBV Photoelectric Photometry Catalogue (1986). III Errors and Problems on DM and HD Stars
Not Available
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Comparsion Stars which Turn Out to be Variable
Not Available
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Johnson BVR Magnitudes for Selected Comparison Stars
Not Available
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Vibrating Neutron Star
Not Available
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Variability of HD 137147 (comparsion Star of U CrB) and "a Flare" of HD 137050
Not Available
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Curva di luce ed elementi del sistema UCrB
Not Available
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Photoelectric Observations of U Coronae Borealis.
Abstract image available at:http://adsabs.harvard.edu/abs/1958ApJ...127..351W
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INHABITED SKY
