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Search for Photometric Eclipses of the Runaway Star 9 Sge
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| Photoelectric Vilnius Photometry of Hipparcos Turn-Off Region Stars
Seven-color photometry in the Vilnius system and photometricclassification in terms of spectral type, absolute magnitude andmetallicity are presented for 145 Hipparcos stars of the turn-offregion, most of which have parallaxes determined to an accuracy of atleast 15%. The stars selected for the observing program included thoseidentified kinematically as intermediate between the thin disk and halo,plus a number of weak-lined stars discovered previously from objectiveprism surveys. The metallicity distribution we find for a kinematicallydefined sample of possible members of the thick disk has a meanabundance [Fe/H]= --0.3 dex and a dispersion of 0.3 dex. Our data seemto suggest a large age for this intermediate population.
| Mesures de vitesses radiales. VII. Accompagnement AU sol DU programme d'observation DU satellite Hipparcos. Radial velocities. VII. Ground based measurements for Hipparcos.
We publish 734 radial velocities of stars distributed in 28 fields of4x4deg. We continue the PPO series (Fehrenbach et al. 1987; Duflot etal. 1990 and 1992), using the Fehrenbach objective prism method.
| An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
| The possible nature of the periodic variability of the radial velocities and light of the runaway Of star HD 188001 (9 Sge)
Results of WBVR photometric and spectroscopic observations of the Ofstar 9 Sge are presented. A variability of radial velocities (about 9km/s) and of light (about 0.06 m) with a period of 32.514 d wasdiscovered. Joint analysis of the radial velocity curve and WBVR lightcurves was carried out. A faint (less than 0.01) variability of theDelta(V-R) color index with the period found is suspected. It issuggested that 9 Sge is an eclipsed binary system with a low-mass (1.5solar mass) companion moving in an eccentric (e of about 0.6) orbit.
| Interstellar reddening in the direction of the globular cluster M71
Interstellar reddening as a function of distance in the direction of theglobular cluster M71 is determined by two-dimensional quantification of96 arcmin foreground stars observed in the Vilnius photometric system.In concentric areas with the radii 30 arcmin and 10 arcmin centered onthe cluster, the reddening shows the same variations, ranging fromE(B-V) = 0.12 to 0.32. The cluster stars are likely to have variableextinction too, at least in the outer regions of the cluster.
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