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Contribution to the study of composite spectra - IX. Spectroscopic orbital elements of 10 systems*
We present the results of a radial-velocity study of 10 spectroscopicbinaries with composite spectra that were observed at Observatoire deHaute-Provence with the CORAVEL instrument. Those systems, including acool, evolved, primary and a hot secondary of type B or A, were found tobe spectroscopic binaries. We computed their orbital elements for thefirst time. For three systems, the large mass function implies i~90°, with the possibility of eclipses. Mean angular separations arevery small (a<= 0.010 arcsec), which makes those systems resolvableonly with multi-pupil large interferometers.
| Spectral Classification of the Hot Components of a Large Sample of Stars with Composite Spectra, and Implication for the Absolute Magnitudes of the Cool Supergiant Components.
A sample of 135 stars with composite spectra has been observed in thenear-UV spectral region with the Aurélie spectrograph at theObservatoire de Haute-Provence. Using the spectral classifications ofthe cool components previously determined with near infrared spectra, weobtained reliable spectral types of the hot components of the samplesystems. The hot components were isolated by the subtraction methodusing MK standards as surrogates of the cool components. We also derivedthe visual magnitude differences between the components usingWillstrop's normalized stellar flux ratios. We propose a photometricmodel for each of these systems on the basis of our spectroscopic dataand the Hipparcos data. We bring to light a discrepancy for the Gsupergiant primaries between the visual absolute magnitudes deduced fromHipparcos parallaxes and those tabulated by Schmidt-Kaler for the GIbstars: we propose a scale of Mv-values for these stars incomposite systems. By way of statistics, about 75% of the hot componentsare dwarf or subgiant stars, and 25% should be giants. The distributionin spectral types is as follows: 41% of B-type components, 57% of typeA, and 2% of type F; 68% of the hot components have a spectral type inthe range B7 to A2. The distribution of the ΔMv-valuesshows a maximum near 0.75 mag.
| Visual polarization measurements in the Cepheus flare
We present polarization measurements on a stellar sample located in alarge area in Cepheus. The observations were made with the 2-m telescopeat the Pic du Midi (France), around 4350 A and with an accuracy of thepolarization degree of the order of 0.0001. At large scales, we findthat the galactic magnetic field as given by the direction of thepolarization (alignment of the dust) is, roughly speaking, parallel tothe galactic plane in the Cassiopeia cloud, with a scale size of theorder of 100 pc, while it is turned by about 90 in the Cepheus cloud. Atsmall scales, in both the Cepheus and the Cassiopeia clouds, the COcontent has little correlation with the degree of polarization.
| A preliminary compilation of DS-programme star positions
A catalog is presented of the double-star-program (DS-program) starpositions, listing right ascensions for 930 DSs and declinations for1225 DSs of the program. The positions were compiled from the observedvalues obtained between 1980 and 1987 with the meridian circles of sixUSSR observatories (the Moscow, Kazan', Kiev, Khar'kov, Odessa, andTashkent Observatories) and the Belgrade Observatory. The measurementsand the treatment of the observational material were performed using therelative method, and the FK-4 system stars were used as reference stars.
| Visual multiples. VIII - 1000 MK types
A total of 1000 new classifications are given for stars brighter than B= 8.0 mag in the Aitken double star catalog. The classificationssupplement 865 classifications obtained in 1981 and 1984. Among thenewly discovered stars are 12 new Ap stars, eight Lambda Bootis stars,one Ba II star, and 60 Am stars. A detailed list of the newclassifications is given.
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