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Studies of late-type binaries. III - A spectroscopic study of V566 Ophiuchi
From a new spectroscopic orbit of the A-type W UMa binary V566 Oph,based on Reticon observations, various parameters are found. The newmass ratio is sufficiently different from other determinations as toinvalidate all recent light-curve solutions. The velocity measuresthemselves are based on fitting theoretical profiles, generated by aphysical model of the binary, to the observed cross-correlationfunction. Such profiles match this function very well, much better infact than Gaussian profiles which are generally used. The improvement issuch that mass ratios based on Gaussian measures should be reexaminedand compared with new measures made with synthetic profiles. From ananalysis of the mean reddening in the field, a mean spectral type of F2is found for V566 Oph, corresponding to a mean effective temperature of6700 K.
| Determinations of the Parallaxes of Barnard's Star BD-70DEG68 and BD-4DEG4157
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| On the distribution of interstellar matter around the sun
Available data on interstellar line or EUV continuum absorptionattributable to the local (r equal to or less than 100 pc) interstellarmedium are presented and analyzed as a whole for clues leading to adeeper understanding of the spatial distribution and physical propertiesof this material. By using these data in conjunction with upper limitsprovided by polarization and color excess surveys and relatingeverything to the neutral-hydrogen column density, it is shown that thedata are consistent with a simple model that assumes the relativelypervasive presence of a tenuous (nH = 0.07 per cu cm), possibly warm (T= 1,000-10,000 K) gas extending uniformly out to considerable distancesfrom the sun in most directions. The only region manifestly clear ofthis material lies in the 200 deg to 270 deg galactic longitude range inboth high and low latitudes. Strong density discontinuities are clearlyobservable at r approximately 100-150 pc in the general directions ofthe Sco-Cen and Per associations and a weaker discontinuity much closerto the sun running along a ridge oriented parallel to the lineconnecting their centers. Beyond these fronts, the space density ofinterstellar matter must fall to very low values that extend out toseveral hundred parsecs or so from the sun. These results are notincompatible with H I, 21-cm, and soft X-ray all-sky surveys. Theimplication of these findings for the theory of the interstellar mediumand EUV visibility is briefly discussed.
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