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Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Supplementary southern standards for UBV(RI)c photometry
We present UBV(RI)c photometry for 80 southern red and blue stars foruse as additional standards. The data are tied to the Johnson UBV andCousins (RI)c systems and extend the range of the available stars forcolor equation determination, especially in (U-B) for blue stars and(V-R) and (V-I) for red stars. Comparisons with published data are madeand particularly good agreement is found with Bessell for the red(Gliese) stars.
| Radial velocities in the region of CR 135
We give mean radial velocities of 63 stars belonging to a 2 deg x 2 degfield centered on Cr 135 in Puppis, where only a few radial velocitiesof bright stars are at present known. We obtained relative radialvelocities which have been fitted to the IAU standard system of radialvelocities by means of some stars with already known radial velocities.We present the histogram of the errors and a general radial-velocitydiagram, as well as a discussion about the possible variable stars andthe cluster membership. The histogram of the errors shows a maximumbetween E = 2.0 and E = 3.0 km/s for an average of six plates per star.The general radial-velocity diagram has a peak at about 20 km/srepresenting principally the field stars. The radial velocities of thefive brightest stars and those of stars previously selected as probablecluster members lie in this peak. On the basis of photometric data, thephysical reality of Cr 135 has been contested. Our results show that if,nevertheless, the cluster exists, its radial velocity is very close tothat of field stars. Cr 135 could also belong to an old association orto a stellar group.
| Broad-band photometry of selected southern ultraviolet-bright stars.
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| A survey of ultraviolet objects
An all-sky survey of ultraviolet objects is presented together with astatistical analysis that leads to the conclusion that there is asignificantly higher population of hot subdwarfs lying below themain-sequence than hitherto thought. The distribution of all ultravioletobjects, main sequence ultraviolet objects, and MK unclassifiedultraviolet objects are shown in galactic coordinates, and the absolutemagnitudes and color-color diagrams for these groups are presented.Scale heights are derived, giving values similar to planetary nebulaefor the hottest groups.
| Wide- and narrow-band photometry of stars in a field around Collinder 135
A field of about 10,000 square arcmin around the cluster Cr 135 isstudied using UBV, H-alpha, and H-beta photometries. The photometricdata do not favor the existence of Cr 135 as a real open cluster. Onlyeight B-type stars lie on a very well-defined main sequence in the UBVphotometric diagrams. These eight stars - which are shown not to begravitationally bound - are located at a mean distance of 630 pc with aforeground color excess amounting to E(B-V) equals 0.06 magnitudes.These stars, together with most of the B stars in the region, can beconsidered probable members of the large, old, Pup-Can association.
| Spectral classification from the ultraviolet line features of S2/68 spectra. V - Supplement series
The paper presents the ultraviolet classification of more than 450 B-Aand F spectra obtained with the sky survey telescope mounted on the TD1satellite. Concerning abnormal objects, attention is given to the Bestars, the binary stars, the helium weak stars, and the lambda Booobjects. With regard to Be stars, it is concluded that the 1930 Awavelength feature is linked to the existence of either shell structuresor Fe II emission lines in the visual spectral range. In addition, it issuggested that stellar spectra at wavelengths of 1410, 1610-20 and 2400A are equivalent to the He-weak group in the classical range.
| Spectral types for early-type stars observed by SKYLAB
MK spectral types are presented for 246 early-type stars observed withthe S-019 ultraviolet stellar astronomy experiment on Skylab. K-linetypes are also given where applicable, and various peculiar stars areidentified. The peculiar stars include five silicon stars, a shell star,a helium-rich star, a silicon-strontium star, a chromium-europium star,and two marginal metallic-line stars.
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