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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
| Absolute parameters for binary systems. II. The late-type system ZZ Ursae Majoris
New light curves of the late-type binary system ZZ UMa were obtainedduring a uvby and H beta monitoring program on low mass eclipsingbinaries, that has been carried out in a six year photometricobservational program \cite[(Clement et al. 1997a]{cle97a}, Paper I).The main goal of the program is to obtain accurate absolute parametersfor stars in the low and intermediate mass range, in order to improvethe Mass-Luminosity Relationship (MLR) at the end of the main sequence.This paper presents a complete analysis of the first uvby beta lightcurves of the late-type detached eclipsing binary ZZ UMa. This binarysystem has been observed during eight campaigns at the Calar AltoObservatory (Almeria, Spain). The activity wave superposed on theeclipse light curve has been estimated, by using a new iterative fittingmethod \cite[(Clement et al. 1997b]{cle97b}, Paper II). Theinterpretation of the wave suggests the existence of two active zones ofsimilar intensity, separated by areas at higher temperature. Once theactivity wave was subtracted from the light curves, we adjusted thegeometrical solution using the EBOP code. Radiative parameters for bothstars have been derived from the light curves. Combining the massesdeduced from the radial velocity curves \cite[(Popper 1995)]{pop95},with the calculated geometrical and radiative values, we computed theabsolute parameters for both components. We can conclude that the systemis composed of two main sequence G-type stars with masses, radii andchemical composition similar to the Sun.
| 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.
| Reddening and polarimetric studies toward IC 1805
Near IR and (V-I) photometry is presented for probable members in thecluster IC 1805. From a color-difference analysis, the ratio of total toselective absorption R(v), is found to be uniform across the cluster andcalculated to be 3.1 + or - 0.1. Assuming a distance modulus to theHyades of 3.3 mag, a distance to IC 1805 of 2.4 + or - 0.1 kpc isobtained by employing several ZAMS fitting calibrations. The resultantC-M diagram contains both MS and ZAMS B type stars, implying thatmassive star formation in the cluster was a continuous process.Photometric and spectroscopic data for foreground stars toward thecluster indicate that at least two-thirds of the reddening of thecluster is due to the general interstellar material (IM). Multicolorpolarimetric measurements are also presented for 24 probable clustermembers and for 49 foreground objects. It is concluded that the visualpolarization across the local galactic spiral arm is 5 percent, and thatthe size distribution of grains within IC 1805 is similar to that in theforeground region. After correcting for foreground IM, the residualintracluster polarization indicates that the cluster may be located neara Parker (1966) magnetic well with field strength similar to that of theforeground IM.
| Catalog of BV magnitudes and spectral classes of 6000 stars
The present catalog, compiled at the Abastumani Observatory, contains BVmagnitudes and spectral classes of about 6000 stars up to V(lim) = 13.0min five circular areas of 18 sq deg located near the salactic-equatorplane. The catalog is intended for star-statistics studies ofstar-formation regions.
| A small cluster near IC 1805
A small group of stars near the edge of the IC 1805 (W4) H II region hasbeen studied partly for evidence of a physical association with thenebula. The two brightest stars have pronounced shell spectra andevidence of hydrogen emission lines. A B8 V star with weak Hg lines, twonormal B stars, and four fainter stars in the field were studied. UBV,H-beta, and Stromgren four-color photometry of nine stars yield areddening of E(B - V) = 0.54 m, a distance of 485 pc, and an age of notgreater than 10 to the 7.4th yr. The two shell stars and two normal Bstars fall on the ZAMS but the Hg star is either a multiple orforeground star and the three fainter stars are probably backgroundstars. The group is not associated with the more distant (2200 pc) IC1805.
| A spectrophotometric survey of stars along the Milky Way. IV
In the present paper a catalogue of spectrophotometric quantities,spectral types, monochromatic magnitudes and colour equivalents is givenfor all stars brighter than the magnitude m4400 = 10.5 in aregion of the Milky Way in Perseus. No absorption is found for starscloser than about r = 100 pc. The absorbing clouds are situated atdistances closer than 1 kpc and at about 2.5 kpc in the local arm andthe Perseus arm, respectively. The space between the two arms is freefrom absorption. It is also concluded that the Perseus arm continuesbeyond l = 140 deg, containing not only hydrogen gas but also dust to atleast l = 150 deg), while the content of OB stars decreases abruptly atl = 140 deg.
| The space density of A stars in a region in Cas.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..107M&db_key=AST
| Photographic UBV photometry of ten open star clusters in a galactic field at 1 = 135°
Abstract image available at:http://adsabs.harvard.edu/abs/1973A&AS...11....3M
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