Apsidal motion in southern eccentric eclipsing binaries: V539 Ara, GG Lup, V526 Sgr and AO Vel
Several new times of minimum light have been observed photoelectricalyfor the early-type double-lined eccentric eclipsing binaries V539 Ara (P= 3.2 deg, e = 0.05), GG Lup (1.9 deg, 0.15), V526 Sgr (1.9 deg, 0.22)and AO Vel (1.6 deg, 0.07). The O{-}C diagrams are analysed using allreliable timings found in the literature and improved values for theelements of the apsidal motion are computed. We find more precise,relatively short periods of apsidal motion of about 162, 102, 155 and 54years for V539 Ara, GG Lup, V526 Sgr and AO Vel, respectively. Thecorresponding internal structure constants, log k_2, are then found tobe 2.33, 2.16, 2.36 and 2.24 under the assumption that the componentstars rotate pseudosynchronously. The relativistic effects arenegligible, being about 6 7% of the total apsidal motion rate in allsystems. Using the light-time effect solution, for V539 Ara we havefound a third component orbiting with a period of about 42 years, for AOVel we confirmed the third body with an orbital period of 33 years.
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Research Note Hipparcos photometry: The least variable stars
The data known as the Hipparcos Photometry obtained with the Hipparcossatellite have been investigated to find those stars which are leastvariable. Such stars are excellent candidates to serve as standards forphotometric systems. Their spectral types suggest in which parts of theHR diagrams stars are most constant. In some cases these values stronglyindicate that previous ground based studies claiming photometricvariability are incorrect or that the level of stellar activity haschanged. Table 2 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/367/297
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Fundamental Stellar Parameters of gamma 2 Velorum from HIPPARCOS Data
We report parallax measurements by the HIPPARCOS satellite of gamma 2Velorum and a few related objects. The distance of gamma 2 Vel is d =258 ^{+41}_{-31} pc, significantly smaller than the commonly adoptedvalue to Vela OB2. For zeta Puppis d = 429 ^{+120}_{-77} pc is inagreement with the canonical distance. The total mass of gamma 2 Velderived from its parallax, the angular size of the semimajor axis asmeasured with intensity interferometry, and the period are M(W-R + O) =29.5 +/- 15.9 Msolar. This result favors the orbital solution of Pike etal. over that of Moffat et al. The stellar parameters for the O starcompanion derived from line-blanketed non-LTE atmosphere models are Teff= 34,000 +/- 1500 K, log L/Lsolar = 5.3 +/- 0.15, from which anevolutionary mass of M = 29 +/- 4 Msolar and an age of 4.0^{+0.8}_{-0.5} Myr is obtained from single-star evolutionary models.With non-LTE model calculations including He and C, we derive aluminosity log L/Lsolar ~ 4.7 +/- 0.2 for the W-R star. Themass-luminosity relation of hydrogen-free W-R stars implies a mass ofMW-R ~ 5 +/- 1.5 Msolar. From our data we favor an age of about 10 Myrfor the bulk of the Vela OB2 stars. Evolutionary scenarios for zeta Pupand gamma 2 Vel are discussed in the light of our results.
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The ROSAT all-sky survey catalogue of optically bright OB-type stars.
For the detailed statistical analysis of the X-ray emission of hot starswe selected all stars of spectral type O and B listed in the Yale BrightStar Catalogue and searched for them in the ROSAT All-Sky Survey. Inthis paper we describe the selection and preparation of the data andpresent a compilation of the derived X-ray data for a complete sample ofbright OB stars.
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Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
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Four-Colour Photometry of Eclipsing Binaries - Part Twenty-Seven - a Photometric Analysis of the Possible Ap-System Ao-Velorum
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995A&AS..109..425C&db_key=AST
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The interstellar medium in the solar vicinity - Analysis of the distribution of colour excesses E(b-y) towards 10 selected areas
The distribution of color excesses, E(b-y), and the distances to about680 stars (mainly of spectral types A and F belonging to ten Kapteyn'sselected areas) are analyzed in order to investigate some of thereddening properties of the interstellar obscuring matter in the solarvicinity. Particular attention among these areas is given to sevenregions with line-of-sight toward the Gum Nebula and the interfacebetween the Local and Loop I Bubbles. It is shown that the Gum Nebulaand the interface between the Local Bubble and the Loop I Bubble arelikely to be the main sources of the diffuse absorbing material in thedirection of the seven low-galactic-latitude areas analyzed.
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Empirical temperature calibrations for early-type stars
Three temperature calibrations of suitable photometric quantities havebeen derived for O and B stars. A sample of 120 stars with reliableT(eff.) determinations has been used for establishing each calibration.The different calibrations have been critically discussed and compared.Temperature determinations for 1009 program stars have been obtainedwith an accuracy of the order of 10 percent.
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A catalog of ultraviolet interstellar extinction excesses for 1415 stars
Ultraviolet interstellar extinction excesses are presented for 1415stars with spectral types B7 and earlier. The excesses with respect to Vare derived from Astronomical Netherlands Satellite (ANS) 5-channel UVphotometry at central wavelengths of approximately 1550, 1800, 2500, and3300 A. A measure of the excess extinction in the 2200-A extinction bumpis also given. The data are valuable for investigating the systematicsof peculiar interstellar extinction and for studying the character of UVinterstellar extinction in the general direction of stars for which theextinction-curve shape is unknown.
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The local system of early type stars - Spatial extent and kinematics
Published uvby and H-beta photometric data and proper motions arecompiled and analyzed to characterize the structure and kinematics ofthe bright early-type O-A0 stars in the solar vicinity, with a focus onthe Gould belt. The selection and calibration techniques are explained,and the data are presented in extensive tables and graphs and discussedin detail. The Gould belt stars of age less than 20 Myr are shown togive belt inclination 19 deg to the Galactic plane and node-lineorientation in the direction of Galactic rotation, while the symmetricaldistribution about the Galactic plane and kinematic properties (purecircular differential rotation) of the belt stars over 60 Myr oldresemble those of fainter nonbelt stars of all ages. The unresolveddiscrepancy between the expansion observed in the youngest nearby starsand the predictions of simple models of expansion from a point isattributed to the inhomogeneous distribution of interstellar matter.
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The VELA star cloud. I - NGC 2547, TR 10, the Gamma Velorum system, and bright stars
The first results of an intermediate-band, large-scale photometricsurvey of the Vela star cloud are discussed. Attention is given to theluminosity and reddening, as well as the apparent or proper motions ofall the CPD stars near NGC 2547, the brightest stars in Trumpler 10, arandom selection of stars in the region of Gamma Velorum, and the HRstars. The similarity of the Alpha Persei cluster with the clusters inthe Vela sheet is shown, and it is found that the Vela sheet, at leastover the region surveyed, is nearly perpendicular to the line of sight.The probability is demonstrated that a thin sheet of coeval (2.5 x 10 tothe 7th yr) stars, some 425 pc distant and with a similar metalabundance, lies in front of a dense dark cloud.
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Space velocities and ages of nearby early-type stars
Photometric distances and space velocities have been calculated for 458B0-A0 stars with apparent magnitudes not exceeding 6.5. UsingStromgren's ubvy-beta photometry the effective temperature and theposition in bolometric magnitude over the zero-age main sequence of thestars were derived. These quantities were used to obtain age and massfor 423 of the stars by interpolation in the models of stellar evolutionfor the chemical composition (X Z) = (0.7, 0.03). A relation forderiving interstellar reddening for normal stars in the intermediategroup is given.
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Structure and age of the local association /Pleiades group/
Intermediate-band indices are used to derive luminosities for some 500early-type stars with well-determined proper motions and radialvelocities. Space motion vectors and galactic coordinates are computedfor the stars considered. It is found that the local association membersare mainly concentrated in the Sco-Cen region in the Southern Hemisphereand the Cas-Tau region in the north.
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The VELA pulsar : member of an association ?
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973ApJ...180..907S&db_key=AST
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Absolute ultraviolet spectrophotometry from the TD1 satellite. II. Observations of B star continua shortward of 2500 angstrom.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&A....29..211V&db_key=AST
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New kinematical data for bright southern OB-stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....5..129L&db_key=AST
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The GUM Nebula: Fossil STRÖMGREN Sphere of the VELA X Supernova
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJ...163L..99B&db_key=AST
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Four-color and H-beta photometry for bright B-type stars in the southern hemisphere.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..621C&db_key=AST
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MK Spectral Types for Bright Southern OB Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...157..313H&db_key=AST
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A Survey of Southern Be Stars
Not Available
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Photoelectric determination of the colors of 286 stars south of declination -15 degrees.
Not Available
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INHABITED SKY
