The Projected Rotational Velocity Distribution of a Sample of OB stars from a Calibration Based on Synthetic He I Lines
We derive projected rotational velocities (v sin i) for a sample of 156Galactic OB star members of 35 clusters, H II regions, and associations.The He I lines at 4026, 4388, and 4471 Å were analyzed in order todefine a calibration of the synthetic He I full widths at half-maximum(FWHMs) versus stellar v sin i. A grid of synthetic spectra of He I lineprofiles was calculated in non-LTE using an extensive helium model atomand updated atomic data. The v sin i values for all stars were derivedusing the He I FWHM calibrations, but also, for those target stars withrelatively sharp lines, v sin i values were obtained from best-fitsynthetic spectra of up to 40 lines of C II, N II, O II, Al III, Mg II,Si III, and S III. This calibration is a useful and efficient tool forestimating the projected rotational velocities of O9-B5 main-sequencestars. The distribution of v sin i for an unbiased sample of early Bstars in the unbound association Cep OB2 is consistent with thedistribution reported elsewhere for other unbound associations.
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Evolution of interacting binaries with a B type primary at birth
We revisited the analytical expression for the mass ratio distributionfor non-evolved binaries with a B type primary. Selection effectsgoverning the observations were taken into account in order to comparetheory with observations. Theory was optimized so as to fit best withthe observed q-distribution of SB1s and SB2s. The accuracy of thistheoretical mass ratio distribution function is severely hindered by theuncertainties on the observations. We present a library of evolutionarycomputations for binaries with a B type primary at birth. Some liberalcomputations including loss of mass and angular momentum during binaryevolution are added to an extensive grid of conservative calculations.Our computations are compared statistically to the observeddistributions of orbital periods and mass ratios of Algols. ConservativeRoche Lobe Over Flow (RLOF) reproduces the observed distribution oforbital periods but fails to explain the observed mass ratios in therange q in [0.4-1]. In order to obtain a better fit the binaries have tolose a significant amount of matter, without losing much angularmomentum.
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New Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate
The birthrate of stars of masses >=10 Msolar is estimatedfrom a sample of just over 400 O3-B2 dwarfs within 1.5 kpc of the Sunand the result extrapolated to estimate the Galactic supernova ratecontributed by such stars. The solar-neighborhood Galactic-plane massivestar birthrate is estimated at ~176 stars kpc-3Myr-1. On the basis of a model in which the Galactic stellardensity distribution comprises a ``disk+central hole'' like that of thedust infrared emission (as proposed by Drimmel and Spergel), theGalactic supernova rate is estimated at probably not less than ~1 normore than ~2 per century and the number of O3-B2 dwarfs within the solarcircle at ~200,000.
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SB9: The ninth catalogue of spectroscopic binary orbits
The Ninth Catalogue of Spectroscopic Binary Orbits(http://sb9.astro.ulb.ac.be) continues the series of compilations ofspectroscopic orbits carried out over the past 35 years by Batten andcollaborators. As of 2004 May 1st, the new Catalogue holds orbits for2386 systems. Some essential differences between this catalogue and itspredecessors are outlined and three straightforward applications arepresented: (1) completeness assessment: period distribution of SB1s andSB2s; (2) shortest periods across the H-R diagram; (3)period-eccentricity relation.
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Catalog of Galactic OB Stars
An all-sky catalog of Galactic OB stars has been created by extendingthe Case-Hamburg Galactic plane luminous-stars surveys to include 5500additional objects drawn from the literature. This work brings the totalnumber of known or reasonably suspected OB stars to over 16,000.Companion databases of UBVβ photometry and MK classifications forthese objects include nearly 30,000 and 20,000 entries, respectively.
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Non-LTE abundances of magnesium, aluminum and sulfur in OB stars near the solar circle
Non-LTE abundances of magnesium, aluminum and sulfur are derived for asample of 23 low-v sin i stars belonging to six northern OBassociations of the Galactic disk within 1 kpc of the Sun. Theabundances are obtained from the fitting of synthetic line profiles tohigh resolution spectra. A comparison of our results with HII regionabundances indicates good agreement for sulfur while the cepheidabundances are higher. The derived abundances of Mg show good overlapwith the cepheid results. The aluminum abundances for OB stars aresignificantly below the cepheid values. But, the OB star results show adependence with effective temperature and need further investigation.The high Al abundances in the cepheids could be the result of mixing. Adiscussion of the oxygen abundance in objects near the solar circlesuggests that the current mean galactic oxygen abundance in this regionis 8.6-8.7 and in agreement with the recently revised oxygen abundancein the solar photosphere. Meaningful comparisons of the absolute S, Aland Mg abundances in OB stars with the Sun must await a reinvestigationof these elements with 3D hydrodynamical model atmospheres for the Sun.No abundance gradients are found within the limited range ingalactocentric distances in the present study. Such variations would beexpected only if there were large metallicity gradients in the disk.
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The total-to-selective extinction ratio determined from near IR photometry of OB stars
The paper presents an extensive list of the total to selectiveextinction ratios R calculated from the infrared magnitudes of 597 O andB stars using the extrapolation method. The IR magnitudes of these starswere taken from the literature. The IR colour excesses are determinedwith the aid of "artificial standards" - Wegner (1994). The individualand mean values of total to selective extinction ratios R differ in mostcases from the average value R=3.10 +/-0.05 - Wegner (1993) in differentOB associations. The relation between total to selective extinctionratios R determined in this paper and those calculated using the "methodof variable extinction" and the Cardelli et al. (1989) formulae isdiscussed. The R values presented in this paper can be used to determineindividual absolute magnitudes of reddened OB stars with knowntrigonometric parallaxes.
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Photometric Studies of CW Cephei
Three-filter observations of the hot, detached close binary CW Cepheiare used as the basis for light curves dating to the mid-1980s. Theephemeris of apsidal rotation is improved as a result of a lengthiertime base. The light-curve synthesis converges to essentially the sameorbital and stellar parameters that have been accepted for almost 40years. For the first time, emphasis is given to a new type ofcomplication confusing the apsidal rotation behavior, and it is shownthat this complication is photometric and not dynamical. In addition, wefind that the light curve is itself beset by substantial complications,which may be associated with the rather feeble stellar winds.
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Atlas of Interstellar Extinction Curves of OB Stars Covering the Whole Available Wavelength Range
The paper presents a collection of 436 extinction curves covering thewhole available range of wavelengths from satellite UV to near-IR. Thedata were taken from the ANS photometric catalogue and from thecompilations of IR photometric measurements. The data curves have beenobtained with the aid of ``artificial standards": Papaj et al. (1993)and Wegner (1994, 1995). The visual magnitudes and spectralclassifications of O and B type stars with EB-V>= 0.05were taken from the SIMBAD database. The curves are given in the form ofplots and tables E{lambda - V} / EB-V versus1/λ. The observed variety of extinction laws among slightlyreddened stars is apparently due to the various physical parameters ofinterstellar clouds.
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Chemical Abundances of OB Stars in Five OB Associations
We present LTE abundances of magnesium, aluminum, sulfur, and iron andnon-LTE abundances of carbon, nitrogen, oxygen, and silicon for a sampleof 15 slowly rotating B stars belonging to five OB associations: CygOB3, Cyg OB7, Lac OB1, Vul OB1, and Cep OB3. These OB associations lieon the Galactic plane and are situated within 3 kpc of the Sun. Of theeight elements sampled, non-LTE abundances for C, N, O, and Si, as wellas LTE abundances for Al and Fe, generally show subsolar abundances,with typical underabundances of ~0.2-0.4 dex. The LTE abundances for Mgand S tend to fall closer to solar values in the five associations.Whether the somewhat larger abundances derived for Mg and S, relative tothe other six elements studied, are significantly different will requirefurther work, while the modest, but persistent, underabundances(relative to solar) found for the other elements confirm a number ofprevious studies of young disk OB stars lying relatively near to theSun. The five associations studied here do not span a significant rangeof Galactocentric distances; however, their derived abundances agreewith what would be expected based upon previous studies that have mappedabundance versus Galactocentric distance and measured abundancegradients in the Milky Way disk.
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HD 218179: a New Long Period Bright EB in Cepheus
Not Available
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Polarimetric studies of the closest of the binaries with the Wolf-Rayet component CQ Cep (II)
Results are presented of measurements of linear polarization of CQ Cepmade with the telescope "Zeiss-1000" of SAO RAS in August 1998 and inJune, September 1999. The polarization curves plotted from theobservations of these two years are in good agreement with each otherand with the curve of CQ Cep of 1984 (Drissen et al., 1986). The resultsof the Fourier analysis made only for polarization observations of 1998(the observations of 1999 contain considerable gaps in phases) alsoturned out close to the results obtained by Drissen and his colleagues.Since these results point to a great degree of concentration of thescattered matter to the orbital plane of the system and to a high degreeof its symmetry about this plane, it can then be suggested that in 1984and 1998 (as well as in 1999) a relatively quiescent state of CQ Cep wasobserved. This state, in which the system is likely to have been for thegreater part of time, is characterized by polarization curve with a highamplitude of variations (ΔP ≍ 0.8%) and an average level P≍ 5%. It follows from the said above that the averaged results ofthe analysis of polarization curves of CQ Cep of 1984 and 1998 mustyield reliable parameters of the system orbit (ipolar =80°±2°, Ω = -24°±5°) andcharacterize well the "quiescent" state of its common envelope(τ0G = 0.44×10-3, &tau0H= 3.65×10-3, H/G = 8.7, Δu =4.8×10-3 and Ap =3.75×10-3).
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Stars with ISM Polarization Observed with HPOL
Polarization data are given for stars whose polarizations are mostlyinterstellar which were observed for various programs with theUniversity of Wisconsin spectropolarimeter (HPOL) during 1989-1994.
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UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
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Photoelectric Photometry of Herbig Ae/be and Related Stars in the Vilnius Photometric System
A catalog of photoelectric photometry of 62 Herbig Ae/Be and relatedstars in the Vilnius system is presented. It contains stars down to V =12 mag located mainly in the northern hemisphere and observed in theperiod of 1994--1996.
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Equivalent width of NA I and K I lines and reddening.
The profile, radial velocity and equivalent width of the interstellarlines of Na I (5890.0, 5895.9Å) and K I (7699.0Å) have beenobtained from Echelle+CCD observations at resolving powerλ/{DELTA}λ~16,500 for 32 O and early B stars sufferingfrom a reddening between E_B-V_=0.06 and 1.57. The data have been usedto search for and calibrate a relation between equivalent width andreddening. When the interstellar lines show a single and sharpcomponent, useful relations to estimate reddening from equivalent widthshave been derived. The relation for Na I is most sensitive in the range0.0<=E_B-V_<=0.4, and the one for K I takes over at higherreddening. Good quality equivalent width measurements allow E_B-V_ to beestimated with an accuracy of about 0.05 mag. For multi-componentprofiles of Na I and K I lines the estimate of reddening is moreambiguous with a general scatter of 0.15mag. Close blends of multiplecomponents allow only an estimate of an upper limit to E_B-V_.
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Derivation of the Galactic rotation curve using space velocities
We present rotation curves of the Galaxy based on the space-velocitiesof 197 OB stars and 144 classical cepheids, respectively, which rangeover a galactocentric distance interval of about 6 to 12kpc. Nosignificant differences between these rotation curves and rotationcurves based solely on radial velocities assuming circular rotation arefound. We derive an angular velocity of the LSR of{OMEGA}_0_=5.5+/-0.4mas/a (OB stars) and {OMEGA}_0_=5.4+/-0.5mas/a(cepheids), which is in agreement with the IAU 1985 value of{OMEGA}_0_=5.5mas/a. If we correct for probable rotations of the FK5system, the corresponding angular velocities are {OMEGA}_0_=6.0mas/a (OBstars) and {OMEGA}_0_=6.2mas/a (cepheids). These values agree betterwith the value of {OMEGA}_0_=6.4mas/a derived from the VLA measurementof the proper motion of SgrA^*^.
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Times of Minima of Five Eclipsing Binaries
Not Available
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An IRAS/ISSA Survey of Bow Shocks Around Runaway Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....110.2914V&db_key=AST
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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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The threshold for stellar winds in hot main-sequence stars
The profiles of ultraviolet resonance lines of C IV were surveyed in asample of 29 cluster and association members in the spectral type rangeO9-B2 III-V, together with a few field stars of interest. Thetemperatures and gravities of the stars were taken from the modelatmosphere analysis by Grigsby, Morrison, & Anderson (1992), and theluminosities were estimated on the basis of cluster and associationdistances from the recent literature. A parameter Pw wasdefined in order to describe the degree and assymetry of the C IVprofile. This parameter, together with total C IV equivalent width, wasfound to be well correlated with stellar luminosity and temperature. Afew anomalous stars were noted: tau Sco, HD 66665, HD 13621, and the ONstars HD12323 and HD 201345. The results suggest a sudden onset ofobservable mass loss at T(effective) = 27,500 +/- 500 K, log (L/solarluminosity) = 4.4 +/- 0.12, in agreement with the previous study byPrinja (1989). At T(effective) = 28,000 K and log g = 4, our non-LTEmodel atmospheres show an enhancement in the ground-state population ofC(+3) in their topmost layer, which could be responsible for initiationof the winds via radiation pressure on the C(+3) ions, or for the onsetof visibility of C(+3) ions in the wind because of an increase in theoptical depth in the C IV lines in the outermost layers.
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An IUE survey of interstellar H I LY alpha absorption. 1: Column densities
We measure Galactic interstellar neutral hydrogen column densities byanalyzing archival interstellar Ly alpha absorption line data toward 554B2 and hotter stars observed at high resolution with the IUE satellite.This study more than doubles the number of lines of sight with measuresof N(H I) based on Ly alpha. We have included the scattered lightbackground correction algorithm of Bianchi and Bohlin in our datareduction. We use the correlation between the Balmer discontinuity(c1) index and the stellar Ly alpha absorption in order toassess the effects of stellar Ly alpha contamination. Approximately 40%of the B stars with measured (c1) index, exhibit seriousstellar Ly alpha contamination. One table contains the derived values ofthe interstellar N(H I) for 393 stars with at most small amounts ofstellar contamination. Another lists the observed values of total N(H I)for 161 stars with suspected stellar Ly alpha contamination and/oruncertain stellar parameters.
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Intrinsic colour indices of O- and B- type stars in the Vilnius photometric system.
Not Available
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Hα Interferometric Optical and Near Infrared Photometric Studies of Star Forming Regions - Part One - the Cepheus-B / SH:2-155 / CEPHEUS-OB3 Association Complex
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&A...273..619M&db_key=AST
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Galactic OB associations in the northern Milky Way Galaxy. I - Longitudes 55 deg to 150 deg
The literature on all OB associations was reviewed, and their IRAS pointsource content was studied, between galactic longitude 55 and 150 deg.Only one third of the 24 associations listed by Ruprecht et al. (1981)have been the subject of individual studies designed to identify thebrightest stars. Distances to all of these were recomputed using themethod of cluster fitting of the B main sequence stars, which makes itpoossible to reexamine the absolute magnitude calibration of the Ostars, as well as for the red supergiant candidate stars. Also examinedwas the composite HR diagram for these associations. Associations withthe best defined main sequences, which also tend to contain very youngclusters, referred to here as OB clusters, have extremely few evolved Band A or red supergiants. Associations with poorly defined mainsequences and few OB clusters have many more evolved stars. They alsoshow an effect in the upper HR diagram referred to as a ledge byFitzpatrick and Garmany (1990) in similar data for the Large MagellanicCloud. It is suggested that the differences in the associations are notjust observational selection effects but represent real differences inage and formation history.
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Non-LTE, line-blanketed model atmospheres for late O- and early B-type stars
The use of non-LTE line-blanketed model atmospheres to analyze thespectra of hot stars is reported. The stars analyzed are members ofclusters and associations, have spectral types in the range O9-B2 andluminosity classes in the range III-IV, have slow to moderate rotation,and are photometrically constant. Sampled line opacities of iron-groupelements were incorporated in the radiative transfer solution; solarabundances were assumed. Good to excellent agreement is obtained betweenthe computed profiles and essentially all the line profiles used to fixthe model, and reliable stellar parameters are derived. The synthetic MII 5581 equivalent widths agree well with the observed ones at the lowend of the temperature range studied, but, above 25,000 K, the syntheticline is generally stronger than the observed line. The behavior of theobserved equivalent widths of N II, N III, C II and C III lines as afunction of Teff is studied. Most of the lines show much scatter, withno consistent trend that could indicate abundance differences from starto star.
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Photoelectric photometry of OB stars in the Vilnius system
Not Available
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Absolute dimensions of eclipsing binaries. XVIII - The Cepheus OB 3 member CW Cephei
Abstract image available at:http://adsabs.harvard.edu/abs/1991A&A...241...98C
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Close binaries observed polarimetrically
Not Available
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Four-colour photometry of eclipsing binaries. XXXIV - Light curves of the CEP OB3 member CW Cephei
This paper presents complete uvby light curves, 1369 points in eachcolor, of the northern early-type detached eclipsing binary CW Cep. Theorbit of CW Cep is slightly eccentric (e = 0.0293) and shows apsidalmotion (U = 45.6 yr). The system is a known member of the Cep OB3association.
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INHABITED SKY
