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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Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
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On the Variability of O and B Supergiants
We investigate the Hipparcos Satellite photometry of O and B supergiantsto see the pattern of activity of these stars. A few stars for whichfurther study is desirable are identified.
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Spectroscopic binary orbits from photoelectric radial velocities. Paper 148: HR 7955
Not Available
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Radial velocities of HIPPARCOS southern B8-F2 type stars
Radial velocities have been determined for a sample of B8-F2 type starsobserved by the Hipparcos satellite. Observations were obtained withinthe framework of an ESO key-program. Radial velocities have beenmeasured using a cross-correlation method, the templates being a grid ofsynthetic spectra. The obtained precision depends on effectivetemperature and projected rotational velocity of the star as well as ona possible asymmetry of the correlation peak generally due to secondarycomponents. New spectroscopic binaries have been detected from theseasymmetries and the variability of the measured radial velocity.Simulations of binary and triple systems have been performed. Forbinaries our results have been compared with Hipparcos binary data.Adding the variable radial velocities, the minimum binary fraction hasbeen found 60% for physical systems. Radial velocities have beendetermined for 581 B8-F2 stars, 159 being new. Taking into accountpublished radial velocities, 39% south A-type stars with V magnitudelower than 7.5 have a radial velocity. Based on observations obtained atthe European Southern Observatory (ESO, La Silla, Chile) and on datafrom the ESA Hipparcos astrometry satellite.}\fnmsep \thanks{Tables 7, 8and 9 are only available in electronic form at the CDS via anonymous ftpto cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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The Pulkovo Spectrophotometric Catalog of Bright Stars in the Range from 320 TO 1080 NM
A spectrophotometric catalog is presented, combining results of numerousobservations made by Pulkovo astronomers at different observing sites.The catalog consists of three parts: the first contains the data for 602stars in the spectral range of 320--735 nm with a resolution of 5 nm,the second one contains 285 stars in the spectral range of 500--1080 nmwith a resolution of 10 nm and the third one contains 278 stars combinedfrom the preceding catalogs in the spectral range of 320--1080 nm with aresolution of 10 nm. The data are presented in absolute energy unitsW/m(2) m, with a step of 2.5 nm and with an accuracy not lower than1.5--2.0%.
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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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Terminal Velocities and the Bistability of Stellar Winds
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...455..269L&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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An atlas of ultraviolet P Cygni profiles
We have selected spectra of 232 stars from the International UltravioletExplorer (IUE) archives for inclusion in an atlas intended for varioususes but tailored especially for the study of stellar winds. The atlascovers the range in spectral types from O3 to F8. The full atlas coversthe reduced and normalized high resolution spectra from the IUE long-and short-wavelength spectrographs. Here we discuss the selection of thestars and the data reduction, and we present in velocity units theprofiles of lines formed in the stellar winds. The selected lines covera wide range of ionizations, allowing a comparison of the profiles fromdifferent ions in the wind of each star and a comparison of thedifferent wind lines as a function spectral type and luminosity. We alsopresent the basic data on the program stars to facilitate study of thedependence of wind features on stellar parameters such as luminosity,temperature, escape velocity, and v sin i. We provide an overview of thecharacteristic behavior of the wind lines in the H-R diagram. Thecomplete spectra are available in digital form through the NASAAstrophysics Data System (ADS). We offer a description of the electronicdatabase that is available through the ADS and guidelines for obtainingaccess to that database.
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Groups of stars with common motion in the Galaxy. Groups of O and B stars
Not Available
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Spectral synthesis in the ultraviolet. IV - A library of mean stellar groups
A library of mean UV stellar energy distributions is derived from IUEspectrophotometry of 218 stars. The spectra cover 1230-3200 A with aspectral resolution of about 6 A. They have been corrected forinterstellar extinction and converted to a common flux and wavelengthscale. Individual stars were combined into standard groups according totheir continuum colors, observed UV spectral morphology, MK luminosityclass, and metal abundance. The library consists of 56 groups: 21dwarf(V), 8 subgiant(IV), 16 giant(III), and supergiant(I + II) groups,covering O3-M4 spectral types. A metal-poor sequence is included,containing four dwarf and two giant groups, as is a metal-enhancedsequence with a single dwarf, subgiant, and giant group. Spectralindices characterizing the continuum and several strong absorptionfeatures are examined as temperature, luminosity, and abundancediagnostics. The library is intended to serve as a basis forinterpreting the composite UV spectra of a wide variety of stellarsystems, e.g., elliptical galaxies, starburst systems, and high-redshiftgalaxies.
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Spectral synthesis in the ultraviolet. III - The spectral morphology of normal stars in the mid-ultraviolet
The morphology of 218 mid-UV spectra of stars ranging from O through Kin spectral type is examined. Several new line and continuum indices aredefined and their usefulness as temperature, luminosity, and metallicitydiscriminants is discussed. Mid-UV stellar continua are found to bemarkedly affected by abundance. A UV excess, delta(2600-V), is computedwhich is more sensitive by a factor of 10 to (Fe/H) than is delta(U-B).The relative strength of spectral lines in the mid-UV is not as stronglyaffected by abundance. Mid-UV spectra are much more sensitive to thetemperature of the stellar population than to either metallicity or thedwarf/giant ratio. Mg II 2800 shows unexpected behavior, displaying nosensitivity to abundance for cool stars and a reversed sensitivity in FGdwarfs such that metal-poor stars have stronger Mg II strengths at thesame temperature than more metal-rich stars.
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Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
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The spectral energy distribution of early-type stars. II - The extinction law towards O-type stars
Photometric measurements through different pass-bands are used todetermine the color-excess E(B-V) for O-type stars in the UV and IRspectral regions. The results are used to examine the extinctioncharacter of the stars. It is found that, in the UV, each O-type starhas its own extinction character. In general, the visual and NIRextinction in the direction of O-type stars are normal.
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The UV silicon spectra of early B stars
Equivalent widths of UV silicon lines obtained from high dispersion IUESWP spectra for a sample of 37 mid- to early B stars are presented.These are compared to other atmospheric diagnostics and to modelatmosphere calculations. It is found that some of the UV silicon linesare extremely sensitive to stellar temperature and luminosity over therange B5-B0.5, or roughly a factor of two in effective temperature. Thepotential usefulness of these lines is stressed, and it is demonstratedthat they could determine temperatures and surface gravities to the sameaccuracy as other commonly used diagnostics once adequate models becomeavailable. Although the available models fail to predict thequantitative behavior of the line strengths, they do, in most instances,describe their qualitative behavior. Since the existing models aresomewhat out of date, the results suggest that models based upon morecomplete opacity tables may be quite reliable.
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Diffuse absorption bands and the 2175 A feature - Results from a sample of galactic stars
Six diffuse absorption bands (5780, 5797, 6196, 6203, 6270 and 6284 A)have been measured in a sample of 26 galactic stars. The strength ofthese features has been compared with the interstellar absorption bandat 2175 A. After canceling the intrinsic correlation due to thegenerally constant gas-to-dust ratio of the interstellar medium, nofurther correlation between the UV bump and the observed DIBs was found,suggesting thst dust and the carrier(s) of the DIBs, although coexistingin the interstellar medium, have an independent history. Some degree ofcorrelation is found, however, among the DIBs themselves, suggesting thepossible existence of 'families' of features. Finally, the data supportthe hypothesis that the Herbig band at 6203.06 A is a blend of twofeatures at 6202.99 and 6205.09 A having a constant intensity ratio.
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The UV silicon spectra of early B stars
The UV silicon spectra of mid to early B stars are examined and comparedto models. It is found that lines are extremely sensitive to stellartemperature and luminosity. Although the models fail to predict thequantitative behavior of the line strengths, they do, in most instances,describe their qualitative behavior.
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Energy Distribution in the Stellar Spectra of Different Spectral Types and Luminosities - Part Five - Normal Stars
Not Available
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Intensities of the resonance lines of neutral and ionized magnesium in stellar spectra
Empirical curves giving the dependence of the equivalent widths of thedoublet 2800 Mg II and the line 2852 Mg I on the spectral class havebeen plotted. Some features of the behavior of these lines in thespectra of stars of the spectral classes A-K have been analyzed. Thelines 2795 Mg II and 2852 Mg I have been used to determine the meanelectron concentration ne(Mg) in the atmospheres of 87 stars of thespectral classes B8-K4.
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The spectral energy distribution of early type stars. I - A catalogue of photometric data of 259 stars from 0.15 to 4.8 microns
For the derivation of physical parameters (e.g., effective temperatureand radius) of early-type stars from their intrinsic spectral-energydistribution, and for the study of foreground interstellar and/orcircumstellar matter, a sample of 237 O, B, and A stars was chosen fromthe ANS catalog (Wesselius et al., 1982). The ANS ultraviolet and theJohnson UBV data (mostly from Nicolet's catalog, 1978) of these starswere supplemented with visual Walraven WULBV, red VRI, and near-infraredJHKLM measurements. All these data are given in the present catalog.Data for 22 stars of spectral type later than A are also included.
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Low dispersion spectrophotometry of bright early-type stars
Intensity distributions for 79 stars of spectral types O9 to A3, plus anF3 star and 7 standard stars, are presented. The observations cover awavelength range from 3300 to 6000 A. The internal errors are discussed.Synthetic uby colors are obtained for all the stars observed, and arecompared with observed published data.
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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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Catalogue of the energy distribution data in spectra of stars in the uniform spectrophotometric system.
Not Available
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IUE low-dispersion reference atlas
This atlas, published by ESA and essentially devoted to normal stars,presents 229 graphic spectra together with the corresponding fluxes andan ultraviolet spectral type. The preparation of this publicationconfirmed that MK classifications cannot simply be transferred to theultraviolet range. A set of transparencies illustrates the referencesequences constructed from the ultraviolet data. A magnetic-tape copy ofall the spectra pertaining to this atlas is available from the StellarData Center in Strasbourg.
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13-COLOR Photometry of B-Type Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1984RMxAA...9...53S&db_key=AST
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IUE low-dispersion spectra flux catalogue. I - Normal stars (magnetic tape)
A magnetic tape catalog of the fluxes (2A-step) of 229 selectedlow-dispersion stellar spectra prepared by the Centre de Calcul deStrasbourg-Cronenbourg is presented in the form of a set of tables. Thecatalog uses the general MK frame and centers on stars exhibiting normalbehavior in the ultraviolet. All the stars included in the catalog arelisted together with their MK and UV spectral classifications. Thespectra were collected by the International Ultraviolet Explorer (IUE)with the aim of establishing reference spectral sequences in theultraviolet range.
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INHABITED SKY
