A Detailed Far-Ultraviolet Spectral Atlas of Main-Sequence B Stars
We have constructed a detailed spectral atlas covering the wavelengthregion 930-1225 Å for 10 sharp-lined B0-B9 stars near the mainsequence. Most of the spectra we assembled are from the archives of theFar Ultraviolet Spectroscopic Explorer satellite, but for nine stars,wavelength coverage above 1188 Å was taken from high-resolutionInternational Ultraviolet Explorer or echelle Hubble SpaceTelescope/Space Telescope Imaging Spectrograph spectra. To represent thetenth star at type B0.2 V, we used the Copernicus atlas of ? Sco. Wemade extensive line identifications in the region 949-1225 Å ofall atomic features having published oscillator strengths at types B0,B2, and B8. These are provided as a supplementary dataproduct—hence the term detailed atlas. Our list of found featurestotals 2288, 1612, and 2469 lines, respectively. We were able toidentify 92%, 98%, and 98% of these features with known atomictransitions with varying degrees of certainty in these spectra. Theremaining lines do not have published oscillator strengths. Photosphericlines account for 94%, 87%, and 91%, respectively, of all ouridentifications, with the remainder being due to interstellar (usuallymolecular H2) lines. We also discuss the numbers of lineswith respect to the distributions of various ions for these three moststudied spectral subtypes. A table is also given of 162 least blendedlines that can be used as possible diagnostics of physical conditions inB star atmospheres.
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A FUSE Survey of the Rotation Rates of Very Massive Stars in the Small and Large Magellanic Clouds
We present projected rotational velocity values for 97 Galactic, 55 SMC,and 106 LMC O-B type stars from archival FUSE observations. The evolvedand unevolved samples from each environment are compared through theKolmogorov-Smirnov test to determine if the distribution of equatorialrotational velocities is metallicity dependent for these massiveobjects. Stellar interior models predict that massive stars with SMCmetallicity will have significantly reduced angular momentum loss on themain sequence compared to their Galactic counterparts. Our results findsome support for this prediction but also show that even at Galacticmetallicity, evolved and unevolved massive stars have fairly similarfractions of stars with large Vsin i values. Macroturbulent broadeningthat is present in the spectral features of Galactic evolved massivestars is lower in the LMC and SMC samples. This suggests the processesthat lead to macroturbulence are dependent upon metallicity.
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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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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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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Five-colour photometry of OB-stars in the Southern Hemisphere
Observations of OB-stars, made in 1959 and 1960 at the Leiden SouthernStation near Hartebeespoortdam, South Africa, with the VBLUW photometerattached to the 90 cm light-collector, are given in this paper. They arecompared with photometry obtained by \cite[Graham (1968),]{gra68}\cite[Walraven & Walraven (1977),]{wal77} \cite[Lub & Pel(1977)]{lub77} and \cite[Van Genderen et al. (1984).]{gen84} Formulaefor the transformation of the present observations to those of\cite[Walraven & Walraven (1977)]{wal77} and \cite[Lub & Pel(1977)]{lub77} are given. Table 4 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/Abstract.html
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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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Red and infrared colours of B stars and the reddening law in the Galaxy
The red and infrared intrinsic colours of B stars are derived fromphotometric observations through the UBV(RI)_CJHK and Hβ filters of257 early-type stars. Those stars for which the UBV and Hβmeasurements match the published spectral class, and which show no othersigns of peculiarity, are used to determine the intrinsic photometriccolours of B stars in the red and infrared. From these intrinsic coloursthe interstellar reddening relationships for the red and infraredcolours are evaluated, and the results are compared with previousestimates of these quantities. The values of R, E(B-V) and the distanceare then determined for the individual stars. R is confirmed to be closeto 3.1 in most cases, but was found to be much larger in somedirections. The relationship between R and the location of a star in theGalaxy is investigated. Usually the abnormally reddened stars seemed tobe associated with known regions of star formation. The paper alsoidentifies seven likely variable stars and a number of stars withpossible dust shells.
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A Radial Velocity Database for Stephenson-Sanduleak Southern Luminous Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....113..823R&db_key=AST
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Cross-correlation characteristics of OB stars from IUE spectroscopy
We present a catalogue of homogeneous measures of the linewidthparameter, v_esin i, for 373 O-type stars and early B supergiants(including the separate components of 25 binary and three triplesystems), produced by cross-correlating high-resolution,short-wavelength IUE spectra against a `template' spectrum of tauSco. Wealso tabulate terminal velocities. There are no O supergiants in oursample with v_esin i<65 km s^-1, and only one supergiant earlier thanB5 has v_esin i<50 km s^-1, confirming that an important linebroadening mechanism in addition to rotation must be present in theseobjects. A calibration of the area under the cross-correlation peakagainst spectral type is used to obtain estimates of continuum intensityratios of the components in 28 spectroscopically binary or multiplesystems. At least seven SB2 systems show evidence for the `Struve-Sahadeeffect', a systematic variation in relative line strength as a functionof orbital phase. The stellar wind profiles of the most rapid rotator inour sample, the O9III:n* star HD 191423 (v_esin i=436km s^-1), show itto have a `wind-compressed disc' similar to that of HD 93521; this starand other rapid rotators are good candidates for studies of non-radialpulsation.
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OB Stellar Associations in Crux. II. Analysis and Discussion
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....111..306T&db_key=AST
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OB Stellar Associations in Crux. I. Observations With the Glazar Space Telescope
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....111..299T&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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A spectroscopic database for Stephenson-Sanduleak Southern Luminous Stars
A database of published spectral classifications for objects in theStepenson-Sanduleak Luminous Stars in the Southern Milky Way catalog hasbeen compiled from the literature. A total of 6182 classifications for2562 stars from 139 sources are incorporated.
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The distribution of neutral hydrogen in the interstellar medium. 1: The data
We compile, from the existing literature, the largest sample to date(842 data points) of hydrogen column density measurements, N(H I), ofthe gas in the interstellar medium. We include only results obtainedfrom absorption measurements toward individual stars (594 in our sample)in an effort to construct a three-dimensional picture of theinterstellar gas. We derive hydrogen column densities toward a fractionof the stars in the sample from published column density measurements ofmetal ions. A three-dimensional physical model derived from this dataset will be presented in a companion paper. The observed stars spandistances from a few parsecs to a few thousand parsecs, and more thanhalf of the sample serves to describe the local interstellar mediumwithin a few hundred parsecs of the Sun. Hydrogen column densities rangefrom 1017 to 1022/sq cm. We describe here thevarious observational methods used to estimate the hydrogen columndensities and present the table with the stellar and hydrogen columndensity data. The provided table is intended as a global reference work,not to introduce new results.
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Stromgren and H-Beta Photometry of Associations and Open Clusters - Part Three - CENTAURUS-OB1 and CRUX-OB1
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994MNRAS.269..289K&db_key=AST
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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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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.
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The distribution of interstellar AL III away from the Galactic plane
IUE spectra are analyzed to study the density distribution ofinterstellar Al III away from the Galactic plane. In most cases, themeasured values of the relative line strengths are consistent with onlymodest levels of line saturation. Al III is found to have an exponentialscale height and 1 sigma errors of 1.02(+0.36, -0.24) kpc. For the sameset of 70 stars, the scale height and 1 sigma errors for H I are0.67(+0.21, -0.16) kpc. The Al III scale height is similar to the valueobtained for free electrons from pulsar dispersion measures. The ionizedgas traced by Al III is somewhat more extended than the neutral gastraced by H I but less extended than the very highly ionized gas tracedby Si IV, C IV, and N V.
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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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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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The density distribution of refractory elements away from the Galactic plane
The density distributions of the three refractory elements Ti II, Ca II,and Fe II away from the Galactic plane are compared with thedistribution of hydrogen and dust by examining plots of N s in b versusz. It is found that Ti II and Ca II are considerably more extended in zthan the H I and dust and that Fe II has an intermediate extension.Although the results are strongly influenced by sample bias, theindicated exponential scale heights for the data sample are h(Ti II) notless than 2 kpc, h(Ca II) = 1 kpc, h(Fe II) = 0.5 kpc, H(H I) = 0.3 kpc,and h(E/B-V) = 0.1 kpc. Furthermore, it is demonstrated that Ti II andCa II are much more smoothly distributed in space than the hydrogen ordust. The large scale heights for Ti II and Ca II and their smoothdistributions are most easily understood as the effect of a mixturealong the line of sight of two H I phases namely, a diffuse cloud phase,in which nearly all of the Ti and Ca are tied up in dust, and anintercloud medium, where refractory elements are less depleted. It isfound that Ti II and Ca II mostly trace the smoothly distributedintercloud medium. The smoothness of the distributions of Ti II and CaII makes them candidates for use as distance indicators.
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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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Highly ionized interstellar gas located in the Galactic disk and halo
High-resolution IUE absorption line spectra have been obtained for 40distant stars in order to study the distribution of interstellar H I, SiIV, C IV, and N V in the Galactic disk and lower halo. Respectivemidplane densities of 2 x 10 to the -9th, 7 x 10 to the -9th, and 3 x 10to the -9th are found for Si IV, C IV, and Ni V. Both column density andvelocity data indicate that the highly ionized gas (HIG) is considerablymore extended in directions away from the Galactic plane than is H I orSi II. The absorption-line velocities for the halo HIG are consistentwith the notion that halo gas in the inner Galaxy rotates more slowlythan gas in the underlying disk. The derived column densities suggest anexponential scale height for the HIG of about 3 kpc; however, a simpleexponential distribution is a poor representation of the distribution ofthe gas. It is concluded that a full explanation of the origin of thehalo HIG will probably require a blending of ideas from the Galacticfountain and the photoionized halo models.
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On the intrinsic UVBY colours of early-type supergiants
The present photoelectric uvby observations of 43 late O-type to earlyA-type supergiants are combined with published results to extend theZhang (1983) determination of the intrinsic color lines in the(b-y)/c(1) diagram. Zhang's conclusion that the H-beta index is wellcorrelated with luminosity class is reaffirmed by the results obtained,although the degree of separation found here is less clear. It is notfound, however, that beta has a significant minimum between the B1 andB3 spectral types.
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Some crucial X-ray observations - One or two SNR(s) in crux?
A new Exosat (LE/CMA) observation of the region in Crux (R.A. ofapproximately 11 h 45 m, Dec. of approximately -62 deg) where Markert etal. (1981) reported the existence of two X-ray SNR's is presented. After'cleaning' the CMA field from the point source component due to the UVemission of the numerous stars in the field, the smoothed X-ray contoursare compared to the 408 MHz radio map of Caswell et al. (1983). Theexistence of two well-separate X-ray emission regions is confirmed byExosat, and the current X-ray/radio picture is not sufficient todistinguish clearly between the assumption of one or two (possiblyinteracting) SNR's in the region.
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A study of B-type supergiants with the uvby,beta photometric system
The applicability of the uvby,beta photometric system to theclassification and study of B-type supergiants (BTS) is investigatedusing published data on 157 BTS and observations of 17 BTS made with the36-in. reflector at McDonald Observatory. The results are presented intabular form and analyzed to produce preliminary calibrations ofluminosity class vs. beta index and of absolute magnitude (Mv) vs. beta(or delta Mv vs. delta beta) for four associations of stars. Theeffectiveness of various color indices as temperature indicators isdiscussed. It is shown that there is good correspondence between MK anduvby,beta classifications of B-type main-sequence stars, giants, andBTS, confirming the usefulness of the uvby,beta system in furtherresearch on BTS.
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New UBVRI photometry for 900 supergiants
A description is presented of the results obtained in connection with asystematic program of supergiant photometry on the Johnson UBVRI system.During the eight years after the start of the program, almost 1000 starshave been observed, about 400 three or more times each. The originalselection of stars used the spectral type catalog of Jaschek et al.(1964) to choose supergiants. Since observations were possible from bothChile and Canada, no declination limits were imposed, and no particularselection criteria were imposed other than to eliminate carbon stars.These are so red as to require enormous extrapolations of thetransformation equations.
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UBV photometry for southern OB stars
New UBV photometry of 1227 OB stars in the southern Milky Way ispresented. For 1113 of these stars, MK spectral types have been reportedpreviously in a comprehensive survey to B = 10.0 mag.
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Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJS...38..309H&db_key=AST
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INHABITED SKY
