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The Effect of Binarity and Metallicity in the Spectra of WC and WO Stars
A statistical analysis of the main emission lines common to the WC andWO stars is made based on an extensive set of spectral data. To definethe trends in equivalent width ( Wλ), line ratios, andline widths, median values are derived for single-spectrum stars ofdifferent spectral class. We find that in Galactic WO and WC4 stars,Wλ (C IV 581 nm) is smaller compared to inextragalactic objects. In both Galactic and extragalactic stars,Wλ (O V 559 nm) smoothly increases towards early WCand WO stars. It is argued that differences in stellar wind structure,in combination with the ambient metallicity, may be the cause of theanomalies. Variation of the profile of the 465 nm blend indicates asubstantial contribution of He II 468 nm for the WCE and WO stars. Inaddition, we comment on the carbon abundances in relation to theevolutionary status of these objects. We also give an estimate of theOB/WR continuum flux ratio in composite-spectrum systems.
| Kinematical Structure of Wolf-Rayet Winds. I.Terminal Wind Velocity
New terminal wind velocities for 164 Wolf-Rayet stars (from the Galaxyand LMC) based on PCyg profiles of lambda1550 CIV resonance line werederived from the archive high and low resolution IUE spectra availableform the INES database. The high resolution data on 59 WR stars (39 fromthe Galaxy and 20 from LMC) were used to calibrate the empiricalrelation lambda_min^Abs- lambda_peak^Emis vs terminal wind velocity,which was then used for determinations of the terminal wind velocitiesfrom the low resolution IUE data. We almost doubled the previous mostextended sample of such measurements. Our new measurements, based onhigh resolution data, are precise within 5-7%. Measurements, based onthe low resolution spectra have the formal errors of approx 40-60%. Acomparison of the present results with other determinations suggestshigher precision of approx 20%. We found that the terminal windvelocities for the Galactic WC and WN stars correlate with the WRspectral subtype. We also found that the LMC WN stars have winds slowerthan their Galactic counterparts, up to two times in the case of the WNEstars. No influence of binarity on terminal wind velocities was found.Our extended set of measurements allowed us to test application of theradiation driven wind theory to the WR stars. We found that, contrary toOB stars, terminal wind velocities of the WR stars correlate only weaklywith stellar temperature. We also note that the terminal to escapevelocity ratio for the WR stars is relatively low: 2.55 pm 1.14 for theGalactic WN stars and 1.78 pm 0.70 for the Galactic WCs. This ratiodecreases with temperature of WR stars, contrary to what is observed inthe case of OB stars. The presented results show complex influence ofchemical composition on the WR winds driving mechanism efficiency. Ourkinematical data on WR winds suggest evolutionary sequence: WNL -->WNE --> WCE --> WCL.
| The VIIth catalogue of galactic Wolf-Rayet stars
The VIIth catalogue of galactic PopulationI Wolf-Rayet stars providesimproved coordinates, spectral types and /bv photometry of known WRstars and adds 71 new WR stars to the previous WR catalogue. This censusof galactic WR stars reaches 227 stars, comprising 127 WN stars, 87 WCstars, 10 WN/WC stars and 3 WO stars. This includes 15 WNL and 11 WCLstars within 30 pc of the Galactic Center. We compile and discuss WRspectral classification, variability, periodicity, binarity, terminalwind velocities, correlation with open clusters and OB associations, andcorrelation with Hi bubbles, Hii regions and ring nebulae. Intrinsiccolours and absolute visual magnitudes per subtype are re-assessed for are-determination of optical photometric distances and galacticdistribution of WR stars. In the solar neighbourhood we find projectedon the galactic plane a surface density of 3.3 WR stars perkpc2, with a WC/WN number ratio of 1.5, and a WR binaryfrequency (including probable binaries) of 39%. The galactocentricdistance (RWR) distribution per subtype shows RWRincreasing with decreasing WR subtype, both for the WN and WC subtypes.This RWR distribution allows for the possibility ofWNE-->WCE and WNL-->WCL subtype evolution.
| Non-thermal emission in Wolf-Rayet stars: are massive companions required?
We examine the radio spectral indices of 23 Wolf-Rayet (WR) stars toidentify the nature of their radio emission. We identify nine systems asnon-thermal emitters. In seven of these systems the non-thermal emissiondominates the radio spectrum, while in the remaining two it is ofcomparable strength to the thermal, stellar wind emission, giving`composite' spectra. Among these nine systems, seven have knownspectroscopic or visual binary companions. The companions are allmassive O or early B-type stars, strongly supporting a connectionbetween the appearance of non-thermal emission in WR stars and thepresence of a massive companion. In three of these binaries, the originof non-thermal emission in a wind-collision region between the stars hasbeen well established in earlier work. The binary systems that exhibitonly thermal emission are all short-period systems where awind-collision zone is deep within the opaque region of the stellar windof the WR star. To detect non-thermal emission in these systems requiresoptically thin lines of sight to the wind-collision region.
| WR 146 - observing the OB-type companion
We present new radio and optical observations of the colliding-windsystem WR146 aimed at understanding the nature of the companion to theWolf-Rayet (WR) star and the collision of their winds. The radioobservations reveal emission from three components: the WR stellar wind,the non-thermal wind-wind interaction region and, for the first time,the stellar wind of the OB companion. This provides the uniquepossibility of determining the mass-loss rate and terminal wind velocityratios of the two winds, independent of distance. Respectively, theseratios are 0.20+/-0.06 and 0.56+/-0.17 for the OB-companion starrelative to the WR star. A new optical spectrum indicates that thesystem is more luminous than had been believed previously. We deducethat the `companion' cannot be a single, low-luminosity O8 star assuggested previously, but is either a high-luminosity O8 star, orpossibly an O8+WC binary system.
| Radio Continuum Measurements of Southern Early-Type Stars. III. Nonthermal Emission from Wolf-Rayet Stars
The Australia Telescope Compact Array (ATCA) has been used to search forradio continuum emission at 2.4 and 1.4 GHz from a sample of 36 southernWolf-Rayet stars. Seven Wolf-Rayet stars were detected at 2.4 GHz, ofwhich two were also detected at 1.4 GHz. We have identified sixWolf-Rayet stars, WR 14, 39, 48, 90, 105, and 112, that have nonthermalemission. The ATCA data confirm that at least 40% of Wolf-Rayet starswith measured spectral indices have nonthermal emission at centimeterwavelengths. Properties of each of the six sources are discussed. Themeasured spectral indices are between 0 and -1.0, and the radioluminosities are of order 10^29 ergs s^-1. So far 10 confirmed sourcesof nonthermal emission are known, including the six ATCA detections andfour previously known cases, WR 125, 140, 146, and 147. In all cases,the nonthermal radio emission almost certainly originates from aninteraction between the Wolf-Rayet stellar wind and the wind from amassive companion star. The radio observations agree well withtheoretical predictions for colliding winds. Synchrotron emission occursfrom relativistic electrons accelerated in strong shocks. The nonthermalspectral indices are likely to be close to -0.5. For WR 39, the detectedradio emission is offset by ~3" from the optical position of WR 39 andby ~2" from the optical position of WR 38B. We suggest that the radioemission may originate from a wind-wind interaction between WR 39 and WR38B, although this is not confirmed. For WR 11, the radio spectral indexincreases from +0.3 between 3 and 6 cm to +1.2 between 13 and 20 cm.This is interpreted as evidence for a highly attenuated nonthermalcomponent that originates well within the ionized wind of the W-R starfrom an interaction with the wind of the O9 companion star.
| Clumping-corrected mass-loss rates of Wolf-Rayet stars
Mass-loss rates of Galactic Wolf-Rayet stars have been determined fromtheir radio emission power and spectral index (alpha = dln {f_ν} /dln ν), accounting for the clumped structure and (potential) variableionization in their outer winds. The average spectral index between mm-and cm- wavelengths is ~ 0.77 for WN stars and ~ 0.75 for WC stars, incontrast with ~ 0.58 expected for smooth winds. The observed wavelengthdependence of alpha can be explained using clumped wind models in somecases, with shocks (at 30-100 stellar radii) producing a higherionization zone in the outer wind. We obtain an empirical formularelating mass-loss with observed optical emission line equivalentwidths, with application to stars without measured radio fluxes.Clumping-corrected mass-loss rates are generally lower than thoseobtained by current smooth wind models. Specifically we find log\mdot(clumpy)-log \mdot(smooth)=-0.19 (sigma=0.28) for WN stars, and log\mdot(clumpy)-log \mdot(smooth)=-0.62 (sigma=0.19) for WC stars. Newmass-loss rate estimates agree very well with (clumping independent)determinations of WR components in binary systems.
| 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.
| Wolf-Rayet stars and O-star runaways with HIPPARCOS. I. Kinematics
Reliable systemic radial velocities are almost impossible to secure forWolf-Rayet stars, difficult for O stars. Therefore, to study the motions- both systematic in the Galaxy and peculiar - of these two relatedtypes of hot, luminous star, we have examined the Hipparcos propermotions of some 70 stars of each type. We find that (a) both groupsfollow Galactic rotation in the same way, (b) both have a similarfraction of ``runaways'', (c) mean kinetic ages based on displacementand motion away from the Galactic plane tend to slightly favour thecluster ejection over the the binary supernova hypothesis for theirformation, and (d) those with significant peculiar supersonic motionrelative to the ambient ISM, tend to form bow shocks in the direction ofthe motion. Based on data from the ESA Hipparcos astrometry satellite.Table~1 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Radio Continuum Measurements of Southern Early-Type Stars. II. A Distance-limited Sample of Wolf-Rayet Stars
A distance-limited sample of southern Wolf-Rayet stars within 3 kpc ofthe Sun has been observed with the Australia Telescope Compact Array at8.64 and 4.80 GHz. Radio continuum flux densities at one or bothfrequencies were obtained for 10 sources and upper limits for 20; foursources are found to be thermal emitters on the basis of the observedspectral index. Five sources are classified as nonthermal. One sourcecould not be classified. We derive mass-loss rates for the thermalsources. After combining them with all existing radio mass-loss rates ofWolf-Rayet stars in the northern and southern hemisphere, we perform acomparison with mass-loss rates derived from optical emission lines. Thetwo methods lead to consistent results, which suggests either that theassumption of a spherically symmetric, stationary, homogeneous stellarwind is correct or that deviations from this assumption affect bothmethods in the same way. Wolf-Rayet mass-loss rates are surprisinglyuniform across spectral type. We find an average mass-loss rate of 4 x10-5 Mȯ yr-1 for all types observed, except for WC9 stars, whichhave rates that are lower by at least a factor of 2. An alternativeexplanation could be partial recombination of helium from He+ to He0 inthe radio region, which would lead to a reduced number of freeelectrons, and therefore reduced radio flux for WC9 stars. Mass-lossrates of 8 x 10-5 Mȯ yr-1 for late WN stars favored in recentstellar evolution models disagree with the observations of thesesubtypes. The results of this survey suggest that ~40% of all Wolf-Rayetstars with measured spectral index are nonthermal emitters at centimeterwavelengths. This percentage is nearly twice as high as that ofnonthermal emitters among OB stars and is higher than that previouslyestimated for WR stars. The nature of the nonthermal emission is stillnot fully understood. Possible causes of nonthermal emission arediscussed. In particular, we speculate that nonthermal emission mayarise from an interaction between a thermal WR wind and surroundingmaterial owing to a shell ejected during a previous evolutionary stageor owing the wind of a companion star.
| Large IRAS Shells Around Galactic Wolf-Rayet Stars and the O Star Phase of Wolf-Rayet Evolution
Abstract image available at:http://adsabs.harvard.edu/abs/1996AJ....112.2828M
| An IRAS-based Search for New Dusty Late-Type WC Wolf-Rayet Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJS..100..413C&db_key=AST
| Spectral analyses of 25 Galactic Wolf-Rayet stars of the carbon sequence.
We present a grid of helium-carbon models for Wolf-Rayet (WR) stars ofthe carbon sequence (WC) with β_ C_=0.2 (carbon mass fraction),thus extending our previously released grid with β_C_=0.6 to adifferent chemical composition. The WR model atmospheres are based onthe so-called standard assumptions. The calculations account for non-LTEradiation transfer in spherically expanding atmospheres. Helium andcarbon are represented by detailed model atoms, especially concerningthe ions Ciii and Civ. Using the model grids 25 Galactic WC stars ofintermediate subtype (WC5 to WC8) are analyzed. Subsequently we performfine analyses by calculating several individual models for each of theprogram stars. Temperatures, radii, mass-loss rates and terminalvelocities are determined together with the carbon to helium ratio. Theanalyzed WC stars are found to form two groups, which can bedistinguished by the strength of their emission lines. Stars with weaklines (WC-w) have effective temperatures close to 50kK and their windsare relatively thin, forming the continuous spectrum in regions withsmall expansion velocities. WC stars with strong lines (WC-s) havehigher effective temperatures (60 to 100kK, referring to the coreradius) and thick winds. Thus there is a strong analogy to thedistribution of the early-type WN stars (WNE-w and WNE-s, respectively).For the WC stars we determine luminosities between 10^4.7^ and10^5.5^Lsun_ and mass-loss rates from 10^-4.8^ to10^-3.9^Mȯ/yr. The carbon mass fraction varies from 0.2 to 0.6. Nocorrelation is found between the carbon abundance and any of the stellarparameters (e.g. temperature, luminosity) or the spectral subtype. Theevolution of WR stars is discussed by comparing the results of ouranalyses with evolutionary tracks.
| 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.
| Terminal Velocities of Wolf-Rayet Star Winds from Low Resolution IUE Spectra
Attracted by the simplicity of the recently published by Prinja (1994)method of determination of terminal wind velocities in hot stars fromlow resolution IUE spectra we investigate its application to WR stars.With a large sample of low resolution IUE spectra of WR stars we foundeven simpler, that is linear instead of square, empirical relationbetween Delta lambda as defined by Prinja (1994) and terminal windvelocity -- vinfty. Using this new empirical relation wepresent vinfty for a sample of 85 galactic and LMC stars, 19of them determined for the first time. We almost tripled the number ofterminal velocity determinations for LMC WR stars. The comparison withother determinations shows that this simple method is accurate to within10-20%. We confirm the correlation between terminal velocity and WCsubtype. We also show that terminal velocities of WN stars are lowerthan that of WCE. A comparison between galactic and LMC stars shows thatthe LMC WN stars have slower winds in most of WN subtypes.
| The ROSAT PSPC survey of the Wolf-Rayet stars
Not Available
| Low resolution IUE spectra of Wolf-Rayet stars.
We present uniformly reduced and measured equivalent widths, FWHM andobserved line fluxes for 94 "single" WR stars (34 galactic WN, 22galactic WC, 31 LMC WN and 7 LMC WC) based on the archive IUE spectra ofWR stars gathered from different observational runs and from differentepochs. The spectra are used for spectral classification in theultraviolet region and for searching correlations among the strength andwidths of emission lines of different ions. Some correlations withoptical and near IR lines observed by other authors are given as well.The set of spectra we use is almost complete to 12 magnitude andrepresentative according to spectral subtype of WR stars.
| A survey of nebulae around galactic wolf-rayet stars in the southern sky, 2.
We present the second half of a charge coupled device (CCD) narrow-bandimaging survey of galactic Wolf-Rayet stars located in the southernhemisphere as listed by van der Hucht et al. (1981). Images of 50Wolf-Rayet stars were taken using a wide-field CCD and narrowbandinterference filters centered on H alpha and (O III) 5007 A wavelengths.The first half of the survey (Marston, Chu, & Garcia-Segura 1993,hereafter Paper I) revealed six new ring nebulae residing aroundWolf-Rayet stars. Here we reveal a possible 11 new rings and theexistence of multiple rings associated with two previously known nebula,RCW 118 and G2.4+1.4 and around the stars WR 16 and WR 43. Combining ourresults with those of Miller & Chu (1993) and Paper I, 92% of thevan der Hucht catalog of Wolf-Rayet stars have now been surveyed. Of the38 possible ring nebulae found in our surveys to date, 22 reside aroundWN subtype Wolf-Rayet stars, 13 around WC stars, one around a triplet ofWolf-Rayet stars and one around a WO star (WR 102). One ring existsaround a WN/WC star (WR 98). A bias toward rings being observed aroundW-R + OB binaries is noted. Such pairings are generally bright, and thedetection of a ring around them may merely be a function of theircombined luminosity. Several Wolf-Rayet stars are shown to be surroundedby multiple rings (two or three) which suggests that a number ofejections of stellar material have taken place during their evolution.
| Spectrophotometry of Wolf-Rayet stars. I - Continuum energy distributions
All available low-resolution IUE spectra are assembled for Galactic,LMC, and SMC W-R stars and are merged with ground-based optical and NIRspectra in order to collate in a systematic fashion the shapes of theseenergy distributions over the wavelength range 0.1-1 micron. They can beconsistently fitted by a power law of the form F(lambda) isapproximately equal to lambda exp -alpha over the range 1500-9000 A toderive color excesses E(B-V) and spectral indices by removing the 2175-Ainterstellar absorption feature. The WN star color excesses derived arefound to be in good agreement with those of Schmutz and Vacca (1991) andKoesterke et al. (1991). Significant heterogeneity in spectral indexvalues was generally seen with any given subtype, but the groupsconsisting of the combined set of Galactic and LMC W-R stars, theseparate WN and WC sequences, and the Galactic and LMC W-R stars allshowed a striking and consistent Gaussian-like frequency distribution ofvalues.
| A study of the neutral hydrogen in direction to the GUM nebula
This paper presents 44 gray-scale maps at constant velocity of thedistribution of H I in the direction of the Gum nebula. It is shown thatthere is no H I shell with a size comparable to the 36 deg diameteroptical nebulosities and that there is a thick H I shell, about 7 deg inradius, shifted from the center of the optical nebula by more than 10deg. The observations are consistent with a model in which the Gumnebula is the remnant of a supernova explosion that occurred about 2.6million yr ago. The presence of two new H I bubbles associated with SWR12 and 14, plus a possible one around WR 13, are disclosed from analysisof the H I gas distribution around the four WR star located beyond theGum nebula. These H I bubbles have characteristics similar to thosepreviously observed. Three shell-like objects probably related to OBstars and H II regions are also described.
| Early-type emission-line stars with large infrared excesses
A catalog is presented of early-type emission-line stars obtained bycross-identification between Wackerling's catalog and the IRAS catalogof point sources. A study of the distribution in space of the starsshows that these stars belong to the extreme Population I; thus thepresent compilation provides a rather complete sample for further studyof the evolution of pre- and post-main sequence stars of medium and highmasses.
| The distribution of massive stars in the Galaxy. I - The Wolf-Rayet stars
Using spectroscopic parallax, the heliocentric and Galactocentricdistances of nearly all of the 157 known Wolf-Rayet stars in the Galaxywere determined. Their distribution both within and perpendicular to theGalactic plane was investigated. The overall distribution within theplane reveals spiral features which are in accord with otherdeterminations of Galactic structure. In addition, it was found that theGalactocentric location of Wolf-Rayet stars is dependent on Wolf-Rayetsubtype, with late WC stars strongly confined to regions within thesolar circle. However, there is only a marginal variation in the WC/WNnumber ratio with distance from the Galactic center. The distribution ofWolf-Rayet stars in the direction perpendicular to the plane revealsthat these objects are closely confined to, but distributedasymmetrically about, the Galactic plane; the verical scale height ofthe distribution is about 45 pc. It is found that the sun is locatedabout 15 pc above the plane defined by these extreme Population Iobjects.
| Distances of Galactic WC stars from emission-line fluxes and a quantification of the WC classification
The extent to which later-type WC stars in the Galaxy show constant fluxin the carbon lines is assessed. It is found the the WC stars are anextremely 'well-behaved' sequence in terms of quantitative spectroscopicproperties. The two classification parameters are closely correlatedwith a scatter of the order of uncertainty. There appear to be naturalbreaks in the sequence between subclasses, except between WC5 and 6. Theclassification is quantified using the C IV 5808 A/C III 5696 A ratio asthe principal defining parameter for WC7-9 stars and the C III 5696 A/OV 5590 A ratio as the principal defining parameter for WC4-6 stars.Preliminary calibration of the line fluxes indicate that the flux of CIV 5808 A in Galactic WC stars is constant at F(0) 5808 = -logF(0)(5808) = 8.1 at 1 kpc for subclasses WC5-7. The intrinsic line fluxratio C(0) = log f(0)(5808/4650) is a smooth function of subclassnumber, decreasing from -0.22 dex for WC4 stars to -0.56 dex for WC9stars.
| An optical spiral arm beyond the Perseus arm
In the second galactic quadrant, optical spiral arm tracers have beencollected in a systematic literature search. A uniform reduction of thedata led to the detection of a distinct structure (probably a spiralarm) beyond the Perseus arm that is separated by a statisticallysignificant gap from the latter.
| Spectrophotometry of Wolf-Rayet stars - Intrinsic colors and absolute magnitudes
Absolute spectrophotometry of about 10-A resolution in the range3400-7300 A have been obtained for southern Wolf-Rayet stars, andline-free magnitudes and colors have been constructed. The emission-linecontamination in the narrow-band ubvr systems of Westerlund (1966) andSmith (1968) is shown to be small for most WN stars, but to be quitesignificant for WC stars. It is suggested that the more severedifferences in intrinsic color from star to star of the same spectralsubtype noted at shorter wavelengths are due to differences inatmospheric extent. True continuum absolute visual magnitudes andintrinsic colors are obtained for the LMC WR stars. The most visuallyluminous WN6-WN7 stars are found to be located in the core of the 30Doradus region.
| The Galactic distribution and subtype evolution of Wolf-Rayet stars. III
Using new classifications for 46 WR stars and new photometry for 78 WRstars, the Galactic WR intrinsic parameters are redetermined, revisingthe WR Galactic distribution. For stars with heliocentric distances lessthan 2.5 kpc, it is found that the WN/WC number ratio is 0.55,indicating a larger influence of mass loss and overshooting thanaccounted for in present evolutionary models. By comparison with atheoretical mass-luminosity relation an average bolometric correction of-4.2 + or - 1.2 is found for WR stars in binaries located in openclusters or associations. A mathematical comparison with thedistribution of O-type stars is used to find the initial masses ofprogenitors of WR, WN, and WC stars. It is suggested that WNL stars withgalactocentric distances beyond about 6.5 kpc evolve into WCE stars,whereas WNL stars within galactocentric distances of about 8.5 kpcevolve into WCL stars.
| C/He abundances in WC stars
Recombination theory has been used to determine the C/He abundances in17 southern WC stars from spectra in the H and K bands. An LTE treatmentof C II provides C/He values in the 0.04-0.3 range, by number, andmaximum allowance for possible non-LTE effects yields values in the0.1-0.7 range, by number. C/He is shown to decrease from WC4 to WC7. Theionization balance is found to be lower than in previous reports.He(+)/He(2+) values are between 2.6 and 3.0 for WC5-8 stars, increasingto 7 for WC9 stars. Continuum slopes and corrections for the emissionline contributions to the H and K magnitudes are evaluated.
| Carbon and helium abundances in Wolf-Rayet WC stars determined from optical recombination lines
Carbon to helium ratios and ionization fractions are derived for 74 WCstars in the Galaxy and the LMC from optically thin recombination linesat visual wavelengths. The range of C/He ratios is 0.13 to 0.79 bynumber, similar to the ratios calculated by Nugis (1975) and about 20times greater than the ratios of Smith and Willis (1982). These ratiosalso agree with the abundances determined in the most recentevolutionary models of massive stars, which include mass loss,convective dredge-up, and new nuclear reaction rates. The range ofvalues found for the C/He ratios implies that the convective cores of WCstars do not occupy a very large mass fraction. The C/He ratio differswithin a subtype by a factor of three or less, but the mean tends toincrease toward earlier subtypes, although the standard deviation fromthe mean is large enough to allow the interpretation that the C/He ratiois constant for all WC subtypes.
| Merged log of IUE observations.
Not Available
| An atlas of optical spectrophotometry of Wolf-Rayet carbon and oxygen stars
The atlas contains a homogeneous set of optical spectrophotometricobservations (3300-7300 A) at moderate resolution (about 10 A) of almostall WC and WO stars in the Galaxy, the LMC, and the SMC. The data arepresented in the form of spectral tracings (in magnitude units) arrangedby subtype, with no correction for interstellar reddening. A montage ofprototype stars of each spectral class is also shown. Comprehensive lineidentifications are given for the optical lines of WC and WO spectra,with major contributions tabulated and unidentified lines noted.
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Osservazione e dati astrometrici
| Costellazione: | Vele |
| Ascensione retta: | 09h13m11.78s |
| Declinazione: | -50°06'25.6" |
| Magnitudine apparente: | 10.748 |
| Moto proprio RA: | -7.4 |
| Moto proprio Dec: | 6.6 |
| B-T magnitude: | 12.066 |
| V-T magnitude: | 10.857 |
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