On the class of Oe stars\fnmsep
We present high-quality spectra of the majority of stars that have beenclassified as Oe and find that their published spectral types aregenerally too early, most likely due to infilling of He I lines. As amatter of fact, all stars classified as Oe actually fall inside therange O9-B0 with the important exception of HD 155806 (O7.5 III) andperhaps HD 39680 (difficult to classify, but likely O8.5 V).Observations of a sample of objects with published spectral types in theO9-B0 range previously classified as peculiar or emission-line starsfail to reveal any new Oe star with spectral type earlier than O9.5.Most objects classified as peculiar in ``classical'' literature showsigns of binarity in our spectra, but no spectral anomalies. We concludethat there is likely a real decline in the fraction of Be stars forspectral types earlier than B0, not due to observational bias. The fewOe stars with spectral types earlier than O9.5 deserve detailedinvestigation in order to provide constraints on the physical reasons ofthe Be phenomenon.Based on observations obtained at the Isaac Newton Telescope (La Palma,Spain).
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A study of RV in Galactic O stars from the 2MASS catalogue
We present new measurements of the interstellar reddening parameterRV=AV/E(B-V) towards 185 O stars, using J, H,Ks photometry from the 2MASS project. The results arecombined with data from the literature of 95 stars where RVhas been derived with the same technique, 22 of which in common with ourpresent sample from the 2MASS project catalogue. The averageRV from these 258 O stars is of 3.19 +/- 0.50. All objectswhose RV departs from this value by more than 2 sigma havebeen recognized. Ten objects have RV higher than this valueand two lower. It is found that anomalous RV can scarcely beassociated with anomalies in the general interstellar medium, e.g. withdifferent behaviour in different spiral arms. They are clearly linked tolocal cloud effect. In the Cygnus region RV values follow thebehaviour of the general interstellar medium, while in the Carina arm,in spite of the relatively larger distance, local cloud effects prevail.An explanation for this is suggested. The relatively few stars of oursample whose Hipparcos parallaxes are reliable, are found to havedistances systematically smaller than the distances derived by thespectroscopic parallaxes. We argue that this effect is consistent withthe recently claimed discovery of grey extinction towards OB stars.This publication makes use of data products from the Two Micron All SkySurvey (2MASS), which is a joint project of the University ofMassachusetts and the Infrared Processing and Analysis Center/CaliforniaInstitute of Technology, funded by the National Aeronautics and SpaceAdministration and the National Science Foundation.Tables 1 and 2 are 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/410/905
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High-velocity NaI and CaII absorption components observed towards the IC 443 SNR
We present high-resolution spectra (R ~ 1.8 km s-1) of theinterstellar NaI and CaII interstellar absorption lines observed towards4 early-type stars with distances of 900-1500 pc in the line-of-sighttowards the IC 443 Supernova Remant (SNR). The spectra of two of thesestars (HD 43582 and HD 254577) exhibit a very complex pattern ofabsorption with cloud components covering a total velocity range of -100km s-1 to +50 km s-1. The relative absorptionstrength of many of the higher velocity components is highly variablebetween these two stars, suggesting that the disturbed interstellar gasin this region possesses significant density gradients and/or largedifferences in ionization and element depletion. In addition, we havedetected three additional high-velocity components at Vhelio= -97.5, -84.0 and -67.6 km s-1 solely in their CaII lines,suggesting that the very highest velocity gas is more ionized and/orwarmer than the lower velocity components or it has a highly variablelevel of gas phase element abundances.The column density ratios of NaI/CaII for the higher velocity cloudcomponents are all <0.2, which is consistent with appreciable levelsof dust grain destruction due to interstellar shocks caused byinteraction of the expanding SNR blast-wave with the ambientinterstellar medium. The distance to IC 443 is confirmed at ~ 1500 pc,which places the remnant at a similar distance to the Gem OB1 stellarassociation. Finally we note that the model of Chevalier (1999), inwhich the SNR is expanding into a clumpy interstellar medium, can bestreproduce the observed patterns of both emission and absorption.
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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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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 Einstein X-ray Observatory Catalog of O-type stars
A catalog of X-ray count rates for all O-type stars surveyed by theEinstein Observatory is presented. The procedures by which the IPC andHigh Resolution Imager rates are converted to emitted X-ray luminositiesare discussed in detail. The catalog contains 289 stars with 89detections and 176 upper bounds for the observed count rates. Precisepositions for 43 O-type stars are given whose previously known locationswere unknown or erroneous. It is argued that most O-type stars are X-raypoint sources, but some are possibly embedded in extended nebulae and/orbubbles. The X-ray spectra of O-type stars are discussed briefly, and itis argued that their mean spectrum can reasonably be taken as an 0.5 keVthermal bremsstrahlung model. It is argued that at least 30 percent ofall O-type stars are variable in X-rays.
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The structure and dynamics of evolved supernova remnants - The IC 443 complex
The extended cloud complex containing the supernova remnant IC 443, theH II region S 249 and members of the Gem OB 1 association is studiedwith IRAS observations at 12, 25, 60 and 100 microns and WSRTobservations at 327 and 1400 MHz and in the 21 cm H I line. IC 443 isshown to consist of three interconnected approximately sphericalsubshells of vastly different radii and centroids. The geometry is fullyconstrained by the structural and kinematic data. Two of these subshellstogether define the usually assumed boundaries of IC 443, while thethird includes the optical filaments which extend beyond the brightnorth-eastern rim. These filaments are shown to have well correlatednonthermal radio counterparts. Physical parameters are derived for theentire complex, individual H II regions and the shocked and recombinedgas within IC 443 from the radio and infrared data. The availableevidence implies that the SNR shock has encountered a pre-existing highdensity shell. It is shown that the system of subshells is fullyconsistent with formation by stellar wind driven bubbles generated byassociation members within the inhomogeneous environment of the complex.
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Blue stragglers and the OBN phenomenon
Observational data for the hottest stars in five OB associations arereported to show that blue stragglers exhibit nitrogen overabundances.The coude spectra were taken in the ranges 3500-5400 A and 3800-4900 Aat ESO and Observatoire de Haute Provence, respectively. The surveycovered the objects HD 34656, HD 42088, HD 96715, HD 151804, HD 152233,HD 192639, HD 193524 and HD 254755, the hottest members of the Aur OB1,Gem OB1, Car OB2, Sco OB2 and Cyg OB1 associations. Five of the bluestragglers in the associations displayed nitrogen abundances. It issuggested that the massive blue stragglers experience rotation-inducedextra-mixing that brings nitrogen enhancement to the surface and keepsthe stars close to the main sequence. The rotationally-induced effectscould also explain the bimodal rotational velocity distribution of mainsequence O stars, whose lifetimes are extended by the extra mixing.
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Star-forming regions near the supernova remnant IC 443
The supernova remnant (SNR) IC 443 (3C 157), along with W28, W44, S147,and HB 21, represents a growing number of examples where SNRs appear tohave collided with nearby molecular clouds or are surrounded by denseshells of neutral hydrogen. In the case of W28, far-infraredobservations have shown that a massive, O-type star and possibly apre-main-sequence B-type star are associated with the molecular cloudand its environment. In the current study, the northern component of theIC 443 molecular cloud has been detected at 20, 27, and 93 microns bythe Far Infrared Sky Survey Experiment. The bolometric luminosity ofthis far-infrared source is about 130 solar luminosities, consistentwith the expected luminosity of a B7 V star. From the far-infrared andradio observations the energetics of this region is described andcompared with other known examples of SNR/molecular cloud associations.These findings are also discussed in the context of theoretical modelswhere SNRs trigger star-forming activity in nearby molecular clouds.
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The initial mass function for massive stars
A machine readable catalog of over 750 galactic O stars with publishedphotometry, spectral types, and luminosity classes has been compiled.The catalog is probably complete to a distance of about 2.5 kpc. Fromthis volume-limited data, the initial mass function (IMF) for stars moremassive than 20 solar masses has been derived. This IMF differs fromthat of Miller and Scalo (1979) and of Lequeux (1979), in havingproportionately more O type stars and not as steep a fall-off in numberof stars with increasing mass. Dividing the sample into stars inside andoutside the solar circle, a substantial difference in the IMF of themost massive stars is found. There are proportionally more toward thegalactic center. This gradient in the IMF may be related to the observedspace density of Wolf-Rayet stars, which are descendants of O typestars.
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Absolute Proper Motions for 117 Type 0-STARS
Not Available
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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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A catalogue of galactic O stars. The ionization of the low density interstellar medium by runaway stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974RMxAA...1..211C&db_key=AST
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A new general O type stars catalogue
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&AS...12..277G&db_key=AST
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Individual reddening laws from O type stars. I. Computation method, first results.
Not Available
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Catalogue d'etoiles O et B.
Not Available
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Photoelectric 4430 A observations of 506 O, B and A stars.
Not Available
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A Study of the i Geminorum Association.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1960ApJ...132..361H&db_key=AST
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The Law of Interstellar Reddening and Absorption.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956ApJ...124..367H&db_key=AST
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Studies in Galactic STRUCTURE.II.LUMINOSITY Classification for 1270 Blue Giant Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1955ApJS....2...41M&db_key=AST
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The Association i Geminorum.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1955ApJ...121...24C&db_key=AST
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Polarization of Stellar Radiation. III. The Polarization of 841 Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1951ApJ...114..241H&db_key=AST
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A Finding List of O and B Stars of High Luminosity.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1951ApJ...113..141N&db_key=AST
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Studies of Faint B-Type Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1950ApJ...111..495P&db_key=AST
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INHABITED SKY
