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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Distances and Metallicities of High- and Intermediate-Velocity Clouds
A table is presented that summarizes published absorption linemeasurements for the high- and intermediate-velocity clouds (HVCs andIVCs). New values are derived for N(H I) in the direction of observedprobes, in order to arrive at reliable abundances and abundance limits(the H I data are described in Paper II). Distances to stellar probesare revisited and calculated consistently, in order to derive distancebrackets or limits for many of the clouds, taking care to properlyinterpret nondetections. The main conclusions are the following. (1)Absolute abundances have been measured using lines of S II, N I, and OI, with the following resulting values: ~0.1 solar for one HVC (complexC), ~0.3 solar for the Magellanic Stream, ~0.5 solar for a southern IVC,and ~solar for two northern IVCs (the IV Arch and LLIV Arch). Finally,approximate values in the range 0.5-2 solar are found for three moreIVCs. (2) Depletion patterns in IVCs are like those in warm disk or halogas. (3) Most distance limits are based on strong UV lines of C II, SiII, and Mg II, a few on Ca II. Distance limits for major HVCs aregreater than 5 kpc, while distance brackets for several IVCs are in therange 0.5-2 kpc. (4) Mass limits for major IVCs are0.5-8×105 Msolar, but for major HVCs theyare more than 106 Msolar. (5) The Ca II/H I ratiovaries by up to a factor 2-5 within a single cloud, somewhat morebetween clouds. (6) The Na I/H I ratio varies by a factor of more than10 within a cloud, and even more between clouds. Thus, Ca II can beuseful for determining both lower and upper distance limits, but Na Ionly yields upper limits.
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Catalogue of H-alpha emission stars in the Northern Milky Way
The ``Catalogue of Stars in the Northern Milky Way Having H-alpha inEmission" appears in Abhandlungen aus der Hamburger Sternwarte, Band XIin the year 1997. It contains 4174 stars, range {32degr <= l() II< 214degr , -10degr < b() II < +10degr } having the Hαline in emission. HBH stars and stars of further 99 lists taken from theliterature till the end of 1994 were included in the catalogue. We givethe cross-identification of stars from all lists used. The catalogue isalso available in the Centre de Données, Strasbourg ftp130.79.128.5 or http://cdsweb.u-strasbg.fr and at the HamburgObservatory via internet.
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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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Catalogue of stars in the northern Milky Way having H-alpha in emission
Not Available
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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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Distance to the anti-center shell
High-resolution, high-sensitivity echelle spectra have been obtainedtowards early-type stars located within the boundaries of theAnti-Center Shell (ACS), an anomalous velocity H I structure in theanticenter region of the Galaxy. The observations indicate that theshell is certainly more distant than 500 pc, and quite possibly moredistant than 2500 pc. No anomalous velocity C II absorption featureswere detected. These results support the hypothesis that the ACS is theresult of collision of high-velocity clouds with the Galactic H I disk.
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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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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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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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A Catalogue of H II Regions.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1959ApJS....4..257S&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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