Automatic Detection of Expanding H I Shells in the Canadian Galactic Plane Survey Data
The identification of expanding H I shells is difficult because of theirvariable morphology. In this paper we present an automatic detector forH I shells, based on the more stable dynamical characteristics ofexpanding bubbles with radii <40 pc. The detection is performed intwo stages. First, artificial neural networks are trained to recognizethe dynamical signature of an expanding bubble in the velocity spectraof 21 cm data. The second stage consists of subsequent validations basedon the potential bubble's morphology. The technique is tested on 11known bubbles, and 10 of them are successfully detected. Conducting asystematic detection on a 48deg×9deg regionin the Perseus arm, we obtain 7100 detections with spatial distributionfollowing the stellar distribution of the Galactic disk. The estimatedradius and expansion velocity distributions for objects with R<=10 pcagree with the distributions predicted by models of adiabaticallyexpanding bubble populations. The fraction of the Perseus arm volumeoccupied by the detected objects, which can be interpreted as the smallbubbles' contribution to the Galactic porosity Q, is calculated toQR<40pc=0.007+0.025-0.003. Four newbubble cases and eight serious candidates, related to known progenitors,are proposed.
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A Galactic O Star Catalog
We have produced a catalog of 378 Galactic O stars with accuratespectral classifications that is complete for V<8 but includes manyfainter stars. The catalog provides cross-identifications with othersources; coordinates (obtained in most cases from Tycho-2 data);astrometric distances for 24 of the nearest stars; optical (Tycho-2,Johnson, and Strömgren) and NIR photometry; group membership,runaway character, and multiplicity information; and a Web-based versionwith links to on-line services.
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On the Origin of the High-Ionization Intermediate-Velocity Gas toward HD 14434
We present Far-Ultraviolet Spectroscopic Explorer and Space TelescopeImaging Spectrograph observations of high-ionization interstellarabsorption toward HD 14434 (l=135.1d, b=-3.8d d~2.3 kpc), an O5.5 V starin the Perseus OB1 association. Intermediate-velocity interstellar Si IVand C IV absorption is present at VLSR=-67 km s-1,while low-ionization gas associated with the Perseus arm is detected atabout -50 km s-1. Neither N V nor O VI is detected atVLSR=-67 km s-1, although Al III and Fe III,tracers of warm ionized gas, are seen. The high-ion column densities inthe -67 km s-1 component are log[N(CIV)]=13.92+/-0.02cm-2, log[N(SiIV)]=13.34+/-0.02 cm-2,log[N(NV)]<=12.65 cm-2, and log[N(OVI)]<=13.73cm-2 (3 σ limits). The observed C IV/Si IV ratio of3.8+/-0.3 in this intermediate-velocity cloud (IVC) is similar to theGalactic average (4.3+/-1.9). Our analysis of the Si IV and C IV linewidths yields a temperature of T~10,450+/-3400 K for this component. Atthis low temperature, neither Si IV nor C IV can be produced viacollisions. We investigate several photoionization models to explain theintermediate-velocity Si IV and C IV absorption toward HD 14434.Photoionization models employing cooling of a hot (T~106 K)diffuse plasma as the source of ionizing radiation reproduce theobserved properties of the IVC toward HD 14434 quite well. The hotplasma responsible for the ionizing radiation in these models may beattributed to hot gas contained in a supershell in or near the Perseusarm or from a more generally distributed hot ionized medium.Based on observations made with the NASA/ESA Hubble Space Telescope,obtained from the data archive at the Space Telescope Science Institute.STScI is operated by the Association of Universities for Research inAstronomy, Inc., under the NASA contract NAS 5-26555.
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Radio observations of interstellar bubbles surrounding massive stars}
We show radio continuum observations of the WR ring nebulae around WR101 and WR 113 obtained using the VLA and HI 21 cm line data of theinterstellar bubble around the O type stars BD +24 deg 3866 and BD+25deg 3952 obtained with the DRAO Synthesis Telescope. We review previousradio continuum and HI line results toward WR and O-type stars.
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On the Absolute Magnitudes of the O Stars
The conclusion published in 1992 by Garmany & Stencel from a studyof northern OB associations, that the absolute magnitudes of the O starsshow ``a large scatter ... intrinsic to the classification system,'' iscritically examined. It is found that the differences between theirderived absolute magnitudes of O stars and this author's 1973calibration exhibit large systematic effects in several associations,ranging from -0.74 to +1.02 mag with substantially smaller dispersions.Of course, when these results are combined, the scatter equals the fullrange of the systematic effects. To investigate the possibility ofdistance errors, the Garmany & Stencel B0-B2.5 stars in the sameassociations are subjected to the same analysis. The results for the Bstars show no significant systematic differences, eliminating errors inthe association distances derived by Garmany & Stencel from the Bstars as the source of the differences found for the O stars. It isnoteworthy that the dispersions in the absolute magnitudes of the Bstars within a given association are similar to or larger than those ofthe O stars. An examination of the distribution on the sky of the starsshows that the O and B stars in the discrepant associations aregenerally not colocated; such was already known to be the case for theimportant Perseus OB1 association. It is suggested that despite theirefforts to improve them, significant problems remain with theassociation memberships adopted by Garmany & Stencel; the relativelysmall dispersions of the O star absolute magnitudes even in thediscrepant cases indicate that they belong to different, usually moredistant associations near the lines of sight to the B associations withwhich they have been mistakenly connected. Several individual cases ofunrecognized multiple systems and classification errors are also foundin the Garmany & Stencel sample. It is concluded that the scatter inthe absolute magnitudes of the O stars is not as large as found byGarmany & Stencel, and not larger than that of the B stars.
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A Search for Interstellar Bubbles surrounding Massive Stars in Perseus OB1
We have examined the interstellar medium in the vicinity of massivestars belonging to the Per OB1 association based on neutral hydrogen 21cm observations obtained with the 100 m radio telescope at Effelsberg(HPBW=8.4′) and complementary data from the Leiden-Dwingeloo H ISurvey (HPBW=36'). The higher angular resolution H I observationsallowed us to discover probable wind-blown bubbles related to fourmassive stars in the association, namely, HD 14442 [O5n(f)p], HD 14947[O5If+], HD 13022 [O9.5II-III((n))], and HD 13338 [O9.5V], while thedetection of a wind-blown bubble associated with HD 16691 [O5If+] isless conclusive. A clear H I shell coincident in position with two B1IIIstars (HD 15233 and Hilt 311) was also detected. Some of these featuresalso have infrared and/or molecular counterparts. The energetics of thestructures related to each massive star is analyzed. The new H Iinterstellar bubbles appear to be similar to the ones found surroundingWolf-Rayet stars and other Of stars. The large-scale maps obtained usingthe lower angular resolution H I data show that most of the early-typestars belonging to Per OB1 are placed in a region of low H I emission.The association could have blown a H I shell of about 350×550 pcin size. This large H I shell has an infrared counterpart.
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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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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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Galactic OB associations in the northern Milky Way Galaxy. I - Longitudes 55 deg to 150 deg
The literature on all OB associations was reviewed, and their IRAS pointsource content was studied, between galactic longitude 55 and 150 deg.Only one third of the 24 associations listed by Ruprecht et al. (1981)have been the subject of individual studies designed to identify thebrightest stars. Distances to all of these were recomputed using themethod of cluster fitting of the B main sequence stars, which makes itpoossible to reexamine the absolute magnitude calibration of the Ostars, as well as for the red supergiant candidate stars. Also examinedwas the composite HR diagram for these associations. Associations withthe best defined main sequences, which also tend to contain very youngclusters, referred to here as OB clusters, have extremely few evolved Band A or red supergiants. Associations with poorly defined mainsequences and few OB clusters have many more evolved stars. They alsoshow an effect in the upper HR diagram referred to as a ledge byFitzpatrick and Garmany (1990) in similar data for the Large MagellanicCloud. It is suggested that the differences in the associations are notjust observational selection effects but represent real differences inage and formation history.
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Distribution and motions of OB stars in the direction of H and KHI Perseus.
Not Available
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The upper main sequence of OB associations. II - The single-lined O stars: Spectral classification of northern stars and lines of C and N
The properties of the stars close to the upper main sequence of OBassociations are studied in order to provide constraints on the theoryof evolution of massive stars. The spectral classification of northernsingle-lined O stars, most of them belonging to the associations CygOB1, Per OB1 and Cas OB6, is presented. The classification is performedaccording to Conti's classification scheme for O stars, amended byMathys (1988). The behavior of the C and N lines of the stars isstudied, in order to determine whether CNO-processed material is visibleat their surface. Three new ON stars have been discovered: BD + 36 deg4063 (O9.71), HD 13268 (O8V), and HD 110360 (O7V).
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Multivariate statistical analysis of OB stars around H and Chi Persei
A multivariate statistical analysis has been carried out on 49 OB starshaving radial velocities and distance moduli in a field around h and ChiPersei. A hierarchical cluster analysis, combined with discriminantanalysis, has revealed the probable presence of two groups: onebelonging to the Perseus spiral arm (mean distance 2100 pc), the otherlocated at a distance of 1150 pc. Comparison of the difference in meanradial velocities of the groups with the value predicted by the formulaof Oort also supports the result obtained.
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Evidences for a bifurcation in massive star evolution. The ON-blue stragglers
The effects of rotationally induced mixing on the evolution of massivestars is examined. The mechanism considered results from baroclinicinstability due to differential rotation which produces two-dimensionalmeteorological-like turbulent motions; the mixing is produced by thesmall-scale three-dimensional tail of the turbulent spectrum. The modelsshow that, due to the high viscosity, the diffusion coefficient would besufficiently large to mix most massive stars during their MS lifetime.However, below some critical rotation velocity, diffusive mixing isefficiently prevented by the mu-gradient. Below critical rotiation, theevolution is essentially classical with unmodifed redwards tracks in theHR diagram. Above critical rotation, the evolutionary tracks go upwardsand bluewards, very close to those of fully homogeneous evolution.Comparisons with observations indicate that turbulent diffusion canaccount for the ON stars lying close to the zero-age sequence.
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The interstellar 217 NM band - A third catalogue of equivalent widths
A catalog of equivalent widths of the 217 nm interstellar absorptionband as well as other parameters characterizing the extinction curve inthe ultraviolet has been compiled for 790 O and B stars. A relativelytight correlation between the equivalent width of the 217 nm band andE(B-V) indicates that the absorber of this band is connected with thepopulation of larger interstellar grains responsible for the visualextinction. The parameter characterizing the amount of extinction in thefar UV is only weakly correlated with E(B-V), a result in accord withthe assumption that a second population of very small grains causes therapid increase of the far-UV extinction.
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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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The local system of early type stars - Spatial extent and kinematics
Published uvby and H-beta photometric data and proper motions arecompiled and analyzed to characterize the structure and kinematics ofthe bright early-type O-A0 stars in the solar vicinity, with a focus onthe Gould belt. The selection and calibration techniques are explained,and the data are presented in extensive tables and graphs and discussedin detail. The Gould belt stars of age less than 20 Myr are shown togive belt inclination 19 deg to the Galactic plane and node-lineorientation in the direction of Galactic rotation, while the symmetricaldistribution about the Galactic plane and kinematic properties (purecircular differential rotation) of the belt stars over 60 Myr oldresemble those of fainter nonbelt stars of all ages. The unresolveddiscrepancy between the expansion observed in the youngest nearby starsand the predictions of simple models of expansion from a point isattributed to the inhomogeneous distribution of interstellar matter.
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Distribution of OB stars and absorbing matter in the region of the association per OB1
The results are given of spectrophotometric investigation of 86 OB starsin the region of the association Per OB1. The blue (4000-4800 A)absolute spectrophotometric gradients, the color excesses, and thedistances of these stars were determined. Analysis of the obtainedresults makes it possible to draw the following conclusions: (1) thecenters of the OB clusters h and Chi Per apparently have a separation ofabout 1000 parsec along the line of sight; (2) the absorbing matter inthe direction of the association Per OB1 is concentrated in the regionsoccupied by the OB stars.
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A comparison of UV extinction in SCO OB2 and Per OB1 associations
The paper presents a comparison of extinction curves constructed basedon consecutive color excesses in optical and UV wavelength ranges. TheANS photometric data make it possible to construct reliable averageextinction curves for Sco OB2 and Per OB1 associations. The resultingcurves show large differences in the UV, up to 1.5 m in the 2200 hump.The far UV extinction, shortward of 2000 A, seems to be independent ofE(B-V) in every association. Then, the presence of at least 2populations of grains in the interstellar space seems to be fullyconfirmed. Several stars with strongly enhanced far UV extinction,probably caused by a circumstellar material, are also reported.
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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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Four-color and H-beta photometry for O-A0 type stars in three regions near the galactic equator
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1982A&AS...49..561W&db_key=AST
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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 spectrophotometric survey of stars along the Milky Way. IV
In the present paper a catalogue of spectrophotometric quantities,spectral types, monochromatic magnitudes and colour equivalents is givenfor all stars brighter than the magnitude m4400 = 10.5 in aregion of the Milky Way in Perseus. No absorption is found for starscloser than about r = 100 pc. The absorbing clouds are situated atdistances closer than 1 kpc and at about 2.5 kpc in the local arm andthe Perseus arm, respectively. The space between the two arms is freefrom absorption. It is also concluded that the Perseus arm continuesbeyond l = 140 deg, containing not only hydrogen gas but also dust to atleast l = 150 deg), while the content of OB stars decreases abruptly atl = 140 deg.
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A general O type stars catalogue. Third edition. Magnetic tape.
Abstract image available at:http://adsabs.harvard.edu/abs/1976A&AS...26..273G
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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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The space distribution of the O stars in the solar neighborhood.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973AJ.....78.1067W&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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Catalogue d'etoiles O et B.
Not Available
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La mesure des vitesses radiales au prisme objectif.
Not Available
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Mesures de vitesses radiales au spectrographe C de l'Observatoire de Haute Provence
Not Available
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INHABITED SKY
