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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X-ray source populations in the Galactic plane
We present the first results from the XMM-Newton Galactic Plane Survey(XGPS). In the first phase of the programme, 22 pointings were used tocover a region of approximately 3 deg2 between 19° and22° in Galactic longitude and +/-0.6° in latitude. In total wehave resolved over 400 point X-ray sources, at >= 5?significance, down to a flux limit of ~2 × 10-14 ergs-1cm-2 (2-10 keV). The sources exhibit a verywide range of spectral hardness, with interstellar absorption identifiedas a major influence. The source populations detected in the soft (0.4-2keV) band and hard (2-6 keV) band show surprisingly little overlap. Themajority of the soft sources appear to be associated with relativelynearby stars with active stellar coronae, judging from their highcoincidence with bright stellar counterparts.The combination of the XGPS measurements in the hard X-ray band with theresults from earlier surveys carried out by ASCA and Chandra reveals theform of the low-latitude X-ray source counts over 4 decades of flux. Itappears that extragalactic sources dominate below ~10-13 ergs-1cm-2 (2-10 keV), with a predominantly Galacticsource population present above this flux threshold. The nature of thefaint Galactic population observed by XMM-Newton remains uncertain,although cataclysmic variables and RS CVn systems may contributesubstantially. XMM-Newton observes an enhanced surface brightness in theGalactic plane in the 2-6 keV band associated with Galactic ridge X-rayemission (GRXE). The integrated contribution of Galactic sources plusthe breakthrough of extragalactic signal accounts for up to 20 per centof the observed surface brightness. The XGPS results are consistent withthe picture suggested from a deep Chandra observation in the Galacticplane, namely that the bulk of the GRXE is truly diffuse.
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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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The total-to-selective extinction ratio determined from near IR photometry of OB stars
The paper presents an extensive list of the total to selectiveextinction ratios R calculated from the infrared magnitudes of 597 O andB stars using the extrapolation method. The IR magnitudes of these starswere taken from the literature. The IR colour excesses are determinedwith the aid of "artificial standards" - Wegner (1994). The individualand mean values of total to selective extinction ratios R differ in mostcases from the average value R=3.10 +/-0.05 - Wegner (1993) in differentOB associations. The relation between total to selective extinctionratios R determined in this paper and those calculated using the "methodof variable extinction" and the Cardelli et al. (1989) formulae isdiscussed. The R values presented in this paper can be used to determineindividual absolute magnitudes of reddened OB stars with knowntrigonometric parallaxes.
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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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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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Millimetre observations of southern translucent clouds
Millimetre emission line observations of ^12^CO J=1-0 are presented fora sample of translucent molecular clouds previously studied by opticalabsorption lines towards background stars. The CO maps provideinformation on the extent, structure, mass and kinematics of theregions. In some clouds, the emission is characterized by a singlecomponent which does not vary much across the region. In other cases,multiple close-lying components or sheets are found, which may vary in aself-similar manner across the cloud. None of the clouds is close tosimple virial equilibrium. Sensitive searches for ^13^CO and C^18^OJ=1-0 emission have been made towards the stellar positions. C^18^O hasbeen detected in only 5 clouds, most of which have extinctions well inexcess of 2 mag. The inferred ^13^CO/C^18^O abundance ratios range from7-25, and the lower limits from >13 to >35. These values are asmuch as five times larger than the overall interstellar([^13^C].[^16^O])/([^12^C] .[^18^O]) ratio, suggesting thatisotope-selective photodissociation plays a role in at least some of theclouds. Searches for other molecules at millimetre wavelengths have beenmade for a few of the best characterized clouds. Surprisingly, noemission was detected from the C_2_H or C_3_H_2_ molecules, even thoughthe abundances of diatomic C_2_ and CH are quite large. On the otherhand, the abundance of HCO^+^ appears comparable to that found in denserclouds, and the abundance of HCN may be up to an order of magnitudelarger than the predictions of models in two clouds.
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Chemical transitions for interstellar C2 and CN in cloud envelopes
Observations were made of absorption from CH, C2, and CN towardmoderately reddened stars in Sco, OB2, Ceo OB3, and Taurus/Auriga. Forthese directions, most of the reddening is associated with a singlecloud complex, for example, the rho Ophiuchus molecular cloud, and as aresult, the observations probe moderately dense material. When combinedwith avaliable data for nearby directions, the survey provides the basisfor a comprehensive analysis of the chemistry for these species. Thechemical transitions affecting C2 and CN in cloud envelopes wereanalyzed. The depth into a cloud at which a transition takes place wascharacterized by tauuv, the grain optical depth at 1000 A.One transition at tauuv approx. = 2, which arises from, theconversion of C(+) into CO, affects the chemistries for both moleculesbecause of the key role this ion plays. A second one involvingproduction terms in the CN chemistry occurs at tauuv ofapprox. = 3; neutral reactions which C2 and CH is more important atlarger values for tauuv. The transition fromphotodissociation to chemical destruction takes place attauuv approx. = 4.5 for C2 and CN. The observational data forstars in Sco OB2, Cep OB3, and Taurus/Auriga were studied with chemicalrate equations containing the most important production and destructionmechanisms. Because the sample of stars in Sco OB2 includes sight lineswith Av ranging from 1-4 mag, sight lines dominated byphotochemistry could be analyzed separately from those controlled bygas-phase destruction. The analysis yielded values for two poorly knownrate constants for reactions involved in the production of CN; thereactions are C2 + N yields CN + C and C(+) + NH yields all products.The other directions were analyzed with the inferred values. Thepredicted column densities for C2 and CN agree with the observed valuesto better than 50%, and in most instances 20%. When combining theestimates for density and temperature derived from chemical modeling andmolecular excitation for a specific cloud, such as the rho Ophiuchusmolecular cloud, the portion of the cloud envelope probed by C2 and CNabsorption was found to be in pressure equilibrium.
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CH(+) in the interstellar medium
This paper describes observations of interstellar CH(+) along the linesof sight to O and B stars with E(B-V)s up to +1.13. Along some lines ofsight with strong detections of CH(+), we find distinct radial velocityshifts between the CH(+) lines and other neutral species, such as Ca Iand CH. The shifts are small but are predicted by shock models of CH(+)formation in which the shock is inclined with respect to the observer.We have also found no column densities exceeding approximately1013.8/sq cm. When these data are examined along with theother CH(+) data collected from the literature, the previously seentendency of CH(+) column density to increase with E(B-V) does notcontinue beyond reddenings of about +0.6. These findings offer supportto the shock model of CH(+) formation for at least some lines of sight.
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Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
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Interstellar C2, CH, and CN in translucent molecular clouds
Optical absorption-line techniques have been applied to the study of anumber of translucent molecular clouds in which the total columndensities are large enough that substantial molecular abundances can bemaintained. Results are presented for a survey of absorption lines ofinterstellar C2, CH, and CN. Detections of CN through the A 2Pi-X2Sigma(+) (1,O) and (2,O) bands of the red system are reported andcompared with observations of the violet system for one line of sight.The population distributions in C2 provide diagnostic information ontemperature and density. The measured column densities of the threespecies can be used to test details of the theory of molecule formationin clouds where photoprocesses still play a significant role. The C2 andCH column densities are strongly correlated with each other and probablyalso with the H2 column density. In contrast, the CN column densitiesare found to vary greatly from cloud to cloud. The observations arediscussed with reference to detailed theoretical models.
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Additional Variable Stars in the Northern Luminous Stars Catalogues
Not Available
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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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A survey of interstellar neutral potassium. I - Abundances and physical conditions in clouds toward 188 early-type stars
Observations of interstellar absorption in the resonance doublet 7664,7698 A of neutral potassium toward 188 early-type stars at a spectralresolution of 8 km/s are reported. The 7664 A line is successfullyseparated from nearly coincident telluric O2 absorption for all but afew of the 165 stars for which K I absorption is detected, makingpossible an abundance analysis by the doublet ratio method. Therelationships between the potassium abundances and other atomicabundances, the abundance of molecular hydrogen, and interstellarreddening are investigated.
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Intermediate-band photometry in the open cluster NGC 6664
Four-color and H-beta photometry is given for early-type stars in theopen cluster NGC 6664. From these data, the true distance modulus isfound to be 10.7 and the reddening is found to range from E/b y) = 0.48to 0.63 across the cluster. The distance modulus agrees well with somevalues from the literature, but the present color excesses are about 0.1mag larger than published values. There are two or perhaps three bluestragglers in the cluster, and its age is estimated to be 46 millionyears.
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Thirteen Stars with Bright Hα
Abstract image available at:http://adsabs.harvard.edu/abs/1981PASP...93..129B
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DDO Observations of Southern Stars
Not Available
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Infrared photometry of southern early-type stars
The paper presents infrared photometry tied to the JHKL (1.2-3.5microns) broadband photometric system for 229 southern early-type stars.To determine data for stars of low reddening intrinsic visual-IR colorindices were used; the E(V-K)/E(B-V) diagram was applied to evaluate theratio of total selective extinction. A mean value of R = 3.12 plus orminus 0.05 was found for stars close to the galactic plane, but a highervalue of R (about 4.0) applies to the Orion and Sco-Oph regions.Infrared two-color diagrams were used to investigate the occurrence ofinfrared excess emission in different classes of shell star; no excesseswere found for supergiants or Of stars. It is concluded that theanomalous position HD 164740 in the two-color diagrams is produced bystrong infrared excess and not by a peculiar extinction law.
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A comparison of optical and radio wavelength observations of CH in the diffuse interstellar medium
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJ...224..125L&db_key=AST
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Infrared colors and the diffuse interstellar bands
Broad-band infrared photometric measurements have been gathered for 105stars which exhibit diffuse interstellar bands in their spectra. Allnormal stars obey a single reddening law, and a value of R equal to 3.08+ or - 0.15 is derived. This value is consistent with other recentdeterminations of R. The diffuse band indicators, the central depth ofthe 4430-A feature and the equivalent widths of the 5780-A and 6284-Afeatures, show as large a scatter with the infrared color excesses asthey do with E(B - V). No single-valued relation between the colorexcesses and the diffuse band strengths appears to exist. This castsdoubt on whether dust grains which produce the visual and infraredextinctions are the carriers for the diffuse interstellar features.
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Optical interstellar lines in dark clouds.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973ApJ...186..149C&db_key=AST
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Etude de la structure galactique a partir d'observations DU calcium interstellaire.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&A....22...69C&db_key=AST
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Photometric Variability of the Wolf-Rayet Star CV Serpentis
Not Available
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The space distribution and kinematics of supergiants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..602H&db_key=AST
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Scanner Observations of λ 4430
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966ApJ...144..921W&db_key=AST
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Observed Variations in the Law of Interstellar Reddening.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1962ApJ...136..100W&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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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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INHABITED SKY
