Modeling the Neutral Hydrogen Interstellar Medium: A Better Kinematic Distance Tool
An advanced approach to the kinematic distance method is developed. Themethod is applicable to second- and third-quadrant Galactic objects withknown velocities. It is based on fitting a model of the density andvelocity features in an isothermal H I disk to observed H I data. Thevelocity field of the gas is modeled with a power law for basic circularrotation, underlying noncircular motions from a two-armed density wavepattern. With a reasonable number of adjustable parameters andconstraints the model reproduces observations toward many Galacticobjects, and accurate distances are found from the modeled velocityfield. High-resolution H I spectral line data from the Canadian GalacticPlane Survey (CGPS; Taylor et al.) are used to discriminate clouds fromthe intercloud medium (the ``stratum'') for which the model is intended.The ability of the model to reproduce these data is demonstrated in one-[Tb(v)] and two- [Tb(l, v)] dimensional fits.Distances to 22 H II regions and SNRs calculated by the fitted velocityfield compare extremely well with other kinematically independentdistances.
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A high-resolution spectroscopy survey of β Cephei pulsations in bright stars
We present a study of absorption line-profile variations in early-B typenear-main-sequence stars without emission lines. We have surveyed atotal of 171 bright stars using the Nordic Optical Telescope (NOTSA),William Herschel Telescope (ING) and Coudé Auxiliary Telescope(ESO). Our sample contains 75% of all O9.5-B2.5 III-V non-emission-linestars brighter than 5.5 mag. We obtained high signal-to-noise,high-resolution spectra of the SiIII λ4560 triplet - for 125stars of our sample we obtained more than one spectrum - and examinedthese for pulsational-like line-profile variations and/or structure. Weconclude that about half of our sample stars show evidence forline-profile variations (LPV). We find evidence for LPV in about 65% ofour sample stars brighter than V=5.5. For stars with rotationalbroadening V sin i 100 km s-1, we find evidence for LPVin about 75% of the cases. We argue that it is likely that these LPV areof pulsational origin, and that hence more than half of thesolar-neighbourhood O9.5-B2.5 III-V stars is pulsating in modes that canbe detected with high-resolution spectroscopy. We detected LPV in 64stars previously unknown to be pulsators, and label these stars as newβ Cep candidates. We conclude that there is no obvious differencein incidence of (pulsational) LPV for early-B type near-main-sequencestars in binaries or in OB associations, with respect to single fieldstars.
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Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://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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Physical parameters of multiple systems like the Trapezium of early spectral types, derived from uvby-beta photometry. II.
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Physical parameters of multiple systems like the Trapezium of early spectral types, derived from uvby-beta photometry. I.
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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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Uvby-Beta Photometry of the Components of the Trapezium-Type Multiple Systems
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Uvby-beta photometry of open clusters. IV. NGC 1444, NGC 1662, NGC 2129, NGC 2169 and NGC 7209.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994RMxAA..28..139P&db_key=AST
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A preliminary compilation of DS-programme star positions
A catalog is presented of the double-star-program (DS-program) starpositions, listing right ascensions for 930 DSs and declinations for1225 DSs of the program. The positions were compiled from the observedvalues obtained between 1980 and 1987 with the meridian circles of sixUSSR observatories (the Moscow, Kazan', Kiev, Khar'kov, Odessa, andTashkent Observatories) and the Belgrade Observatory. The measurementsand the treatment of the observational material were performed using therelative method, and the FK-4 system stars were used as reference stars.
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Absolute magnitudes of B emission line stars - Correlation between the luminosity excess and the effective temperature
A new determination of the visual absolute magnitude of Be stars iscarried out. For this, a new calibration of visual absolute magnitudesof B stars of luminosity classes, V, IV, and III is first obtained froma sample of 215 stars. The absolute luminosity excess in the visual isdetermined for a sample of 49 Be stars. It is found that this excess iscorrelated with the effective temperature of the underlying stars. Awell defined correlation between this excess and the emission in thefirst two Balmer lines is established. From these results, using asimple model of circumstellar envelope, it is inferred that the zones ofthe circumstellar envelope contributing to the emission in the continuumand in the lines have to be rather small. It is also deduced that theemission measure of the envelope is correlated with the temperature ofthe central star and that the irregular photometric variations of Bestars are an envelope-opacity phenomenon.
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Empirical temperature calibrations for early-type stars
Three temperature calibrations of suitable photometric quantities havebeen derived for O and B stars. A sample of 120 stars with reliableT(eff.) determinations has been used for establishing each calibration.The different calibrations have been critically discussed and compared.Temperature determinations for 1009 program stars have been obtainedwith an accuracy of the order of 10 percent.
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Yellow evolved stars in open clusters
This paper describes a program in which Galactic cluster post-AGBcandidates were first identified and then analyzed for clustermembership via radial velocities, monitored for possible photometricvariations, examined for evidence of mass loss, and classified ascompletely as possible in terms of their basic stellar parameters. Theintrinsically brightest supergiants are found in the youngest clusters.With increasing cluster age, the absolute luminosities attained by thesupergiants decline. It appears that the evolutionary tracks ofluminosity class II stars are more similar to those of class I than ofclass III. Only two superluminous giant star candidates are found inopen clusters.
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Kinematics of Trapezium-type multiple star systems
Photographic observations and catalog data were used to investigate thekinematics of Trapezium-type multiple systems with OB primaries.Particular emphasis is placed on Orion Trapezium, and it is concludedthat observations do not disprove the hypothesis of the positivity ofthe total energy of Orion Trapezium type multiple stars. In addition,the kinematics of 15 other systems was analyzed; time-dependentdistances are plotted for the Trapezia components, showing a systematicincrease of the distance with time; linear displacement velocities ofthe components are also calculated.
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Trapezium-type multiple systems
Trapezia are detected among multiple stars with primaries of O and Bspectral types. Data from Salukvadze (1979) displaying the relationshipbetween Trapezium-type systems and associations and galactic clustersare presented. The kinematics of 15 Trapezium-type multiple systems withprimaries of O-B2 spectral classes is examined. It is observed that 14of the 15 Trapezia studied showed expansion and an example of thiseffect is provided.
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Catalog of O-B stars observed with Tokyo Meridian Circle
A catalog of the O-B stars, selected from 'Blaauw-Parenago' list andRubin's catalog, has been compiled on the FK4 system by the observationsmade with Gautier 8-inch Meridian Circle at the Tokyo AstronomicalObservatory during the period, 1971 to 1979. It contains 1059 stars andwas compiled for the future establishment of high precision propermotions of O-B stars.
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Trapezium-type multiple systems
The non-stable nature of stellar motions in Trapezium-type multiplesystems is discussed. The disintegration time of such systems is severalorders of magnitude less than the life-time of their components, andconsiderably less than the disintegration time of stellar associations.The importance of ground-based and orbital observations ofTrapezium-type systems is stressed.
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Kinematics of multiple Trapezium type systems
The kinematics of selected multiple Trapezium type systems is studied onthe basis of currently available observational data, includingphotographic records. Among the 15 systems studied, 14 exhibitexpansion. Of these, 11 have an overall expansion, while three have onecomponent far from the primary component.
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Exciting stars and the distances of the diffuse nebulae
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Observations of a Bright Blue Compact Reflection Nebula in Perseus
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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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Variable Stars in the Northern Luminous Stars Catalogues
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On the connection of Trapezium type multiple systems with associations, galactic clusters, and emission nebulae
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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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Catalog of multiple Trapezium type systems
Not Available
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Circular polarization observations of the interstellar magnetic field
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976ApJ...208..727M&db_key=AST
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On the polarizing interstellar dust
An interpretation for the parameter k in Serkowski's (1971)normalization for linear polarization is given in relation to achanging-alignment model for interstellar grains. Present observationsindicate that a correlation between k and dust size changes along theline of sight. Linear and circular polarization measurements seem to beconsistent with an absorbing material for the polarizing component ofthe interstellar grains. Polarization position-angle observations arealso analyzed.
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Catalogue of early-type stars measured in a narrow-band photometric system
A compilation of the photoelectric measurements in the Barbier-Morguleffsystem is presented. The catalogue includes data for 773 stars ofspectral type 08 to F6. 706 stars have been measured at least twice.
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