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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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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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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UBVRI photometry and polarimetry of the stars in S252 (NGC 2175). II. Interpretation.
Photoelectric UBVRI photometry and polarimetry and photographic UBVRphotometry have been used to study the stellar cluster NGC2175associated with the Hii region-molecular cloud complex Sharpless252. Thecolour excess E_B-V_ of stars in NGC2175 ranges from the foregroundcolour excess of 0.4mag up to 1.7mag. The distance modulus of S252obtained by fitting ZAMS to the colour-magnitude diagrams of NGC2175 is11.7+/-0.3mag (2.2+/-0.3kpc). The lower part of the colour-magnitudediagrams of the main cluster contains stars still contracting towardsZAMS indicating an age of the order of one million years for thecluster. The age of a small subcluster to the east of the Hii region isa few million years. High stellar polarizations up to 12% have beenobserved. The average wavelength of the maximum polarization in S252 is0.53+/-0.01μm and the polarization efficiency is near the empiricalmaximum value 3A_v_. The polarization field in S252 is regular butcannot be explained by a single magnetic field direction.
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UBVRI photometry and polarimetry of the stars in S 252 (NGC 2175). I. The observations.
Photoelectric UBVRI photometry and polarimetry and photographic UBVRphotometry of stars in the direction of the galactic H II regionSharpless 252 are reported
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Groups of stars with common motion in the Galaxy. Groups of O and B stars
Not Available
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Groups of stars with common motion in the Galaxy - Groups of B stars of luminosity classes I and II and their comparison with groups of long-period Cepheids and open clusters
In a sample of 93 stars of luminosity classes I and II, ten groups withcommon motion in space are isolated. The reality of five groups isestablished by numerical experiment. A comparison is made with groups oflong-period Cepheids and open clusters. Regularities in the distributionof groups of different objects in space are found. The reality of therotation of a star aggregate consisting of three Cepheid groups isestablished.
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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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Hot components and circumstellar grains in M supergiant syncretic binaries
Ultraviolet and infrared spectra were obtained in order to study grainsin cool star and hot star syncretic type binaries. Grains are found inonly about half of the syncretic systems. The results suggest thatgrains have not formed in many syncretic systems because of ultravioletradiation from the hot star. Circumstellar extinction could not beunambiguously detected in those systems with grains.
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Spectroscopic binary frequency among CNO stars
Radial velocities of 35 stars with carbon, nitrogen, and oxygen (CNO)anomalies in the OB spectral range have been measured. Using these newdata, it has been confirmed that the short-period spectroscopic binaryfrequency among the OBN stars is substantially larger than among the OBCstars. After allowance for the undiscovered systems, practically allstars with nitrogen anomalies belong to short-period spectroscopicbinaries, while the frequency among the OBC stars is statisticallysimilar to the frequency of normal supergiants. Among the stars withmoderate nitrogen anomalies, a frequency of short-period binaries whichranges between 50 percent (N-enhanced) and 83 percent (N-deficient) wasfound.
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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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The variation of interstellar extinction in the ultraviolet
One hundred and fifty-four reddened stars that are apparently normal inthe visible were selected from the S2/68 Ultraviolet Sky Survey. Theultraviolet data for 92 of these cannot be explained in terms of a fixedinterstellar extinction law. Between 1400 and 2740 A, the extinctioncurve for each star can be well represented by two parts; astraight-line scattering component and a Lorentzian 2200 A absorptionfeature. Independent variations are found in both parts and these cannotbe explained by photometric or spectral classification errors. Bothparts vary smoothly, implying that there is no fixed extinction law, andone star in three is found to depart from the mean law by more than 1mag at either 1500 or 2200 A. The two variations allow not only all 154stars to be explained but also anomalous stars reported by otherauthors. These are not special but merely situated towards the limits ofthe variations. A variation in the relative proportions of graphite andsilicate grains goes some way towards explaining the observations. Theprofile of the 2200 A feature is determined, the symmetrical shape isconfirmed, and the profile fits a Lorentzian very closely.
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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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The evolutionary status of OB stars with peculiar nitrogen spectra
The majority (60 percent) of OB stars exhibiting nitrogen abundancepeculiarities are members of stellar associations. The rate ofmembership is typical of O and WR stars. Bolometric magnitudes for the46 known associated peculiar OB stars (25 overabundant and 21 deficient)demonstrated that most of the anomalous stars are the brightest in theassociations. Grouping the anomalous stars in an aggregate age-classwith the next-brightest stars in the associations and then examining thecluster age reveals that nitrogen-rich OB stars are found in young andold clusters and nitrogen-poor objects are in intermediate ageassociations. Further details show that 30 solar mass OB have a nitrogenenrichment in the main sequence. Old clusters with nitrogen-rich OBstars can contain blue stragglers, which are also nitrogen-enriched.Some of the nitrogen-enriched stars are WNE progenitors or are a branchof a late evolutionary phase. Finally, nitrogen-rich OB stars areusually hotter than nitrogen-poor OB stars.
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Ultraviolet interstellar extinction toward 1367 stars observed by ANS
Five-band UV photometry is used to investigate the character ofinterstellar extinction toward 1367 stars of spectral type B3 andearlier, with observations producing a galactic average of 5.11, 4.78,6.52, 4.10 and 1.95 at 1550, 1800, 2200, 2500, and 3300 A, respectively.Differences in the strengths of the UV extinction features of thesestars appear to be independent, since objects with either strong or weak2200 A extinction can have strong, normal or weak far-UV extinction.Further investigation reveals that some of the deviant stars areembedded in localized regions whose average extinction curves divergedramatically from the galactic mean. The anomalous extinction of theseregions attests to localized inhomogeneities in the UV characteristicsof interstellar dust. Because the evaluation of UV extinction toward aparticular star would be more accurate if based on the average curve ofthe region immediately surrounding that star rather than that of theentire Galaxy, it is recommended that the galactic average presented beused with caution to correct astronomical data of individual objects.
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H I absorption measurements of seven low-latitude pulsars
The neutral hydrogen absorption spectra of seven low-latitude pulsarsare measured and used to estimate their distances and mean electrondensities along the lines of sight. Calculations made in terms of theSchmidt (1965) galactic rotation model on the basis of the spectralobservations made using the Arecibo 305-m telescope indicate thatpulsars 1919+21 and 1929+10 are within 1.5 kpc of the earth and pulsars2016+28 and 2020+28 are further than 1.3 kpc. Considerations ofabsorption spectra, dispersion and rotation measurements and Stromgrenspheres along the line of sight indicate that PSR 0525+21 isapproximately as distant as the Crab Nebula pulsar (2 kpc), while PSR0540+23 is more distant. Absorption in PSR 0611+22 is found to besimilar to that of the nearby supernova remnant IC 443, but theresemblance may be due to the small change of velocity with distance inthe direction of the anticenter. The dispersion measured and distancesof 32 known pulsars indicates extended regions of enhanced electrondensity in the inner part of the Galaxy and the Gum Nebula, withelectron density elsewhere generally between 0.02 and 0.03/cu cm.Possible sources of the ionization include stellar UV radiation.
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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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Correlations of the band at 2175 A with other interstellar features
Using published spectrophotometric and filter-photometric data from theOAO-2 and TD-1A satellites, equivalent widths of the ultraviolet 2175-Aband are determined for 194 stars. This list of data is used to studycorrelations between the 2175-A band and the diffuse 4430-A, 5780-A, and5797-A bands as well as the hydrogen column density and the equivalentwidth of the sodium D2 line.
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The OBn and OBc stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976ApJ...205..419W&db_key=AST
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The correlation between the ultraviolet lambda 2200 feature and the diffuse lambda 4430 band.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975MNRAS.173..237N&db_key=AST
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Wavelength dependence of interstellar polarization and ratio of total to selective extinction
A multichannel polarimeter-photometer which uses dichroic filters toseparate the (UBVR) spectral regions is described. The instrument wasused with a 24-inch rotatable tube telescope for polarimetricobservation of nearby stars. Polarization data for 364 nearby stars aretabulated, together with the wavelength dependence of linear andinterstellar polarization.
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Wavelength dependence of polarization. XXVI. The wavelength of maximum polarization as a characteristic parameter of interstellar grains.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..581C&db_key=AST
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Calcium II K-line profiles in front of distant OB stars.
Abstract image available at:http://adsabs.harvard.edu/abs/1972A&A....17..425R
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Some Spectroscopic Characteristics of the OB Stars: an Investigation of the Space Distribution of Certain OB Stars and the Reference Frame of the Classification
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJS...23..257W&db_key=AST
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On the Inferred Presence of Balmer Emission Features in the Spectra of Early-Type Stars. II. MK Spectral Classification and Balmer-Line Photometry
Not Available
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Some New Variables in Nearby Associations and Galactic Clusters
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1967ApJS...14..301H&db_key=AST
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On Beta Cephei Stars: a Search for Beta Cephei Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1967ApJS...14..263H&db_key=AST
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Catalogue d'etoiles O et B.
Not Available
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INHABITED SKY
