Stellar tracers of the Cygnus Arm. II. A young open cluster in Camelopardalis OB3
Context: Cam OB3 is the only defined OB association believed to belongto the outer Galactic arm or Cygnus arm. Very few members have beenobserved and the distance modulus to the association is not well known.Aims: We attempt a more complete description of the population of CamOB3 and a better determination of its distance modulus. Methods: Wepresent uvby photometry of the area surrounding the O-type starsBD +56°864 and LS I +57°138, finding a clearsequence of the early-type stars that define an uncatalogued opencluster, which we call Alicante 1. We also present spectroscopy of starsin this cluster and the surrounding association. Results: From thespectral types for 18 very likely members of the association and UBVphotometry found in the literature, we derive individual reddenings,finding a extinction law close to standard and an average distancemodulus DM = 13.0 ± 0.4. This value is in excellent agreementwith the distance modulus to the new cluster Alicante 1 found by fittingthe photometric sequence to the ZAMS. In spite of the presence ofseveral O-type stars, Alicante 1 is a very sparsely populated opencluster, with an almost total absence of early B-type stars.Conclusions: Our results definitely confirm that Cam OB3 is located onthe Cygnus arm and identify the first open cluster known to belong tothe association.Partially based on observations collected at the 2.2-m telescope (CalarAlto, Spain), the Isaac Newton Telescope (La Palma, Spain) andObservatoire de Haute Provence (CNRS), France.
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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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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Interstellar Extinction in the Direction of the Association Cam OB3
Interstellar extinction is investigated in a 1.5 square degree area atthe Galactic equator ({\msf ℓ} = 146\degr, l b = +2.6\degr) inCamelopardalis, in the direction of the association Cam OB3. The studyis based on photometric classification, interstellar extinction anddistance determination of 1300 stars down to 15.5 mag. We find that theinterstellar dust in this direction is concentrated mostly between 150pc and 1 kpc, i.e. in the Orion spiral arm. There is no dust and O--Bstar concentration at the expected distance of the Perseus arm. Anincrease of the extinction and of the number of early-type stars isobserved at {\msf >}3.3 kpc. These features may be tracers of theOuter spiral arm. The Cam OB3 association at 4.23 kpc should also belocated within this arm.
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Stellar tracers of the Cygnus Arm. I. Spectroscopic study of bright photometric candidates
We present medium-resolution spectroscopy of a sample of stars in thesecond Galactic quadrant selected from the literature because theircolours suggest that they are moderately-reddened early-type stars atvery large distances. From the derived spectral types and observedcolours, we calculate distances to all these objects. For a sizablefraction of our sample, we find distances well in excess of what isexpected for Perseus Arm objects, even allowing for rather generouserrors. In the interval l=150degr -180degr , there is a large number ofobjects with distances in excess of 4 kpc, which are likely tracing theOuter or Cygnus Arm. In particular, we find that the association Cam OB3is placed on this Arm. Based on our results, the extent and definitionof the associations Cas OB4 and Aur OB2 need to be reevaluated.Based on observations made at Observatoire de Haute Provence (CNRS),France.
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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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Interstellar extinction law near the Galactic equator along the Camelopardalis, Perseus and Cassiopeia border
The interstellar reddening law is investigated along the Galacticequator near the Cam, Per and Cas border. We used seven-color photometryof O-B5 stars in the Vilnius photometric system in the optical range,photometry of the ANS orbiting observatory in the ultraviolet range andbroad-band color indices V- K in the infrared. In the optical range(345-660 nm) the interstellar reddening law is found to be nearlynormal. In the ultraviolet wavelengths shorter than the 330 nm ANSpassband, the extinction is found to be slightly larger than theaverage. Some stars, for example HD 24432, exhibit much strongerultraviolet extinction which is well seen already in the 345 nm passbandof the Vilnius system. However, such stars are rare. The ratio R =A_V/EB-V is found to be 2.9, i.e., it is slightly smallerthan the normal. This is confirmed by the study of the wavelength ofmaximum polarization of reddened stars in the area. Both the ultravioletanomaly and the smaller R value are in good agreement with the Cardelliet al. (\cite{carcm88}) prediction. We conclude that in the investigatedarea it is safe to use normal ratios of color excesses to calculatereddening-free Q-parameters for the classification of stars fromphotometric data in the optical spectral range.
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Properties of galactic B[e] supergiants. I. CI Camelopardalis
We present a study of the high-resolution (R=60 000) optical spectrum ofthe B[e] supergiant CI Cam obtained 4 years after its all-wavelengthoutburst. The profiles of most of the emission lines show atriple-peaked structure, an effect previously not observed. The Na ID-lines clearly have 2 interstellar absorption components, suggestingthat the system is most probably located within the Perseus arm at adistance of le 3 kpc. Uncertainties of the distance toward the object,its luminosity, and physical parameters of the circumstellar disk arediscussed. Simple observational tests are suggested to clarify theseissues.
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Interstellar Extinction Along the Camelopardalis and Perseus Border
Interstellar extinction in a ~ 100 sq. degree area at theCamelopardalis and Perseus border is investigated. The study is basedon the results of photoelectric photometry of 455 stars in theseven-color Vilnius photometric system published earlier. The nearest100 stars with Hipparcos parallaxes show that the extinction starts togrow at a distance of 110--150 pc. At a distance of 1 kpc theextinction A_V is within 1.2 and 2.4 mag. At larger distances theextinction determination is affected by the limiting magnitude effect.At distances >1.5 kpc a number of O--B stars with the extinctionsbetween 2 and 4 mag are found.
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Photometry and Classification of Stars Along the Camelopardalis and Perseus Border
Seven-color photometry in the Vilnius system for 309 stars down to 12.5mag in the area along the galactic equator near the Camelopardalis andPerseus border is presented. Photometric spectral and luminosity classesof the stars are determined.
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Spectroscopy and photometry of the emission-line B-type stars AS 78 and MWC 657
We present the results of low- and high-resolution spectroscopic andmulticolour photometric observations of two early-type emission-linestars, AS 78 and MWC 657. Theywere identified by Dong & Hu (\cite{dong}) with the IRAS sources03549+5602 and 22407+6008, respectively, among many other sourcesdisplaying a very strong infrared excess, V-[25] >= 8 mag AS 78 isrecognized as a photometric variable for the first time. A large near-IRexcess radiation is detected in AS 78 and confirmed by new,higher-quality, data for MWC 657. Significant variations in the Balmerline profiles are detected for both objects. Modelling of the Balmerline profiles of AS 78 obtained in 1994 yields the following parametersof the star and its wind: Teff ~ 17 000 K, logLbol/Lsun ~ 4.0, dot M ~ 10-6Msun yr-1. The photometric and new spectroscopicdata indicate that the star's Teff increases with time, whilethe stellar wind changes its structure. Distances towards both objectsare estimated on the basis of their radial velocities and the galacticrotation curve. Consideration of different options about the nature andevolutionary state of both objects leads us to suggest that they arebinary systems containing a B-type intermediate-luminosity star and agaseous disk around the less luminous component. Table 9 is onlyavailable in electronic form at the CDS via anonymous ftp (130.79.128.5)or via 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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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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Catalogue of proper motions in the declination of stars of the Moscow zenith zone.
Not Available
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The Catalogue of the Right-Ascension of 200 Stars Observed with the Moscow PZT during 1973.8 to 1981.0
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 Catalogue of Declinations and Proper-Motions of Moscow PZT Stars
Not Available
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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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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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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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Wavelength dependence of polarization. XXV. Rotation of the position angle by the interstellar medium.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..565C&db_key=AST
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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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Catalogue d'etoiles O et B.
Not Available
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Photoelectric 4430 A observations of 506 O, B and A stars.
Not Available
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Radial Velocities of Distant OB Stars in the Anticenter Region of the Galaxy
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1965ApJ...142..934R&db_key=AST
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Photoelectric measures of the 4430 A diffuse interstellar band
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963MNRAS.125..141W&db_key=AST
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Interstellar Absorption Lines in Distant Stars. I. Northern Milky way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1957ApJ...125...42M&db_key=AST
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Stellar Spectra in Milky way Regions.VI. a Region in Camelopardalis.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956ApJS....2..298M&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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INHABITED SKY
