On the diffuse bands related to the C2 interstellar molecule
The recently published idea that intensities of some weak diffuseinterstellar bands (DIBs) are related to the C2 molecule column densityhave been examined. We use a set of high quality echelle spectra ofheavily reddened stars, acquired at the Bohyunsan Optical AstronomicalObservatory (South Korea), with a resolution R=30 000. The high quality(high S/N ratio) of our spectra is proved by the fact that despite usingthe most widely used Phillips (2, 0) band of the C2 molecule (near 8760Å), we can trace the (3, 0) Phillips band (near 7725 Å) aswell. Equivalent widths of four (5176, 5542, 5546 and 5769 Å) outof 16 examined DIBs demonstrate relatively good correlation with C2column density. However, a majority of the studied DIBs, alreadyreported as "C2" ones, most likely are not related to this simplestcarbon molecule. A removal of peculiar objects like HD 34078 from theanalyzed sample does not substantially change the level of correlations.
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Interstellar Ca II Line Intensities and the Distances of the OB stars
We show that the equivalent widths of the well-known interstellar Ca IIH and K lines can be used to determine the distances to OB stars in ourGalaxy. The equivalent widths, measured in the spectra of 147 early-typestars, are strongly related to the Hipparcos parallaxes of thoseobjects. The lines fitted to the parallax-equivalent width data aregiven by the formulae π=1/[2.78EW(K)+95] and π=1/[4.58EW(H)+102],where π is in arcseconds and EW is in milliangstroms. The form of theformulae, yielding a finite parallax even for zero absorption, showsthat space within ~100 pc of the Sun contains very little Ca II, whichis in agreement with the known dimensions of the Local Bubble. Using CaII lines for distance determination does not require the knowledge ofthe absolute magnitude of the object; it is thus well suited for targetsfor which the absolute calibration is either not precise (OBsupergiants) or not available at all (peculiar objects). We alsodemonstrate that neither the reddening E(B-V) nor the equivalent widthsof interstellar K I and CH lines are suitable candidates for distanceestimation, their relation with parallaxes being far less tight than forCa II.
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Profiles of Very Weak Diffuse Interstellar Bands around 6440 Å
Profiles of very weak diffuse interstellar bands (DIBs) between 6400 and6470 Å observed with high resolution and very high S/N aredemonstrated. We show that with the increasing quality of reddenedstellar spectra, the whole spectral range is covered with weak or veryweak DIBs-at least one every 2-3 Å. We also present the details ofthe profiles of a few stronger features; the presence of substructuresresembles the profiles of strong DIBs observed in high resolution duringthe last decade and supports the hypothesis of a molecular origin of atleast a majority of DIBs.
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Correlations between diffuse interstellar bands and atomic lines
We present and discuss correlations between strengths of the well-known,strong interstellar atomic lines of KI and CaII, and four selected,strong unidentified diffuse interstellar bands (DIBs): 5780, 5797, 5850and 6614. In order to analyse a homogeneous sample of echellehigh-resolution spectra it has been chosen to use measurements fromTerskol Observatory in Northern Caucasus plus a selected number ofhigher resolution observations performed using other instruments. Wedemonstrate that the strength of certain DIBs correlate well withneutral potassium lines and to a much lower degree with ionized calciumlines. This fact suggests that the degree of irradiation of a cloud withUV photons, capable to ionize interstellar atoms, plays a crucial rolein the formation/maintenance of certain molecular species: possiblecarriers of DIBs.
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Grey extinction in the solar neighbourhood?
Some of the close O and B dwarfs appear to be fainter than indicated bytheir Hipparcos distances, intrinsic absolute magnitudes attributed totheir spectral types, and estimated selective interstellar extinction.This discrepancy is explained in the paper by the grey (neutral)interstellar extinction in the visual range of spectrum. The measure ofsuch an effect is related to discrete features of the interstellarmatter.
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Optical Brightness Variability of LSI+61o303: Improving the Photometric Period
The UBV observations of the variable radio source LSI+61o303carried out at the Crimean Station of the Sternberg AstronomicalInstitute in 1989-1990 and 1999-2002 are presented. We constructed acombined light curve of the star spanning 6400 days from our andpublished data. Slow brightness variability with an amplitude of 0.1mag was detected. Using the entire combined series, we searched for aperiodicity in a frequency range close to the radio period P = 26.5days. The optical period was found to be exactly equal to the radioperiod. The shape and amplitude of the mean curves constructed with theradio period change from V to U: the detected double wave shows up mostclearly in the U band.
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New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
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The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
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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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Equivalent width of NA I and K I lines and reddening.
The profile, radial velocity and equivalent width of the interstellarlines of Na I (5890.0, 5895.9Å) and K I (7699.0Å) have beenobtained from Echelle+CCD observations at resolving powerλ/{DELTA}λ~16,500 for 32 O and early B stars sufferingfrom a reddening between E_B-V_=0.06 and 1.57. The data have been usedto search for and calibrate a relation between equivalent width andreddening. When the interstellar lines show a single and sharpcomponent, useful relations to estimate reddening from equivalent widthshave been derived. The relation for Na I is most sensitive in the range0.0<=E_B-V_<=0.4, and the one for K I takes over at higherreddening. Good quality equivalent width measurements allow E_B-V_ to beestimated with an accuracy of about 0.05 mag. For multi-componentprofiles of Na I and K I lines the estimate of reddening is moreambiguous with a general scatter of 0.15mag. Close blends of multiplecomponents allow only an estimate of an upper limit to E_B-V_.
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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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Intrinsic colour indices of O- and B- type stars in the Vilnius photometric system.
Not Available
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Stellar spectrophotometric standards. II
Not Available
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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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Groups of stars with common motion in the Galaxy. Groups of O and B stars
Not Available
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Photoelectric photometry of OB stars in the Vilnius system
Not Available
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Distribution and motions of OB stars in the direction of H and KHI Perseus.
Not Available
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Search for the light-curve variability of the source LSI + 61 deg 303, a star with regular radio bursts
A search for the light-curve variability of LSI + 61 deg 303, a radioburster with a period of 26.52d, was carried out. During the 35dobservational cycle, the light-variation amplitude reached a value ofabout 0.1m in W,B,V,R. Sharp declines with subsequent return to the meanlevel on a time scale of 10-15 min were observed. The position of thesource on the (W-B, B-V) color-color diagram corresponds to a B0e starwith an E(B-V) color excess of 1.07m.
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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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Catalog of BV magnitudes and spectral classes of 6000 stars
The present catalog, compiled at the Abastumani Observatory, contains BVmagnitudes and spectral classes of about 6000 stars up to V(lim) = 13.0min five circular areas of 18 sq deg located near the salactic-equatorplane. The catalog is intended for star-statistics studies ofstar-formation regions.
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Meridian observations made with the Carlsberg Automatic Meridian Circle at Brorfelde (Copenhagen University Observatory) 1981-1982
The 7-inch transit circle instrument with which the present position andmagnitude catalog for 1577 stars with visual magnitudes greater than11.0 was obtained had been equipped with a photoelectric moving slitmicrometer and a minicomputer to control the entire observationalprocess. Positions are reduced relative to the FK4 system for each nightover the whole meridian rather than the usual narrow zones. Thepositions of the FK4 stars used in the least squares solution are alsogiven in the catalog.
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A search for ring nebulae around Of stars
The Palomar Sky Survey prints have been used in a search for ringnebulae produced by the stellar wind, which involved the examination ofthe fields around 72 types of Of stars. It is found that for about halfof these stars, such ring nebulae as might exist would probably beunobservable because of the heavy absorption of bright H-alphabackground emission. Nevertheless, the H II regions surrounding 14 ofthe Of stars are found to exhibit ringlike structure.
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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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The high-luminosity boundary of the beta CEP instability strip.
Abstract image available at:http://adsabs.harvard.edu/abs/1972AJ.....77..381P
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A Comparison of the Luminosities of Perseus-Arm Stars in the Hγ and MK Systems
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972ApJ...171..285C&db_key=AST
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M Supergiants in the Perseus Arm
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJ...160.1149H&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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Optical and Radio Evidence of Large-Scale Peculiar Motions in the Cassiopeiaperseus Arm
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968ApJ...152.1019R&db_key=AST
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Catalogue d'etoiles O et B.
Not Available
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INHABITED SKY
